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1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
2 *
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 #ifndef OVSDB_IDL_H
17 #define OVSDB_IDL_H 1
18
19 /* Open vSwitch Database Interface Definition Language (OVSDB IDL).
20 *
21 * The OVSDB IDL maintains an in-memory replica of a database. It issues RPC
22 * requests to an OVSDB database server and parses the responses, converting
23 * raw JSON into data structures that are easier for clients to digest. Most
24 * notably, references to rows via UUID become C pointers.
25 *
26 * The IDL also assists with issuing database transactions. The client creates
27 * a transaction, manipulates the IDL data structures, and commits or aborts
28 * the transaction. The IDL then composes and issues the necessary JSON-RPC
29 * requests and reports to the client whether the transaction completed
30 * successfully.
31 */
32
33 #include <stdbool.h>
34 #include <stdint.h>
35 #include "compiler.h"
36 #include "ovsdb-types.h"
37
38 struct json;
39 struct ovsdb_datum;
40 struct ovsdb_idl_class;
41 struct ovsdb_idl_column;
42 struct ovsdb_idl_table_class;
43 struct uuid;
44
45 struct ovsdb_idl *ovsdb_idl_create(const char *remote,
46 const struct ovsdb_idl_class *,
47 bool monitor_everything_by_default,
48 bool retry);
49 void ovsdb_idl_destroy(struct ovsdb_idl *);
50
51 void ovsdb_idl_run(struct ovsdb_idl *);
52 void ovsdb_idl_wait(struct ovsdb_idl *);
53
54 void ovsdb_idl_set_lock(struct ovsdb_idl *, const char *lock_name);
55 bool ovsdb_idl_has_lock(const struct ovsdb_idl *);
56 bool ovsdb_idl_is_lock_contended(const struct ovsdb_idl *);
57
58 unsigned int ovsdb_idl_get_seqno(const struct ovsdb_idl *);
59 bool ovsdb_idl_has_ever_connected(const struct ovsdb_idl *);
60 void ovsdb_idl_force_reconnect(struct ovsdb_idl *);
61 void ovsdb_idl_verify_write_only(struct ovsdb_idl *);
62
63 bool ovsdb_idl_is_alive(const struct ovsdb_idl *);
64 int ovsdb_idl_get_last_error(const struct ovsdb_idl *);
65 \f
66 /* Choosing columns and tables to replicate. */
67
68 /* Modes with which the IDL can monitor a column.
69 *
70 * If no bits are set, the column is not monitored at all. Its value will
71 * always appear to the client to be the default value for its type.
72 *
73 * If OVSDB_IDL_MONITOR is set, then the column is replicated. Its value will
74 * reflect the value in the database. If OVSDB_IDL_ALERT is also set, then the
75 * value returned by ovsdb_idl_get_seqno() will change when the column's value
76 * changes.
77 *
78 * The possible mode combinations are:
79 *
80 * - 0, for a column that a client doesn't care about.
81 *
82 * - (OVSDB_IDL_MONITOR | OVSDB_IDL_ALERT), for a column that a client wants
83 * to track and possibly update.
84 *
85 * - OVSDB_IDL_MONITOR, for columns that a client treats as "write-only",
86 * that is, it updates them but doesn't want to get alerted about its own
87 * updates. It also won't be alerted about other clients' updates, so this
88 * is suitable only for use by a client that "owns" a particular column.
89 *
90 * - OVDSB_IDL_ALERT without OVSDB_IDL_MONITOR is not valid.
91 */
92 #define OVSDB_IDL_MONITOR (1 << 0) /* Monitor this column? */
93 #define OVSDB_IDL_ALERT (1 << 1) /* Alert client when column updated? */
94
95 void ovsdb_idl_add_column(struct ovsdb_idl *, const struct ovsdb_idl_column *);
96 void ovsdb_idl_add_table(struct ovsdb_idl *,
97 const struct ovsdb_idl_table_class *);
98
99 void ovsdb_idl_omit(struct ovsdb_idl *, const struct ovsdb_idl_column *);
100 void ovsdb_idl_omit_alert(struct ovsdb_idl *, const struct ovsdb_idl_column *);
101 \f
102 /* Reading the database replica. */
103
104 const struct ovsdb_idl_row *ovsdb_idl_get_row_for_uuid(
105 const struct ovsdb_idl *, const struct ovsdb_idl_table_class *,
106 const struct uuid *);
107 const struct ovsdb_idl_row *ovsdb_idl_first_row(
108 const struct ovsdb_idl *, const struct ovsdb_idl_table_class *);
109 const struct ovsdb_idl_row *ovsdb_idl_next_row(const struct ovsdb_idl_row *);
110
111 const struct ovsdb_datum *ovsdb_idl_read(const struct ovsdb_idl_row *,
112 const struct ovsdb_idl_column *);
113 const struct ovsdb_datum *ovsdb_idl_get(const struct ovsdb_idl_row *,
114 const struct ovsdb_idl_column *,
115 enum ovsdb_atomic_type key_type,
116 enum ovsdb_atomic_type value_type);
117
118 bool ovsdb_idl_row_is_synthetic(const struct ovsdb_idl_row *);
119 \f
120 /* Transactions.
121 *
122 * A transaction may modify the contents of a database by modifying the values
123 * of columns, deleting rows, inserting rows, or adding checks that columns in
124 * the database have not changed ("verify" operations), through
125 * ovsdb_idl_txn_*() functions. (The OVSDB IDL code generator produces helper
126 * functions that internally call the ovsdb_idl_txn_*() functions. These are
127 * likely to be more convenient.)
