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