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git.proxmox.com Git - mirror_ovs.git/blob - ovsdb/server.c
1 /* Copyright (c) 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.
23 /* Initializes 'session' as a session within 'server'. */
25 ovsdb_session_init(struct ovsdb_session
*session
, struct ovsdb_server
*server
)
27 session
->server
= server
;
28 ovs_list_init(&session
->completions
);
29 hmap_init(&session
->waiters
);
32 /* Destroys 'session'. */
34 ovsdb_session_destroy(struct ovsdb_session
*session
)
36 ovs_assert(hmap_is_empty(&session
->waiters
));
37 hmap_destroy(&session
->waiters
);
40 /* Searches 'session' for an ovsdb_lock_waiter named 'lock_name' and returns
41 * it if it finds one, otherwise NULL. */
42 struct ovsdb_lock_waiter
*
43 ovsdb_session_get_lock_waiter(const struct ovsdb_session
*session
,
44 const char *lock_name
)
46 struct ovsdb_lock_waiter
*waiter
;
48 HMAP_FOR_EACH_WITH_HASH (waiter
, session_node
, hash_string(lock_name
, 0),
50 if (!strcmp(lock_name
, waiter
->lock_name
)) {
57 /* Returns the waiter that owns 'lock'.
59 * A lock always has an owner, so this function will never return NULL. */
60 struct ovsdb_lock_waiter
*
61 ovsdb_lock_get_owner(const struct ovsdb_lock
*lock
)
63 return CONTAINER_OF(ovs_list_front(&lock
->waiters
),
64 struct ovsdb_lock_waiter
, lock_node
);
67 /* Removes 'waiter' from its lock's list. This means that, if 'waiter' was
68 * formerly the owner of its lock, then it no longer owns it.
70 * Returns the session that now owns 'waiter'. This is NULL if 'waiter' was
71 * the lock's owner and no other sessions were waiting for the lock. In this
72 * case, the lock has been destroyed, so the caller must be sure not to refer
73 * to it again. A nonnull return value reflects a change in the lock's
74 * ownership if and only if 'waiter' formerly owned the lock. */
75 struct ovsdb_session
*
76 ovsdb_lock_waiter_remove(struct ovsdb_lock_waiter
*waiter
)
78 struct ovsdb_lock
*lock
= waiter
->lock
;
80 ovs_list_remove(&waiter
->lock_node
);
83 if (ovs_list_is_empty(&lock
->waiters
)) {
84 hmap_remove(&lock
->server
->locks
, &lock
->hmap_node
);
90 return ovsdb_lock_get_owner(lock
)->session
;
93 /* Destroys 'waiter', which must have already been removed from its lock's
94 * waiting list with ovsdb_lock_waiter_remove().
96 * Removing and destroying locks are decoupled because a lock initially created
97 * by the "steal" request, that is later stolen by another client, remains in
98 * the database session until the database client sends an "unlock" request. */
100 ovsdb_lock_waiter_destroy(struct ovsdb_lock_waiter
*waiter
)
102 ovs_assert(!waiter
->lock
);
103 hmap_remove(&waiter
->session
->waiters
, &waiter
->session_node
);
104 free(waiter
->lock_name
);
108 /* Returns true if 'waiter' owns its associated lock. */
110 ovsdb_lock_waiter_is_owner(const struct ovsdb_lock_waiter
*waiter
)
112 return waiter
->lock
&& waiter
== ovsdb_lock_get_owner(waiter
->lock
);
115 /* Initializes 'server'.
117 * The caller must call ovsdb_server_add_db() for each database to which
118 * 'server' should provide access. */
120 ovsdb_server_init(struct ovsdb_server
*server
)
122 shash_init(&server
->dbs
);
123 hmap_init(&server
->locks
);
126 /* Adds 'db' to the set of databases served out by 'server'. Returns true if
127 * successful, false if 'db''s name is the same as some database already in
130 ovsdb_server_add_db(struct ovsdb_server
*server
, struct ovsdb
*db
)
132 return shash_add_once(&server
->dbs
, db
->schema
->name
, db
);
135 /* Removes 'db' from the set of databases served out by 'server'. Returns
136 * true if successful, false if there is no db associated with
137 * db->schema->name. */
139 ovsdb_server_remove_db(struct ovsdb_server
*server
, struct ovsdb
*db
)
141 void *data
= shash_find_and_delete(&server
->dbs
, db
->schema
->name
);
148 /* Destroys 'server'. */
150 ovsdb_server_destroy(struct ovsdb_server
*server
)
152 shash_destroy(&server
->dbs
);
153 hmap_destroy(&server
->locks
);
156 static struct ovsdb_lock
*
157 ovsdb_server_create_lock__(struct ovsdb_server
*server
, const char *lock_name
,
160 struct ovsdb_lock
*lock
;
162 HMAP_FOR_EACH_WITH_HASH (lock
, hmap_node
, hash
, &server
->locks
) {
163 if (!strcmp(lock
->name
, lock_name
)) {
168 lock
= xzalloc(sizeof *lock
);
169 lock
->server
= server
;
170 lock
->name
= xstrdup(lock_name
);
171 hmap_insert(&server
->locks
, &lock
->hmap_node
, hash
);
172 ovs_list_init(&lock
->waiters
);
177 /* Attempts to acquire the lock named 'lock_name' for 'session' within
178 * 'server'. Returns the new lock waiter.
180 * If 'mode' is OVSDB_LOCK_STEAL, then the new lock waiter is always the owner
181 * of the lock. '*victimp' receives the session of the previous owner or NULL
182 * if the lock was previously unowned. (If the victim itself originally
183 * obtained the lock through a "steal" operation, then this function also
184 * removes the victim from the lock's waiting list.)
186 * If 'mode' is OVSDB_LOCK_WAIT, then the new lock waiter is the owner of the
187 * lock only if this lock had no existing owner. '*victimp' is set to NULL. */
188 struct ovsdb_lock_waiter
*
189 ovsdb_server_lock(struct ovsdb_server
*server
,
190 struct ovsdb_session
*session
,
191 const char *lock_name
,
192 enum ovsdb_lock_mode mode
,
193 struct ovsdb_session
**victimp
)
195 uint32_t hash
= hash_string(lock_name
, 0);
196 struct ovsdb_lock_waiter
*waiter
, *victim
;
197 struct ovsdb_lock
*lock
;
199 lock
= ovsdb_server_create_lock__(server
, lock_name
, hash
);
200 victim
= (mode
== OVSDB_LOCK_STEAL
&& !ovs_list_is_empty(&lock
->waiters
)
201 ? ovsdb_lock_get_owner(lock
)
204 waiter
= xmalloc(sizeof *waiter
);
206 waiter
->lock_name
= xstrdup(lock_name
);
208 if (mode
== OVSDB_LOCK_STEAL
) {
209 ovs_list_push_front(&lock
->waiters
, &waiter
->lock_node
);
211 ovs_list_push_back(&lock
->waiters
, &waiter
->lock_node
);
213 waiter
->session
= session
;
214 hmap_insert(&waiter
->session
->waiters
, &waiter
->session_node
, hash
);
216 if (victim
&& victim
->mode
== OVSDB_LOCK_STEAL
) {
217 ovsdb_lock_waiter_remove(victim
);
219 *victimp
= victim
? victim
->session
: NULL
;