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1b1d2e6d BP |
1 | /* |
2 | * Copyright (c) 2017, 2018 Nicira, Inc. | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at: | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | ||
17 | #include <config.h> | |
18 | ||
19 | #include "raft.h" | |
20 | #include "raft-private.h" | |
21 | ||
22 | #include <errno.h> | |
23 | #include <unistd.h> | |
24 | ||
25 | #include "hash.h" | |
26 | #include "jsonrpc.h" | |
27 | #include "lockfile.h" | |
28 | #include "openvswitch/dynamic-string.h" | |
29 | #include "openvswitch/hmap.h" | |
30 | #include "openvswitch/json.h" | |
31 | #include "openvswitch/list.h" | |
32 | #include "openvswitch/poll-loop.h" | |
33 | #include "openvswitch/vlog.h" | |
34 | #include "ovsdb-error.h" | |
35 | #include "ovsdb-parser.h" | |
36 | #include "ovsdb/log.h" | |
37 | #include "raft-rpc.h" | |
38 | #include "random.h" | |
39 | #include "socket-util.h" | |
40 | #include "stream.h" | |
41 | #include "timeval.h" | |
42 | #include "unicode.h" | |
43 | #include "unixctl.h" | |
44 | #include "util.h" | |
45 | #include "uuid.h" | |
46 | ||
47 | VLOG_DEFINE_THIS_MODULE(raft); | |
48 | ||
49 | /* Roles for a Raft server: | |
50 | * | |
51 | * - Followers: Servers in touch with the current leader. | |
52 | * | |
53 | * - Candidate: Servers unaware of a current leader and seeking election to | |
54 | * leader. | |
55 | * | |
56 | * - Leader: Handles all client requests. At most one at a time. | |
57 | * | |
58 | * In normal operation there is exactly one leader and all of the other servers | |
59 | * are followers. */ | |
60 | enum raft_role { | |
61 | RAFT_FOLLOWER, | |
62 | RAFT_CANDIDATE, | |
63 | RAFT_LEADER | |
64 | }; | |
65 | ||
67dba070 HZ |
66 | /* Flags for unit tests. */ |
67 | enum raft_failure_test { | |
68 | FT_NO_TEST, | |
69 | FT_CRASH_BEFORE_SEND_APPEND_REQ, | |
70 | FT_CRASH_AFTER_SEND_APPEND_REQ, | |
71 | FT_CRASH_BEFORE_SEND_EXEC_REP, | |
72 | FT_CRASH_AFTER_SEND_EXEC_REP, | |
73 | FT_CRASH_BEFORE_SEND_EXEC_REQ, | |
74 | FT_CRASH_AFTER_SEND_EXEC_REQ, | |
75 | FT_CRASH_AFTER_RECV_APPEND_REQ_UPDATE, | |
76 | FT_DELAY_ELECTION | |
77 | }; | |
78 | static enum raft_failure_test failure_test; | |
79 | ||
1b1d2e6d BP |
80 | /* A connection between this Raft server and another one. */ |
81 | struct raft_conn { | |
82 | struct ovs_list list_node; /* In struct raft's 'conns' list. */ | |
83 | struct jsonrpc_session *js; /* JSON-RPC connection. */ | |
84 | struct uuid sid; /* This server's unique ID. */ | |
85 | char *nickname; /* Short name for use in log messages. */ | |
86 | bool incoming; /* True if incoming, false if outgoing. */ | |
87 | unsigned int js_seqno; /* Seqno for noticing (re)connections. */ | |
88 | }; | |
89 | ||
90 | static void raft_conn_close(struct raft_conn *); | |
91 | ||
92 | /* A "command", that is, a request to append an entry to the log. | |
93 | * | |
94 | * The Raft specification only allows clients to issue commands to the leader. | |
95 | * With this implementation, clients may issue a command on any server, which | |
96 | * then relays the command to the leader if necessary. | |
97 | * | |
98 | * This structure is thus used in three cases: | |
99 | * | |
100 | * 1. We are the leader and the command was issued to us directly. | |
101 | * | |
102 | * 2. We are a follower and relayed the command to the leader. | |
103 | * | |
104 | * 3. We are the leader and a follower relayed the command to us. | |
105 | */ | |
106 | struct raft_command { | |
107 | /* All cases. */ | |
108 | struct hmap_node hmap_node; /* In struct raft's 'commands' hmap. */ | |
109 | unsigned int n_refs; /* Reference count. */ | |
110 | enum raft_command_status status; /* Execution status. */ | |
7ef36089 | 111 | struct uuid eid; /* Entry ID of result. */ |
1b1d2e6d BP |
112 | |
113 | /* Case 1 only. */ | |
114 | uint64_t index; /* Index in log (0 if being relayed). */ | |
115 | ||
1b1d2e6d BP |
116 | /* Case 2 only. */ |
117 | long long int timestamp; /* Issue or last ping time, for expiration. */ | |
118 | ||
119 | /* Case 3 only. */ | |
120 | struct uuid sid; /* The follower (otherwise UUID_ZERO). */ | |
121 | }; | |
122 | ||
123 | static void raft_command_complete(struct raft *, struct raft_command *, | |
124 | enum raft_command_status); | |
125 | ||
126 | static void raft_complete_all_commands(struct raft *, | |
127 | enum raft_command_status); | |
128 | ||
129 | /* Type of deferred action, see struct raft_waiter. */ | |
130 | enum raft_waiter_type { | |
131 | RAFT_W_ENTRY, | |
132 | RAFT_W_TERM, | |
133 | RAFT_W_RPC, | |
134 | }; | |
135 | ||
136 | /* An action deferred until a log write commits to disk. */ | |
137 | struct raft_waiter { | |
138 | struct ovs_list list_node; | |
139 | uint64_t commit_ticket; | |
140 | ||
141 | enum raft_waiter_type type; | |
142 | union { | |
143 | /* RAFT_W_ENTRY. | |
144 | * | |
145 | * Waits for a RAFT_REC_ENTRY write to our local log to commit. Upon | |
146 | * completion, updates 'log_synced' to indicate that the new log entry | |
147 | * or entries are committed and, if we are leader, also updates our | |
148 | * local 'match_index'. */ | |
149 | struct { | |
150 | uint64_t index; | |
151 | } entry; | |
152 | ||
153 | /* RAFT_W_TERM. | |
154 | * | |
155 | * Waits for a RAFT_REC_TERM or RAFT_REC_VOTE record write to commit. | |
156 | * Upon completion, updates 'synced_term' and 'synced_vote', which | |
157 | * triggers sending RPCs deferred by the uncommitted 'term' and | |
158 | * 'vote'. */ | |
159 | struct { | |
160 | uint64_t term; | |
161 | struct uuid vote; | |
162 | } term; | |
163 | ||
164 | /* RAFT_W_RPC. | |
165 | * | |
166 | * Sometimes, sending an RPC to a peer must be delayed until an entry, | |
167 | * a term, or a vote mentioned in the RPC is synced to disk. This | |
168 | * waiter keeps a copy of such an RPC until the previous waiters have | |
169 | * committed. */ | |
170 | union raft_rpc *rpc; | |
171 | }; | |
172 | }; | |
173 | ||
174 | static struct raft_waiter *raft_waiter_create(struct raft *, | |
175 | enum raft_waiter_type, | |
176 | bool start_commit); | |
177 | static void raft_waiters_destroy(struct raft *); | |
178 | ||
179 | /* The Raft state machine. */ | |
180 | struct raft { | |
181 | struct hmap_node hmap_node; /* In 'all_rafts'. */ | |
182 | struct ovsdb_log *log; | |
183 | ||
184 | /* Persistent derived state. | |
185 | * | |
186 | * This must be updated on stable storage before responding to RPCs. It can be | |
187 | * derived from the header, snapshot, and log in 'log'. */ | |
188 | ||
189 | struct uuid cid; /* Cluster ID (immutable for the cluster). */ | |
190 | struct uuid sid; /* Server ID (immutable for the server). */ | |
191 | char *local_address; /* Local address (immutable for the server). */ | |
192 | char *local_nickname; /* Used for local server in log messages. */ | |
193 | char *name; /* Schema name (immutable for the cluster). */ | |
194 | ||
195 | /* Contains "struct raft_server"s and represents the server configuration | |
196 | * most recently added to 'log'. */ | |
197 | struct hmap servers; | |
198 | ||
8e354614 HZ |
199 | #define ELECTION_BASE_MSEC 1000 |
200 | #define ELECTION_RANGE_MSEC 1000 | |
201 | /* The election timeout base value for leader election, in milliseconds. | |
202 | * It can be set by unixctl cluster/change-election-timer. Default value is | |
203 | * ELECTION_BASE_MSEC. */ | |
204 | uint64_t election_timer; | |
205 | /* If not 0, it is the new value of election_timer being proposed. */ | |
206 | uint64_t election_timer_new; | |
207 | ||
1b1d2e6d BP |
208 | /* Persistent state on all servers. |
209 | * | |
210 | * Must be updated on stable storage before responding to RPCs. */ | |
211 | ||
212 | /* Current term and the vote for that term. These might be on the way to | |
213 | * disk now. */ | |
214 | uint64_t term; /* Initialized to 0 and only increases. */ | |
215 | struct uuid vote; /* All-zeros if no vote yet in 'term'. */ | |
216 | ||
217 | /* The term and vote that have been synced to disk. */ | |
218 | uint64_t synced_term; | |
219 | struct uuid synced_vote; | |
220 | ||
221 | /* The log. | |
222 | * | |
223 | * A log entry with index 1 never really exists; the initial snapshot for a | |
224 | * Raft is considered to include this index. The first real log entry has | |
225 | * index 2. | |
226 | * | |
227 | * A new Raft instance contains an empty log: log_start=2, log_end=2. | |
228 | * Over time, the log grows: log_start=2, log_end=N. | |
229 | * At some point, the server takes a snapshot: log_start=N, log_end=N. | |
230 | * The log continues to grow: log_start=N, log_end=N+1... | |
231 | * | |
232 | * Must be updated on stable storage before responding to RPCs. */ | |
233 | struct raft_entry *entries; /* Log entry i is in log[i - log_start]. */ | |
234 | uint64_t log_start; /* Index of first entry in log. */ | |
235 | uint64_t log_end; /* Index of last entry in log, plus 1. */ | |
236 | uint64_t log_synced; /* Index of last synced entry. */ | |
237 | size_t allocated_log; /* Allocated entries in 'log'. */ | |
238 | ||
239 | /* Snapshot state (see Figure 5.1) | |
240 | * | |
241 | * This is the state of the cluster as of the last discarded log entry, | |
242 | * that is, at log index 'log_start - 1' (called prevIndex in Figure 5.1). | |
243 | * Only committed log entries can be included in a snapshot. */ | |
244 | struct raft_entry snap; | |
245 | ||
246 | /* Volatile state. | |
247 | * | |
248 | * The snapshot is always committed, but the rest of the log might not be yet. | |
249 | * 'last_applied' tracks what entries have been passed to the client. If the | |
250 | * client hasn't yet read the latest snapshot, then even the snapshot isn't | |
251 | * applied yet. Thus, the invariants are different for these members: | |
252 | * | |
253 | * log_start - 2 <= last_applied <= commit_index < log_end. | |
254 | * log_start - 1 <= commit_index < log_end. | |
255 | */ | |
256 | ||
257 | enum raft_role role; /* Current role. */ | |
258 | uint64_t commit_index; /* Max log index known to be committed. */ | |
259 | uint64_t last_applied; /* Max log index applied to state machine. */ | |
260 | struct uuid leader_sid; /* Server ID of leader (zero, if unknown). */ | |
261 | ||
1b1d2e6d BP |
262 | long long int election_base; /* Time of last heartbeat from leader. */ |
263 | long long int election_timeout; /* Time at which we start an election. */ | |
264 | ||
265 | /* Used for joining a cluster. */ | |
266 | bool joining; /* Attempting to join the cluster? */ | |
267 | struct sset remote_addresses; /* Addresses to try to find other servers. */ | |
268 | long long int join_timeout; /* Time to re-send add server request. */ | |
269 | ||
270 | /* Used for leaving a cluster. */ | |
271 | bool leaving; /* True if we are leaving the cluster. */ | |
272 | bool left; /* True if we have finished leaving. */ | |
273 | long long int leave_timeout; /* Time to re-send remove server request. */ | |
274 | ||
275 | /* Failure. */ | |
276 | bool failed; /* True if unrecoverable error has occurred. */ | |
277 | ||
278 | /* File synchronization. */ | |
279 | struct ovs_list waiters; /* Contains "struct raft_waiter"s. */ | |
280 | ||
281 | /* Network connections. */ | |
282 | struct pstream *listener; /* For connections from other Raft servers. */ | |
283 | long long int listen_backoff; /* For retrying creating 'listener'. */ | |
284 | struct ovs_list conns; /* Contains struct raft_conns. */ | |
285 | ||
286 | /* Leaders only. Reinitialized after becoming leader. */ | |
287 | struct hmap add_servers; /* Contains "struct raft_server"s to add. */ | |
288 | struct raft_server *remove_server; /* Server being removed. */ | |
289 | struct hmap commands; /* Contains "struct raft_command"s. */ | |
1b1d2e6d BP |
290 | long long int ping_timeout; /* Time at which to send a heartbeat */ |
291 | ||
292 | /* Candidates only. Reinitialized at start of election. */ | |
293 | int n_votes; /* Number of votes for me. */ | |
923f01ca HZ |
294 | |
295 | /* Followers and candidates only. */ | |
296 | bool candidate_retrying; /* The earlier election timed-out and we are | |
297 | now retrying. */ | |
298 | bool had_leader; /* There has been leader elected since last | |
299 | election initiated. This is to help setting | |
300 | candidate_retrying. */ | |
1b1d2e6d BP |
301 | }; |
302 | ||
303 | /* All Raft structures. */ | |
304 | static struct hmap all_rafts = HMAP_INITIALIZER(&all_rafts); | |
305 | ||
306 | static void raft_init(void); | |
307 | ||
308 | static struct ovsdb_error *raft_read_header(struct raft *) | |
309 | OVS_WARN_UNUSED_RESULT; | |
310 | ||
311 | static void raft_send_execute_command_reply(struct raft *, | |
312 | const struct uuid *sid, | |
313 | const struct uuid *eid, | |
314 | enum raft_command_status, | |
315 | uint64_t commit_index); | |
316 | ||
317 | static void raft_update_our_match_index(struct raft *, uint64_t min_index); | |
318 | ||
319 | static void raft_send_remove_server_reply__( | |
320 | struct raft *, const struct uuid *target_sid, | |
321 | const struct uuid *requester_sid, struct unixctl_conn *requester_conn, | |
322 | bool success, const char *comment); | |
17bd4149 | 323 | static void raft_finished_leaving_cluster(struct raft *); |
1b1d2e6d BP |
324 | |
325 | static void raft_server_init_leader(struct raft *, struct raft_server *); | |
326 | ||
327 | static bool raft_rpc_is_heartbeat(const union raft_rpc *); | |
328 | static bool raft_is_rpc_synced(const struct raft *, const union raft_rpc *); | |
329 | ||
330 | static void raft_handle_rpc(struct raft *, const union raft_rpc *); | |
17bd4149 | 331 | |
02acb41a BP |
332 | static bool raft_send_at(struct raft *, const union raft_rpc *, |
333 | int line_number); | |
334 | #define raft_send(raft, rpc) raft_send_at(raft, rpc, __LINE__) | |
335 | ||
336 | static bool raft_send_to_conn_at(struct raft *, const union raft_rpc *, | |
337 | struct raft_conn *, int line_number); | |
338 | #define raft_send_to_conn(raft, rpc, conn) \ | |
339 | raft_send_to_conn_at(raft, rpc, conn, __LINE__) | |
340 | ||
1b1d2e6d BP |
341 | static void raft_send_append_request(struct raft *, |
342 | struct raft_server *, unsigned int n, | |
343 | const char *comment); | |
344 | ||
345 | static void raft_become_leader(struct raft *); | |
346 | static void raft_become_follower(struct raft *); | |
0f954f32 HZ |
347 | static void raft_reset_election_timer(struct raft *); |
348 | static void raft_reset_ping_timer(struct raft *); | |
1b1d2e6d BP |
349 | static void raft_send_heartbeats(struct raft *); |
350 | static void raft_start_election(struct raft *, bool leadership_transfer); | |
351 | static bool raft_truncate(struct raft *, uint64_t new_end); | |
352 | static void raft_get_servers_from_log(struct raft *, enum vlog_level); | |
8e354614 | 353 | static void raft_get_election_timer_from_log(struct raft *); |
1b1d2e6d BP |
354 | |
355 | static bool raft_handle_write_error(struct raft *, struct ovsdb_error *); | |
356 | ||
357 | static void raft_run_reconfigure(struct raft *); | |
358 | ||
923f01ca | 359 | static void raft_set_leader(struct raft *, const struct uuid *sid); |
1b1d2e6d BP |
360 | static struct raft_server * |
361 | raft_find_server(const struct raft *raft, const struct uuid *sid) | |
362 | { | |
363 | return raft_server_find(&raft->servers, sid); | |
364 | } | |
365 | ||
366 | static char * | |
367 | raft_make_address_passive(const char *address_) | |
368 | { | |
369 | if (!strncmp(address_, "unix:", 5)) { | |
370 | return xasprintf("p%s", address_); | |
371 | } else { | |
372 | char *address = xstrdup(address_); | |
0b043300 BP |
373 | char *host, *port; |
374 | inet_parse_host_port_tokens(strchr(address, ':') + 1, &host, &port); | |
1b1d2e6d BP |
375 | |
376 | struct ds paddr = DS_EMPTY_INITIALIZER; | |
377 | ds_put_format(&paddr, "p%.3s:%s:", address, port); | |
378 | if (strchr(host, ':')) { | |
379 | ds_put_format(&paddr, "[%s]", host); | |
380 | } else { | |
381 | ds_put_cstr(&paddr, host); | |
382 | } | |
383 | free(address); | |
384 | return ds_steal_cstr(&paddr); | |
385 | } | |
386 | } | |
387 | ||
388 | static struct raft * | |
389 | raft_alloc(void) | |
390 | { | |
391 | raft_init(); | |
392 | ||
393 | struct raft *raft = xzalloc(sizeof *raft); | |
394 | hmap_node_nullify(&raft->hmap_node); | |
395 | hmap_init(&raft->servers); | |
396 | raft->log_start = raft->log_end = 1; | |
397 | raft->role = RAFT_FOLLOWER; | |
398 | sset_init(&raft->remote_addresses); | |
399 | raft->join_timeout = LLONG_MAX; | |
400 | ovs_list_init(&raft->waiters); | |
401 | raft->listen_backoff = LLONG_MIN; | |
402 | ovs_list_init(&raft->conns); | |
403 | hmap_init(&raft->add_servers); | |
404 | hmap_init(&raft->commands); | |
405 | ||
8e354614 | 406 | raft->election_timer = ELECTION_BASE_MSEC; |
1b1d2e6d BP |
407 | |
408 | return raft; | |
409 | } | |
410 | ||
411 | /* Creates an on-disk file that represents a new Raft cluster and initializes | |
412 | * it to consist of a single server, the one on which this function is called. | |
413 | * | |
414 | * Creates the local copy of the cluster's log in 'file_name', which must not | |
415 | * already exist. Gives it the name 'name', which should be the database | |
416 | * schema name and which is used only to match up this database with the server | |
417 | * added to the cluster later if the cluster ID is unavailable. | |
418 | * | |
419 | * The new server is located at 'local_address', which must take one of the | |
420 | * forms "tcp:IP:PORT" or "ssl:IP:PORT", where IP is an IPv4 address or a | |
421 | * square bracket enclosed IPv6 address and PORT is a TCP port number. | |
422 | * | |
423 | * This only creates the on-disk file. Use raft_open() to start operating the | |
424 | * new server. | |
425 | * | |
426 | * Returns null if successful, otherwise an ovsdb_error describing the | |
427 | * problem. */ | |
428 | struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
429 | raft_create_cluster(const char *file_name, const char *name, | |
430 | const char *local_address, const struct json *data) | |
431 | { | |
432 | /* Parse and verify validity of the local address. */ | |
433 | struct ovsdb_error *error = raft_address_validate(local_address); | |
434 | if (error) { | |
435 | return error; | |
436 | } | |
437 | ||
438 | /* Create log file. */ | |
439 | struct ovsdb_log *log; | |
440 | error = ovsdb_log_open(file_name, RAFT_MAGIC, OVSDB_LOG_CREATE_EXCL, | |
441 | -1, &log); | |
442 | if (error) { | |
443 | return error; | |
444 | } | |
445 | ||
446 | /* Write log file. */ | |
447 | struct raft_header h = { | |
448 | .sid = uuid_random(), | |
449 | .cid = uuid_random(), | |
450 | .name = xstrdup(name), | |
451 | .local_address = xstrdup(local_address), | |
452 | .joining = false, | |
453 | .remote_addresses = SSET_INITIALIZER(&h.remote_addresses), | |
454 | .snap_index = 1, | |
455 | .snap = { | |
456 | .term = 1, | |
457 | .data = json_nullable_clone(data), | |
458 | .eid = uuid_random(), | |
459 | .servers = json_object_create(), | |
460 | }, | |
461 | }; | |
462 | shash_add_nocopy(json_object(h.snap.servers), | |
463 | xasprintf(UUID_FMT, UUID_ARGS(&h.sid)), | |
464 | json_string_create(local_address)); | |
465 | error = ovsdb_log_write_and_free(log, raft_header_to_json(&h)); | |
466 | raft_header_uninit(&h); | |
467 | if (!error) { | |
468 | error = ovsdb_log_commit_block(log); | |
469 | } | |
470 | ovsdb_log_close(log); | |
471 | ||
472 | return error; | |
473 | } | |
474 | ||
475 | /* Creates a database file that represents a new server in an existing Raft | |
476 | * cluster. | |
477 | * | |
478 | * Creates the local copy of the cluster's log in 'file_name', which must not | |
479 | * already exist. Gives it the name 'name', which must be the same name | |
480 | * passed in to raft_create_cluster() earlier. | |
481 | * | |
482 | * 'cid' is optional. If specified, the new server will join only the cluster | |
483 | * with the given cluster ID. | |
484 | * | |
485 | * The new server is located at 'local_address', which must take one of the | |
486 | * forms "tcp:IP:PORT" or "ssl:IP:PORT", where IP is an IPv4 address or a | |
487 | * square bracket enclosed IPv6 address and PORT is a TCP port number. | |
488 | * | |
489 | * Joining the cluster requires contacting it. Thus, 'remote_addresses' | |
490 | * specifies the addresses of existing servers in the cluster. One server out | |
491 | * of the existing cluster is sufficient, as long as that server is reachable | |
492 | * and not partitioned from the current cluster leader. If multiple servers | |
493 | * from the cluster are specified, then it is sufficient for any of them to | |
494 | * meet this criterion. | |
495 | * | |
496 | * This only creates the on-disk file and does no network access. Use | |
497 | * raft_open() to start operating the new server. (Until this happens, the | |
498 | * new server has not joined the cluster.) | |
499 | * | |
500 | * Returns null if successful, otherwise an ovsdb_error describing the | |
501 | * problem. */ | |
502 | struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
503 | raft_join_cluster(const char *file_name, | |
504 | const char *name, const char *local_address, | |
505 | const struct sset *remote_addresses, | |
506 | const struct uuid *cid) | |
507 | { | |
508 | ovs_assert(!sset_is_empty(remote_addresses)); | |
509 | ||
510 | /* Parse and verify validity of the addresses. */ | |
511 | struct ovsdb_error *error = raft_address_validate(local_address); | |
512 | if (error) { | |
513 | return error; | |
514 | } | |
515 | const char *addr; | |
516 | SSET_FOR_EACH (addr, remote_addresses) { | |
517 | error = raft_address_validate(addr); | |
518 | if (error) { | |
519 | return error; | |
520 | } | |
521 | if (!strcmp(addr, local_address)) { | |
522 | return ovsdb_error(NULL, "remote addresses cannot be the same " | |
523 | "as the local address"); | |
524 | } | |
525 | } | |
526 | ||
527 | /* Verify validity of the cluster ID (if provided). */ | |
528 | if (cid && uuid_is_zero(cid)) { | |
529 | return ovsdb_error(NULL, "all-zero UUID is not valid cluster ID"); | |
530 | } | |
531 | ||
532 | /* Create log file. */ | |
533 | struct ovsdb_log *log; | |
534 | error = ovsdb_log_open(file_name, RAFT_MAGIC, OVSDB_LOG_CREATE_EXCL, | |
535 | -1, &log); | |
536 | if (error) { | |
537 | return error; | |
538 | } | |
539 | ||
540 | /* Write log file. */ | |
541 | struct raft_header h = { | |
542 | .sid = uuid_random(), | |
543 | .cid = cid ? *cid : UUID_ZERO, | |
544 | .name = xstrdup(name), | |
545 | .local_address = xstrdup(local_address), | |
546 | .joining = true, | |
547 | /* No snapshot yet. */ | |
548 | }; | |
549 | sset_clone(&h.remote_addresses, remote_addresses); | |