128 *
129 * Reading and writing columns and inserting and deleting rows are all
130 * straightforward. The reasons to verify columns are less obvious.
131 * Verification is the key to maintaining transactional integrity. Because
132 * OVSDB handles multiple clients, it can happen that between the time that
133 * OVSDB client A reads a column and writes a new value, OVSDB client B has
134 * written that column. Client A's write should not ordinarily overwrite
135 * client B's, especially if the column in question is a "map" column that
136 * contains several more or less independent data items. If client A adds a
137 * "verify" operation before it writes the column, then the transaction fails
138 * in case client B modifies it first. Client A will then see the new value of
139 * the column and compose a new transaction based on the new contents written
140 * by client B.
141 *
142 * When a transaction is complete, which must be before the next call to
143 * ovsdb_idl_run() on 'idl', call ovsdb_idl_txn_commit() or
144 * ovsdb_idl_txn_abort().
145 *
146 * The life-cycle of a transaction looks like this:
147 *
148 * 1. Create the transaction and record the initial sequence number:
149 *
150 * seqno = ovsdb_idl_get_seqno(idl);
151 * txn = ovsdb_idl_txn_create(idl);
152 *
153 * 2. Modify the database with ovsdb_idl_txn_*() functions directly or
154 * indirectly.
155 *
156 * 3. Commit the transaction by calling ovsdb_idl_txn_commit(). The first call
157 * to this function probably returns TXN_INCOMPLETE. The client must keep
158 * calling again along as this remains true, calling ovsdb_idl_run() in
159 * between to let the IDL do protocol processing. (If the client doesn't
160 * have anything else to do in the meantime, it can use
161 * ovsdb_idl_txn_commit_block() to avoid having to loop itself.)
162 *
163 * 4. If the final status is TXN_TRY_AGAIN, wait for ovsdb_idl_get_seqno() to
164 * change from the saved 'seqno' (it's possible that it's already changed,
165 * in which case the client should not wait at all), then start over from
166 * step 1. Only a call to ovsdb_idl_run() will change the return value of
167 * ovsdb_idl_get_seqno(). (ovsdb_idl_txn_commit_block() calls
168 * ovsdb_idl_run().)
169 */
170
171 enum ovsdb_idl_txn_status {
172 TXN_UNCOMMITTED, /* Not yet committed or aborted. */
173 TXN_UNCHANGED, /* Transaction didn't include any changes. */
174 TXN_INCOMPLETE, /* Commit in progress, please wait. */
175 TXN_ABORTED, /* ovsdb_idl_txn_abort() called. */
176 TXN_SUCCESS, /* Commit successful. */
177 TXN_TRY_AGAIN, /* Commit failed because a "verify" operation
178 * reported an inconsistency, due to a network
179 * problem, or other transient failure. Wait
180 * for a change, then try again. */
181 TXN_NOT_LOCKED, /* Server hasn't given us the lock yet. */
182 TXN_ERROR /* Commit failed due to a hard error. */
183 };
184
185 const char *ovsdb_idl_txn_status_to_string(enum ovsdb_idl_txn_status);
186
187 struct ovsdb_idl_txn *ovsdb_idl_txn_create(struct ovsdb_idl *);
188 void ovsdb_idl_txn_add_comment(struct ovsdb_idl_txn *, const char *, ...)
189 PRINTF_FORMAT (2, 3);
190 void ovsdb_idl_txn_set_dry_run(struct ovsdb_idl_txn *);
191 void ovsdb_idl_txn_increment(struct ovsdb_idl_txn *,
192 const struct ovsdb_idl_row *,
193 const struct ovsdb_idl_column *);
194 void ovsdb_idl_txn_destroy(struct ovsdb_idl_txn *);
195 void ovsdb_idl_txn_wait(const struct ovsdb_idl_txn *);
196 enum ovsdb_idl_txn_status ovsdb_idl_txn_commit(struct ovsdb_idl_txn *);
197 enum ovsdb_idl_txn_status ovsdb_idl_txn_commit_block(struct ovsdb_idl_txn *);
198 void ovsdb_idl_txn_abort(struct ovsdb_idl_txn *);
199
200 const char *ovsdb_idl_txn_get_error(const struct ovsdb_idl_txn *);
201
202 int64_t ovsdb_idl_txn_get_increment_new_value(const struct ovsdb_idl_txn *);
203 const struct uuid *ovsdb_idl_txn_get_insert_uuid(const struct ovsdb_idl_txn *,
204 const struct uuid *);
205
206 void ovsdb_idl_txn_write(const struct ovsdb_idl_row *,
207 const struct ovsdb_idl_column *,
208 struct ovsdb_datum *);
209 void ovsdb_idl_txn_write_clone(const struct ovsdb_idl_row *,
210 const struct ovsdb_idl_column *,
211 const struct ovsdb_datum *);
212 void ovsdb_idl_txn_delete(const struct ovsdb_idl_row *);
213 const struct ovsdb_idl_row *ovsdb_idl_txn_insert(
214 struct ovsdb_idl_txn *, const struct ovsdb_idl_table_class *,
215 const struct uuid *);
216
217 struct ovsdb_idl *ovsdb_idl_txn_get_idl (struct ovsdb_idl_txn *);
218
219 #endif /* ovsdb-idl.h */