1 /* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
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:
7 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 /* Open vSwitch Database Interface Definition Language (OVSDB IDL).
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.
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
36 #include "ovsdb-types.h"
40 struct ovsdb_idl_class;
41 struct ovsdb_idl_column;
42 struct ovsdb_idl_table_class;
45 struct ovsdb_idl *ovsdb_idl_create(const char *remote,
46 const struct ovsdb_idl_class *,
47 bool monitor_everything_by_default);
48 void ovsdb_idl_destroy(struct ovsdb_idl *);
50 void ovsdb_idl_run(struct ovsdb_idl *);
51 void ovsdb_idl_wait(struct ovsdb_idl *);
53 void ovsdb_idl_set_lock(struct ovsdb_idl *, const char *lock_name);
54 bool ovsdb_idl_has_lock(const struct ovsdb_idl *);
55 bool ovsdb_idl_is_lock_contended(const struct ovsdb_idl *);
57 unsigned int ovsdb_idl_get_seqno(const struct ovsdb_idl *);
58 bool ovsdb_idl_has_ever_connected(const struct ovsdb_idl *);
59 void ovsdb_idl_force_reconnect(struct ovsdb_idl *);
61 /* Choosing columns and tables to replicate. */
63 /* Modes with which the IDL can monitor a column.
65 * If no bits are set, the column is not monitored at all. Its value will
66 * always appear to the client to be the default value for its type.
68 * If OVSDB_IDL_MONITOR is set, then the column is replicated. Its value will
69 * reflect the value in the database. If OVSDB_IDL_ALERT is also set, then the
70 * value returned by ovsdb_idl_get_seqno() will change when the column's value
73 * The possible mode combinations are:
75 * - 0, for a column that a client doesn't care about.
77 * - (OVSDB_IDL_MONITOR | OVSDB_IDL_ALERT), for a column that a client wants
78 * to track and possibly update.
80 * - OVSDB_IDL_MONITOR, for columns that a client treats as "write-only",
81 * that is, it updates them but doesn't want to get alerted about its own
82 * updates. It also won't be alerted about other clients' updates, so this
83 * is suitable only for use by a client that "owns" a particular column.
85 * - OVDSB_IDL_ALERT without OVSDB_IDL_MONITOR is not valid.
87 #define OVSDB_IDL_MONITOR (1 << 0) /* Monitor this column? */
88 #define OVSDB_IDL_ALERT (1 << 1) /* Alert client when column updated? */
90 void ovsdb_idl_add_column(struct ovsdb_idl *, const struct ovsdb_idl_column *);
91 void ovsdb_idl_add_table(struct ovsdb_idl *,
92 const struct ovsdb_idl_table_class *);
94 void ovsdb_idl_omit(struct ovsdb_idl *, const struct ovsdb_idl_column *);
95 void ovsdb_idl_omit_alert(struct ovsdb_idl *, const struct ovsdb_idl_column *);
97 /* Reading the database replica. */
99 const struct ovsdb_idl_row *ovsdb_idl_get_row_for_uuid(
100 const struct ovsdb_idl *, const struct ovsdb_idl_table_class *,
101 const struct uuid *);
102 const struct ovsdb_idl_row *ovsdb_idl_first_row(
103 const struct ovsdb_idl *, const struct ovsdb_idl_table_class *);
104 const struct ovsdb_idl_row *ovsdb_idl_next_row(const struct ovsdb_idl_row *);
106 const struct ovsdb_datum *ovsdb_idl_read(const struct ovsdb_idl_row *,
107 const struct ovsdb_idl_column *);
108 const struct ovsdb_datum *ovsdb_idl_get(const struct ovsdb_idl_row *,
109 const struct ovsdb_idl_column *,
110 enum ovsdb_atomic_type key_type,
111 enum ovsdb_atomic_type value_type);
113 bool ovsdb_idl_row_is_synthetic(const struct ovsdb_idl_row *);
117 * A transaction may modify the contents of a database by modifying the values
118 * of columns, deleting rows, inserting rows, or adding checks that columns in
119 * the database have not changed ("verify" operations), through
120 * ovsdb_idl_txn_*() functions. (The OVSDB IDL code generator produces helper
121 * functions that internally call the ovsdb_idl_txn_*() functions. These are
122 * likely to be more convenient.)
124 * Reading and writing columns and inserting and deleting rows are all
125 * straightforward. The reasons to verify columns are less obvious.