550 | error = ovsdb_log_write_and_free(log, raft_header_to_json(&h)); | |
551 | raft_header_uninit(&h); | |
552 | if (!error) { | |
553 | error = ovsdb_log_commit_block(log); | |
554 | } | |
555 | ovsdb_log_close(log); | |
556 | ||
557 | return error; | |
558 | } | |
559 | ||
560 | /* Reads the initial header record from 'log', which must be a Raft clustered | |
561 | * database log, and populates '*md' with the information read from it. The | |
562 | * caller must eventually destroy 'md' with raft_metadata_destroy(). | |
563 | * | |
564 | * On success, returns NULL. On failure, returns an error that the caller must | |
565 | * eventually destroy and zeros '*md'. */ | |
566 | struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
567 | raft_read_metadata(struct ovsdb_log *log, struct raft_metadata *md) | |
568 | { | |
569 | struct raft *raft = raft_alloc(); | |
570 | raft->log = log; | |
571 | ||
572 | struct ovsdb_error *error = raft_read_header(raft); | |
573 | if (!error) { | |
574 | md->sid = raft->sid; | |
575 | md->name = xstrdup(raft->name); | |
576 | md->local = xstrdup(raft->local_address); | |
577 | md->cid = raft->cid; | |
578 | } else { | |
579 | memset(md, 0, sizeof *md); | |
580 | } | |
581 | ||
582 | raft->log = NULL; | |
583 | raft_close(raft); | |
584 | return error; | |
585 | } | |
586 | ||
587 | /* Frees the metadata in 'md'. */ | |
588 | void | |
589 | raft_metadata_destroy(struct raft_metadata *md) | |
590 | { | |
591 | if (md) { | |
592 | free(md->name); | |
593 | free(md->local); | |
594 | } | |
595 | } | |
596 | ||
597 | static const struct raft_entry * | |
598 | raft_get_entry(const struct raft *raft, uint64_t index) | |
599 | { | |
600 | ovs_assert(index >= raft->log_start); | |
601 | ovs_assert(index < raft->log_end); | |
602 | return &raft->entries[index - raft->log_start]; | |
603 | } | |
604 | ||
605 | static uint64_t | |
606 | raft_get_term(const struct raft *raft, uint64_t index) | |
607 | { | |
608 | return (index == raft->log_start - 1 | |
609 | ? raft->snap.term | |
610 | : raft_get_entry(raft, index)->term); | |
611 | } | |
612 | ||
613 | static const struct json * | |
614 | raft_servers_for_index(const struct raft *raft, uint64_t index) | |
615 | { | |
616 | ovs_assert(index >= raft->log_start - 1); | |
617 | ovs_assert(index < raft->log_end); | |
618 | ||
619 | const struct json *servers = raft->snap.servers; | |
620 | for (uint64_t i = raft->log_start; i <= index; i++) { | |
621 | const struct raft_entry *e = raft_get_entry(raft, i); | |
622 | if (e->servers) { | |
623 | servers = e->servers; | |
624 | } | |
625 | } | |
626 | return servers; | |
627 | } | |
628 | ||
629 | static void | |
630 | raft_set_servers(struct raft *raft, const struct hmap *new_servers, | |
631 | enum vlog_level level) | |
632 | { | |
633 | struct raft_server *s, *next; | |
634 | HMAP_FOR_EACH_SAFE (s, next, hmap_node, &raft->servers) { | |
635 | if (!raft_server_find(new_servers, &s->sid)) { | |
636 | ovs_assert(s != raft->remove_server); | |
637 | ||
638 | hmap_remove(&raft->servers, &s->hmap_node); | |
639 | VLOG(level, "server %s removed from configuration", s->nickname); | |
640 | raft_server_destroy(s); | |
641 | } | |
642 | } | |
643 | ||
644 | HMAP_FOR_EACH_SAFE (s, next, hmap_node, new_servers) { | |
645 | if (!raft_find_server(raft, &s->sid)) { | |
646 | VLOG(level, "server %s added to configuration", s->nickname); | |
647 | ||
648 | struct raft_server *new | |
649 | = raft_server_add(&raft->servers, &s->sid, s->address); | |
650 | raft_server_init_leader(raft, new); | |
651 | } | |
652 | } | |
653 | } | |
654 | ||
655 | static uint64_t | |
656 | raft_add_entry(struct raft *raft, | |
657 | uint64_t term, struct json *data, const struct uuid *eid, | |
8e354614 | 658 | struct json *servers, uint64_t election_timer) |
1b1d2e6d BP |
659 | { |
660 | if (raft->log_end - raft->log_start >= raft->allocated_log) { | |
661 | raft->entries = x2nrealloc(raft->entries, &raft->allocated_log, | |
662 | sizeof *raft->entries); | |
663 | } | |
664 | ||
665 | uint64_t index = raft->log_end++; | |
666 | struct raft_entry *entry = &raft->entries[index - raft->log_start]; | |
667 | entry->term = term; | |
668 | entry->data = data; | |
669 | entry->eid = eid ? *eid : UUID_ZERO; | |
670 | entry->servers = servers; | |
8e354614 | 671 | entry->election_timer = election_timer; |
1b1d2e6d BP |
672 | return index; |
673 | } | |
674 | ||
8e354614 HZ |
675 | /* Writes a RAFT_REC_ENTRY record for 'term', 'data', 'eid', 'servers', |
676 | * 'election_timer' to * 'raft''s log and returns an error indication. */ | |
1b1d2e6d BP |
677 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT |
678 | raft_write_entry(struct raft *raft, uint64_t term, struct json *data, | |
8e354614 HZ |
679 | const struct uuid *eid, struct json *servers, |
680 | uint64_t election_timer) | |
1b1d2e6d BP |
681 | { |
682 | struct raft_record r = { | |
683 | .type = RAFT_REC_ENTRY, | |
684 | .term = term, | |
685 | .entry = { | |
8e354614 HZ |
686 | .index = raft_add_entry(raft, term, data, eid, servers, |
687 | election_timer), | |
1b1d2e6d BP |
688 | .data = data, |
689 | .servers = servers, | |
8e354614 | 690 | .election_timer = election_timer, |
1b1d2e6d BP |
691 | .eid = eid ? *eid : UUID_ZERO, |
692 | }, | |
693 | }; | |
694 | return ovsdb_log_write_and_free(raft->log, raft_record_to_json(&r)); | |
695 | } | |
696 | ||
697 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
698 | raft_write_state(struct ovsdb_log *log, | |
699 | uint64_t term, const struct uuid *vote) | |
700 | { | |
701 | struct raft_record r = { .term = term }; | |
702 | if (vote && !uuid_is_zero(vote)) { | |
703 | r.type = RAFT_REC_VOTE; | |
704 | r.sid = *vote; | |
705 | } else { | |
706 | r.type = RAFT_REC_TERM; | |
707 | } | |
708 | return ovsdb_log_write_and_free(log, raft_record_to_json(&r)); | |
709 | } | |
710 | ||
711 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
712 | raft_apply_record(struct raft *raft, unsigned long long int rec_idx, | |
713 | const struct raft_record *r) | |
714 | { | |
715 | /* Apply "term", which is present in most kinds of records (and otherwise | |
716 | * 0). | |
717 | * | |
718 | * A Raft leader can replicate entries from previous terms to the other | |
719 | * servers in the cluster, retaining the original terms on those entries | |
720 | * (see section 3.6.2 "Committing entries from previous terms" for more | |
721 | * information), so it's OK for the term in a log record to precede the | |
722 | * current term. */ | |
723 | if (r->term > raft->term) { | |
724 | raft->term = raft->synced_term = r->term; | |
725 | raft->vote = raft->synced_vote = UUID_ZERO; | |
726 | } | |
727 | ||
728 | switch (r->type) { | |
729 | case RAFT_REC_ENTRY: | |
730 | if (r->entry.index < raft->commit_index) { | |
731 | return ovsdb_error(NULL, "record %llu attempts to truncate log " | |
732 | "from %"PRIu64" to %"PRIu64" entries, but " | |
733 | "commit index is already %"PRIu64, | |
734 | rec_idx, raft->log_end, r->entry.index, | |
735 | raft->commit_index); | |
736 | } else if (r->entry.index > raft->log_end) { | |
737 | return ovsdb_error(NULL, "record %llu with index %"PRIu64" skips " | |
738 | "past expected index %"PRIu64, | |
739 | rec_idx, r->entry.index, raft->log_end); | |
740 | } | |
741 | ||
742 | if (r->entry.index < raft->log_end) { | |
743 | /* This can happen, but it is notable. */ | |
744 | VLOG_DBG("record %llu truncates log from %"PRIu64" to %"PRIu64 | |
745 | " entries", rec_idx, raft->log_end, r->entry.index); | |
746 | raft_truncate(raft, r->entry.index); | |
747 | } | |
748 | ||
749 | uint64_t prev_term = (raft->log_end > raft->log_start | |
750 | ? raft->entries[raft->log_end | |
751 | - raft->log_start - 1].term | |
752 | : raft->snap.term); | |
753 | if (r->term < prev_term) { | |
754 | return ovsdb_error(NULL, "record %llu with index %"PRIu64" term " | |
755 | "%"PRIu64" precedes previous entry's term " | |
756 | "%"PRIu64, | |
757 | rec_idx, r->entry.index, r->term, prev_term); | |
758 | } | |
759 | ||
760 | raft->log_synced = raft_add_entry( | |
761 | raft, r->term, | |
762 | json_nullable_clone(r->entry.data), &r->entry.eid, | |
8e354614 HZ |
763 | json_nullable_clone(r->entry.servers), |
764 | r->entry.election_timer); | |
1b1d2e6d BP |
765 | return NULL; |
766 | ||
767 | case RAFT_REC_TERM: | |
768 | return NULL; | |
769 | ||
770 | case RAFT_REC_VOTE: | |
771 | if (r->term < raft->term) { | |
772 | return ovsdb_error(NULL, "record %llu votes for term %"PRIu64" " | |
773 | "but current term is %"PRIu64, | |
774 | rec_idx, r->term, raft->term); | |
775 | } else if (!uuid_is_zero(&raft->vote) | |
776 | && !uuid_equals(&raft->vote, &r->sid)) { | |
777 | return ovsdb_error(NULL, "record %llu votes for "SID_FMT" in term " | |
778 | "%"PRIu64" but a previous record for the " | |
779 | "same term voted for "SID_FMT, rec_idx, | |
780 | SID_ARGS(&raft->vote), r->term, | |
781 | SID_ARGS(&r->sid)); | |
782 | } else { | |
783 | raft->vote = raft->synced_vote = r->sid; | |
784 | return NULL; | |
785 | } | |
786 | break; | |
787 | ||
788 | case RAFT_REC_NOTE: | |
789 | if (!strcmp(r->note, "left")) { | |
790 | return ovsdb_error(NULL, "record %llu indicates server has left " | |
791 | "the cluster; it cannot be added back (use " | |
792 | "\"ovsdb-tool join-cluster\" to add a new " | |
793 | "server)", rec_idx); | |
794 | } | |
795 | return NULL; | |
796 | ||
797 | case RAFT_REC_COMMIT_INDEX: | |
798 | if (r->commit_index < raft->commit_index) { | |
799 | return ovsdb_error(NULL, "record %llu regresses commit index " | |
800 | "from %"PRIu64 " to %"PRIu64, | |
801 | rec_idx, raft->commit_index, r->commit_index); | |
802 | } else if (r->commit_index >= raft->log_end) { | |
803 | return ovsdb_error(NULL, "record %llu advances commit index to " | |
804 | "%"PRIu64 " but last log index is %"PRIu64, | |
805 | rec_idx, r->commit_index, raft->log_end - 1); | |
806 | } else { | |
807 | raft->commit_index = r->commit_index; | |
808 | return NULL; | |
809 | } | |
810 | break; | |
811 | ||
812 | case RAFT_REC_LEADER: | |
813 | /* XXX we could use this to take back leadership for quick restart */ | |
814 | return NULL; | |
815 | ||
816 | default: | |
817 | OVS_NOT_REACHED(); | |
818 | } | |
819 | } | |
820 | ||
821 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
822 | raft_read_header(struct raft *raft) | |
823 | { | |
824 | /* Read header record. */ | |
825 | struct json *json; | |
826 | struct ovsdb_error *error = ovsdb_log_read(raft->log, &json); | |
827 | if (error || !json) { | |
828 | /* Report error or end-of-file. */ | |
829 | return error; | |
830 | } | |
831 | ovsdb_log_mark_base(raft->log); | |
832 | ||
833 | struct raft_header h; | |
834 | error = raft_header_from_json(&h, json); | |
835 | json_destroy(json); | |
836 | if (error) { | |
837 | return error; | |
838 | } | |
839 | ||
840 | raft->sid = h.sid; | |
841 | raft->cid = h.cid; | |
842 | raft->name = xstrdup(h.name); | |
843 | raft->local_address = xstrdup(h.local_address); | |
844 | raft->local_nickname = raft_address_to_nickname(h.local_address, &h.sid); | |
845 | raft->joining = h.joining; | |
846 | ||
847 | if (h.joining) { | |
848 | sset_clone(&raft->remote_addresses, &h.remote_addresses); | |
849 | } else { | |
850 | raft_entry_clone(&raft->snap, &h.snap); | |
851 | raft->log_start = raft->log_end = h.snap_index + 1; | |
852 | raft->commit_index = h.snap_index; | |
853 | raft->last_applied = h.snap_index - 1; | |
854 | } | |
855 | ||
856 | raft_header_uninit(&h); | |
857 | ||
858 | return NULL; | |
859 | } | |
860 | ||
861 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
862 | raft_read_log(struct raft *raft) | |
863 | { | |
864 | for (unsigned long long int i = 1; ; i++) { | |
865 | struct json *json; | |
866 | struct ovsdb_error *error = ovsdb_log_read(raft->log, &json); | |
867 | if (!json) { | |
868 | if (error) { | |
869 | /* We assume that the error is due to a partial write while | |
870 | * appending to the file before a crash, so log it and | |
871 | * continue. */ | |
872 | char *error_string = ovsdb_error_to_string_free(error); | |
873 | VLOG_WARN("%s", error_string); | |
874 | free(error_string); | |
875 | error = NULL; | |
876 | } | |
877 | break; | |
878 | } | |
879 | ||
880 | struct raft_record r; | |
881 | error = raft_record_from_json(&r, json); | |
882 | if (!error) { | |
883 | error = raft_apply_record(raft, i, &r); | |
884 | raft_record_uninit(&r); | |
885 | } | |
ce52f1ee | 886 | json_destroy(json); |
1b1d2e6d BP |
887 | if (error) { |
888 | return ovsdb_wrap_error(error, "error reading record %llu from " | |
889 | "%s log", i, raft->name); | |
890 | } | |
891 | } | |
892 | ||
893 | /* Set the most recent servers. */ | |
894 | raft_get_servers_from_log(raft, VLL_DBG); | |
895 | ||
8e354614 HZ |
896 | /* Set the most recent election_timer. */ |
897 | raft_get_election_timer_from_log(raft); | |
898 | ||
1b1d2e6d BP |
899 | return NULL; |
900 | } | |
901 | ||
902 | static void | |
0f954f32 | 903 | raft_reset_election_timer(struct raft *raft) |
1b1d2e6d | 904 | { |
8e354614 | 905 | unsigned int duration = (raft->election_timer |
1b1d2e6d BP |
906 | + random_range(ELECTION_RANGE_MSEC)); |
907 | raft->election_base = time_msec(); | |
67dba070 HZ |
908 | if (failure_test == FT_DELAY_ELECTION) { |
909 | /* Slow down this node so that it won't win the next election. */ | |
8e354614 | 910 | duration += raft->election_timer; |
67dba070 | 911 | } |
1b1d2e6d BP |
912 | raft->election_timeout = raft->election_base + duration; |
913 | } | |
914 | ||
0f954f32 HZ |
915 | static void |
916 | raft_reset_ping_timer(struct raft *raft) | |
917 | { | |
8e354614 | 918 | raft->ping_timeout = time_msec() + raft->election_timer / 3; |
0f954f32 HZ |
919 | } |
920 | ||
1b1d2e6d BP |
921 | static void |
922 | raft_add_conn(struct raft *raft, struct jsonrpc_session *js, | |
923 | const struct uuid *sid, bool incoming) | |
924 | { | |
925 | struct raft_conn *conn = xzalloc(sizeof *conn); | |
926 | ovs_list_push_back(&raft->conns, &conn->list_node); | |
927 | conn->js = js; | |
928 | if (sid) { | |
929 | conn->sid = *sid; | |
930 | } | |
931 | conn->nickname = raft_address_to_nickname(jsonrpc_session_get_name(js), | |
932 | &conn->sid); | |
933 | conn->incoming = incoming; | |
934 | conn->js_seqno = jsonrpc_session_get_seqno(conn->js); | |
935 | } | |
936 | ||
937 | /* Starts the local server in an existing Raft cluster, using the local copy of | |
938 | * the cluster's log in 'file_name'. Takes ownership of 'log', whether | |
939 | * successful or not. */ | |
940 | struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
941 | raft_open(struct ovsdb_log *log, struct raft **raftp) | |
942 | { | |
943 | struct raft *raft = raft_alloc(); | |
944 | raft->log = log; | |
945 | ||
946 | struct ovsdb_error *error = raft_read_header(raft); | |
947 | if (error) { | |
948 | goto error; | |
949 | } | |
950 | ||
951 | if (!raft->joining) { | |
952 | error = raft_read_log(raft); | |
953 | if (error) { | |
954 | goto error; | |
955 | } | |
956 | ||
957 | /* Find our own server. */ | |
958 | if (!raft_find_server(raft, &raft->sid)) { | |
959 | error = ovsdb_error(NULL, "server does not belong to cluster"); | |
960 | goto error; | |
961 | } | |
962 | ||
963 | /* If there's only one server, start an election right away so that the | |
964 | * cluster bootstraps quickly. */ | |
965 | if (hmap_count(&raft->servers) == 1) { | |
966 | raft_start_election(raft, false); | |
967 | } | |
968 | } else { | |
969 | raft->join_timeout = time_msec() + 1000; | |
970 | } | |
971 | ||
ac3ba8c6 HZ |
972 | raft_reset_ping_timer(raft); |
973 | raft_reset_election_timer(raft); | |
974 | ||
1b1d2e6d BP |
975 | *raftp = raft; |
976 | hmap_insert(&all_rafts, &raft->hmap_node, hash_string(raft->name, 0)); | |
977 | return NULL; | |
978 | ||
979 | error: | |
980 | raft_close(raft); | |
981 | *raftp = NULL; | |
982 | return error; | |
983 | } | |
984 | ||
985 | /* Returns the name of 'raft', which in OVSDB is the database schema name. */ | |
986 | const char * | |
987 | raft_get_name(const struct raft *raft) | |
988 | { | |
989 | return raft->name; | |
990 | } | |
991 | ||
992 | /* Returns the cluster ID of 'raft'. If 'raft' has not yet completed joining | |
993 | * its cluster, then 'cid' will be all-zeros (unless the administrator | |
994 | * specified a cluster ID running "ovsdb-tool join-cluster"). | |
995 | * | |
996 | * Each cluster has a unique cluster ID. */ | |
997 | const struct uuid * | |
998 | raft_get_cid(const struct raft *raft) | |
999 | { | |
1000 | return &raft->cid; | |
1001 | } | |
1002 | ||
1003 | /* Returns the server ID of 'raft'. Each server has a unique server ID. */ | |
1004 | const struct uuid * | |
1005 | raft_get_sid(const struct raft *raft) | |
1006 | { | |
1007 | return &raft->sid; | |
1008 | } | |
1009 | ||
1010 | /* Returns true if 'raft' has completed joining its cluster, has not left or | |
1011 | * initiated leaving the cluster, does not have failed disk storage, and is | |
1012 | * apparently connected to the leader in a healthy way (or is itself the | |
4d9b28cb HZ |
1013 | * leader). |
1014 | * | |
1015 | * If 'raft' is candidate: | |
1016 | * a) if it is the first round of election, consider it as connected, hoping | |
1017 | * it will successfully elect a new leader soon. | |
1018 | * b) if it is already retrying, consider it as disconnected (so that clients | |
1019 | * may decide to reconnect to other members). */ | |
1b1d2e6d BP |
1020 | bool |
1021 | raft_is_connected(const struct raft *raft) | |
1022 | { | |
923f01ca | 1023 | bool ret = (!raft->candidate_retrying |
1b1d2e6d BP |
1024 | && !raft->joining |
1025 | && !raft->leaving | |
1026 | && !raft->left | |
1027 | && !raft->failed); | |
923f01ca HZ |
1028 | VLOG_DBG("raft_is_connected: %s\n", ret? "true": "false"); |
1029 | return ret; | |
1b1d2e6d BP |
1030 | } |
1031 | ||
1032 | /* Returns true if 'raft' is the cluster leader. */ | |
1033 | bool | |
1034 | raft_is_leader(const struct raft *raft) | |
1035 | { | |
1036 | return raft->role == RAFT_LEADER; | |
1037 | } | |
1038 | ||
1039 | /* Returns true if 'raft' is the process of joining its cluster. */ | |
1040 | bool | |
1041 | raft_is_joining(const struct raft *raft) | |
1042 | { | |
1043 | return raft->joining; | |
1044 | } | |
1045 | ||
1046 | /* Only returns *connected* connections. */ | |
1047 | static struct raft_conn * | |
1048 | raft_find_conn_by_sid(struct raft *raft, const struct uuid *sid) | |
1049 | { | |
1050 | if (!uuid_is_zero(sid)) { | |
1051 | struct raft_conn *conn; | |
1052 | LIST_FOR_EACH (conn, list_node, &raft->conns) { | |
1053 | if (uuid_equals(sid, &conn->sid) | |
1054 | && jsonrpc_session_is_connected(conn->js)) { | |
1055 | return conn; | |
1056 | } | |
1057 | } | |
1058 | } | |
1059 | return NULL; | |
1060 | } | |
1061 | ||
1062 | static struct raft_conn * | |
1063 | raft_find_conn_by_address(struct raft *raft, const char *address) | |
1064 | { | |
1065 | struct raft_conn *conn; | |
1066 | LIST_FOR_EACH (conn, list_node, &raft->conns) { | |
1067 | if (!strcmp(jsonrpc_session_get_name(conn->js), address)) { | |
1068 | return conn; | |
1069 | } | |
1070 | } | |
1071 | return NULL; | |
1072 | } | |
1073 | ||
1074 | static void OVS_PRINTF_FORMAT(3, 4) | |
1075 | raft_record_note(struct raft *raft, const char *note, | |
1076 | const char *comment_format, ...) | |
1077 | { | |
1078 | va_list args; | |
1079 | va_start(args, comment_format); | |
1080 | char *comment = xvasprintf(comment_format, args); | |
1081 | va_end(args); | |
1082 | ||
1083 | struct raft_record r = { | |
1084 | .type = RAFT_REC_NOTE, | |
1085 | .comment = comment, | |
1086 | .note = CONST_CAST(char *, note), | |
1087 | }; | |
1088 | ignore(ovsdb_log_write_and_free(raft->log, raft_record_to_json(&r))); | |
1089 | ||
1090 | free(comment); | |
1091 | } | |
1092 | ||
1093 | /* If we're leader, try to transfer leadership to another server, logging | |
1094 | * 'reason' as the human-readable reason (it should be a phrase suitable for | |
1095 | * following "because") . */ | |
1096 | void | |
1097 | raft_transfer_leadership(struct raft *raft, const char *reason) | |
1098 | { | |
1099 | if (raft->role != RAFT_LEADER) { | |
1100 | return; | |
1101 | } | |
1102 | ||
1103 | struct raft_server *s; | |
1104 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
1105 | if (!uuid_equals(&raft->sid, &s->sid) | |
1106 | && s->phase == RAFT_PHASE_STABLE) { | |
1107 | struct raft_conn *conn = raft_find_conn_by_sid(raft, &s->sid); | |
1108 | if (!conn) { | |
1109 | continue; | |
1110 | } | |
1111 | ||
1112 | union raft_rpc rpc = { | |
1113 | .become_leader = { | |
1114 | .common = { | |
1115 | .comment = CONST_CAST(char *, reason), | |
1116 | .type = RAFT_RPC_BECOME_LEADER, | |
1117 | .sid = s->sid, | |
1118 | }, | |
1119 | .term = raft->term, | |
1120 | } | |
1121 | }; | |
02acb41a | 1122 | raft_send_to_conn(raft, &rpc, conn); |
1b1d2e6d BP |
1123 | |
1124 | raft_record_note(raft, "transfer leadership", | |
1125 | "transferring leadership to %s because %s", | |
1126 | s->nickname, reason); | |
1127 | break; | |
1128 | } | |
1129 | } | |
1130 | } | |
1131 | ||
1132 | /* Send a RemoveServerRequest to the rest of the servers in the cluster. | |
1133 | * | |
1134 | * If we know which server is the leader, we can just send the request to it. | |
1135 | * However, we might not know which server is the leader, and we might never | |
1136 | * find out if the remove request was actually previously committed by a | |
1137 | * majority of the servers (because in that case the new leader will not send | |
1138 | * AppendRequests or heartbeats to us). Therefore, we instead send | |
1139 | * RemoveRequests to every server. This theoretically has the same problem, if | |
1140 | * the current cluster leader was not previously a member of the cluster, but | |
1141 | * it seems likely to be more robust in practice. */ | |
1142 | static void | |
1143 | raft_send_remove_server_requests(struct raft *raft) | |
1144 | { | |
1145 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
1146 | VLOG_INFO_RL(&rl, "sending remove request (joining=%s, leaving=%s)", | |
1147 | raft->joining ? "true" : "false", | |
1148 | raft->leaving ? "true" : "false"); | |
1149 | const struct raft_server *s; | |
1150 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
1151 | if (!uuid_equals(&s->sid, &raft->sid)) { | |
1152 | union raft_rpc rpc = (union raft_rpc) { | |
1153 | .remove_server_request = { | |
1154 | .common = { | |
1155 | .type = RAFT_RPC_REMOVE_SERVER_REQUEST, | |
1156 | .sid = s->sid, | |
1157 | }, | |
1158 | .sid = raft->sid, | |
1159 | }, | |
1160 | }; | |
1161 | raft_send(raft, &rpc); | |
1162 | } | |
1163 | } | |
1164 | ||
8e354614 | 1165 | raft->leave_timeout = time_msec() + raft->election_timer; |
1b1d2e6d BP |
1166 | } |
1167 | ||
1168 | /* Attempts to start 'raft' leaving its cluster. The caller can check progress | |
1169 | * using raft_is_leaving() and raft_left(). */ | |
1170 | void | |
1171 | raft_leave(struct raft *raft) | |
1172 | { | |
1173 | if (raft->joining || raft->failed || raft->leaving || raft->left) { | |
1174 | return; | |
1175 | } | |
1176 | VLOG_INFO(SID_FMT": starting to leave cluster "CID_FMT, | |
1177 | SID_ARGS(&raft->sid), CID_ARGS(&raft->cid)); | |
1178 | raft->leaving = true; | |
1179 | raft_transfer_leadership(raft, "this server is leaving the cluster"); | |
1180 | raft_become_follower(raft); | |
1181 | raft_send_remove_server_requests(raft); | |
8e354614 | 1182 | raft->leave_timeout = time_msec() + raft->election_timer; |
1b1d2e6d BP |
1183 | } |
1184 | ||
1185 | /* Returns true if 'raft' is currently attempting to leave its cluster. */ | |
1186 | bool | |
1187 | raft_is_leaving(const struct raft *raft) | |
1188 | { | |
1189 | return raft->leaving; | |
1190 | } | |
1191 | ||
1192 | /* Returns true if 'raft' successfully left its cluster. */ | |
1193 | bool | |
1194 | raft_left(const struct raft *raft) | |
1195 | { | |
1196 | return raft->left; | |
1197 | } | |
1198 | ||
1199 | /* Returns true if 'raft' has experienced a disk I/O failure. When this | |
1200 | * returns true, only closing and reopening 'raft' allows for recovery. */ | |
1201 | bool | |
1202 | raft_failed(const struct raft *raft) | |
1203 | { | |
1204 | return raft->failed; | |
1205 | } | |
1206 | ||
1207 | /* Forces 'raft' to attempt to take leadership of the cluster by deposing the | |
1208 | * current cluster. */ | |
1209 | void | |
1210 | raft_take_leadership(struct raft *raft) | |
1211 | { | |
1212 | if (raft->role != RAFT_LEADER) { | |
1213 | raft_start_election(raft, true); | |
1214 | } | |
1215 | } | |
1216 | ||
1217 | /* Closes everything owned by 'raft' that might be visible outside the process: | |
1218 | * network connections, commands, etc. This is part of closing 'raft'; it is | |
1219 | * also used if 'raft' has failed in an unrecoverable way. */ | |
1220 | static void | |
1221 | raft_close__(struct raft *raft) | |
1222 | { | |
1223 | if (!hmap_node_is_null(&raft->hmap_node)) { | |
1224 | hmap_remove(&all_rafts, &raft->hmap_node); | |
1225 | hmap_node_nullify(&raft->hmap_node); | |
1226 | } | |
1227 | ||
1228 | raft_complete_all_commands(raft, RAFT_CMD_SHUTDOWN); | |
1229 | ||
1230 | struct raft_server *rs = raft->remove_server; | |
1231 | if (rs) { | |
1232 | raft_send_remove_server_reply__(raft, &rs->sid, &rs->requester_sid, | |
1233 | rs->requester_conn, false, | |
1234 | RAFT_SERVER_SHUTDOWN); | |
1235 | raft_server_destroy(raft->remove_server); | |
1236 | raft->remove_server = NULL; | |
1237 | } | |
1238 | ||
1239 | struct raft_conn *conn, *next; | |
1240 | LIST_FOR_EACH_SAFE (conn, next, list_node, &raft->conns) { | |
1241 | raft_conn_close(conn); | |
1242 | } | |
1243 | } | |
1244 | ||
1245 | /* Closes and frees 'raft'. | |
1246 | * | |
1247 | * A server's cluster membership is independent of whether the server is | |
1248 | * actually running. When a server that is a member of a cluster closes, the | |
1249 | * cluster treats this as a server failure. */ | |
1250 | void | |
1251 | raft_close(struct raft *raft) | |
1252 | { | |
1253 | if (!raft) { | |
1254 | return; | |
1255 | } | |
1256 | ||
1257 | raft_transfer_leadership(raft, "this server is shutting down"); | |
1258 | ||
1259 | raft_close__(raft); | |
1260 | ||
1261 | ovsdb_log_close(raft->log); | |
1262 | ||
1263 | raft_servers_destroy(&raft->servers); | |
1264 | ||
1265 | for (uint64_t index = raft->log_start; index < raft->log_end; index++) { | |
1266 | struct raft_entry *e = &raft->entries[index - raft->log_start]; | |
1267 | raft_entry_uninit(e); | |
1268 | } | |
1269 | free(raft->entries); | |
1270 | ||
1271 | raft_entry_uninit(&raft->snap); | |
1272 | ||
1273 | raft_waiters_destroy(raft); | |
1274 | ||
1275 | raft_servers_destroy(&raft->add_servers); | |
1276 | ||
1277 | hmap_destroy(&raft->commands); | |
1278 | ||
1279 | pstream_close(raft->listener); | |
1280 | ||
1281 | sset_destroy(&raft->remote_addresses); | |
1282 | free(raft->local_address); | |
1283 | free(raft->local_nickname); | |
1284 | free(raft->name); | |
1285 | ||
1286 | free(raft); | |
1287 | } | |
1288 | ||
1289 | static bool | |
1290 | raft_conn_receive(struct raft *raft, struct raft_conn *conn, | |
1291 | union raft_rpc *rpc) | |
1292 | { | |
1293 | struct jsonrpc_msg *msg = jsonrpc_session_recv(conn->js); | |
1294 | if (!msg) { | |
1295 | return false; | |
1296 | } | |
1297 | ||
1298 | struct ovsdb_error *error = raft_rpc_from_jsonrpc(&raft->cid, &raft->sid, | |
1299 | msg, rpc); | |
1300 | jsonrpc_msg_destroy(msg); | |
1301 | if (error) { | |
1302 | char *s = ovsdb_error_to_string_free(error); | |
1303 | VLOG_INFO("%s: %s", jsonrpc_session_get_name(conn->js), s); | |
1304 | free(s); | |
1305 | return false; | |
1306 | } | |
1307 | ||
1308 | if (uuid_is_zero(&conn->sid)) { | |
1309 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(50, 50); | |
1310 | conn->sid = rpc->common.sid; | |
1311 | VLOG_INFO_RL(&rl, "%s: learned server ID "SID_FMT, | |
1312 | jsonrpc_session_get_name(conn->js), SID_ARGS(&conn->sid)); | |
1313 | } else if (!uuid_equals(&conn->sid, &rpc->common.sid)) { | |
1314 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); | |
1315 | VLOG_WARN_RL(&rl, "%s: ignoring message with unexpected server ID " | |
1316 | SID_FMT" (expected "SID_FMT")", | |
1317 | jsonrpc_session_get_name(conn->js), | |
1318 | SID_ARGS(&rpc->common.sid), SID_ARGS(&conn->sid)); | |
1319 | raft_rpc_uninit(rpc); | |
1320 | return false; | |
1321 | } | |
1322 | ||
1323 | const char *address = (rpc->type == RAFT_RPC_HELLO_REQUEST | |
1324 | ? rpc->hello_request.address | |
1325 | : rpc->type == RAFT_RPC_ADD_SERVER_REQUEST | |
1326 | ? rpc->add_server_request.address | |
1327 | : NULL); | |
1328 | if (address) { | |
1329 | char *new_nickname = raft_address_to_nickname(address, &conn->sid); | |
1330 | if (strcmp(conn->nickname, new_nickname)) { | |
1331 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(50, 50); | |
1332 | VLOG_INFO_RL(&rl, "%s: learned remote address %s", | |
1333 | jsonrpc_session_get_name(conn->js), address); | |
1334 | ||
1335 | free(conn->nickname); | |
1336 | conn->nickname = new_nickname; | |
1337 | } else { | |
1338 | free(new_nickname); | |
1339 | } | |
1340 | } | |
1341 | ||
1342 | return true; | |
1343 | } | |
1344 | ||
1345 | static const char * | |
1346 | raft_get_nickname(const struct raft *raft, const struct uuid *sid, | |
1347 | char buf[SID_LEN + 1], size_t bufsize) | |
1348 | { | |
1349 | if (uuid_equals(sid, &raft->sid)) { | |
1350 | return raft->local_nickname; | |
1351 | } | |
1352 | ||
1353 | const char *s = raft_servers_get_nickname__(&raft->servers, sid); | |
1354 | if (s) { | |
1355 | return s; | |
1356 | } | |
1357 | ||
1358 | return raft_servers_get_nickname(&raft->add_servers, sid, buf, bufsize); | |
1359 | } | |
1360 | ||
1361 | static void | |
02acb41a BP |
1362 | log_rpc(const union raft_rpc *rpc, const char *direction, |
1363 | const struct raft_conn *conn, int line_number) | |
1b1d2e6d BP |
1364 | { |
1365 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(600, 600); | |
1366 | if (!raft_rpc_is_heartbeat(rpc) && !VLOG_DROP_DBG(&rl)) { | |
1367 | struct ds s = DS_EMPTY_INITIALIZER; | |
02acb41a BP |
1368 | if (line_number) { |
1369 | ds_put_format(&s, "raft.c:%d ", line_number); | |
1370 | } | |
1371 | ds_put_format(&s, "%s%s ", direction, conn->nickname); | |
1b1d2e6d | 1372 | raft_rpc_format(rpc, &s); |
02acb41a | 1373 | VLOG_DBG("%s", ds_cstr(&s)); |
1b1d2e6d BP |
1374 | ds_destroy(&s); |
1375 | } | |
1376 | } | |
1377 | ||
1378 | static void | |
1379 | raft_send_add_server_request(struct raft *raft, struct raft_conn *conn) | |
1380 | { | |
1381 | union raft_rpc rq = { | |
1382 | .add_server_request = { | |
1383 | .common = { | |
1384 | .type = RAFT_RPC_ADD_SERVER_REQUEST, | |
1385 | .sid = UUID_ZERO, | |
1386 | .comment = NULL, | |
1387 | }, | |
1388 | .address = raft->local_address, | |
1389 | }, | |
1390 | }; | |
02acb41a | 1391 | raft_send_to_conn(raft, &rq, conn); |
1b1d2e6d BP |
1392 | } |
1393 | ||
1394 | static void | |
1395 | raft_conn_run(struct raft *raft, struct raft_conn *conn) | |
1396 | { | |
1397 | jsonrpc_session_run(conn->js); | |
1398 | ||
1399 | unsigned int new_seqno = jsonrpc_session_get_seqno(conn->js); | |
1400 | bool just_connected = (new_seqno != conn->js_seqno | |
1401 | && jsonrpc_session_is_connected(conn->js)); | |
1402 | conn->js_seqno = new_seqno; | |
1403 | if (just_connected) { | |
1404 | if (raft->joining) { | |
1405 | raft_send_add_server_request(raft, conn); | |
1406 | } else if (raft->leaving) { | |
1407 | union raft_rpc rq = { | |
1408 | .remove_server_request = { | |
1409 | .common = { | |
1410 | .type = RAFT_RPC_REMOVE_SERVER_REQUEST, | |
1411 | .sid = conn->sid, | |
1412 | }, | |
1413 | .sid = raft->sid, | |
1414 | }, | |
1415 | }; | |
02acb41a | 1416 | raft_send_to_conn(raft, &rq, conn); |
1b1d2e6d BP |
1417 | } else { |
1418 | union raft_rpc rq = (union raft_rpc) { | |
1419 | .hello_request = { | |
1420 | .common = { | |
1421 | .type = RAFT_RPC_HELLO_REQUEST, | |
1422 | .sid = conn->sid, | |
1423 | }, | |
1424 | .address = raft->local_address, | |
1425 | }, | |
1426 | }; | |
02acb41a | 1427 | raft_send_to_conn(raft, &rq, conn); |
1b1d2e6d BP |
1428 | } |
1429 | } | |
1430 | ||
1431 | for (size_t i = 0; i < 50; i++) { | |
1432 | union raft_rpc rpc; | |
1433 | if (!raft_conn_receive(raft, conn, &rpc)) { | |
1434 | break; | |
1435 | } | |
1436 | ||
02acb41a | 1437 | log_rpc(&rpc, "<--", conn, 0); |
1b1d2e6d BP |
1438 | raft_handle_rpc(raft, &rpc); |
1439 | raft_rpc_uninit(&rpc); | |
1440 | } | |
1441 | } | |
1442 | ||
1443 | static void | |
1444 | raft_waiter_complete_rpc(struct raft *raft, const union raft_rpc *rpc) | |
1445 | { | |
1446 | uint64_t term = raft_rpc_get_term(rpc); | |
1447 | if (term && term < raft->term) { | |
1448 | /* Drop the message because it's for an expired term. */ | |
1449 | return; | |
1450 | } | |
1451 | ||
1452 | if (!raft_is_rpc_synced(raft, rpc)) { | |
1453 | /* This is a bug. A reply message is deferred because some state in | |
1454 | * the message, such as a term or index, has not been committed to | |
1455 | * disk, and they should only be completed when that commit is done. | |
1456 | * But this message is being completed before the commit is finished. | |
1457 | * Complain, and hope that someone reports the bug. */ | |
1458 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
1459 | if (VLOG_DROP_ERR(&rl)) { | |
1460 | return; | |
1461 | } | |
1462 | ||
1463 | struct ds s = DS_EMPTY_INITIALIZER; | |
1464 | ||
1465 | if (term > raft->synced_term) { | |
1466 | ds_put_format(&s, " because message term %"PRIu64" is " | |
1467 | "past synced term %"PRIu64, | |
1468 | term, raft->synced_term); | |
1469 | } | |
1470 | ||
1471 | uint64_t index = raft_rpc_get_min_sync_index(rpc); | |
1472 | if (index > raft->log_synced) { | |
1473 | ds_put_format(&s, " %s message index %"PRIu64" is past last " | |
1474 | "synced index %"PRIu64, | |
1475 | s.length ? "and" : "because", | |
1476 | index, raft->log_synced); | |
1477 | } | |
1478 | ||
1479 | const struct uuid *vote = raft_rpc_get_vote(rpc); | |
1480 | if (vote && !uuid_equals(vote, &raft->synced_vote)) { | |
1481 | char buf1[SID_LEN + 1]; | |
1482 | char buf2[SID_LEN + 1]; | |
1483 | ds_put_format(&s, " %s vote %s differs from synced vote %s", | |
1484 | s.length ? "and" : "because", | |
1485 | raft_get_nickname(raft, vote, buf1, sizeof buf1), | |
1486 | raft_get_nickname(raft, &raft->synced_vote, | |
1487 | buf2, sizeof buf2)); | |
1488 | } | |
1489 | ||
1490 | char buf[SID_LEN + 1]; | |
1491 | ds_put_format(&s, ": %s ", | |
1492 | raft_get_nickname(raft, &rpc->common.sid, | |
1493 | buf, sizeof buf)); | |
1494 | raft_rpc_format(rpc, &s); | |
1495 | VLOG_ERR("internal error: deferred %s message completed " | |
1496 | "but not ready to send%s", | |
1497 | raft_rpc_type_to_string(rpc->type), ds_cstr(&s)); | |
1498 | ds_destroy(&s); | |
1499 | ||
1500 | return; | |
1501 | } | |
1502 | ||
1503 | struct raft_conn *dst = raft_find_conn_by_sid(raft, &rpc->common.sid); | |
1504 | if (dst) { | |
02acb41a | 1505 | raft_send_to_conn(raft, rpc, dst); |
1b1d2e6d BP |
1506 | } |
1507 | } | |
1508 | ||
1509 | static void | |
1510 | raft_waiter_complete(struct raft *raft, struct raft_waiter *w) | |
1511 | { | |
1512 | switch (w->type) { | |
1513 | case RAFT_W_ENTRY: | |
1514 | if (raft->role == RAFT_LEADER) { | |
1515 | raft_update_our_match_index(raft, w->entry.index); | |
1516 | } | |
1517 | raft->log_synced = w->entry.index; | |
1518 | break; | |
1519 | ||
1520 | case RAFT_W_TERM: | |
1521 | raft->synced_term = w->term.term; | |
1522 | raft->synced_vote = w->term.vote; | |
1523 | break; | |
1524 | ||
1525 | case RAFT_W_RPC: | |
1526 | raft_waiter_complete_rpc(raft, w->rpc); | |
1527 | break; | |
1528 | } | |
1529 | } | |
1530 | ||
1531 | static void | |
1532 | raft_waiter_destroy(struct raft_waiter *w) | |
1533 | { | |
1534 | if (!w) { | |
1535 | return; | |
1536 | } | |
1537 | ||
1538 | ovs_list_remove(&w->list_node); | |
1539 | ||
1540 | switch (w->type) { | |
1541 | case RAFT_W_ENTRY: | |
1542 | case RAFT_W_TERM: | |
1543 | break; | |
1544 | ||
1545 | case RAFT_W_RPC: | |
1546 | raft_rpc_uninit(w->rpc); | |
1547 | free(w->rpc); | |
1548 | break; | |
1549 | } | |
1550 | free(w); | |
1551 | } | |
1552 | ||
1553 | static void | |
1554 | raft_waiters_run(struct raft *raft) | |
1555 | { | |
1556 | if (ovs_list_is_empty(&raft->waiters)) { | |
1557 | return; | |
1558 | } | |
1559 | ||
1560 | uint64_t cur = ovsdb_log_commit_progress(raft->log); | |
1561 | struct raft_waiter *w, *next; | |
1562 | LIST_FOR_EACH_SAFE (w, next, list_node, &raft->waiters) { | |
1563 | if (cur < w->commit_ticket) { | |
1564 | break; | |
1565 | } | |
1566 | raft_waiter_complete(raft, w); | |
1567 | raft_waiter_destroy(w); | |
1568 | } | |
1569 | } | |
1570 | ||
1571 | static void | |
1572 | raft_waiters_wait(struct raft *raft) | |
1573 | { | |
1574 | struct raft_waiter *w; | |
1575 | LIST_FOR_EACH (w, list_node, &raft->waiters) { | |
1576 | ovsdb_log_commit_wait(raft->log, w->commit_ticket); | |
1577 | break; | |
1578 | } | |
1579 | } | |
1580 | ||
1581 | static void | |
1582 | raft_waiters_destroy(struct raft *raft) | |
1583 | { | |
1584 | struct raft_waiter *w, *next; | |
1585 | LIST_FOR_EACH_SAFE (w, next, list_node, &raft->waiters) { | |
1586 | raft_waiter_destroy(w); | |
1587 | } | |
1588 | } | |
1589 | ||
1590 | static bool OVS_WARN_UNUSED_RESULT | |
1591 | raft_set_term(struct raft *raft, uint64_t term, const struct uuid *vote) | |
1592 | { | |
1593 | struct ovsdb_error *error = raft_write_state(raft->log, term, vote); | |
1594 | if (!raft_handle_write_error(raft, error)) { | |
1595 | return false; | |
1596 | } | |
1597 | ||
1598 | struct raft_waiter *w = raft_waiter_create(raft, RAFT_W_TERM, true); | |
1599 | raft->term = w->term.term = term; | |
1600 | raft->vote = w->term.vote = vote ? *vote : UUID_ZERO; | |
1601 | return true; | |
1602 | } | |
1603 | ||
1604 | static void | |
1605 | raft_accept_vote(struct raft *raft, struct raft_server *s, | |
1606 | const struct uuid *vote) | |
1607 | { | |
1608 | if (uuid_equals(&s->vote, vote)) { | |
1609 | return; | |
1610 | } | |
1611 | if (!uuid_is_zero(&s->vote)) { | |
1612 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); | |
1613 | char buf1[SID_LEN + 1]; | |
1614 | char buf2[SID_LEN + 1]; | |
1615 | VLOG_WARN_RL(&rl, "server %s changed its vote from %s to %s", | |
1616 | s->nickname, | |
1617 | raft_get_nickname(raft, &s->vote, buf1, sizeof buf1), | |
1618 | raft_get_nickname(raft, vote, buf2, sizeof buf2)); | |
1619 | } | |
1620 | s->vote = *vote; | |
1621 | if (uuid_equals(vote, &raft->sid) | |
1622 | && ++raft->n_votes > hmap_count(&raft->servers) / 2) { | |
1623 | raft_become_leader(raft); | |
1624 | } | |
1625 | } | |
1626 | ||
1627 | static void | |
1628 | raft_start_election(struct raft *raft, bool leadership_transfer) | |
1629 | { | |
1630 | if (raft->leaving) { | |
1631 | return; | |
1632 | } | |
1633 | ||
1634 | struct raft_server *me = raft_find_server(raft, &raft->sid); | |
1635 | if (!me) { | |
1636 | return; | |
1637 | } | |
1638 | ||
1639 | if (!raft_set_term(raft, raft->term + 1, &raft->sid)) { | |
1640 | return; | |
1641 | } | |
1642 | ||
1b1d2e6d | 1643 | ovs_assert(raft->role != RAFT_LEADER); |
1b1d2e6d | 1644 | raft->role = RAFT_CANDIDATE; |
923f01ca HZ |
1645 | /* If there was no leader elected since last election, we know we are |
1646 | * retrying now. */ | |
1647 | raft->candidate_retrying = !raft->had_leader; | |
1648 | raft->had_leader = false; | |
1b1d2e6d BP |
1649 | |
1650 | raft->n_votes = 0; | |
1651 | ||
1652 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); | |
1653 | if (!VLOG_DROP_INFO(&rl)) { | |
1654 | long long int now = time_msec(); | |
1655 | if (now >= raft->election_timeout) { | |
1656 | VLOG_INFO("term %"PRIu64": %lld ms timeout expired, " | |
1657 | "starting election", | |
1658 | raft->term, now - raft->election_base); | |
1659 | } else { | |
1660 | VLOG_INFO("term %"PRIu64": starting election", raft->term); | |
1661 | } | |
1662 | } | |
0f954f32 | 1663 | raft_reset_election_timer(raft); |
1b1d2e6d BP |
1664 | |
1665 | struct raft_server *peer; | |
1666 | HMAP_FOR_EACH (peer, hmap_node, &raft->servers) { | |
1667 | peer->vote = UUID_ZERO; | |
1668 | if (uuid_equals(&raft->sid, &peer->sid)) { | |
1669 | continue; | |
1670 | } | |
1671 | ||
1672 | union raft_rpc rq = { | |
1673 | .vote_request = { | |
1674 | .common = { | |
1675 | .type = RAFT_RPC_VOTE_REQUEST, | |
1676 | .sid = peer->sid, | |
1677 | }, | |
1678 | .term = raft->term, | |
1679 | .last_log_index = raft->log_end - 1, | |
1680 | .last_log_term = ( | |
1681 | raft->log_end > raft->log_start | |
1682 | ? raft->entries[raft->log_end - raft->log_start - 1].term | |
1683 | : raft->snap.term), | |
1684 | .leadership_transfer = leadership_transfer, | |
1685 | }, | |
1686 | }; | |
1687 | raft_send(raft, &rq); | |
1688 | } | |
1689 | ||
1690 | /* Vote for ourselves. */ | |
1691 | raft_accept_vote(raft, me, &raft->sid); | |
1692 | } | |
1693 | ||
1694 | static void | |
1695 | raft_open_conn(struct raft *raft, const char *address, const struct uuid *sid) | |
1696 | { | |
1697 | if (strcmp(address, raft->local_address) | |
1698 | && !raft_find_conn_by_address(raft, address)) { | |
1699 | raft_add_conn(raft, jsonrpc_session_open(address, true), sid, false); | |
1700 | } | |
1701 | } | |
1702 | ||
1703 | static void | |
1704 | raft_conn_close(struct raft_conn *conn) | |
1705 | { | |
1706 | jsonrpc_session_close(conn->js); | |
1707 | ovs_list_remove(&conn->list_node); | |
1708 | free(conn->nickname); | |
1709 | free(conn); | |
1710 | } | |
1711 | ||
1712 | /* Returns true if 'conn' should stay open, false if it should be closed. */ | |
1713 | static bool | |
1714 | raft_conn_should_stay_open(struct raft *raft, struct raft_conn *conn) | |
1715 | { | |
1716 | /* Close the connection if it's actually dead. If necessary, we'll | |
1717 | * initiate a new session later. */ | |
1718 | if (!jsonrpc_session_is_alive(conn->js)) { | |
1719 | return false; | |
1720 | } | |
1721 | ||
1722 | /* Keep incoming sessions. We trust the originator to decide to drop | |
1723 | * it. */ | |
1724 | if (conn->incoming) { | |
1725 | return true; | |
1726 | } | |
1727 | ||
1728 | /* If we are joining the cluster, keep sessions to the remote addresses | |
1729 | * that are supposed to be part of the cluster we're joining. */ | |
1730 | if (raft->joining && sset_contains(&raft->remote_addresses, | |
1731 | jsonrpc_session_get_name(conn->js))) { | |
1732 | return true; | |
1733 | } | |
1734 | ||
1735 | /* We have joined the cluster. If we did that "recently", then there is a | |
1736 | * chance that we do not have the most recent server configuration log | |
1737 | * entry. If so, it's a waste to disconnect from the servers that were in | |
1738 | * remote_addresses and that will probably appear in the configuration, | |
1739 | * just to reconnect to them a moment later when we do get the | |
1740 | * configuration update. If we are not ourselves in the configuration, | |
1741 | * then we know that there must be a new configuration coming up, so in | |
1742 | * that case keep the connection. */ | |
1743 | if (!raft_find_server(raft, &raft->sid)) { | |
1744 | return true; | |
1745 | } | |
1746 | ||
1747 | /* Keep the connection only if the server is part of the configuration. */ | |
1748 | return raft_find_server(raft, &conn->sid); | |
1749 | } | |
1750 | ||
1751 | /* Allows 'raft' to maintain the distributed log. Call this function as part | |
1752 | * of the process's main loop. */ | |
1753 | void | |
1754 | raft_run(struct raft *raft) | |
1755 | { | |
1756 | if (raft->left || raft->failed) { | |
1757 | return; | |
1758 | } | |
1759 | ||
1760 | raft_waiters_run(raft); | |
1761 | ||
1762 | if (!raft->listener && time_msec() >= raft->listen_backoff) { | |
1763 | char *paddr = raft_make_address_passive(raft->local_address); | |
1764 | int error = pstream_open(paddr, &raft->listener, DSCP_DEFAULT); | |
1765 | if (error) { | |
1766 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); | |
1767 | VLOG_WARN_RL(&rl, "%s: listen failed (%s)", | |
1768 | paddr, ovs_strerror(error)); | |
1769 | raft->listen_backoff = time_msec() + 1000; | |
1770 | } | |
1771 | free(paddr); | |
1772 | } | |
1773 | ||
1774 | if (raft->listener) { | |
1775 | struct stream *stream; | |
1776 | int error = pstream_accept(raft->listener, &stream); | |
1777 | if (!error) { | |
1778 | raft_add_conn(raft, jsonrpc_session_open_unreliably( | |
1779 | jsonrpc_open(stream), DSCP_DEFAULT), NULL, | |
1780 | true); | |
1781 | } else if (error != EAGAIN) { | |
1782 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); | |
1783 | VLOG_WARN_RL(&rl, "%s: accept failed: %s", | |
1784 | pstream_get_name(raft->listener), | |
1785 | ovs_strerror(error)); | |
1786 | } | |
1787 | } | |
1788 | ||
1789 | /* Run RPCs for all open sessions. */ | |
1790 | struct raft_conn *conn; | |
1791 | LIST_FOR_EACH (conn, list_node, &raft->conns) { | |
1792 | raft_conn_run(raft, conn); | |
1793 | } | |
1794 | ||
1795 | /* Close unneeded sessions. */ | |
1796 | struct raft_conn *next; | |
1797 | LIST_FOR_EACH_SAFE (conn, next, list_node, &raft->conns) { | |
1798 | if (!raft_conn_should_stay_open(raft, conn)) { | |
1799 | raft_conn_close(conn); | |