126 * Verification is the key to maintaining transactional integrity. Because
127 * OVSDB handles multiple clients, it can happen that between the time that
128 * OVSDB client A reads a column and writes a new value, OVSDB client B has
129 * written that column. Client A's write should not ordinarily overwrite
130 * client B's, especially if the column in question is a "map" column that
131 * contains several more or less independent data items. If client A adds a
132 * "verify" operation before it writes the column, then the transaction fails
133 * in case client B modifies it first. Client A will then see the new value of
134 * the column and compose a new transaction based on the new contents written
137 * When a transaction is complete, which must be before the next call to
138 * ovsdb_idl_run() on 'idl', call ovsdb_idl_txn_commit() or
139 * ovsdb_idl_txn_abort().
141 * The life-cycle of a transaction looks like this:
143 * 1. Create the transaction and record the initial sequence number:
145 * seqno = ovsdb_idl_get_seqno(idl);
146 * txn = ovsdb_idl_txn_create(idl);
148 * 2. Modify the database with ovsdb_idl_txn_*() functions directly or
151 * 3. Commit the transaction by calling ovsdb_idl_txn_commit(). The first call
152 * to this function probably returns TXN_INCOMPLETE. The client must keep
153 * calling again along as this remains true, calling ovsdb_idl_run() in
154 * between to let the IDL do protocol processing. (If the client doesn't
155 * have anything else to do in the meantime, it can use
156 * ovsdb_idl_txn_commit_block() to avoid having to loop itself.)
158 * 4. If the final status is TXN_TRY_AGAIN, wait for ovsdb_idl_get_seqno() to
159 * change from the saved 'seqno' (it's possible that it's already changed,
160 * in which case the client should not wait at all), then start over from
161 * step 1. Only a call to ovsdb_idl_run() will change the return value of
162 * ovsdb_idl_get_seqno(). (ovsdb_idl_txn_commit_block() calls
166 enum ovsdb_idl_txn_status {
167 TXN_UNCOMMITTED, /* Not yet committed or aborted. */
168 TXN_UNCHANGED, /* Transaction didn't include any changes. */
169 TXN_INCOMPLETE, /* Commit in progress, please wait. */
170 TXN_ABORTED, /* ovsdb_idl_txn_abort() called. */
171 TXN_SUCCESS, /* Commit successful. */
172 TXN_TRY_AGAIN, /* Commit failed because a "verify" operation
173 * reported an inconsistency, due to a network
174 * problem, or other transient failure. Wait
175 * for a change, then try again. */
176 TXN_NOT_LOCKED, /* Server hasn't given us the lock yet. */
177 TXN_ERROR /* Commit failed due to a hard error. */
180 const char *ovsdb_idl_txn_status_to_string(enum ovsdb_idl_txn_status);
182 struct ovsdb_idl_txn *ovsdb_idl_txn_create(struct ovsdb_idl *);
183 void ovsdb_idl_txn_add_comment(struct ovsdb_idl_txn *, const char *, ...)
184 PRINTF_FORMAT (2, 3);
185 void ovsdb_idl_txn_set_dry_run(struct ovsdb_idl_txn *);
186 void ovsdb_idl_txn_increment(struct ovsdb_idl_txn *,
187 const struct ovsdb_idl_row *,
188 const struct ovsdb_idl_column *);
189 void ovsdb_idl_txn_destroy(struct ovsdb_idl_txn *);
190 void ovsdb_idl_txn_wait(const struct ovsdb_idl_txn *);
191 enum ovsdb_idl_txn_status ovsdb_idl_txn_commit(struct ovsdb_idl_txn *);
192 enum ovsdb_idl_txn_status ovsdb_idl_txn_commit_block(struct ovsdb_idl_txn *);
193 void ovsdb_idl_txn_abort(struct ovsdb_idl_txn *);
195 const char *ovsdb_idl_txn_get_error(const struct ovsdb_idl_txn *);
197 int64_t ovsdb_idl_txn_get_increment_new_value(const struct ovsdb_idl_txn *);
198 const struct uuid *ovsdb_idl_txn_get_insert_uuid(const struct ovsdb_idl_txn *,
199 const struct uuid *);
201 void ovsdb_idl_txn_write(const struct ovsdb_idl_row *,
202 const struct ovsdb_idl_column *,
203 struct ovsdb_datum *);
204 void ovsdb_idl_txn_delete(const struct ovsdb_idl_row *);
205 const struct ovsdb_idl_row *ovsdb_idl_txn_insert(
206 struct ovsdb_idl_txn *, const struct ovsdb_idl_table_class *,
207 const struct uuid *);
209 struct ovsdb_idl *ovsdb_idl_txn_get_idl (struct ovsdb_idl_txn *);
211 #endif /* ovsdb-idl.h */