1800 | } | |
1801 | } | |
1802 | ||
1803 | /* Open needed sessions. */ | |
1804 | struct raft_server *server; | |
1805 | HMAP_FOR_EACH (server, hmap_node, &raft->servers) { | |
1806 | raft_open_conn(raft, server->address, &server->sid); | |
1807 | } | |
1808 | if (raft->joining) { | |
1809 | const char *address; | |
1810 | SSET_FOR_EACH (address, &raft->remote_addresses) { | |
1811 | raft_open_conn(raft, address, NULL); | |
1812 | } | |
1813 | } | |
1814 | ||
1815 | if (!raft->joining && time_msec() >= raft->election_timeout) { | |
89771c1e HZ |
1816 | if (raft->role == RAFT_LEADER) { |
1817 | /* Check if majority of followers replied, then reset | |
1818 | * election_timeout and reset s->replied. Otherwise, become | |
1819 | * follower. | |
1820 | * | |
1821 | * Raft paper section 6.2: Leaders: A server might be in the leader | |
1822 | * state, but if it isn’t the current leader, it could be | |
1823 | * needlessly delaying client requests. For example, suppose a | |
1824 | * leader is partitioned from the rest of the cluster, but it can | |
1825 | * still communicate with a particular client. Without additional | |
1826 | * mechanism, it could delay a request from that client forever, | |
1827 | * being unable to replicate a log entry to any other servers. | |
1828 | * Meanwhile, there might be another leader of a newer term that is | |
1829 | * able to communicate with a majority of the cluster and would be | |
1830 | * able to commit the client’s request. Thus, a leader in Raft | |
1831 | * steps down if an election timeout elapses without a successful | |
1832 | * round of heartbeats to a majority of its cluster; this allows | |
1833 | * clients to retry their requests with another server. */ | |
1834 | int count = 0; | |
1835 | HMAP_FOR_EACH (server, hmap_node, &raft->servers) { | |
1836 | if (server->replied) { | |
1837 | count ++; | |
1838 | } | |
1839 | } | |
1840 | if (count >= hmap_count(&raft->servers) / 2) { | |
1841 | HMAP_FOR_EACH (server, hmap_node, &raft->servers) { | |
1842 | server->replied = false; | |
1843 | } | |
1844 | raft_reset_election_timer(raft); | |
1845 | } else { | |
1846 | raft_become_follower(raft); | |
1847 | raft_start_election(raft, false); | |
1848 | } | |
1849 | } else { | |
1850 | raft_start_election(raft, false); | |
1851 | } | |
1852 | ||
1b1d2e6d BP |
1853 | } |
1854 | ||
1855 | if (raft->leaving && time_msec() >= raft->leave_timeout) { | |
1856 | raft_send_remove_server_requests(raft); | |
1857 | } | |
1858 | ||
1859 | if (raft->joining && time_msec() >= raft->join_timeout) { | |
1860 | raft->join_timeout = time_msec() + 1000; | |
1861 | LIST_FOR_EACH (conn, list_node, &raft->conns) { | |
1862 | raft_send_add_server_request(raft, conn); | |
1863 | } | |
1864 | } | |
1865 | ||
5a9b53a5 HZ |
1866 | long long int now = time_msec(); |
1867 | if (now >= raft->ping_timeout) { | |
1b1d2e6d BP |
1868 | if (raft->role == RAFT_LEADER) { |
1869 | raft_send_heartbeats(raft); | |
5a9b53a5 HZ |
1870 | } |
1871 | /* Check if any commands timeout. Timeout is set to twice the time of | |
1872 | * election base time so that commands can complete properly during | |
1873 | * leader election. E.g. a leader crashed and current node with pending | |
1874 | * commands becomes new leader: the pending commands can still complete | |
1875 | * if the crashed leader has replicated the transactions to majority of | |
1876 | * followers before it crashed. */ | |
1877 | struct raft_command *cmd, *next_cmd; | |
1878 | HMAP_FOR_EACH_SAFE (cmd, next_cmd, hmap_node, &raft->commands) { | |
1879 | if (cmd->timestamp | |
8e354614 | 1880 | && now - cmd->timestamp > raft->election_timer * 2) { |
5a9b53a5 | 1881 | raft_command_complete(raft, cmd, RAFT_CMD_TIMEOUT); |
1b1d2e6d BP |
1882 | } |
1883 | } | |
f4bef8b3 | 1884 | raft_reset_ping_timer(raft); |
1b1d2e6d BP |
1885 | } |
1886 | ||
1887 | /* Do this only at the end; if we did it as soon as we set raft->left or | |
1888 | * raft->failed in handling the RemoveServerReply, then it could easily | |
1889 | * cause references to freed memory in RPC sessions, etc. */ | |
1890 | if (raft->left || raft->failed) { | |
1891 | raft_close__(raft); | |
1892 | } | |
1893 | } | |
1894 | ||
1895 | static void | |
1896 | raft_wait_session(struct jsonrpc_session *js) | |
1897 | { | |
1898 | if (js) { | |
1899 | jsonrpc_session_wait(js); | |
1900 | jsonrpc_session_recv_wait(js); | |
1901 | } | |
1902 | } | |
1903 | ||
1904 | /* Causes the next call to poll_block() to wake up when 'raft' needs to do | |
1905 | * something. */ | |
1906 | void | |
1907 | raft_wait(struct raft *raft) | |
1908 | { | |
1909 | if (raft->left || raft->failed) { | |
1910 | return; | |
1911 | } | |
1912 | ||
1913 | raft_waiters_wait(raft); | |
1914 | ||
1915 | if (raft->listener) { | |
1916 | pstream_wait(raft->listener); | |
1917 | } else { | |
1918 | poll_timer_wait_until(raft->listen_backoff); | |
1919 | } | |
1920 | ||
1921 | struct raft_conn *conn; | |
1922 | LIST_FOR_EACH (conn, list_node, &raft->conns) { | |
1923 | raft_wait_session(conn->js); | |
1924 | } | |
1925 | ||
1926 | if (!raft->joining) { | |
1927 | poll_timer_wait_until(raft->election_timeout); | |
1928 | } else { | |
1929 | poll_timer_wait_until(raft->join_timeout); | |
1930 | } | |
1931 | if (raft->leaving) { | |
1932 | poll_timer_wait_until(raft->leave_timeout); | |
1933 | } | |
1934 | if (raft->role == RAFT_LEADER || !hmap_is_empty(&raft->commands)) { | |
1935 | poll_timer_wait_until(raft->ping_timeout); | |
1936 | } | |
1937 | } | |
1938 | ||
1939 | static struct raft_waiter * | |
1940 | raft_waiter_create(struct raft *raft, enum raft_waiter_type type, | |
1941 | bool start_commit) | |
1942 | { | |
1943 | struct raft_waiter *w = xzalloc(sizeof *w); | |
1944 | ovs_list_push_back(&raft->waiters, &w->list_node); | |
1945 | w->commit_ticket = start_commit ? ovsdb_log_commit_start(raft->log) : 0; | |
1946 | w->type = type; | |
1947 | return w; | |
1948 | } | |
1949 | ||
1950 | /* Returns a human-readable representation of 'status' (or NULL if 'status' is | |
1951 | * invalid). */ | |
1952 | const char * | |
1953 | raft_command_status_to_string(enum raft_command_status status) | |
1954 | { | |
1955 | switch (status) { | |
1956 | case RAFT_CMD_INCOMPLETE: | |
1957 | return "operation still in progress"; | |
1958 | case RAFT_CMD_SUCCESS: | |
1959 | return "success"; | |
1960 | case RAFT_CMD_NOT_LEADER: | |
1961 | return "not leader"; | |
1962 | case RAFT_CMD_BAD_PREREQ: | |
1963 | return "prerequisite check failed"; | |
1964 | case RAFT_CMD_LOST_LEADERSHIP: | |
1965 | return "lost leadership"; | |
1966 | case RAFT_CMD_SHUTDOWN: | |
1967 | return "server shutdown"; | |
1968 | case RAFT_CMD_IO_ERROR: | |
1969 | return "I/O error"; | |
1970 | case RAFT_CMD_TIMEOUT: | |
1971 | return "timeout"; | |
1972 | default: | |
1973 | return NULL; | |
1974 | } | |
1975 | } | |
1976 | ||
1977 | /* Converts human-readable status in 's' into status code in '*statusp'. | |
1978 | * Returns true if successful, false if 's' is unknown. */ | |
1979 | bool | |
1980 | raft_command_status_from_string(const char *s, | |
1981 | enum raft_command_status *statusp) | |
1982 | { | |
1983 | for (enum raft_command_status status = 0; ; status++) { | |
1984 | const char *s2 = raft_command_status_to_string(status); | |
1985 | if (!s2) { | |
1986 | *statusp = 0; | |
1987 | return false; | |
1988 | } else if (!strcmp(s, s2)) { | |
1989 | *statusp = status; | |
1990 | return true; | |
1991 | } | |
1992 | } | |
1993 | } | |
1994 | ||
1995 | static const struct uuid * | |
1996 | raft_get_eid(const struct raft *raft, uint64_t index) | |
1997 | { | |
1998 | for (; index >= raft->log_start; index--) { | |
1999 | const struct raft_entry *e = raft_get_entry(raft, index); | |
2000 | if (e->data) { | |
2001 | return &e->eid; | |
2002 | } | |
2003 | } | |
2004 | return &raft->snap.eid; | |
2005 | } | |
2006 | ||
2cd62f75 | 2007 | const struct uuid * |
1b1d2e6d BP |
2008 | raft_current_eid(const struct raft *raft) |
2009 | { | |
2010 | return raft_get_eid(raft, raft->log_end - 1); | |
2011 | } | |
2012 | ||
2013 | static struct raft_command * | |
2014 | raft_command_create_completed(enum raft_command_status status) | |
2015 | { | |
2016 | ovs_assert(status != RAFT_CMD_INCOMPLETE); | |
2017 | ||
2018 | struct raft_command *cmd = xzalloc(sizeof *cmd); | |
2019 | cmd->n_refs = 1; | |
2020 | cmd->status = status; | |
2021 | return cmd; | |
2022 | } | |
2023 | ||
2024 | static struct raft_command * | |
2025 | raft_command_create_incomplete(struct raft *raft, uint64_t index) | |
2026 | { | |
2027 | struct raft_command *cmd = xzalloc(sizeof *cmd); | |
2028 | cmd->n_refs = 2; /* One for client, one for raft->commands. */ | |
2029 | cmd->index = index; | |
2030 | cmd->status = RAFT_CMD_INCOMPLETE; | |
2031 | hmap_insert(&raft->commands, &cmd->hmap_node, cmd->index); | |
2032 | return cmd; | |
2033 | } | |
2034 | ||
2035 | static struct raft_command * OVS_WARN_UNUSED_RESULT | |
2036 | raft_command_initiate(struct raft *raft, | |
2037 | const struct json *data, const struct json *servers, | |
8e354614 | 2038 | uint64_t election_timer, const struct uuid *eid) |
1b1d2e6d BP |
2039 | { |
2040 | /* Write to local log. */ | |
2041 | uint64_t index = raft->log_end; | |
2042 | if (!raft_handle_write_error( | |
2043 | raft, raft_write_entry( | |
2044 | raft, raft->term, json_nullable_clone(data), eid, | |
8e354614 HZ |
2045 | json_nullable_clone(servers), |
2046 | election_timer))) { | |
1b1d2e6d BP |
2047 | return raft_command_create_completed(RAFT_CMD_IO_ERROR); |
2048 | } | |
2049 | ||
2050 | struct raft_command *cmd = raft_command_create_incomplete(raft, index); | |
7ef36089 HZ |
2051 | ovs_assert(eid); |
2052 | cmd->eid = *eid; | |
5a9b53a5 | 2053 | cmd->timestamp = time_msec(); |
1b1d2e6d BP |
2054 | |
2055 | raft_waiter_create(raft, RAFT_W_ENTRY, true)->entry.index = cmd->index; | |
2056 | ||
67dba070 HZ |
2057 | if (failure_test == FT_CRASH_BEFORE_SEND_APPEND_REQ) { |
2058 | ovs_fatal(0, "Raft test: crash before sending append_request."); | |
2059 | } | |
1b1d2e6d BP |
2060 | /* Write to remote logs. */ |
2061 | struct raft_server *s; | |
2062 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
2063 | if (!uuid_equals(&s->sid, &raft->sid) && s->next_index == index) { | |
2064 | raft_send_append_request(raft, s, 1, "execute command"); | |
2065 | s->next_index++; | |
2066 | } | |
2067 | } | |
67dba070 HZ |
2068 | if (failure_test == FT_CRASH_AFTER_SEND_APPEND_REQ) { |
2069 | ovs_fatal(0, "Raft test: crash after sending append_request."); | |
2070 | } | |
0f954f32 | 2071 | raft_reset_ping_timer(raft); |
1b1d2e6d BP |
2072 | |
2073 | return cmd; | |
2074 | } | |
2075 | ||
5a9b53a5 HZ |
2076 | static void |
2077 | log_all_commands(struct raft *raft) | |
2078 | { | |
2079 | struct raft_command *cmd, *next; | |
2080 | HMAP_FOR_EACH_SAFE (cmd, next, hmap_node, &raft->commands) { | |
2081 | VLOG_DBG("raft command eid: "UUID_FMT, UUID_ARGS(&cmd->eid)); | |
2082 | } | |
2083 | } | |
2084 | ||
1b1d2e6d | 2085 | static struct raft_command * OVS_WARN_UNUSED_RESULT |
8e354614 HZ |
2086 | raft_command_execute__(struct raft *raft, const struct json *data, |
2087 | const struct json *servers, uint64_t election_timer, | |
1b1d2e6d BP |
2088 | const struct uuid *prereq, struct uuid *result) |
2089 | { | |
2090 | if (raft->joining || raft->leaving || raft->left || raft->failed) { | |
2091 | return raft_command_create_completed(RAFT_CMD_SHUTDOWN); | |
2092 | } | |
2093 | ||
2094 | if (raft->role != RAFT_LEADER) { | |
2095 | /* Consider proxying the command to the leader. We can only do that if | |
2096 | * we know the leader and the command does not change the set of | |
2097 | * servers. We do not proxy commands without prerequisites, even | |
2098 | * though we could, because in an OVSDB context a log entry doesn't | |
2099 | * make sense without context. */ | |
8e354614 | 2100 | if (servers || election_timer || !data |
1b1d2e6d BP |
2101 | || raft->role != RAFT_FOLLOWER || uuid_is_zero(&raft->leader_sid) |
2102 | || !prereq) { | |
2103 | return raft_command_create_completed(RAFT_CMD_NOT_LEADER); | |
2104 | } | |
2105 | } | |
2106 | ||
2107 | struct uuid eid = data ? uuid_random() : UUID_ZERO; | |
2108 | if (result) { | |
2109 | *result = eid; | |
2110 | } | |
2111 | ||
2112 | if (raft->role != RAFT_LEADER) { | |
2113 | const union raft_rpc rpc = { | |
2114 | .execute_command_request = { | |
2115 | .common = { | |
2116 | .type = RAFT_RPC_EXECUTE_COMMAND_REQUEST, | |
2117 | .sid = raft->leader_sid, | |
2118 | }, | |
2119 | .data = CONST_CAST(struct json *, data), | |
2120 | .prereq = *prereq, | |
2121 | .result = eid, | |
2122 | } | |
2123 | }; | |
67dba070 HZ |
2124 | if (failure_test == FT_CRASH_BEFORE_SEND_EXEC_REQ) { |
2125 | ovs_fatal(0, "Raft test: crash before sending " | |
2126 | "execute_command_request"); | |
2127 | } | |
1b1d2e6d BP |
2128 | if (!raft_send(raft, &rpc)) { |
2129 | /* Couldn't send command, so it definitely failed. */ | |
2130 | return raft_command_create_completed(RAFT_CMD_NOT_LEADER); | |
2131 | } | |
67dba070 HZ |
2132 | if (failure_test == FT_CRASH_AFTER_SEND_EXEC_REQ) { |
2133 | ovs_fatal(0, "Raft test: crash after sending " | |
2134 | "execute_command_request"); | |
2135 | } | |
1b1d2e6d BP |
2136 | |
2137 | struct raft_command *cmd = raft_command_create_incomplete(raft, 0); | |
2138 | cmd->timestamp = time_msec(); | |
2139 | cmd->eid = eid; | |
5a9b53a5 | 2140 | log_all_commands(raft); |
1b1d2e6d BP |
2141 | return cmd; |
2142 | } | |
2143 | ||
2144 | const struct uuid *current_eid = raft_current_eid(raft); | |
2145 | if (prereq && !uuid_equals(prereq, current_eid)) { | |
2146 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
2147 | VLOG_INFO_RL(&rl, "current entry eid "UUID_FMT" does not match " | |
2148 | "prerequisite "UUID_FMT, | |
2149 | UUID_ARGS(current_eid), UUID_ARGS(prereq)); | |
2150 | return raft_command_create_completed(RAFT_CMD_BAD_PREREQ); | |
2151 | } | |
2152 | ||
8e354614 | 2153 | return raft_command_initiate(raft, data, servers, election_timer, &eid); |
1b1d2e6d BP |
2154 | } |
2155 | ||
2156 | /* Initiates appending a log entry to 'raft'. The log entry consists of 'data' | |
2157 | * and, if 'prereq' is nonnull, it is only added to the log if the previous | |
2158 | * entry in the log has entry ID 'prereq'. If 'result' is nonnull, it is | |
2159 | * populated with the entry ID for the new log entry. | |
2160 | * | |
2161 | * Returns a "struct raft_command" that may be used to track progress adding | |
2162 | * the log entry. The caller must eventually free the returned structure, with | |
2163 | * raft_command_unref(). */ | |
2164 | struct raft_command * OVS_WARN_UNUSED_RESULT | |
2165 | raft_command_execute(struct raft *raft, const struct json *data, | |
2166 | const struct uuid *prereq, struct uuid *result) | |
2167 | { | |
8e354614 | 2168 | return raft_command_execute__(raft, data, NULL, 0, prereq, result); |
1b1d2e6d BP |
2169 | } |
2170 | ||
2171 | /* Returns the status of 'cmd'. */ | |
2172 | enum raft_command_status | |
2173 | raft_command_get_status(const struct raft_command *cmd) | |
2174 | { | |
2175 | ovs_assert(cmd->n_refs > 0); | |
2176 | return cmd->status; | |
2177 | } | |
2178 | ||
2179 | /* Returns the index of the log entry at which 'cmd' was committed. | |
2180 | * | |
2181 | * This function works only with successful commands. */ | |
2182 | uint64_t | |
2183 | raft_command_get_commit_index(const struct raft_command *cmd) | |
2184 | { | |
2185 | ovs_assert(cmd->n_refs > 0); | |
2186 | ovs_assert(cmd->status == RAFT_CMD_SUCCESS); | |
2187 | return cmd->index; | |
2188 | } | |
2189 | ||
2190 | /* Frees 'cmd'. */ | |
2191 | void | |
2192 | raft_command_unref(struct raft_command *cmd) | |
2193 | { | |
2194 | if (cmd) { | |
2195 | ovs_assert(cmd->n_refs > 0); | |
2196 | if (!--cmd->n_refs) { | |
2197 | free(cmd); | |
2198 | } | |
2199 | } | |
2200 | } | |
2201 | ||
2202 | /* Causes poll_block() to wake up when 'cmd' has status to report. */ | |
2203 | void | |
2204 | raft_command_wait(const struct raft_command *cmd) | |
2205 | { | |
2206 | if (cmd->status != RAFT_CMD_INCOMPLETE) { | |
2207 | poll_immediate_wake(); | |
2208 | } | |
2209 | } | |
2210 | ||
2211 | static void | |
2212 | raft_command_complete(struct raft *raft, | |
2213 | struct raft_command *cmd, | |
2214 | enum raft_command_status status) | |
2215 | { | |
5a9b53a5 HZ |
2216 | VLOG_DBG("raft_command_complete eid "UUID_FMT" status: %s", |
2217 | UUID_ARGS(&cmd->eid), raft_command_status_to_string(status)); | |
1b1d2e6d BP |
2218 | if (!uuid_is_zero(&cmd->sid)) { |
2219 | uint64_t commit_index = status == RAFT_CMD_SUCCESS ? cmd->index : 0; | |
2220 | raft_send_execute_command_reply(raft, &cmd->sid, &cmd->eid, status, | |
2221 | commit_index); | |
2222 | } | |
2223 | ||
2224 | ovs_assert(cmd->status == RAFT_CMD_INCOMPLETE); | |
2225 | ovs_assert(cmd->n_refs > 0); | |
2226 | hmap_remove(&raft->commands, &cmd->hmap_node); | |
2227 | cmd->status = status; | |
2228 | raft_command_unref(cmd); | |
2229 | } | |
2230 | ||
2231 | static void | |
2232 | raft_complete_all_commands(struct raft *raft, enum raft_command_status status) | |
2233 | { | |
2234 | struct raft_command *cmd, *next; | |
2235 | HMAP_FOR_EACH_SAFE (cmd, next, hmap_node, &raft->commands) { | |
2236 | raft_command_complete(raft, cmd, status); | |
2237 | } | |
2238 | } | |
2239 | ||
1b1d2e6d BP |
2240 | static struct raft_command * |
2241 | raft_find_command_by_eid(struct raft *raft, const struct uuid *eid) | |
2242 | { | |
2243 | struct raft_command *cmd; | |
2244 | ||
2245 | HMAP_FOR_EACH (cmd, hmap_node, &raft->commands) { | |
2246 | if (uuid_equals(&cmd->eid, eid)) { | |
2247 | return cmd; | |
2248 | } | |
2249 | } | |
2250 | return NULL; | |
2251 | } | |
2252 | \f | |
2253 | #define RAFT_RPC(ENUM, NAME) \ | |
2254 | static void raft_handle_##NAME(struct raft *, const struct raft_##NAME *); | |
2255 | RAFT_RPC_TYPES | |
2256 | #undef RAFT_RPC | |
2257 | ||
2258 | static void | |
2259 | raft_handle_hello_request(struct raft *raft OVS_UNUSED, | |
2260 | const struct raft_hello_request *hello OVS_UNUSED) | |
2261 | { | |
2262 | } | |
2263 | ||
2264 | /* 'sid' is the server being added. */ | |
2265 | static void | |
2266 | raft_send_add_server_reply__(struct raft *raft, const struct uuid *sid, | |
2267 | const char *address, | |
2268 | bool success, const char *comment) | |
2269 | { | |
2270 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10); | |
2271 | if (!VLOG_DROP_INFO(&rl)) { | |
2272 | struct ds s = DS_EMPTY_INITIALIZER; | |
2273 | char buf[SID_LEN + 1]; | |
2274 | ds_put_format(&s, "adding %s ("SID_FMT" at %s) " | |
2275 | "to cluster "CID_FMT" %s", | |
2276 | raft_get_nickname(raft, sid, buf, sizeof buf), | |
2277 | SID_ARGS(sid), address, CID_ARGS(&raft->cid), | |
2278 | success ? "succeeded" : "failed"); | |
2279 | if (comment) { | |
2280 | ds_put_format(&s, " (%s)", comment); | |
2281 | } | |
2282 | VLOG_INFO("%s", ds_cstr(&s)); | |
2283 | ds_destroy(&s); | |
2284 | } | |
2285 | ||
2286 | union raft_rpc rpy = { | |
2287 | .add_server_reply = { | |
2288 | .common = { | |
2289 | .type = RAFT_RPC_ADD_SERVER_REPLY, | |
2290 | .sid = *sid, | |
2291 | .comment = CONST_CAST(char *, comment), | |
2292 | }, | |
2293 | .success = success, | |
2294 | } | |
2295 | }; | |
2296 | ||
2297 | struct sset *remote_addresses = &rpy.add_server_reply.remote_addresses; | |
2298 | sset_init(remote_addresses); | |
2299 | if (!raft->joining) { | |
2300 | struct raft_server *s; | |
2301 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
2302 | if (!uuid_equals(&s->sid, &raft->sid)) { | |
2303 | sset_add(remote_addresses, s->address); | |
2304 | } | |
2305 | } | |
2306 | } | |
2307 | ||
2308 | raft_send(raft, &rpy); | |
2309 | ||
2310 | sset_destroy(remote_addresses); | |
2311 | } | |
2312 | ||
2313 | static void | |
17bd4149 BP |
2314 | raft_send_remove_server_reply_rpc(struct raft *raft, |
2315 | const struct uuid *dst_sid, | |
2316 | const struct uuid *target_sid, | |
1b1d2e6d BP |
2317 | bool success, const char *comment) |
2318 | { | |
17bd4149 BP |
2319 | if (uuid_equals(&raft->sid, dst_sid)) { |
2320 | if (success && uuid_equals(&raft->sid, target_sid)) { | |
2321 | raft_finished_leaving_cluster(raft); | |
2322 | } | |
2323 | return; | |
2324 | } | |
2325 | ||
1b1d2e6d BP |
2326 | const union raft_rpc rpy = { |
2327 | .remove_server_reply = { | |
2328 | .common = { | |
2329 | .type = RAFT_RPC_REMOVE_SERVER_REPLY, | |
17bd4149 | 2330 | .sid = *dst_sid, |
1b1d2e6d BP |
2331 | .comment = CONST_CAST(char *, comment), |
2332 | }, | |
17bd4149 BP |
2333 | .target_sid = (uuid_equals(dst_sid, target_sid) |
2334 | ? UUID_ZERO | |
2335 | : *target_sid), | |
1b1d2e6d BP |
2336 | .success = success, |
2337 | } | |
2338 | }; | |
2339 | raft_send(raft, &rpy); | |
2340 | } | |
2341 | ||
2342 | static void | |
2343 | raft_send_remove_server_reply__(struct raft *raft, | |
2344 | const struct uuid *target_sid, | |
2345 | const struct uuid *requester_sid, | |
2346 | struct unixctl_conn *requester_conn, | |
2347 | bool success, const char *comment) | |
2348 | { | |
2349 | struct ds s = DS_EMPTY_INITIALIZER; | |
2350 | ds_put_format(&s, "request "); | |
2351 | if (!uuid_is_zero(requester_sid)) { | |
2352 | char buf[SID_LEN + 1]; | |
2353 | ds_put_format(&s, "by %s", | |
2354 | raft_get_nickname(raft, requester_sid, buf, sizeof buf)); | |
2355 | } else { | |
2356 | ds_put_cstr(&s, "via unixctl"); | |
2357 | } | |
2358 | ds_put_cstr(&s, " to remove "); | |
2359 | if (!requester_conn && uuid_equals(target_sid, requester_sid)) { | |
2360 | ds_put_cstr(&s, "itself"); | |
2361 | } else { | |
2362 | char buf[SID_LEN + 1]; | |
2363 | ds_put_cstr(&s, raft_get_nickname(raft, target_sid, buf, sizeof buf)); | |
17bd4149 BP |
2364 | if (uuid_equals(target_sid, &raft->sid)) { |
2365 | ds_put_cstr(&s, " (ourselves)"); | |
2366 | } | |
1b1d2e6d BP |
2367 | } |
2368 | ds_put_format(&s, " from cluster "CID_FMT" %s", | |
2369 | CID_ARGS(&raft->cid), | |
2370 | success ? "succeeded" : "failed"); | |
2371 | if (comment) { | |
2372 | ds_put_format(&s, " (%s)", comment); | |
2373 | } | |
2374 | ||
2375 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10); | |
2376 | VLOG_INFO_RL(&rl, "%s", ds_cstr(&s)); | |
2377 | ||
2378 | /* Send RemoveServerReply to the requester (which could be a server or a | |
2379 | * unixctl connection. Also always send it to the removed server; this | |
2380 | * allows it to be sure that it's really removed and update its log and | |
2381 | * disconnect permanently. */ | |
2382 | if (!uuid_is_zero(requester_sid)) { | |
17bd4149 | 2383 | raft_send_remove_server_reply_rpc(raft, requester_sid, target_sid, |
1b1d2e6d BP |
2384 | success, comment); |
2385 | } | |
2386 | if (!uuid_equals(requester_sid, target_sid)) { | |
17bd4149 BP |
2387 | raft_send_remove_server_reply_rpc(raft, target_sid, target_sid, |
2388 | success, comment); | |
1b1d2e6d BP |
2389 | } |
2390 | if (requester_conn) { | |
2391 | if (success) { | |
2392 | unixctl_command_reply(requester_conn, ds_cstr(&s)); | |
2393 | } else { | |
2394 | unixctl_command_reply_error(requester_conn, ds_cstr(&s)); | |
2395 | } | |
2396 | } | |
2397 | ||
2398 | ds_destroy(&s); | |
2399 | } | |
2400 | ||
2401 | static void | |
2402 | raft_send_add_server_reply(struct raft *raft, | |
2403 | const struct raft_add_server_request *rq, | |
2404 | bool success, const char *comment) | |
2405 | { | |
2406 | return raft_send_add_server_reply__(raft, &rq->common.sid, rq->address, | |
2407 | success, comment); | |
2408 | } | |
2409 | ||
2410 | static void | |
2411 | raft_send_remove_server_reply(struct raft *raft, | |
2412 | const struct raft_remove_server_request *rq, | |
2413 | bool success, const char *comment) | |
2414 | { | |
2415 | return raft_send_remove_server_reply__(raft, &rq->sid, &rq->common.sid, | |
2416 | rq->requester_conn, success, | |
2417 | comment); | |
2418 | } | |
2419 | ||
2420 | static void | |
2421 | raft_become_follower(struct raft *raft) | |
2422 | { | |
2423 | raft->leader_sid = UUID_ZERO; | |
2424 | if (raft->role == RAFT_FOLLOWER) { | |
2425 | return; | |
2426 | } | |
2427 | ||
2428 | raft->role = RAFT_FOLLOWER; | |
0f954f32 | 2429 | raft_reset_election_timer(raft); |
1b1d2e6d BP |
2430 | |
2431 | /* Notify clients about lost leadership. | |
2432 | * | |
2433 | * We do not reverse our changes to 'raft->servers' because the new | |
2434 | * configuration is already part of the log. Possibly the configuration | |
2435 | * log entry will not be committed, but until we know that we must use the | |
2436 | * new configuration. Our AppendEntries processing will properly update | |
2437 | * the server configuration later, if necessary. */ | |
2438 | struct raft_server *s; | |
2439 | HMAP_FOR_EACH (s, hmap_node, &raft->add_servers) { | |
2440 | raft_send_add_server_reply__(raft, &s->sid, s->address, false, | |
2441 | RAFT_SERVER_LOST_LEADERSHIP); | |
2442 | } | |
2443 | if (raft->remove_server) { | |
2444 | raft_send_remove_server_reply__(raft, &raft->remove_server->sid, | |
2445 | &raft->remove_server->requester_sid, | |
2446 | raft->remove_server->requester_conn, | |
2447 | false, RAFT_SERVER_LOST_LEADERSHIP); | |
2448 | raft_server_destroy(raft->remove_server); | |
2449 | raft->remove_server = NULL; | |
2450 | } | |
2451 | ||
2452 | raft_complete_all_commands(raft, RAFT_CMD_LOST_LEADERSHIP); | |
2453 | } | |
2454 | ||
2455 | static void | |
2456 | raft_send_append_request(struct raft *raft, | |
2457 | struct raft_server *peer, unsigned int n, | |
2458 | const char *comment) | |
2459 | { | |
2460 | ovs_assert(raft->role == RAFT_LEADER); | |
2461 | ||
2462 | const union raft_rpc rq = { | |
2463 | .append_request = { | |
2464 | .common = { | |
2465 | .type = RAFT_RPC_APPEND_REQUEST, | |
2466 | .sid = peer->sid, | |
2467 | .comment = CONST_CAST(char *, comment), | |
2468 | }, | |
2469 | .term = raft->term, | |
2470 | .prev_log_index = peer->next_index - 1, | |
2471 | .prev_log_term = (peer->next_index - 1 >= raft->log_start | |
2472 | ? raft->entries[peer->next_index - 1 | |
2473 | - raft->log_start].term | |
2474 | : raft->snap.term), | |
2475 | .leader_commit = raft->commit_index, | |
2476 | .entries = &raft->entries[peer->next_index - raft->log_start], | |
2477 | .n_entries = n, | |
2478 | }, | |
2479 | }; | |
2480 | raft_send(raft, &rq); | |
2481 | } | |
2482 | ||
2483 | static void | |
2484 | raft_send_heartbeats(struct raft *raft) | |
2485 | { | |
2486 | struct raft_server *s; | |
2487 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
2488 | if (!uuid_equals(&raft->sid, &s->sid)) { | |
2489 | raft_send_append_request(raft, s, 0, "heartbeat"); | |
2490 | } | |
2491 | } | |
2492 | ||
2493 | /* Send anyone waiting for a command to complete a ping to let them | |
2494 | * know we're still working on it. */ | |
2495 | struct raft_command *cmd; | |
2496 | HMAP_FOR_EACH (cmd, hmap_node, &raft->commands) { | |
2497 | if (!uuid_is_zero(&cmd->sid)) { | |
2498 | raft_send_execute_command_reply(raft, &cmd->sid, | |
2499 | &cmd->eid, | |
2500 | RAFT_CMD_INCOMPLETE, 0); | |
2501 | } | |
2502 | } | |
0f954f32 HZ |
2503 | |
2504 | raft_reset_ping_timer(raft); | |
1b1d2e6d BP |
2505 | } |
2506 | ||
2507 | /* Initializes the fields in 's' that represent the leader's view of the | |
2508 | * server. */ | |
2509 | static void | |
2510 | raft_server_init_leader(struct raft *raft, struct raft_server *s) | |
2511 | { | |
2512 | s->next_index = raft->log_end; | |
2513 | s->match_index = 0; | |
2514 | s->phase = RAFT_PHASE_STABLE; | |
89771c1e | 2515 | s->replied = false; |
1b1d2e6d BP |
2516 | } |
2517 | ||
923f01ca HZ |
2518 | static void |
2519 | raft_set_leader(struct raft *raft, const struct uuid *sid) | |
2520 | { | |
2521 | raft->leader_sid = *sid; | |
2522 | raft->had_leader = true; | |
2523 | raft->candidate_retrying = false; | |
2524 | } | |
2525 | ||
1b1d2e6d BP |
2526 | static void |
2527 | raft_become_leader(struct raft *raft) | |
2528 | { | |
5a9b53a5 | 2529 | log_all_commands(raft); |
1b1d2e6d BP |
2530 | |
2531 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); | |
2532 | VLOG_INFO_RL(&rl, "term %"PRIu64": elected leader by %d+ of " | |
2533 | "%"PRIuSIZE" servers", raft->term, | |
2534 | raft->n_votes, hmap_count(&raft->servers)); | |
2535 | ||
2536 | ovs_assert(raft->role != RAFT_LEADER); | |
2537 | raft->role = RAFT_LEADER; | |
923f01ca | 2538 | raft_set_leader(raft, &raft->sid); |
89771c1e | 2539 | raft_reset_election_timer(raft); |
0f954f32 | 2540 | raft_reset_ping_timer(raft); |
1b1d2e6d BP |
2541 | |
2542 | struct raft_server *s; | |
2543 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
2544 | raft_server_init_leader(raft, s); | |
2545 | } | |
2546 | ||
8e354614 HZ |
2547 | raft->election_timer_new = 0; |
2548 | ||
1b1d2e6d BP |
2549 | raft_update_our_match_index(raft, raft->log_end - 1); |
2550 | raft_send_heartbeats(raft); | |
2551 | ||
2552 | /* Write the fact that we are leader to the log. This is not used by the | |
2553 | * algorithm (although it could be, for quick restart), but it is used for | |
2554 | * offline analysis to check for conformance with the properties that Raft | |
2555 | * guarantees. */ | |
2556 | struct raft_record r = { | |
2557 | .type = RAFT_REC_LEADER, | |
2558 | .term = raft->term, | |
2559 | .sid = raft->sid, | |
2560 | }; | |
2561 | ignore(ovsdb_log_write_and_free(raft->log, raft_record_to_json(&r))); | |
2562 | ||
2563 | /* Initiate a no-op commit. Otherwise we might never find out what's in | |
2564 | * the log. See section 6.4 item 1: | |
2565 | * | |
2566 | * The Leader Completeness Property guarantees that a leader has all | |
2567 | * committed entries, but at the start of its term, it may not know | |
2568 | * which those are. To find out, it needs to commit an entry from its | |
2569 | * term. Raft handles this by having each leader commit a blank no-op | |
2570 | * entry into the log at the start of its term. As soon as this no-op | |
2571 | * entry is committed, the leader’s commit index will be at least as | |
2572 | * large as any other servers’ during its term. | |
2573 | */ | |
8e354614 HZ |
2574 | raft_command_unref(raft_command_execute__(raft, NULL, NULL, 0, NULL, |
2575 | NULL)); | |
1b1d2e6d BP |
2576 | } |
2577 | ||
2578 | /* Processes term 'term' received as part of RPC 'common'. Returns true if the | |
2579 | * caller should continue processing the RPC, false if the caller should reject | |
2580 | * it due to a stale term. */ | |
2581 | static bool | |
2582 | raft_receive_term__(struct raft *raft, const struct raft_rpc_common *common, | |
2583 | uint64_t term) | |
2584 | { | |
2585 | /* Section 3.3 says: | |
2586 | * | |
2587 | * Current terms are exchanged whenever servers communicate; if one | |
2588 | * server’s current term is smaller than the other’s, then it updates | |
2589 | * its current term to the larger value. If a candidate or leader | |
2590 | * discovers that its term is out of date, it immediately reverts to | |
2591 | * follower state. If a server receives a request with a stale term | |
2592 | * number, it rejects the request. | |
2593 | */ | |
2594 | if (term > raft->term) { | |
2595 | if (!raft_set_term(raft, term, NULL)) { | |
2596 | /* Failed to update the term to 'term'. */ | |
2597 | return false; | |
2598 | } | |
2599 | raft_become_follower(raft); | |
2600 | } else if (term < raft->term) { | |
2601 | char buf[SID_LEN + 1]; | |
2602 | VLOG_INFO("rejecting term %"PRIu64" < current term %"PRIu64" received " | |
2603 | "in %s message from server %s", | |
2604 | term, raft->term, | |
2605 | raft_rpc_type_to_string(common->type), | |
2606 | raft_get_nickname(raft, &common->sid, buf, sizeof buf)); | |
2607 | return false; | |
2608 | } | |
2609 | return true; | |
2610 | } | |
2611 | ||
2612 | static void | |
2613 | raft_get_servers_from_log(struct raft *raft, enum vlog_level level) | |
2614 | { | |
2615 | const struct json *servers_json = raft->snap.servers; | |
2616 | for (uint64_t index = raft->log_end - 1; index >= raft->log_start; | |
2617 | index--) { | |
2618 | struct raft_entry *e = &raft->entries[index - raft->log_start]; | |
2619 | if (e->servers) { | |
2620 | servers_json = e->servers; | |
2621 | break; | |
2622 | } | |
2623 | } | |
2624 | ||
2625 | struct hmap servers; | |
2626 | struct ovsdb_error *error = raft_servers_from_json(servers_json, &servers); | |
2627 | ovs_assert(!error); | |
2628 | raft_set_servers(raft, &servers, level); | |
2629 | raft_servers_destroy(&servers); | |
2630 | } | |
2631 | ||
2632 | /* Truncates the log, so that raft->log_end becomes 'new_end'. | |
2633 | * | |
2634 | * Doesn't write anything to disk. In theory, we could truncate the on-disk | |
2635 | * log file, but we don't have the right information to know how long it should | |
2636 | * be. What we actually do is to append entries for older indexes to the | |
2637 | * on-disk log; when we re-read it later, these entries truncate the log. | |
2638 | * | |
2639 | * Returns true if any of the removed log entries were server configuration | |
2640 | * entries, false otherwise. */ | |
2641 | static bool | |
2642 | raft_truncate(struct raft *raft, uint64_t new_end) | |
2643 | { | |
2644 | ovs_assert(new_end >= raft->log_start); | |
2645 | if (raft->log_end > new_end) { | |
2646 | char buf[SID_LEN + 1]; | |
2647 | VLOG_INFO("%s truncating %"PRIu64 " entries from end of log", | |
2648 | raft_get_nickname(raft, &raft->sid, buf, sizeof buf), | |
2649 | raft->log_end - new_end); | |
2650 | } | |
2651 | ||
2652 | bool servers_changed = false; | |
2653 | while (raft->log_end > new_end) { | |
2654 | struct raft_entry *entry = &raft->entries[--raft->log_end | |
2655 | - raft->log_start]; | |
2656 | if (entry->servers) { | |
2657 | servers_changed = true; | |
2658 | } | |
2659 | raft_entry_uninit(entry); | |
2660 | } | |
2661 | return servers_changed; | |
2662 | } | |
2663 | ||
2664 | static const struct json * | |
2665 | raft_peek_next_entry(struct raft *raft, struct uuid *eid) | |
2666 | { | |
2667 | /* Invariant: log_start - 2 <= last_applied <= commit_index < log_end. */ | |
2668 | ovs_assert(raft->log_start <= raft->last_applied + 2); | |
2669 | ovs_assert(raft->last_applied <= raft->commit_index); | |
2670 | ovs_assert(raft->commit_index < raft->log_end); | |
2671 | ||
2672 | if (raft->joining || raft->failed) { | |
2673 | return NULL; | |
2674 | } | |
2675 | ||
2676 | if (raft->log_start == raft->last_applied + 2) { | |
2677 | *eid = raft->snap.eid; | |
2678 | return raft->snap.data; | |
2679 | } | |
2680 | ||
2681 | while (raft->last_applied < raft->commit_index) { | |
2682 | const struct raft_entry *e = raft_get_entry(raft, | |
2683 | raft->last_applied + 1); | |
2684 | if (e->data) { | |
2685 | *eid = e->eid; | |
2686 | return e->data; | |
2687 | } | |
2688 | raft->last_applied++; | |
2689 | } | |
2690 | return NULL; | |
2691 | } | |
2692 | ||
2693 | static const struct json * | |
2694 | raft_get_next_entry(struct raft *raft, struct uuid *eid) | |
2695 | { | |
2696 | const struct json *data = raft_peek_next_entry(raft, eid); | |
2697 | if (data) { | |
2698 | raft->last_applied++; | |
2699 | } | |
2700 | return data; | |
2701 | } | |
2702 | ||
0f954f32 HZ |
2703 | /* Updates commit index in raft log. If commit index is already up-to-date |
2704 | * it does nothing and return false, otherwise, returns true. */ | |
2705 | static bool | |
1b1d2e6d BP |
2706 | raft_update_commit_index(struct raft *raft, uint64_t new_commit_index) |
2707 | { | |
2708 | if (new_commit_index <= raft->commit_index) { | |
0f954f32 | 2709 | return false; |
1b1d2e6d BP |
2710 | } |
2711 | ||
2712 | if (raft->role == RAFT_LEADER) { | |
2713 | while (raft->commit_index < new_commit_index) { | |
2714 | uint64_t index = ++raft->commit_index; | |
2715 | const struct raft_entry *e = raft_get_entry(raft, index); | |
1b1d2e6d BP |
2716 | if (e->data) { |
2717 | struct raft_command *cmd | |
5a9b53a5 | 2718 | = raft_find_command_by_eid(raft, &e->eid); |
1b1d2e6d | 2719 | if (cmd) { |
5a9b53a5 HZ |
2720 | if (!cmd->index) { |
2721 | VLOG_DBG("Command completed after role change from" | |
2722 | " follower to leader "UUID_FMT, | |
2723 | UUID_ARGS(&e->eid)); | |
2724 | cmd->index = index; | |
2725 | } | |
1b1d2e6d BP |
2726 | raft_command_complete(raft, cmd, RAFT_CMD_SUCCESS); |
2727 | } | |
2728 | } | |
8e354614 HZ |
2729 | if (e->election_timer) { |
2730 | VLOG_INFO("Election timer changed from %"PRIu64" to %"PRIu64, | |
2731 | raft->election_timer, e->election_timer); | |
2732 | raft->election_timer = e->election_timer; | |
2733 | raft->election_timer_new = 0; | |
2734 | } | |
8b37ed75 BP |
2735 | if (e->servers) { |
2736 | /* raft_run_reconfigure() can write a new Raft entry, which can | |
2737 | * reallocate raft->entries, which would invalidate 'e', so | |
2738 | * this case must be last, after the one for 'e->data'. */ | |
2739 | raft_run_reconfigure(raft); | |
2740 | } | |
1b1d2e6d BP |
2741 | } |
2742 | } else { | |
8e354614 HZ |
2743 | while (raft->commit_index < new_commit_index) { |
2744 | uint64_t index = ++raft->commit_index; | |
2745 | const struct raft_entry *e = raft_get_entry(raft, index); | |
2746 | if (e->election_timer) { | |
2747 | VLOG_INFO("Election timer changed from %"PRIu64" to %"PRIu64, | |
2748 | raft->election_timer, e->election_timer); | |
2749 | raft->election_timer = e->election_timer; | |
2750 | } | |
2751 | } | |
5a9b53a5 HZ |
2752 | /* Check if any pending command can be completed, and complete it. |
2753 | * This can happen when leader fail-over before sending | |
2754 | * execute_command_reply. */ | |
2755 | const struct uuid *eid = raft_get_eid(raft, new_commit_index); | |
2756 | struct raft_command *cmd = raft_find_command_by_eid(raft, eid); | |
2757 | if (cmd) { | |
2758 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
2759 | VLOG_INFO_RL(&rl, | |
2760 | "Command completed without reply (eid: "UUID_FMT", " | |
2761 | "commit index: %"PRIu64")", | |
2762 | UUID_ARGS(eid), new_commit_index); | |
2763 | cmd->index = new_commit_index; | |
2764 | raft_command_complete(raft, cmd, RAFT_CMD_SUCCESS); | |
2765 | } | |
1b1d2e6d BP |
2766 | } |
2767 | ||
2768 | /* Write the commit index to the log. The next time we restart, this | |
2769 | * allows us to start exporting a reasonably fresh log, instead of a log | |
2770 | * that only contains the snapshot. */ | |
2771 | struct raft_record r = { | |
2772 | .type = RAFT_REC_COMMIT_INDEX, | |
2773 | .commit_index = raft->commit_index, | |
2774 | }; | |
2775 | ignore(ovsdb_log_write_and_free(raft->log, raft_record_to_json(&r))); | |
0f954f32 | 2776 | return true; |
1b1d2e6d BP |
2777 | } |
2778 | ||
2779 | /* This doesn't use rq->entries (but it does use rq->n_entries). */ | |
2780 | static void | |
2781 | raft_send_append_reply(struct raft *raft, const struct raft_append_request *rq, | |
2782 | enum raft_append_result result, const char *comment) | |
2783 | { | |
2784 | /* Figure 3.1: "If leaderCommit > commitIndex, set commitIndex = | |
2785 | * min(leaderCommit, index of last new entry)" */ | |
2786 | if (result == RAFT_APPEND_OK && rq->leader_commit > raft->commit_index) { | |
2787 | raft_update_commit_index( | |
2788 | raft, MIN(rq->leader_commit, rq->prev_log_index + rq->n_entries)); | |
2789 | } | |
2790 | ||
2791 | /* Send reply. */ | |
2792 | union raft_rpc reply = { | |
2793 | .append_reply = { | |
2794 | .common = { | |
2795 | .type = RAFT_RPC_APPEND_REPLY, | |
2796 | .sid = rq->common.sid, | |
2797 | .comment = CONST_CAST(char *, comment), | |
2798 | }, | |
2799 | .term = raft->term, | |
2800 | .log_end = raft->log_end, | |
2801 | .prev_log_index = rq->prev_log_index, | |
2802 | .prev_log_term = rq->prev_log_term, | |
2803 | .n_entries = rq->n_entries, | |
2804 | .result = result, | |
2805 | } | |
2806 | }; | |
2807 | raft_send(raft, &reply); | |
2808 | } | |
2809 | ||
2810 | /* If 'prev_log_index' exists in 'raft''s log, in term 'prev_log_term', returns | |
2811 | * NULL. Otherwise, returns an explanation for the mismatch. */ | |
2812 | static const char * | |
2813 | match_index_and_term(const struct raft *raft, | |
2814 | uint64_t prev_log_index, uint64_t prev_log_term) | |
2815 | { | |
2816 | if (prev_log_index < raft->log_start - 1) { | |
2817 | return "mismatch before start of log"; | |
2818 | } else if (prev_log_index == raft->log_start - 1) { | |
2819 | if (prev_log_term != raft->snap.term) { | |
2820 | return "prev_term mismatch"; | |
2821 | } | |
2822 | } else if (prev_log_index < raft->log_end) { | |
2823 | if (raft->entries[prev_log_index - raft->log_start].term | |
2824 | != prev_log_term) { | |
2825 | return "term mismatch"; | |
2826 | } | |
2827 | } else { | |
2828 | /* prev_log_index >= raft->log_end */ | |
2829 | return "mismatch past end of log"; | |
2830 | } | |
2831 | return NULL; | |
2832 | } | |
2833 | ||
2834 | static void | |
2835 | raft_handle_append_entries(struct raft *raft, | |
2836 | const struct raft_append_request *rq, | |
2837 | uint64_t prev_log_index, uint64_t prev_log_term, | |
2838 | const struct raft_entry *entries, | |
2839 | unsigned int n_entries) | |
2840 | { | |
2841 | /* Section 3.5: "When sending an AppendEntries RPC, the leader includes | |
2842 | * the index and term of the entry in its log that immediately precedes | |
2843 | * the new entries. If the follower does not find an entry in its log | |
2844 | * with the same index and term, then it refuses the new entries." */ | |
2845 | const char *mismatch = match_index_and_term(raft, prev_log_index, | |
2846 | prev_log_term); | |
2847 | if (mismatch) { | |
2848 | VLOG_INFO("rejecting append_request because previous entry " | |
2849 | "%"PRIu64",%"PRIu64" not in local log (%s)", | |
2850 | prev_log_term, prev_log_index, mismatch); | |
2851 | raft_send_append_reply(raft, rq, RAFT_APPEND_INCONSISTENCY, mismatch); | |
2852 | return; | |
2853 | } | |
2854 | ||
2855 | /* Figure 3.1: "If an existing entry conflicts with a new one (same | |
2856 | * index but different terms), delete the existing entry and all that | |
2857 | * follow it." */ | |
2858 | unsigned int i; | |
2859 | bool servers_changed = false; | |
2860 | for (i = 0; ; i++) { | |
2861 | if (i >= n_entries) { | |
2862 | /* No change. */ | |
2863 | if (rq->common.comment | |
2864 | && !strcmp(rq->common.comment, "heartbeat")) { | |
2865 | raft_send_append_reply(raft, rq, RAFT_APPEND_OK, "heartbeat"); | |
2866 | } else { | |
2867 | raft_send_append_reply(raft, rq, RAFT_APPEND_OK, "no change"); | |
2868 | } | |
2869 | return; | |
2870 | } | |
2871 | ||
2872 | uint64_t log_index = (prev_log_index + 1) + i; | |
2873 | if (log_index >= raft->log_end) { | |
2874 | break; | |
2875 | } | |
2876 | if (raft->entries[log_index - raft->log_start].term | |
2877 | != entries[i].term) { | |
2878 | if (raft_truncate(raft, log_index)) { | |
2879 | servers_changed = true; | |
2880 | } | |
2881 | break; | |
2882 | } | |
2883 | } | |
2884 | ||
67dba070 HZ |
2885 | if (failure_test == FT_CRASH_AFTER_RECV_APPEND_REQ_UPDATE) { |
2886 | ovs_fatal(0, "Raft test: crash after receiving append_request with " | |
2887 | "update."); | |
2888 | } | |
1b1d2e6d BP |
2889 | /* Figure 3.1: "Append any entries not already in the log." */ |
2890 | struct ovsdb_error *error = NULL; | |
2891 | bool any_written = false; | |
2892 | for (; i < n_entries; i++) { | |
2893 | const struct raft_entry *e = &entries[i]; | |
2894 | error = raft_write_entry(raft, e->term, | |
2895 | json_nullable_clone(e->data), &e->eid, | |
8e354614 HZ |
2896 | json_nullable_clone(e->servers), |
2897 | e->election_timer); | |
1b1d2e6d BP |
2898 | if (error) { |
2899 | break; | |
2900 | } | |
2901 | any_written = true; | |
2902 | if (e->servers) { | |
2903 | servers_changed = true; | |
2904 | } | |
2905 | } | |
2906 | ||
2907 | if (any_written) { | |
2908 | raft_waiter_create(raft, RAFT_W_ENTRY, true)->entry.index | |
2909 | = raft->log_end - 1; | |
2910 | } | |
2911 | if (servers_changed) { | |
2912 | /* The set of servers might have changed; check. */ | |
2913 | raft_get_servers_from_log(raft, VLL_INFO); | |
2914 | } | |
2915 | ||
2916 | if (error) { | |
2917 | char *s = ovsdb_error_to_string_free(error); | |
2918 | VLOG_ERR("%s", s); | |
2919 | free(s); | |
2920 | raft_send_append_reply(raft, rq, RAFT_APPEND_IO_ERROR, "I/O error"); | |
2921 | return; | |
2922 | } | |
2923 | ||
2924 | raft_send_append_reply(raft, rq, RAFT_APPEND_OK, "log updated"); | |
2925 | } | |
2926 | ||
2927 | static bool | |
2928 | raft_update_leader(struct raft *raft, const struct uuid *sid) | |
2929 | { | |
2930 | if (raft->role == RAFT_LEADER) { | |
2931 | char buf[SID_LEN + 1]; | |
2932 | VLOG_ERR("this server is leader but server %s claims to be", | |
2933 | raft_get_nickname(raft, sid, buf, sizeof buf)); | |
2934 | return false; | |
2935 | } else if (!uuid_equals(sid, &raft->leader_sid)) { | |
2936 | if (!uuid_is_zero(&raft->leader_sid)) { | |
2937 | char buf1[SID_LEN + 1]; | |
2938 | char buf2[SID_LEN + 1]; | |
2939 | VLOG_ERR("leader for term %"PRIu64" changed from %s to %s", | |
2940 | raft->term, | |
2941 | raft_get_nickname(raft, &raft->leader_sid, | |
2942 | buf1, sizeof buf1), | |
2943 | raft_get_nickname(raft, sid, buf2, sizeof buf2)); | |
2944 | } else { | |
2945 | char buf[SID_LEN + 1]; | |
2946 | VLOG_INFO("server %s is leader for term %"PRIu64, | |
2947 | raft_get_nickname(raft, sid, buf, sizeof buf), | |
2948 | raft->term); | |
2949 | } | |
923f01ca | 2950 | raft_set_leader(raft, sid); |
1b1d2e6d BP |
2951 | |
2952 | /* Record the leader to the log. This is not used by the algorithm | |
2953 | * (although it could be, for quick restart), but it is used for | |
2954 | * offline analysis to check for conformance with the properties | |
2955 | * that Raft guarantees. */ | |
2956 | struct raft_record r = { | |
2957 | .type = RAFT_REC_LEADER, | |
2958 | .term = raft->term, | |
2959 | .sid = *sid, | |
2960 | }; | |
2961 | ignore(ovsdb_log_write_and_free(raft->log, raft_record_to_json(&r))); | |
2962 | } | |
2963 | return true; | |
2964 | } | |
2965 | ||
2966 | static void | |
2967 | raft_handle_append_request(struct raft *raft, | |
2968 | const struct raft_append_request *rq) | |
2969 | { | |
2970 | /* We do not check whether the server that sent the request is part of the | |
2971 | * cluster. As section 4.1 says, "A server accepts AppendEntries requests | |
2972 | * from a leader that is not part of the server’s latest configuration. | |
2973 | * Otherwise, a new server could never be added to the cluster (it would | |
2974 | * never accept any log entries preceding the configuration entry that adds | |
2975 | * the server)." */ | |
2976 | if (!raft_update_leader(raft, &rq->common.sid)) { | |
2977 | raft_send_append_reply(raft, rq, RAFT_APPEND_INCONSISTENCY, | |
2978 | "usurped leadership"); | |
2979 | return; | |
2980 | } | |
0f954f32 | 2981 | raft_reset_election_timer(raft); |
1b1d2e6d BP |
2982 | |
2983 | /* First check for the common case, where the AppendEntries request is | |
2984 | * entirely for indexes covered by 'log_start' ... 'log_end - 1', something | |
2985 | * like this: | |
2986 | * | |
2987 | * rq->prev_log_index | |
2988 | * | first_entry_index | |
2989 | * | | nth_entry_index | |
2990 | * | | | | |
2991 | * v v v | |
2992 | * +---+---+---+---+ | |
2993 | * T | T | T | T | T | | |
2994 | * +---+-------+---+ | |
2995 | * +---+---+---+---+ | |
2996 | * T | T | T | T | T | | |
2997 | * +---+---+---+---+ | |
2998 | * ^ ^ | |
2999 | * | | | |
3000 | * log_start log_end | |
3001 | * */ | |
3002 | uint64_t first_entry_index = rq->prev_log_index + 1; | |
3003 | uint64_t nth_entry_index = rq->prev_log_index + rq->n_entries; | |
3004 | if (OVS_LIKELY(first_entry_index >= raft->log_start)) { | |
3005 | raft_handle_append_entries(raft, rq, | |
3006 | rq->prev_log_index, rq->prev_log_term, | |
3007 | rq->entries, rq->n_entries); | |
3008 | return; | |
3009 | } | |
3010 | ||
3011 | /* Now a series of checks for odd cases, where the AppendEntries request | |
3012 | * extends earlier than the beginning of our log, into the log entries | |
3013 | * discarded by the most recent snapshot. */ | |
3014 | ||
3015 | /* | |
3016 | * Handle the case where the indexes covered by rq->entries[] are entirely | |
3017 | * disjoint with 'log_start - 1' ... 'log_end - 1', as shown below. So, | |
3018 | * everything in the AppendEntries request must already have been | |
3019 | * committed, and we might as well return true. | |
3020 | * | |
3021 | * rq->prev_log_index | |
3022 | * | first_entry_index | |
3023 | * | | nth_entry_index | |
3024 | * | | | | |
3025 | * v v v | |
3026 | * +---+---+---+---+ | |
3027 | * T | T | T | T | T | | |
3028 | * +---+-------+---+ | |
3029 | * +---+---+---+---+ | |
3030 | * T | T | T | T | T | | |
3031 | * +---+---+---+---+ | |
3032 | * ^ ^ | |
3033 | * | | | |
3034 | * log_start log_end | |
3035 | */ | |
3036 | if (nth_entry_index < raft->log_start - 1) { | |
3037 | raft_send_append_reply(raft, rq, RAFT_APPEND_OK, | |
3038 | "append before log start"); | |
3039 | return; | |
3040 | } | |
3041 | ||
3042 | /* | |
3043 | * Handle the case where the last entry in rq->entries[] has the same index | |
3044 | * as 'log_start - 1', so we can compare their terms: | |
3045 | * | |
3046 | * rq->prev_log_index | |
3047 | * | first_entry_index | |
3048 | * | | nth_entry_index | |
3049 | * | | | | |
3050 | * v v v | |
3051 | * +---+---+---+---+ | |
3052 | * T | T | T | T | T | | |
3053 | * +---+-------+---+ | |
3054 | * +---+---+---+---+ | |
3055 | * T | T | T | T | T | | |
3056 | * +---+---+---+---+ | |
3057 | * ^ ^ | |
3058 | * | | | |
3059 | * log_start log_end | |
3060 | * | |
3061 | * There's actually a sub-case where rq->n_entries == 0, in which we | |
3062 | * compare rq->prev_term: | |
3063 | * | |
3064 | * rq->prev_log_index | |
3065 | * | | |
3066 | * | | |
3067 | * | | |
3068 | * v | |
3069 | * T | |
3070 | * | |
3071 | * +---+---+---+---+ | |
3072 | * T | T | T | T | T | | |
3073 | * +---+---+---+---+ | |
3074 | * ^ ^ | |
3075 | * | | | |
3076 | * log_start log_end | |
3077 | */ | |
3078 | if (nth_entry_index == raft->log_start - 1) { | |
3079 | if (rq->n_entries | |
3080 | ? raft->snap.term == rq->entries[rq->n_entries - 1].term | |
3081 | : raft->snap.term == rq->prev_log_term) { | |
3082 | raft_send_append_reply(raft, rq, RAFT_APPEND_OK, "no change"); | |
3083 | } else { | |
3084 | raft_send_append_reply(raft, rq, RAFT_APPEND_INCONSISTENCY, | |
3085 | "term mismatch"); | |
3086 | } | |
3087 | return; | |
3088 | } | |
3089 | ||
3090 | /* | |
3091 | * We now know that the data in rq->entries[] overlaps the data in | |
3092 | * raft->entries[], as shown below, with some positive 'ofs': | |
3093 | * | |
3094 | * rq->prev_log_index | |
3095 | * | first_entry_index | |
3096 | * | | nth_entry_index | |
3097 | * | | | | |
3098 | * v v v | |
3099 | * +---+---+---+---+---+ | |
3100 | * T | T | T | T | T | T | | |
3101 | * +---+-------+---+---+ | |
3102 | * +---+---+---+---+ | |
3103 | * T | T | T | T | T | | |
3104 | * +---+---+---+---+ | |
3105 | * ^ ^ | |
3106 | * | | | |
3107 | * log_start log_end | |
3108 | * | |
3109 | * |<-- ofs -->| | |
3110 | * | |
3111 | * We transform this into the following by trimming the first 'ofs' | |
3112 | * elements off of rq->entries[], ending up with the following. Notice how | |
3113 | * we retain the term but not the data for rq->entries[ofs - 1]: | |
3114 | * | |
3115 | * first_entry_index + ofs - 1 | |
3116 | * | first_entry_index + ofs | |
3117 | * | | nth_entry_index + ofs | |
3118 | * | | | | |
3119 | * v v v | |
3120 | * +---+---+ | |
3121 | * T | T | T | | |
3122 | * +---+---+ | |
3123 | * +---+---+---+---+ | |
3124 | * T | T | T | T | T | | |
3125 | * +---+---+---+---+ | |
3126 | * ^ ^ | |
3127 | * | | | |
3128 | * log_start log_end | |
3129 | */ | |
3130 | uint64_t ofs = raft->log_start - first_entry_index; | |
3131 | raft_handle_append_entries(raft, rq, | |
3132 | raft->log_start - 1, rq->entries[ofs - 1].term, | |
3133 | &rq->entries[ofs], rq->n_entries - ofs); | |
3134 | } | |
3135 | ||
3136 | /* Returns true if 'raft' has another log entry or snapshot to read. */ | |
3137 | bool | |
3138 | raft_has_next_entry(const struct raft *raft_) | |
3139 | { | |
3140 | struct raft *raft = CONST_CAST(struct raft *, raft_); | |
3141 | struct uuid eid; | |
3142 | return raft_peek_next_entry(raft, &eid) != NULL; | |
3143 | } | |
3144 | ||
3145 | /* Returns the next log entry or snapshot from 'raft', or NULL if there are | |
3146 | * none left to read. Stores the entry ID of the log entry in '*eid'. Stores | |
3147 | * true in '*is_snapshot' if the returned data is a snapshot, false if it is a | |
3148 | * log entry. */ | |
3149 | const struct json * | |
3150 | raft_next_entry(struct raft *raft, struct uuid *eid, bool *is_snapshot) | |
3151 | { | |
3152 | const struct json *data = raft_get_next_entry(raft, eid); | |
3153 | *is_snapshot = data == raft->snap.data; | |
3154 | return data; | |
3155 | } | |
3156 | ||
3157 | /* Returns the log index of the last-read snapshot or log entry. */ | |
3158 | uint64_t | |
3159 | raft_get_applied_index(const struct raft *raft) | |
3160 | { | |
3161 | return raft->last_applied; | |
3162 | } | |
3163 | ||
3164 | /* Returns the log index of the last snapshot or log entry that is available to | |
3165 | * be read. */ | |
3166 | uint64_t | |
3167 | raft_get_commit_index(const struct raft *raft) | |
3168 | { | |
3169 | return raft->commit_index; | |
3170 | } | |
3171 | ||
3172 | static struct raft_server * | |
3173 | raft_find_peer(struct raft *raft, const struct uuid *uuid) | |
3174 | { | |
3175 | struct raft_server *s = raft_find_server(raft, uuid); | |
3176 | return s && !uuid_equals(&raft->sid, &s->sid) ? s : NULL; | |
3177 | } | |
3178 | ||
3179 | static struct raft_server * | |
3180 | raft_find_new_server(struct raft *raft, const struct uuid *uuid) | |
3181 | { | |
3182 | return raft_server_find(&raft->add_servers, uuid); | |
3183 | } | |
3184 | ||
3185 | /* Figure 3.1: "If there exists an N such that N > commitIndex, a | |
3186 | * majority of matchIndex[i] >= N, and log[N].term == currentTerm, set | |
3187 | * commitIndex = N (sections 3.5 and 3.6)." */ | |
3188 | static void | |
3189 | raft_consider_updating_commit_index(struct raft *raft) | |
3190 | { | |
3191 | /* This loop cannot just bail out when it comes across a log entry that | |
3192 | * does not match the criteria. For example, Figure 3.7(d2) shows a | |
3193 | * case where the log entry for term 2 cannot be committed directly | |
3194 | * (because it is not for the current term) but it can be committed as | |
3195 | * a side effect of commit the entry for term 4 (the current term). | |
3196 | * XXX Is there a more efficient way to do this? */ | |
3197 | ovs_assert(raft->role == RAFT_LEADER); | |
3198 | ||
3199 | uint64_t new_commit_index = raft->commit_index; | |
3200 | for (uint64_t idx = MAX(raft->commit_index + 1, raft->log_start); | |
3201 | idx < raft->log_end; idx++) { | |
3202 | if (raft->entries[idx - raft->log_start].term == raft->term) { | |
3203 | size_t count = 0; | |
3204 | struct raft_server *s2; | |
3205 | HMAP_FOR_EACH (s2, hmap_node, &raft->servers) { | |
3206 | if (s2->match_index >= idx) { | |
3207 | count++; | |
3208 | } | |
3209 | } | |
3210 | if (count > hmap_count(&raft->servers) / 2) { | |
3211 | VLOG_DBG("index %"PRIu64" committed to %"PRIuSIZE" servers, " | |
3212 | "applying", idx, count); | |
3213 | new_commit_index = idx; | |
3214 | } | |
3215 | } | |
3216 | } | |
0f954f32 HZ |
3217 | if (raft_update_commit_index(raft, new_commit_index)) { |
3218 | raft_send_heartbeats(raft); | |
3219 | } | |
1b1d2e6d BP |
3220 | } |
3221 | ||
3222 | static void | |
3223 | raft_update_match_index(struct raft *raft, struct raft_server *s, | |
3224 | uint64_t min_index) | |
3225 | { | |
3226 | ovs_assert(raft->role == RAFT_LEADER); | |
3227 | if (min_index > s->match_index) { | |
3228 | s->match_index = min_index; | |
3229 | raft_consider_updating_commit_index(raft); | |
3230 | } | |
3231 | } | |
3232 | ||
3233 | static void | |
3234 | raft_update_our_match_index(struct raft *raft, uint64_t min_index) | |
3235 | { | |
e8208c66 BP |
3236 | struct raft_server *server = raft_find_server(raft, &raft->sid); |
3237 | if (server) { | |
3238 | raft_update_match_index(raft, server, min_index); | |
3239 | } | |
1b1d2e6d BP |
3240 | } |
3241 | ||
3242 | static void | |
3243 | raft_send_install_snapshot_request(struct raft *raft, | |
3244 | const struct raft_server *s, | |
3245 | const char *comment) | |
3246 | { | |
3247 | union raft_rpc rpc = { | |
3248 | .install_snapshot_request = { | |
3249 | .common = { | |
3250 | .type = RAFT_RPC_INSTALL_SNAPSHOT_REQUEST, | |
3251 | .sid = s->sid, | |
3252 | .comment = CONST_CAST(char *, comment), | |
3253 | }, | |
3254 | .term = raft->term, | |
3255 | .last_index = raft->log_start - 1, | |
3256 | .last_term = raft->snap.term, | |
3257 | .last_servers = raft->snap.servers, | |
3258 | .last_eid = raft->snap.eid, | |
3259 | .data = raft->snap.data, | |
8e354614 | 3260 | .election_timer = raft->election_timer, |
1b1d2e6d BP |
3261 | } |
3262 | }; | |
3263 | raft_send(raft, &rpc); | |
3264 | } | |
3265 | ||
3266 | static void | |
3267 | raft_handle_append_reply(struct raft *raft, | |
3268 | const struct raft_append_reply *rpy) | |
3269 | { | |
3270 | if (raft->role != RAFT_LEADER) { | |
3271 | VLOG_INFO("rejected append_reply (not leader)"); | |
3272 | return; | |
3273 | } | |
3274 | ||
3275 | /* Most commonly we'd be getting an AppendEntries reply from a configured | |
3276 | * server (e.g. a peer), but we can also get them from servers in the | |
3277 | * process of being added. */ | |
3278 | struct raft_server *s = raft_find_peer(raft, &rpy->common.sid); | |
3279 | if (!s) { | |
3280 | s = raft_find_new_server(raft, &rpy->common.sid); | |
3281 | if (!s) { | |
3282 | VLOG_INFO("rejected append_reply from unknown server "SID_FMT, | |
3283 | SID_ARGS(&rpy->common.sid)); | |
3284 | return; | |
3285 | } | |
3286 | } | |
3287 | ||
89771c1e | 3288 | s->replied = true; |
1b1d2e6d BP |
3289 | if (rpy->result == RAFT_APPEND_OK) { |
3290 | /* Figure 3.1: "If successful, update nextIndex and matchIndex for | |
3291 | * follower (section 3.5)." */ | |
3292 | uint64_t min_index = rpy->prev_log_index + rpy->n_entries + 1; | |
3293 | if (s->next_index < min_index) { | |
3294 | s->next_index = min_index; | |
3295 | } | |
3296 | raft_update_match_index(raft, s, min_index - 1); | |
3297 | } else { | |
3298 | /* Figure 3.1: "If AppendEntries fails because of log inconsistency, | |
3299 | * decrement nextIndex and retry (section 3.5)." | |
3300 | * | |
3301 | * We also implement the optimization suggested in section 4.2.1: | |
3302 | * "Various approaches can make nextIndex converge to its correct value | |
3303 | * more quickly, including those described in Chapter 3. The simplest | |
3304 | * approach to solving this particular problem of adding a new server, | |
3305 | * however, is to have followers return the length of their logs in the | |
3306 | * AppendEntries response; this allows the leader to cap the follower’s | |
3307 | * nextIndex accordingly." */ | |
3308 | s->next_index = (s->next_index > 0 | |
3309 | ? MIN(s->next_index - 1, rpy->log_end) | |
3310 | : 0); | |
3311 | ||
3312 | if (rpy->result == RAFT_APPEND_IO_ERROR) { | |
3313 | /* Append failed but not because of a log inconsistency. Because | |
3314 | * of the I/O error, there's no point in re-sending the append | |
3315 | * immediately. */ | |
3316 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
3317 | VLOG_INFO_RL(&rl, "%s reported I/O error", s->nickname); | |
3318 | return; | |
3319 | } | |
3320 | } | |
3321 | ||
3322 | /* | |
3323 | * Our behavior here must depend on the value of next_index relative to | |
3324 | * log_start and log_end. There are three cases: | |
3325 | * | |
3326 | * Case 1 | Case 2 | Case 3 | |
3327 | * <---------------->|<------------->|<------------------> | |
3328 | * | | | |
3329 | * | |
3330 | * +---+---+---+---+ | |
3331 | * T | T | T | T | T | | |
3332 | * +---+---+---+---+ | |
3333 | * ^ ^ | |
3334 | * | | | |
3335 | * log_start log_end | |
3336 | */ | |
3337 | if (s->next_index < raft->log_start) { | |
3338 | /* Case 1. */ | |
3339 | raft_send_install_snapshot_request(raft, s, NULL); | |
3340 | } else if (s->next_index < raft->log_end) { | |
3341 | /* Case 2. */ | |
3342 | raft_send_append_request(raft, s, 1, NULL); | |
3343 | } else { | |
3344 | /* Case 3. */ | |
3345 | if (s->phase == RAFT_PHASE_CATCHUP) { | |
3346 | s->phase = RAFT_PHASE_CAUGHT_UP; | |
3347 | raft_run_reconfigure(raft); | |
3348 | } | |
3349 | } | |
3350 | } | |
3351 | ||
3352 | static bool | |
3353 | raft_should_suppress_disruptive_server(struct raft *raft, | |
3354 | const union raft_rpc *rpc) | |
3355 | { | |
3356 | if (rpc->type != RAFT_RPC_VOTE_REQUEST) { | |
3357 | return false; | |
3358 | } | |
3359 | ||
3360 | /* Section 4.2.3 "Disruptive Servers" says: | |
3361 | * | |
3362 | * ...if a server receives a RequestVote request within the minimum | |
3363 | * election timeout of hearing from a current leader, it does not update | |
3364 | * its term or grant its vote... | |
3365 | * | |
3366 | * ...This change conflicts with the leadership transfer mechanism as | |
3367 | * described in Chapter 3, in which a server legitimately starts an | |
3368 | * election without waiting an election timeout. In that case, | |
3369 | * RequestVote messages should be processed by other servers even when | |
3370 | * they believe a current cluster leader exists. Those RequestVote | |
3371 | * requests can include a special flag to indicate this behavior (“I | |
3372 | * have permission to disrupt the leader--it told me to!”). | |
3373 | * | |
3374 | * This clearly describes how the followers should act, but not the leader. | |
3375 | * We just ignore vote requests that arrive at a current leader. This | |
3376 | * seems to be fairly safe, since a majority other than the current leader | |
3377 | * can still elect a new leader and the first AppendEntries from that new | |
3378 | * leader will depose the current leader. */ | |
3379 | const struct raft_vote_request *rq = raft_vote_request_cast(rpc); | |
3380 | if (rq->leadership_transfer) { | |
3381 | return false; | |
3382 | } | |
3383 | ||
3384 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
3385 | long long int now = time_msec(); | |
3386 | switch (raft->role) { | |
3387 | case RAFT_LEADER: | |
3388 | VLOG_WARN_RL(&rl, "ignoring vote request received as leader"); | |
3389 | return true; | |
3390 | ||
3391 | case RAFT_FOLLOWER: | |
8e354614 | 3392 | if (now < raft->election_base + raft->election_timer) { |
1b1d2e6d | 3393 | VLOG_WARN_RL(&rl, "ignoring vote request received after only " |
8e354614 HZ |
3394 | "%lld ms (minimum election time is %"PRIu64" ms)", |
3395 | now - raft->election_base, raft->election_timer); | |
1b1d2e6d BP |
3396 | return true; |
3397 | } | |
3398 | return false; | |
3399 | ||
3400 | case RAFT_CANDIDATE: | |
3401 | return false; | |
3402 | ||
3403 | default: | |
3404 | OVS_NOT_REACHED(); | |
3405 | } | |
3406 | } | |
3407 | ||
3408 | /* Returns true if a reply should be sent. */ | |
3409 | static bool | |
3410 | raft_handle_vote_request__(struct raft *raft, | |
3411 | const struct raft_vote_request *rq) | |
3412 | { | |
3413 | /* Figure 3.1: "If votedFor is null or candidateId, and candidate's vote is | |
3414 | * at least as up-to-date as receiver's log, grant vote (sections 3.4, | |
3415 | * 3.6)." */ | |
3416 | if (uuid_equals(&raft->vote, &rq->common.sid)) { | |
3417 | /* Already voted for this candidate in this term. Resend vote. */ | |
3418 | return true; | |
3419 | } else if (!uuid_is_zero(&raft->vote)) { | |
3420 | /* Already voted for different candidate in this term. Send a reply | |
3421 | * saying what candidate we did vote for. This isn't a necessary part | |
3422 | * of the Raft protocol but it can make debugging easier. */ | |
3423 | return true; | |
3424 | } | |
3425 | ||
3426 | /* Section 3.6.1: "The RequestVote RPC implements this restriction: the RPC | |
3427 | * includes information about the candidate’s log, and the voter denies its | |
3428 | * vote if its own log is more up-to-date than that of the candidate. Raft | |
3429 | * determines which of two logs is more up-to-date by comparing the index | |
3430 | * and term of the last entries in the logs. If the logs have last entries | |
3431 | * with different terms, then the log with the later term is more | |
3432 | * up-to-date. If the logs end with the same term, then whichever log is | |
3433 | * longer is more up-to-date." */ | |
3434 | uint64_t last_term = (raft->log_end > raft->log_start | |
3435 | ? raft->entries[raft->log_end - 1 | |
3436 | - raft->log_start].term | |
3437 | : raft->snap.term); | |
3438 | if (last_term > rq->last_log_term | |
3439 | || (last_term == rq->last_log_term | |
3440 | && raft->log_end - 1 > rq->last_log_index)) { | |
3441 | /* Our log is more up-to-date than the peer's. Withhold vote. */ | |
3442 | return false; | |
3443 | } | |
3444 | ||
3445 | /* Record a vote for the peer. */ | |
3446 | if (!raft_set_term(raft, raft->term, &rq->common.sid)) { | |
3447 | return false; | |
3448 | } | |
3449 | ||
0f954f32 | 3450 | raft_reset_election_timer(raft); |
1b1d2e6d BP |
3451 | |
3452 | return true; | |
3453 | } | |
3454 | ||
3455 | static void | |
3456 | raft_send_vote_reply(struct raft *raft, const struct uuid *dst, | |
3457 | const struct uuid *vote) | |
3458 | { | |
3459 | union raft_rpc rpy = { | |
3460 | .vote_reply = { | |
3461 | .common = { | |
3462 | .type = RAFT_RPC_VOTE_REPLY, | |
3463 | .sid = *dst, | |
3464 | }, | |
3465 | .term = raft->term, | |
3466 | .vote = *vote, | |
3467 | }, | |
3468 | }; | |
3469 | raft_send(raft, &rpy); | |
3470 | } | |
3471 | ||
3472 | static void | |
3473 | raft_handle_vote_request(struct raft *raft, | |
3474 | const struct raft_vote_request *rq) | |
3475 | { | |
3476 | if (raft_handle_vote_request__(raft, rq)) { | |
3477 | raft_send_vote_reply(raft, &rq->common.sid, &raft->vote); | |
3478 | } | |
3479 | } | |
3480 | ||
3481 | static void | |
3482 | raft_handle_vote_reply(struct raft *raft, | |
3483 | const struct raft_vote_reply *rpy) | |
3484 | { | |
3485 | if (!raft_receive_term__(raft, &rpy->common, rpy->term)) { | |
3486 | return; | |
3487 | } | |
3488 | ||
3489 | if (raft->role != RAFT_CANDIDATE) { | |
3490 | return; | |
3491 | } | |
3492 | ||
3493 | struct raft_server *s = raft_find_peer(raft, &rpy->common.sid); | |
3494 | if (s) { | |
3495 | raft_accept_vote(raft, s, &rpy->vote); | |
3496 | } | |
3497 | } | |
3498 | ||
3499 | /* Returns true if 'raft''s log contains reconfiguration entries that have not | |
3500 | * yet been committed. */ | |
3501 | static bool | |
3502 | raft_has_uncommitted_configuration(const struct raft *raft) | |
3503 | { | |
3504 | for (uint64_t i = raft->commit_index + 1; i < raft->log_end; i++) { | |
3505 | ovs_assert(i >= raft->log_start); | |
3506 | const struct raft_entry *e = &raft->entries[i - raft->log_start]; | |
3507 | if (e->servers) { | |
3508 | return true; | |
3509 | } | |
3510 | } | |
3511 | return false; | |
3512 | } | |
3513 | ||
3514 | static void | |
3515 | raft_log_reconfiguration(struct raft *raft) | |
3516 | { | |
3517 | struct json *servers_json = raft_servers_to_json(&raft->servers); | |
3518 | raft_command_unref(raft_command_execute__( | |
8e354614 | 3519 | raft, NULL, servers_json, 0, NULL, NULL)); |
1b1d2e6d BP |
3520 | json_destroy(servers_json); |
3521 | } | |
3522 | ||
3523 | static void | |
3524 | raft_run_reconfigure(struct raft *raft) | |
3525 | { | |
3526 | ovs_assert(raft->role == RAFT_LEADER); | |
3527 | ||
3528 | /* Reconfiguration only progresses when configuration changes commit. */ | |
3529 | if (raft_has_uncommitted_configuration(raft)) { | |
3530 | return; | |
3531 | } | |
3532 | ||
3533 | /* If we were waiting for a configuration change to commit, it's done. */ | |
3534 | struct raft_server *s; | |
3535 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
3536 | if (s->phase == RAFT_PHASE_COMMITTING) { | |
3537 | raft_send_add_server_reply__(raft, &s->sid, s->address, | |
3538 | true, RAFT_SERVER_COMPLETED); | |
3539 | s->phase = RAFT_PHASE_STABLE; | |
3540 | } | |
3541 | } | |
3542 | if (raft->remove_server) { | |
3543 | raft_send_remove_server_reply__(raft, &raft->remove_server->sid, | |
3544 | &raft->remove_server->requester_sid, | |
3545 | raft->remove_server->requester_conn, | |
3546 | true, RAFT_SERVER_COMPLETED); | |
3547 | raft_server_destroy(raft->remove_server); | |
3548 | raft->remove_server = NULL; | |
3549 | } | |
3550 | ||
3551 | /* If a new server is caught up, add it to the configuration. */ | |
3552 | HMAP_FOR_EACH (s, hmap_node, &raft->add_servers) { | |
3553 | if (s->phase == RAFT_PHASE_CAUGHT_UP) { | |
3554 | /* Move 's' from 'raft->add_servers' to 'raft->servers'. */ | |
3555 | hmap_remove(&raft->add_servers, &s->hmap_node); | |
3556 | hmap_insert(&raft->servers, &s->hmap_node, uuid_hash(&s->sid)); | |
3557 | ||
3558 | /* Mark 's' as waiting for commit. */ | |
3559 | s->phase = RAFT_PHASE_COMMITTING; | |
3560 | ||
3561 | raft_log_reconfiguration(raft); | |
3562 | ||
3563 | /* When commit completes we'll transition to RAFT_PHASE_STABLE and | |
3564 | * send a RAFT_SERVER_OK reply. */ | |
3565 | ||
3566 | return; | |
3567 | } | |
3568 | } | |
3569 | ||
3570 | /* Remove a server, if one is scheduled for removal. */ | |
3571 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
3572 | if (s->phase == RAFT_PHASE_REMOVE) { | |
3573 | hmap_remove(&raft->servers, &s->hmap_node); | |
3574 | raft->remove_server = s; | |
3575 | ||
3576 | raft_log_reconfiguration(raft); | |
3577 | ||
3578 | return; | |
3579 | } | |
3580 | } | |
3581 | } | |
3582 | ||
3583 | static void | |
3584 | raft_handle_add_server_request(struct raft *raft, | |
3585 | const struct raft_add_server_request *rq) | |
3586 | { | |
3587 | /* Figure 4.1: "1. Reply NOT_LEADER if not leader (section 6.2)." */ | |
3588 | if (raft->role != RAFT_LEADER) { | |
3589 | raft_send_add_server_reply(raft, rq, false, RAFT_SERVER_NOT_LEADER); | |
3590 | return; | |
3591 | } | |
3592 | ||
3593 | /* Check for an existing server. */ | |
3594 | struct raft_server *s = raft_find_server(raft, &rq->common.sid); | |
3595 | if (s) { | |
3596 | /* If the server is scheduled to be removed, cancel it. */ | |
3597 | if (s->phase == RAFT_PHASE_REMOVE) { | |
3598 | s->phase = RAFT_PHASE_STABLE; | |
3599 | raft_send_add_server_reply(raft, rq, false, RAFT_SERVER_CANCELED); | |
3600 | return; | |
3601 | } | |
3602 | ||
3603 | /* If the server is being added, then it's in progress. */ | |
3604 | if (s->phase != RAFT_PHASE_STABLE) { | |
3605 | raft_send_add_server_reply(raft, rq, | |
3606 | false, RAFT_SERVER_IN_PROGRESS); | |
3607 | } | |
3608 | ||
3609 | /* Nothing to do--server is already part of the configuration. */ | |
3610 | raft_send_add_server_reply(raft, rq, | |
3611 | true, RAFT_SERVER_ALREADY_PRESENT); | |
3612 | return; | |
3613 | } | |
3614 | ||
3615 | /* Check for a server being removed. */ | |
3616 | if (raft->remove_server | |
3617 | && uuid_equals(&rq->common.sid, &raft->remove_server->sid)) { | |
3618 | raft_send_add_server_reply(raft, rq, false, RAFT_SERVER_COMMITTING); | |
3619 | return; | |
3620 | } | |
3621 | ||
3622 | /* Check for a server already being added. */ | |
3623 | if (raft_find_new_server(raft, &rq->common.sid)) { | |
3624 | raft_send_add_server_reply(raft, rq, false, RAFT_SERVER_IN_PROGRESS); | |
3625 | return; | |
3626 | } | |
3627 | ||
3628 | /* Add server to 'add_servers'. */ | |
3629 | s = raft_server_add(&raft->add_servers, &rq->common.sid, rq->address); | |
3630 | raft_server_init_leader(raft, s); | |
3631 | s->requester_sid = rq->common.sid; | |
3632 | s->requester_conn = NULL; | |
3633 | s->phase = RAFT_PHASE_CATCHUP; | |
3634 | ||
3635 | /* Start sending the log. If this is the first time we've tried to add | |
3636 | * this server, then this will quickly degenerate into an InstallSnapshot | |
3637 | * followed by a series of AddEntries, but if it's a retry of an earlier | |
3638 | * AddRequest that was interrupted (e.g. by a timeout or a loss of | |
3639 | * leadership) then it will gracefully resume populating the log. | |
3640 | * | |
3641 | * See the last few paragraphs of section 4.2.1 for further insight. */ | |
3642 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10); | |
3643 | VLOG_INFO_RL(&rl, | |
3644 | "starting to add server %s ("SID_FMT" at %s) " | |
3645 | "to cluster "CID_FMT, s->nickname, SID_ARGS(&s->sid), | |
3646 | rq->address, CID_ARGS(&raft->cid)); | |
3647 | raft_send_append_request(raft, s, 0, "initialize new server"); | |
3648 | } | |
3649 | ||
3650 | static void | |
3651 | raft_handle_add_server_reply(struct raft *raft, | |
3652 | const struct raft_add_server_reply *rpy) | |
3653 | { | |
3654 | if (!raft->joining) { | |
3655 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
3656 | VLOG_WARN_RL(&rl, "received add_server_reply even though we're " | |
3657 | "already part of the cluster"); | |
3658 | return; | |
3659 | } | |
3660 | ||
3661 | if (rpy->success) { | |
3662 | raft->joining = false; | |
3663 | ||
3664 | /* It is tempting, at this point, to check that this server is part of | |
3665 | * the current configuration. However, this is not necessarily the | |
3666 | * case, because the log entry that added this server to the cluster | |
3667 | * might have been committed by a majority of the cluster that does not | |
3668 | * include this one. This actually happens in testing. */ | |
3669 | } else { | |
3670 | const char *address; | |
3671 | SSET_FOR_EACH (address, &rpy->remote_addresses) { | |
3672 | if (sset_add(&raft->remote_addresses, address)) { | |
3673 | VLOG_INFO("%s: learned new server address for joining cluster", | |
3674 | address); | |
3675 | } | |
3676 | } | |
3677 | } | |
3678 | } | |
3679 | ||
3680 | /* This is called by raft_unixctl_kick() as well as via RPC. */ | |
3681 | static void | |
3682 | raft_handle_remove_server_request(struct raft *raft, | |
3683 | const struct raft_remove_server_request *rq) | |
3684 | { | |
3685 | /* Figure 4.1: "1. Reply NOT_LEADER if not leader (section 6.2)." */ | |
3686 | if (raft->role != RAFT_LEADER) { | |
3687 | raft_send_remove_server_reply(raft, rq, false, RAFT_SERVER_NOT_LEADER); | |
3688 | return; | |
3689 | } | |
3690 | ||
3691 | /* If the server to remove is currently waiting to be added, cancel it. */ | |
3692 | struct raft_server *target = raft_find_new_server(raft, &rq->sid); | |
3693 | if (target) { | |
3694 | raft_send_add_server_reply__(raft, &target->sid, target->address, | |
3695 | false, RAFT_SERVER_CANCELED); | |
3696 | hmap_remove(&raft->add_servers, &target->hmap_node); | |
3697 | raft_server_destroy(target); | |
3698 | return; | |
3699 | } | |
3700 | ||
3701 | /* If the server isn't configured, report that. */ | |
3702 | target = raft_find_server(raft, &rq->sid); | |
3703 | if (!target) { | |
3704 | raft_send_remove_server_reply(raft, rq, | |
3705 | true, RAFT_SERVER_ALREADY_GONE); | |
3706 | return; | |
3707 | } | |
3708 | ||
3709 | /* Check whether we're waiting for the addition of the server to commit. */ | |
3710 | if (target->phase == RAFT_PHASE_COMMITTING) { | |
3711 | raft_send_remove_server_reply(raft, rq, false, RAFT_SERVER_COMMITTING); | |
3712 | return; | |
3713 | } | |
3714 | ||
3715 | /* Check whether the server is already scheduled for removal. */ | |
3716 | if (target->phase == RAFT_PHASE_REMOVE) { | |
3717 | raft_send_remove_server_reply(raft, rq, | |
3718 | false, RAFT_SERVER_IN_PROGRESS); | |
3719 | return; | |
3720 | } | |
3721 | ||
3722 | /* Make sure that if we remove this server then that at least one other | |
3723 | * server will be left. We don't count servers currently being added (in | |
3724 | * 'add_servers') since those could fail. */ | |
3725 | struct raft_server *s; | |
3726 | int n = 0; | |
3727 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
3728 | if (s != target && s->phase != RAFT_PHASE_REMOVE) { | |
3729 | n++; | |
3730 | } | |
3731 | } | |
3732 | if (!n) { | |
3733 | raft_send_remove_server_reply(raft, rq, false, RAFT_SERVER_EMPTY); | |
3734 | return; | |
3735 | } | |
3736 | ||
3737 | /* Mark the server for removal. */ | |
3738 | target->phase = RAFT_PHASE_REMOVE; | |
3739 | if (rq->requester_conn) { | |
3740 | target->requester_sid = UUID_ZERO; | |
3741 | unixctl_command_reply(rq->requester_conn, "started removal"); | |
3742 | } else { | |
3743 | target->requester_sid = rq->common.sid; | |
3744 | target->requester_conn = NULL; | |
3745 | } | |
3746 | ||
3747 | raft_run_reconfigure(raft); | |
3748 | /* Operation in progress, reply will be sent later. */ | |
3749 | } | |
3750 | ||
3751 | static void | |
17bd4149 | 3752 | raft_finished_leaving_cluster(struct raft *raft) |
1b1d2e6d | 3753 | { |
17bd4149 BP |
3754 | VLOG_INFO(SID_FMT": finished leaving cluster "CID_FMT, |
3755 | SID_ARGS(&raft->sid), CID_ARGS(&raft->cid)); | |
1b1d2e6d | 3756 | |
17bd4149 BP |
3757 | raft_record_note(raft, "left", "this server left the cluster"); |
3758 | ||
3759 | raft->leaving = false; | |
3760 | raft->left = true; | |
3761 | } | |
1b1d2e6d | 3762 | |
17bd4149 BP |
3763 | static void |
3764 | raft_handle_remove_server_reply(struct raft *raft, | |
3765 | const struct raft_remove_server_reply *rpc) | |
3766 | { | |
3767 | if (rpc->success | |
3768 | && (uuid_is_zero(&rpc->target_sid) | |
3769 | || uuid_equals(&rpc->target_sid, &raft->sid))) { | |
3770 | raft_finished_leaving_cluster(raft); | |
1b1d2e6d BP |
3771 | } |
3772 | } | |
3773 | ||
3774 | static bool | |
3775 | raft_handle_write_error(struct raft *raft, struct ovsdb_error *error) | |
3776 | { | |
3777 | if (error && !raft->failed) { | |
3778 | raft->failed = true; | |
3779 | ||
3780 | char *s = ovsdb_error_to_string_free(error); | |
3781 | VLOG_WARN("%s: entering failure mode due to I/O error (%s)", | |
3782 | raft->name, s); | |
3783 | free(s); | |
3784 | } | |
3785 | return !raft->failed; | |
3786 | } | |
3787 | ||
3788 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
3789 | raft_write_snapshot(struct raft *raft, struct ovsdb_log *log, | |
3790 | uint64_t new_log_start, | |
3791 | const struct raft_entry *new_snapshot) | |
3792 | { | |
3793 | struct raft_header h = { | |
3794 | .sid = raft->sid, | |
3795 | .cid = raft->cid, | |
3796 | .name = raft->name, | |
3797 | .local_address = raft->local_address, | |
3798 | .snap_index = new_log_start - 1, | |
3799 | .snap = *new_snapshot, | |
3800 | }; | |
3801 | struct ovsdb_error *error = ovsdb_log_write_and_free( | |
3802 | log, raft_header_to_json(&h)); | |
3803 | if (error) { | |
3804 | return error; | |
3805 | } | |
3806 | ovsdb_log_mark_base(raft->log); | |
3807 | ||
3808 | /* Write log records. */ | |
3809 | for (uint64_t index = new_log_start; index < raft->log_end; index++) { | |
3810 | const struct raft_entry *e = &raft->entries[index - raft->log_start]; | |
3811 | struct raft_record r = { | |
3812 | .type = RAFT_REC_ENTRY, | |
3813 | .term = e->term, | |
3814 | .entry = { | |
3815 | .index = index, | |
3816 | .data = e->data, | |
3817 | .servers = e->servers, | |
8e354614 | 3818 | .election_timer = e->election_timer, |
1b1d2e6d BP |
3819 | .eid = e->eid, |
3820 | }, | |
3821 | }; | |
3822 | error = ovsdb_log_write_and_free(log, raft_record_to_json(&r)); | |
3823 | if (error) { | |
3824 | return error; | |
3825 | } | |
3826 | } | |
3827 | ||
3828 | /* Write term and vote (if any). | |
3829 | * | |
3830 | * The term is redundant if we wrote a log record for that term above. The | |
3831 | * vote, if any, is never redundant. | |
3832 | */ | |
3833 | error = raft_write_state(log, raft->term, &raft->vote); | |
3834 | if (error) { | |
3835 | return error; | |
3836 | } | |
3837 | ||
3838 | /* Write commit_index if it's beyond the new start of the log. */ | |
3839 | if (raft->commit_index >= new_log_start) { | |
3840 | struct raft_record r = { | |
3841 | .type = RAFT_REC_COMMIT_INDEX, | |
3842 | .commit_index = raft->commit_index, | |
3843 | }; | |
3844 | return ovsdb_log_write_and_free(log, raft_record_to_json(&r)); | |
3845 | } | |
3846 | return NULL; | |
3847 | } | |
3848 | ||
3849 | static struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
3850 | raft_save_snapshot(struct raft *raft, | |
3851 | uint64_t new_start, const struct raft_entry *new_snapshot) | |
3852 | ||
3853 | { | |
3854 | struct ovsdb_log *new_log; | |
3855 | struct ovsdb_error *error; | |
3856 | error = ovsdb_log_replace_start(raft->log, &new_log); | |
3857 | if (error) { | |
3858 | return error; | |
3859 | } | |
3860 | ||
3861 | error = raft_write_snapshot(raft, new_log, new_start, new_snapshot); | |
3862 | if (error) { | |
3863 | ovsdb_log_replace_abort(new_log); | |
3864 | return error; | |
3865 | } | |
3866 | ||
3867 | return ovsdb_log_replace_commit(raft->log, new_log); | |
3868 | } | |
3869 | ||
3870 | static bool | |
3871 | raft_handle_install_snapshot_request__( | |
3872 | struct raft *raft, const struct raft_install_snapshot_request *rq) | |
3873 | { | |
0f954f32 | 3874 | raft_reset_election_timer(raft); |
1b1d2e6d BP |
3875 | |
3876 | /* | |
3877 | * Our behavior here depend on new_log_start in the snapshot compared to | |
3878 | * log_start and log_end. There are three cases: | |
3879 | * | |
3880 | * Case 1 | Case 2 | Case 3 | |
3881 | * <---------------->|<------------->|<------------------> | |
3882 | * | | | |
3883 | * | |
3884 | * +---+---+---+---+ | |
3885 | * T | T | T | T | T | | |
3886 | * +---+---+---+---+ | |
3887 | * ^ ^ | |
3888 | * | | | |
3889 | * log_start log_end | |
3890 | */ | |
3891 | uint64_t new_log_start = rq->last_index + 1; | |
3892 | if (new_log_start < raft->log_start) { | |
3893 | /* Case 1: The new snapshot covers less than our current one. Nothing | |
3894 | * to do. */ | |
3895 | return true; | |
3896 | } else if (new_log_start < raft->log_end) { | |
3897 | /* Case 2: The new snapshot starts in the middle of our log. We could | |
3898 | * discard the first 'new_log_start - raft->log_start' entries in the | |
3899 | * log. But there's not much value in that, since snapshotting is | |
3900 | * supposed to be a local decision. Just skip it. */ | |
3901 | return true; | |
3902 | } | |
3903 | ||
3904 | /* Case 3: The new snapshot starts past the end of our current log, so | |
3905 | * discard all of our current log. */ | |
3906 | const struct raft_entry new_snapshot = { | |
3907 | .term = rq->last_term, | |
3908 | .data = rq->data, | |
3909 | .eid = rq->last_eid, | |
3910 | .servers = rq->last_servers, | |
8e354614 | 3911 | .election_timer = rq->election_timer, |
1b1d2e6d BP |
3912 | }; |
3913 | struct ovsdb_error *error = raft_save_snapshot(raft, new_log_start, | |
3914 | &new_snapshot); | |
3915 | if (error) { | |
3916 | char *error_s = ovsdb_error_to_string(error); | |
3917 | VLOG_WARN("could not save snapshot: %s", error_s); | |
3918 | free(error_s); | |
3919 | return false; | |
3920 | } | |
3921 | ||
3922 | for (size_t i = 0; i < raft->log_end - raft->log_start; i++) { | |
3923 | raft_entry_uninit(&raft->entries[i]); | |
3924 | } | |
3925 | raft->log_start = raft->log_end = new_log_start; | |
3926 | raft->log_synced = raft->log_end - 1; | |
3927 | raft->commit_index = raft->log_start - 1; | |
3928 | if (raft->last_applied < raft->commit_index) { | |
3929 | raft->last_applied = raft->log_start - 2; | |
3930 | } | |
3931 | ||
3932 | raft_entry_uninit(&raft->snap); | |
3933 | raft_entry_clone(&raft->snap, &new_snapshot); | |
3934 | ||
3935 | raft_get_servers_from_log(raft, VLL_INFO); | |
8e354614 | 3936 | raft_get_election_timer_from_log(raft); |
1b1d2e6d BP |
3937 | |
3938 | return true; | |
3939 | } | |
3940 | ||
3941 | static void | |
3942 | raft_handle_install_snapshot_request( | |
3943 | struct raft *raft, const struct raft_install_snapshot_request *rq) | |
3944 | { | |
3945 | if (raft_handle_install_snapshot_request__(raft, rq)) { | |
3946 | union raft_rpc rpy = { | |
3947 | .install_snapshot_reply = { | |
3948 | .common = { | |
3949 | .type = RAFT_RPC_INSTALL_SNAPSHOT_REPLY, | |
3950 | .sid = rq->common.sid, | |
3951 | }, | |
3952 | .term = raft->term, | |
3953 | .last_index = rq->last_index, | |
3954 | .last_term = rq->last_term, | |
3955 | }, | |
3956 | }; | |
3957 | raft_send(raft, &rpy); | |
3958 | } | |
3959 | } | |
3960 | ||
3961 | static void | |
3962 | raft_handle_install_snapshot_reply( | |
3963 | struct raft *raft, const struct raft_install_snapshot_reply *rpy) | |
3964 | { | |
3965 | /* We might get an InstallSnapshot reply from a configured server (e.g. a | |
3966 | * peer) or a server in the process of being added. */ | |
3967 | struct raft_server *s = raft_find_peer(raft, &rpy->common.sid); | |
3968 | if (!s) { | |
3969 | s = raft_find_new_server(raft, &rpy->common.sid); | |
3970 | if (!s) { | |
3971 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
3972 | VLOG_INFO_RL(&rl, "cluster "CID_FMT": received %s from " | |
3973 | "unknown server "SID_FMT, CID_ARGS(&raft->cid), | |
3974 | raft_rpc_type_to_string(rpy->common.type), | |
3975 | SID_ARGS(&rpy->common.sid)); | |
3976 | return; | |
3977 | } | |
3978 | } | |
3979 | ||
3980 | if (rpy->last_index != raft->log_start - 1 || | |
3981 | rpy->last_term != raft->snap.term) { | |
3982 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
3983 | VLOG_INFO_RL(&rl, "cluster "CID_FMT": server %s installed " | |
3984 | "out-of-date snapshot, starting over", | |
3985 | CID_ARGS(&raft->cid), s->nickname); | |
3986 | raft_send_install_snapshot_request(raft, s, | |
3987 | "installed obsolete snapshot"); | |
3988 | return; | |
3989 | } | |
3990 | ||
3991 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10); | |
3992 | VLOG_INFO_RL(&rl, "cluster "CID_FMT": installed snapshot on server %s " | |
3993 | " up to %"PRIu64":%"PRIu64, CID_ARGS(&raft->cid), | |
3994 | s->nickname, rpy->last_term, rpy->last_index); | |
3995 | s->next_index = raft->log_end; | |
3996 | raft_send_append_request(raft, s, 0, "snapshot installed"); | |
3997 | } | |
3998 | ||
3999 | /* Returns true if 'raft' has grown enough since the last snapshot that | |
4000 | * reducing the log to a snapshot would be valuable, false otherwise. */ | |
4001 | bool | |
4002 | raft_grew_lots(const struct raft *raft) | |
4003 | { | |
4004 | return ovsdb_log_grew_lots(raft->log); | |
4005 | } | |
4006 | ||
4007 | /* Returns the number of log entries that could be trimmed off the on-disk log | |
4008 | * by snapshotting. */ | |
4009 | uint64_t | |
4010 | raft_get_log_length(const struct raft *raft) | |
4011 | { | |
4012 | return (raft->last_applied < raft->log_start | |
4013 | ? 0 | |
4014 | : raft->last_applied - raft->log_start + 1); | |
4015 | } | |
4016 | ||
4017 | /* Returns true if taking a snapshot of 'raft', with raft_store_snapshot(), is | |
4018 | * possible. */ | |
4019 | bool | |
4020 | raft_may_snapshot(const struct raft *raft) | |
4021 | { | |
4022 | return (!raft->joining | |
4023 | && !raft->leaving | |
4024 | && !raft->left | |
4025 | && !raft->failed | |
4026 | && raft->last_applied >= raft->log_start); | |
4027 | } | |
4028 | ||
4029 | /* Replaces the log for 'raft', up to the last log entry read, by | |
4030 | * 'new_snapshot_data'. Returns NULL if successful, otherwise an error that | |
4031 | * the caller must eventually free. | |
4032 | * | |
4033 | * This function can only succeed if raft_may_snapshot() returns true. It is | |
4034 | * only valuable to call it if raft_get_log_length() is significant and | |
4035 | * especially if raft_grew_lots() returns true. */ | |
4036 | struct ovsdb_error * OVS_WARN_UNUSED_RESULT | |
4037 | raft_store_snapshot(struct raft *raft, const struct json *new_snapshot_data) | |
4038 | { | |
4039 | if (raft->joining) { | |
4040 | return ovsdb_error(NULL, | |
4041 | "cannot store a snapshot while joining cluster"); | |
4042 | } else if (raft->leaving) { | |
4043 | return ovsdb_error(NULL, | |
4044 | "cannot store a snapshot while leaving cluster"); | |
4045 | } else if (raft->left) { | |
4046 | return ovsdb_error(NULL, | |
4047 | "cannot store a snapshot after leaving cluster"); | |
4048 | } else if (raft->failed) { | |
4049 | return ovsdb_error(NULL, | |
4050 | "cannot store a snapshot following failure"); | |
4051 | } | |
4052 | ||
4053 | if (raft->last_applied < raft->log_start) { | |
4054 | return ovsdb_error(NULL, "not storing a duplicate snapshot"); | |
4055 | } | |
4056 | ||
4057 | uint64_t new_log_start = raft->last_applied + 1; | |
a521491b | 4058 | struct raft_entry new_snapshot = { |
1b1d2e6d | 4059 | .term = raft_get_term(raft, new_log_start - 1), |
a521491b | 4060 | .data = json_clone(new_snapshot_data), |
1b1d2e6d | 4061 | .eid = *raft_get_eid(raft, new_log_start - 1), |
a521491b | 4062 | .servers = json_clone(raft_servers_for_index(raft, new_log_start - 1)), |
8e354614 | 4063 | .election_timer = raft->election_timer, |
1b1d2e6d BP |
4064 | }; |
4065 | struct ovsdb_error *error = raft_save_snapshot(raft, new_log_start, | |
4066 | &new_snapshot); | |
4067 | if (error) { | |
a521491b | 4068 | raft_entry_uninit(&new_snapshot); |
1b1d2e6d BP |
4069 | return error; |
4070 | } | |
4071 | ||
4072 | raft->log_synced = raft->log_end - 1; | |
4073 | raft_entry_uninit(&raft->snap); | |
a521491b | 4074 | raft->snap = new_snapshot; |
1b1d2e6d BP |
4075 | for (size_t i = 0; i < new_log_start - raft->log_start; i++) { |
4076 | raft_entry_uninit(&raft->entries[i]); | |
4077 | } | |
4078 | memmove(&raft->entries[0], &raft->entries[new_log_start - raft->log_start], | |
4079 | (raft->log_end - new_log_start) * sizeof *raft->entries); | |
4080 | raft->log_start = new_log_start; | |
4081 | return NULL; | |
4082 | } | |
4083 | ||
4084 | static void | |
4085 | raft_handle_become_leader(struct raft *raft, | |
4086 | const struct raft_become_leader *rq) | |
4087 | { | |
4088 | if (raft->role == RAFT_FOLLOWER) { | |
4089 | char buf[SID_LEN + 1]; | |
4090 | VLOG_INFO("received leadership transfer from %s in term %"PRIu64, | |
4091 | raft_get_nickname(raft, &rq->common.sid, buf, sizeof buf), | |
4092 | rq->term); | |
4093 | raft_start_election(raft, true); | |
4094 | } | |
4095 | } | |
4096 | ||
4097 | static void | |
4098 | raft_send_execute_command_reply(struct raft *raft, | |
4099 | const struct uuid *sid, | |
4100 | const struct uuid *eid, | |
4101 | enum raft_command_status status, | |
4102 | uint64_t commit_index) | |
4103 | { | |
67dba070 HZ |
4104 | if (failure_test == FT_CRASH_BEFORE_SEND_EXEC_REP) { |
4105 | ovs_fatal(0, "Raft test: crash before sending execute_command_reply"); | |
4106 | } | |
1b1d2e6d BP |
4107 | union raft_rpc rpc = { |
4108 | .execute_command_reply = { | |
4109 | .common = { | |
4110 | .type = RAFT_RPC_EXECUTE_COMMAND_REPLY, | |
4111 | .sid = *sid, | |
4112 | }, | |
4113 | .result = *eid, | |
4114 | .status = status, | |
4115 | .commit_index = commit_index, | |
4116 | }, | |
4117 | }; | |
4118 | raft_send(raft, &rpc); | |
67dba070 HZ |
4119 | if (failure_test == FT_CRASH_AFTER_SEND_EXEC_REP) { |
4120 | ovs_fatal(0, "Raft test: crash after sending execute_command_reply."); | |
4121 | } | |
1b1d2e6d BP |
4122 | } |
4123 | ||
4124 | static enum raft_command_status | |
4125 | raft_handle_execute_command_request__( | |
4126 | struct raft *raft, const struct raft_execute_command_request *rq) | |
4127 | { | |
4128 | if (raft->role != RAFT_LEADER) { | |
4129 | return RAFT_CMD_NOT_LEADER; | |
4130 | } | |
4131 | ||
4132 | const struct uuid *current_eid = raft_current_eid(raft); | |
4133 | if (!uuid_equals(&rq->prereq, current_eid)) { | |
4134 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
4135 | VLOG_INFO_RL(&rl, "current entry eid "UUID_FMT" does not match " | |
4136 | "prerequisite "UUID_FMT" in execute_command_request", | |
4137 | UUID_ARGS(current_eid), UUID_ARGS(&rq->prereq)); | |
4138 | return RAFT_CMD_BAD_PREREQ; | |
4139 | } | |
4140 | ||
4141 | struct raft_command *cmd = raft_command_initiate(raft, rq->data, | |
8e354614 | 4142 | NULL, 0, &rq->result); |
1b1d2e6d BP |
4143 | cmd->sid = rq->common.sid; |
4144 | ||
4145 | enum raft_command_status status = cmd->status; | |
4146 | if (status != RAFT_CMD_INCOMPLETE) { | |
4147 | raft_command_unref(cmd); | |
4148 | } | |
4149 | return status; | |
4150 | } | |
4151 | ||
4152 | static void | |
4153 | raft_handle_execute_command_request( | |
4154 | struct raft *raft, const struct raft_execute_command_request *rq) | |
4155 | { | |
4156 | enum raft_command_status status | |
4157 | = raft_handle_execute_command_request__(raft, rq); | |
4158 | if (status != RAFT_CMD_INCOMPLETE) { | |
4159 | raft_send_execute_command_reply(raft, &rq->common.sid, &rq->result, | |
4160 | status, 0); | |
4161 | } | |
4162 | } | |
4163 | ||
4164 | static void | |
4165 | raft_handle_execute_command_reply( | |
4166 | struct raft *raft, const struct raft_execute_command_reply *rpy) | |
4167 | { | |
4168 | struct raft_command *cmd = raft_find_command_by_eid(raft, &rpy->result); | |
4169 | if (!cmd) { | |
4170 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5); | |
4171 | char buf[SID_LEN + 1]; | |
4172 | VLOG_INFO_RL(&rl, | |
4173 | "%s received \"%s\" reply from %s for unknown command", | |
4174 | raft->local_nickname, | |
4175 | raft_command_status_to_string(rpy->status), | |
4176 | raft_get_nickname(raft, &rpy->common.sid, | |
4177 | buf, sizeof buf)); | |
4178 | return; | |
4179 | } | |
4180 | ||
4181 | if (rpy->status == RAFT_CMD_INCOMPLETE) { | |
4182 | cmd->timestamp = time_msec(); | |
4183 | } else { | |
4184 | cmd->index = rpy->commit_index; | |
4185 | raft_command_complete(raft, cmd, rpy->status); | |
4186 | } | |
4187 | } | |
4188 | ||
4189 | static void | |
4190 | raft_handle_rpc(struct raft *raft, const union raft_rpc *rpc) | |
4191 | { | |
4192 | uint64_t term = raft_rpc_get_term(rpc); | |
4193 | if (term | |
4194 | && !raft_should_suppress_disruptive_server(raft, rpc) | |
4195 | && !raft_receive_term__(raft, &rpc->common, term)) { | |
4196 | if (rpc->type == RAFT_RPC_APPEND_REQUEST) { | |
4197 | /* Section 3.3: "If a server receives a request with a stale term | |
4198 | * number, it rejects the request." */ | |
4199 | raft_send_append_reply(raft, raft_append_request_cast(rpc), | |
4200 | RAFT_APPEND_INCONSISTENCY, "stale term"); | |
4201 | } | |
4202 | return; | |
4203 | } | |
4204 | ||
4205 | switch (rpc->type) { | |
4206 | #define RAFT_RPC(ENUM, NAME) \ | |
4207 | case ENUM: \ | |
4208 | raft_handle_##NAME(raft, &rpc->NAME); \ | |
4209 | break; | |
4210 | RAFT_RPC_TYPES | |
4211 | #undef RAFT_RPC | |
4212 | default: | |
4213 | OVS_NOT_REACHED(); | |
4214 | } | |
4215 | } | |
4216 | \f | |
4217 | static bool | |
4218 | raft_rpc_is_heartbeat(const union raft_rpc *rpc) | |
4219 | { | |
4220 | return ((rpc->type == RAFT_RPC_APPEND_REQUEST | |
4221 | || rpc->type == RAFT_RPC_APPEND_REPLY) | |
4222 | && rpc->common.comment | |
4223 | && !strcmp(rpc->common.comment, "heartbeat")); | |
4224 | } | |
4225 | ||
4226 | \f | |
4227 | static bool | |
02acb41a BP |
4228 | raft_send_to_conn_at(struct raft *raft, const union raft_rpc *rpc, |
4229 | struct raft_conn *conn, int line_number) | |
1b1d2e6d | 4230 | { |
02acb41a | 4231 | log_rpc(rpc, "-->", conn, line_number); |
1b1d2e6d BP |
4232 | return !jsonrpc_session_send( |
4233 | conn->js, raft_rpc_to_jsonrpc(&raft->cid, &raft->sid, rpc)); | |
4234 | } | |
4235 | ||
4236 | static bool | |
4237 | raft_is_rpc_synced(const struct raft *raft, const union raft_rpc *rpc) | |
4238 | { | |
4239 | uint64_t term = raft_rpc_get_term(rpc); | |
4240 | uint64_t index = raft_rpc_get_min_sync_index(rpc); | |
4241 | const struct uuid *vote = raft_rpc_get_vote(rpc); | |
4242 | ||
4243 | return (term <= raft->synced_term | |
4244 | && index <= raft->log_synced | |
4245 | && (!vote || uuid_equals(vote, &raft->synced_vote))); | |
4246 | } | |
4247 | ||
4248 | static bool | |
02acb41a | 4249 | raft_send_at(struct raft *raft, const union raft_rpc *rpc, int line_number) |
1b1d2e6d BP |
4250 | { |
4251 | const struct uuid *dst = &rpc->common.sid; | |
4252 | if (uuid_equals(dst, &raft->sid)) { | |
4253 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); | |
02acb41a BP |
4254 | VLOG_WARN_RL(&rl, "attempted to send RPC to self from raft.c:%d", |
4255 | line_number); | |
1b1d2e6d BP |
4256 | return false; |
4257 | } | |
4258 | ||
4259 | struct raft_conn *conn = raft_find_conn_by_sid(raft, dst); | |
4260 | if (!conn) { | |
4261 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); | |
4262 | char buf[SID_LEN + 1]; | |
02acb41a BP |
4263 | VLOG_DBG_RL(&rl, "%s: no connection to %s, cannot send RPC " |
4264 | "from raft.c:%d", raft->local_nickname, | |
4265 | raft_get_nickname(raft, dst, buf, sizeof buf), | |
4266 | line_number); | |
1b1d2e6d BP |
4267 | return false; |
4268 | } | |
4269 | ||
4270 | if (!raft_is_rpc_synced(raft, rpc)) { | |
4271 | raft_waiter_create(raft, RAFT_W_RPC, false)->rpc = raft_rpc_clone(rpc); | |
4272 | return true; | |
4273 | } | |
4274 | ||
02acb41a | 4275 | return raft_send_to_conn_at(raft, rpc, conn, line_number); |
1b1d2e6d BP |
4276 | } |
4277 | \f | |
4278 | static struct raft * | |
4279 | raft_lookup_by_name(const char *name) | |
4280 | { | |
4281 | struct raft *raft; | |
4282 | ||
4283 | HMAP_FOR_EACH_WITH_HASH (raft, hmap_node, hash_string(name, 0), | |
4284 | &all_rafts) { | |
4285 | if (!strcmp(raft->name, name)) { | |
4286 | return raft; | |
4287 | } | |
4288 | } | |
4289 | return NULL; | |
4290 | } | |
4291 | ||
4292 | static void | |
4293 | raft_unixctl_cid(struct unixctl_conn *conn, | |
4294 | int argc OVS_UNUSED, const char *argv[], | |
4295 | void *aux OVS_UNUSED) | |
4296 | { | |
4297 | struct raft *raft = raft_lookup_by_name(argv[1]); | |
4298 | if (!raft) { | |
4299 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4300 | } else if (uuid_is_zero(&raft->cid)) { | |
4301 | unixctl_command_reply_error(conn, "cluster id not yet known"); | |
4302 | } else { | |
4303 | char *uuid = xasprintf(UUID_FMT, UUID_ARGS(&raft->cid)); | |
4304 | unixctl_command_reply(conn, uuid); | |
4305 | free(uuid); | |
4306 | } | |
4307 | } | |
4308 | ||
4309 | static void | |
4310 | raft_unixctl_sid(struct unixctl_conn *conn, | |
4311 | int argc OVS_UNUSED, const char *argv[], | |
4312 | void *aux OVS_UNUSED) | |
4313 | { | |
4314 | struct raft *raft = raft_lookup_by_name(argv[1]); | |
4315 | if (!raft) { | |
4316 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4317 | } else { | |
4318 | char *uuid = xasprintf(UUID_FMT, UUID_ARGS(&raft->sid)); | |
4319 | unixctl_command_reply(conn, uuid); | |
4320 | free(uuid); | |
4321 | } | |
4322 | } | |
4323 | ||
4324 | static void | |
4325 | raft_put_sid(const char *title, const struct uuid *sid, | |
4326 | const struct raft *raft, struct ds *s) | |
4327 | { | |
4328 | ds_put_format(s, "%s: ", title); | |
4329 | if (uuid_equals(sid, &raft->sid)) { | |
4330 | ds_put_cstr(s, "self"); | |
4331 | } else if (uuid_is_zero(sid)) { | |
4332 | ds_put_cstr(s, "unknown"); | |
4333 | } else { | |
4334 | char buf[SID_LEN + 1]; | |
4335 | ds_put_cstr(s, raft_get_nickname(raft, sid, buf, sizeof buf)); | |
4336 | } | |
4337 | ds_put_char(s, '\n'); | |
4338 | } | |
4339 | ||
4340 | static void | |
4341 | raft_unixctl_status(struct unixctl_conn *conn, | |
4342 | int argc OVS_UNUSED, const char *argv[], | |
4343 | void *aux OVS_UNUSED) | |
4344 | { | |
4345 | struct raft *raft = raft_lookup_by_name(argv[1]); | |
4346 | if (!raft) { | |
4347 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4348 | return; | |
4349 | } | |
4350 | ||
4351 | struct ds s = DS_EMPTY_INITIALIZER; | |
4352 | ds_put_format(&s, "%s\n", raft->local_nickname); | |
4353 | ds_put_format(&s, "Name: %s\n", raft->name); | |
4354 | ds_put_format(&s, "Cluster ID: "); | |
4355 | if (!uuid_is_zero(&raft->cid)) { | |
4356 | ds_put_format(&s, CID_FMT" ("UUID_FMT")\n", | |
4357 | CID_ARGS(&raft->cid), UUID_ARGS(&raft->cid)); | |
4358 | } else { | |
4359 | ds_put_format(&s, "not yet known\n"); | |
4360 | } | |
4361 | ds_put_format(&s, "Server ID: "SID_FMT" ("UUID_FMT")\n", | |
4362 | SID_ARGS(&raft->sid), UUID_ARGS(&raft->sid)); | |
4363 | ds_put_format(&s, "Address: %s\n", raft->local_address); | |
4364 | ds_put_format(&s, "Status: %s\n", | |
4365 | raft->joining ? "joining cluster" | |
4366 | : raft->leaving ? "leaving cluster" | |
4367 | : raft->left ? "left cluster" | |
4368 | : raft->failed ? "failed" | |
4369 | : "cluster member"); | |
4370 | if (raft->joining) { | |
4371 | ds_put_format(&s, "Remotes for joining:"); | |
4372 | const char *address; | |
4373 | SSET_FOR_EACH (address, &raft->remote_addresses) { | |
4374 | ds_put_format(&s, " %s", address); | |
4375 | } | |
4376 | ds_put_char(&s, '\n'); | |
4377 | } | |
4378 | if (raft->role == RAFT_LEADER) { | |
4379 | struct raft_server *as; | |
4380 | HMAP_FOR_EACH (as, hmap_node, &raft->add_servers) { | |
4381 | ds_put_format(&s, "Adding server %s ("SID_FMT" at %s) (%s)\n", | |
4382 | as->nickname, SID_ARGS(&as->sid), as->address, | |
4383 | raft_server_phase_to_string(as->phase)); | |
4384 | } | |
4385 | ||
4386 | struct raft_server *rs = raft->remove_server; | |
4387 | if (rs) { | |
4388 | ds_put_format(&s, "Removing server %s ("SID_FMT" at %s) (%s)\n", | |
4389 | rs->nickname, SID_ARGS(&rs->sid), rs->address, | |
4390 | raft_server_phase_to_string(rs->phase)); | |
4391 | } | |
4392 | } | |
4393 | ||
4394 | ds_put_format(&s, "Role: %s\n", | |
4395 | raft->role == RAFT_LEADER ? "leader" | |
4396 | : raft->role == RAFT_CANDIDATE ? "candidate" | |
4397 | : raft->role == RAFT_FOLLOWER ? "follower" | |
4398 | : "<error>"); | |
4399 | ds_put_format(&s, "Term: %"PRIu64"\n", raft->term); | |
4400 | raft_put_sid("Leader", &raft->leader_sid, raft, &s); | |
4401 | raft_put_sid("Vote", &raft->vote, raft, &s); | |
4402 | ds_put_char(&s, '\n'); | |
4403 | ||
8e354614 HZ |
4404 | ds_put_format(&s, "Election timer: %"PRIu64, raft->election_timer); |
4405 | if (raft->role == RAFT_LEADER && raft->election_timer_new) { | |
4406 | ds_put_format(&s, " (changing to %"PRIu64")", | |
4407 | raft->election_timer_new); | |
4408 | } | |
4409 | ds_put_char(&s, '\n'); | |
4410 | ||
1b1d2e6d BP |
4411 | ds_put_format(&s, "Log: [%"PRIu64", %"PRIu64"]\n", |
4412 | raft->log_start, raft->log_end); | |
4413 | ||
4414 | uint64_t n_uncommitted = raft->log_end - raft->commit_index - 1; | |
4415 | ds_put_format(&s, "Entries not yet committed: %"PRIu64"\n", n_uncommitted); | |
4416 | ||
4417 | uint64_t n_unapplied = raft->log_end - raft->last_applied - 1; | |
4418 | ds_put_format(&s, "Entries not yet applied: %"PRIu64"\n", n_unapplied); | |
4419 | ||
4420 | const struct raft_conn *c; | |
4421 | ds_put_cstr(&s, "Connections:"); | |
4422 | LIST_FOR_EACH (c, list_node, &raft->conns) { | |
4423 | bool connected = jsonrpc_session_is_connected(c->js); | |
4424 | ds_put_format(&s, " %s%s%s%s", | |
4425 | connected ? "" : "(", | |
4426 | c->incoming ? "<-" : "->", c->nickname, | |
4427 | connected ? "" : ")"); | |
4428 | } | |
4429 | ds_put_char(&s, '\n'); | |
4430 | ||
4431 | ds_put_cstr(&s, "Servers:\n"); | |
4432 | struct raft_server *server; | |
4433 | HMAP_FOR_EACH (server, hmap_node, &raft->servers) { | |
4434 | ds_put_format(&s, " %s ("SID_FMT" at %s)", | |
4435 | server->nickname, | |
4436 | SID_ARGS(&server->sid), server->address); | |
4437 | if (uuid_equals(&server->sid, &raft->sid)) { | |
4438 | ds_put_cstr(&s, " (self)"); | |
4439 | } | |
4440 | if (server->phase != RAFT_PHASE_STABLE) { | |
4441 | ds_put_format (&s, " (%s)", | |
4442 | raft_server_phase_to_string(server->phase)); | |
4443 | } | |
4444 | if (raft->role == RAFT_CANDIDATE) { | |
4445 | if (!uuid_is_zero(&server->vote)) { | |
4446 | char buf[SID_LEN + 1]; | |
4447 | ds_put_format(&s, " (voted for %s)", | |
4448 | raft_get_nickname(raft, &server->vote, | |
4449 | buf, sizeof buf)); | |
4450 | } | |
4451 | } else if (raft->role == RAFT_LEADER) { | |
4452 | ds_put_format(&s, " next_index=%"PRIu64" match_index=%"PRIu64, | |
4453 | server->next_index, server->match_index); | |
4454 | } | |
4455 | ds_put_char(&s, '\n'); | |
4456 | } | |
4457 | ||
4458 | unixctl_command_reply(conn, ds_cstr(&s)); | |
4459 | ds_destroy(&s); | |
4460 | } | |
4461 | ||
4462 | static void | |
4463 | raft_unixctl_leave__(struct unixctl_conn *conn, struct raft *raft) | |
4464 | { | |
4465 | if (raft_is_leaving(raft)) { | |
4466 | unixctl_command_reply_error(conn, | |
4467 | "already in progress leaving cluster"); | |
4468 | } else if (raft_is_joining(raft)) { | |
4469 | unixctl_command_reply_error(conn, | |
4470 | "can't leave while join in progress"); | |
4471 | } else if (raft_failed(raft)) { | |
4472 | unixctl_command_reply_error(conn, | |
4473 | "can't leave after failure"); | |
4474 | } else { | |
4475 | raft_leave(raft); | |
4476 | unixctl_command_reply(conn, NULL); | |
4477 | } | |
4478 | } | |
4479 | ||
4480 | static void | |
4481 | raft_unixctl_leave(struct unixctl_conn *conn, int argc OVS_UNUSED, | |
4482 | const char *argv[], void *aux OVS_UNUSED) | |
4483 | { | |
4484 | struct raft *raft = raft_lookup_by_name(argv[1]); | |
4485 | if (!raft) { | |
4486 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4487 | return; | |
4488 | } | |
4489 | ||
4490 | raft_unixctl_leave__(conn, raft); | |
4491 | } | |
4492 | ||
4493 | static struct raft_server * | |
4494 | raft_lookup_server_best_match(struct raft *raft, const char *id) | |
4495 | { | |
4496 | struct raft_server *best = NULL; | |
4497 | int best_score = -1; | |
4498 | int n_best = 0; | |
4499 | ||
4500 | struct raft_server *s; | |
4501 | HMAP_FOR_EACH (s, hmap_node, &raft->servers) { | |
4502 | int score = (!strcmp(id, s->address) | |
4503 | ? INT_MAX | |
4504 | : uuid_is_partial_match(&s->sid, id)); | |
4505 | if (score > best_score) { | |
4506 | best = s; | |
4507 | best_score = score; | |
4508 | n_best = 1; | |
4509 | } else if (score == best_score) { | |
4510 | n_best++; | |
4511 | } | |
4512 | } | |
4513 | return n_best == 1 ? best : NULL; | |
4514 | } | |
4515 | ||
4516 | static void | |
4517 | raft_unixctl_kick(struct unixctl_conn *conn, int argc OVS_UNUSED, | |
4518 | const char *argv[], void *aux OVS_UNUSED) | |
4519 | { | |
4520 | const char *cluster_name = argv[1]; | |
4521 | const char *server_name = argv[2]; | |
4522 | ||
4523 | struct raft *raft = raft_lookup_by_name(cluster_name); | |
4524 | if (!raft) { | |
4525 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4526 | return; | |
4527 | } | |
4528 | ||
4529 | struct raft_server *server = raft_lookup_server_best_match(raft, | |
4530 | server_name); | |
4531 | if (!server) { | |
4532 | unixctl_command_reply_error(conn, "unknown server"); | |
4533 | return; | |
4534 | } | |
4535 | ||
4536 | if (uuid_equals(&server->sid, &raft->sid)) { | |
4537 | raft_unixctl_leave__(conn, raft); | |
4538 | } else if (raft->role == RAFT_LEADER) { | |
4539 | const struct raft_remove_server_request rq = { | |
4540 | .sid = server->sid, | |
4541 | .requester_conn = conn, | |
4542 | }; | |
4543 | raft_handle_remove_server_request(raft, &rq); | |
4544 | } else { | |
4545 | const union raft_rpc rpc = { | |
4546 | .remove_server_request = { | |
4547 | .common = { | |
4548 | .type = RAFT_RPC_REMOVE_SERVER_REQUEST, | |
4549 | .sid = raft->leader_sid, | |
4550 | .comment = "via unixctl" | |
4551 | }, | |
4552 | .sid = server->sid, | |
4553 | } | |
4554 | }; | |
4555 | if (raft_send(raft, &rpc)) { | |
4556 | unixctl_command_reply(conn, "sent removal request to leader"); | |
4557 | } else { | |
4558 | unixctl_command_reply_error(conn, | |
4559 | "failed to send removal request"); | |
4560 | } | |
4561 | } | |
4562 | } | |
4563 | ||
8e354614 HZ |
4564 | static void |
4565 | raft_get_election_timer_from_log(struct raft *raft) | |
4566 | { | |
4567 | if (raft->snap.election_timer) { | |
4568 | raft->election_timer = raft->snap.election_timer; | |
4569 | } | |
4570 | for (uint64_t index = raft->commit_index; index >= raft->log_start; | |
4571 | index--) { | |
4572 | struct raft_entry *e = &raft->entries[index - raft->log_start]; | |
4573 | if (e->election_timer) { | |
4574 | raft->election_timer = e->election_timer; | |
4575 | break; | |
4576 | } | |
4577 | } | |
4578 | } | |
4579 | ||
4580 | static void | |
4581 | raft_log_election_timer(struct raft *raft) | |
4582 | { | |
4583 | raft_command_unref(raft_command_execute__(raft, NULL, NULL, | |
4584 | raft->election_timer_new, NULL, | |
4585 | NULL)); | |
4586 | } | |
4587 | ||
4588 | static void | |
4589 | raft_unixctl_change_election_timer(struct unixctl_conn *conn, | |
4590 | int argc OVS_UNUSED, const char *argv[], | |
4591 | void *aux OVS_UNUSED) | |
4592 | { | |
4593 | const char *cluster_name = argv[1]; | |
4594 | const char *election_timer_str = argv[2]; | |
4595 | ||
4596 | struct raft *raft = raft_lookup_by_name(cluster_name); | |
4597 | if (!raft) { | |
4598 | unixctl_command_reply_error(conn, "unknown cluster"); | |
4599 | return; | |
4600 | } | |
4601 | ||
4602 | if (raft->role != RAFT_LEADER) { | |
4603 | unixctl_command_reply_error(conn, "election timer must be changed" | |
4604 | " through leader."); | |
4605 | return; | |
4606 | } | |
4607 | ||
4608 | /* If there are pending changes for election timer, reject it. */ | |
4609 | if (raft->election_timer_new) { | |
4610 | unixctl_command_reply_error(conn, "election timer change pending."); | |
4611 | return; | |
4612 | } | |
4613 | ||
4614 | uint64_t election_timer = atoll(election_timer_str); | |
4615 | if (election_timer == raft->election_timer) { | |
4616 | unixctl_command_reply(conn, "change election timer to current value."); | |
4617 | return; | |
4618 | } | |
4619 | ||
4620 | /* Election timer smaller than 100ms or bigger than 10min doesn't make | |
4621 | * sense. */ | |
4622 | if (election_timer < 100 || election_timer > 600000) { | |
4623 | unixctl_command_reply_error(conn, "election timer must be between " | |
4624 | "100 and 600000, in msec."); | |
4625 | return; | |
4626 | } | |
4627 | ||
4628 | /* If election timer is to be enlarged, it should be done gradually so that | |
4629 | * it won't cause timeout when new value is applied on leader but not yet | |
4630 | * applied on some of the followers. */ | |
4631 | if (election_timer > raft->election_timer * 2) { | |
4632 | unixctl_command_reply_error(conn, "election timer increase should not " | |
4633 | "exceed the current value x 2."); | |
4634 | return; | |
4635 | } | |
4636 | ||
4637 | raft->election_timer_new = election_timer; | |
4638 | raft_log_election_timer(raft); | |
4639 | unixctl_command_reply(conn, "change of election timer initiated."); | |
4640 | } | |
4641 | ||
67dba070 HZ |
4642 | static void |
4643 | raft_unixctl_failure_test(struct unixctl_conn *conn OVS_UNUSED, | |
4644 | int argc OVS_UNUSED, const char *argv[], | |
4645 | void *aux OVS_UNUSED) | |
4646 | { | |
4647 | const char *test = argv[1]; | |
4648 | if (!strcmp(test, "crash-before-sending-append-request")) { | |
4649 | failure_test = FT_CRASH_BEFORE_SEND_APPEND_REQ; | |
4650 | } else if (!strcmp(test, "crash-after-sending-append-request")) { | |
4651 | failure_test = FT_CRASH_AFTER_SEND_APPEND_REQ; | |
4652 | } else if (!strcmp(test, "crash-before-sending-execute-command-reply")) { | |
4653 | failure_test = FT_CRASH_BEFORE_SEND_EXEC_REP; | |
4654 | } else if (!strcmp(test, "crash-after-sending-execute-command-reply")) { | |
4655 | failure_test = FT_CRASH_AFTER_SEND_EXEC_REP; | |
4656 | } else if (!strcmp(test, "crash-before-sending-execute-command-request")) { | |
4657 | failure_test = FT_CRASH_BEFORE_SEND_EXEC_REQ; | |
4658 | } else if (!strcmp(test, "crash-after-sending-execute-command-request")) { | |
4659 | failure_test = FT_CRASH_AFTER_SEND_EXEC_REQ; | |
4660 | } else if (!strcmp(test, "crash-after-receiving-append-request-update")) { | |
4661 | failure_test = FT_CRASH_AFTER_RECV_APPEND_REQ_UPDATE; | |
4662 | } else if (!strcmp(test, "delay-election")) { | |
4663 | failure_test = FT_DELAY_ELECTION; | |
4664 | struct raft *raft; | |
4665 | HMAP_FOR_EACH (raft, hmap_node, &all_rafts) { | |
4666 | if (raft->role == RAFT_FOLLOWER) { | |
4667 | raft_reset_election_timer(raft); | |
4668 | } | |
4669 | } | |
4670 | } else if (!strcmp(test, "clear")) { | |
4671 | failure_test = FT_NO_TEST; | |
4672 | unixctl_command_reply(conn, "test dismissed"); | |
4673 | return; | |
4674 | } else { | |
4675 | unixctl_command_reply_error(conn, "unknown test scenario"); | |
4676 | return; | |
4677 | } | |
4678 | unixctl_command_reply(conn, "test engaged"); | |
4679 | } | |
4680 | ||
1b1d2e6d BP |
4681 | static void |
4682 | raft_init(void) | |
4683 | { | |
4684 | static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER; | |
4685 | if (!ovsthread_once_start(&once)) { | |
4686 | return; | |
4687 | } | |
4688 | unixctl_command_register("cluster/cid", "DB", 1, 1, | |
4689 | raft_unixctl_cid, NULL); | |
4690 | unixctl_command_register("cluster/sid", "DB", 1, 1, | |
4691 | raft_unixctl_sid, NULL); | |
4692 | unixctl_command_register("cluster/status", "DB", 1, 1, | |
4693 | raft_unixctl_status, NULL); | |
4694 | unixctl_command_register("cluster/leave", "DB", 1, 1, | |
4695 | raft_unixctl_leave, NULL); | |
4696 | unixctl_command_register("cluster/kick", "DB SERVER", 2, 2, | |
4697 | raft_unixctl_kick, NULL); | |
8e354614 HZ |
4698 | unixctl_command_register("cluster/change-election-timer", "DB TIME", 2, 2, |
4699 | raft_unixctl_change_election_timer, NULL); | |
67dba070 HZ |
4700 | unixctl_command_register("cluster/failure-test", "FAILURE SCENARIO", 1, 1, |
4701 | raft_unixctl_failure_test, NULL); | |
1b1d2e6d BP |
4702 | ovsthread_once_done(&once); |
4703 | } |