-/* Copyright (c) 2011 Nicira Networks
+/* Copyright (c) 2011, 2012 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include "server.h"
-/* Initializes 'session' as a session that operates on 'db'. */
+#include "hash.h"
+#include "ovsdb.h"
+
+/* Initializes 'session' as a session within 'server'. */
void
-ovsdb_session_init(struct ovsdb_session *session, struct ovsdb *db)
+ovsdb_session_init(struct ovsdb_session *session, struct ovsdb_server *server)
{
- session->db = db;
+ session->server = server;
list_init(&session->completions);
+ hmap_init(&session->waiters);
}
/* Destroys 'session'. */
void
-ovsdb_session_destroy(struct ovsdb_session *session OVS_UNUSED)
+ovsdb_session_destroy(struct ovsdb_session *session)
+{
+ ovs_assert(hmap_is_empty(&session->waiters));
+ hmap_destroy(&session->waiters);
+}
+
+/* Searches 'session' for an ovsdb_lock_waiter named 'lock_name' and returns
+ * it if it finds one, otherwise NULL. */
+struct ovsdb_lock_waiter *
+ovsdb_session_get_lock_waiter(const struct ovsdb_session *session,
+ const char *lock_name)
+{
+ struct ovsdb_lock_waiter *waiter;
+
+ HMAP_FOR_EACH_WITH_HASH (waiter, session_node, hash_string(lock_name, 0),
+ &session->waiters) {
+ if (!strcmp(lock_name, waiter->lock_name)) {
+ return waiter;
+ }
+ }
+ return NULL;
+}
+
+/* Returns the waiter that owns 'lock'.
+ *
+ * A lock always has an owner, so this function will never return NULL. */
+struct ovsdb_lock_waiter *
+ovsdb_lock_get_owner(const struct ovsdb_lock *lock)
+{
+ return CONTAINER_OF(list_front(&lock->waiters),
+ struct ovsdb_lock_waiter, lock_node);
+}
+
+/* Removes 'waiter' from its lock's list. This means that, if 'waiter' was
+ * formerly the owner of its lock, then it no longer owns it.
+ *
+ * Returns the session that now owns 'waiter'. This is NULL if 'waiter' was
+ * the lock's owner and no other sessions were waiting for the lock. In this
+ * case, the lock has been destroyed, so the caller must be sure not to refer
+ * to it again. A nonnull return value reflects a change in the lock's
+ * ownership if and only if 'waiter' formerly owned the lock. */
+struct ovsdb_session *
+ovsdb_lock_waiter_remove(struct ovsdb_lock_waiter *waiter)
+{
+ struct ovsdb_lock *lock = waiter->lock;
+
+ list_remove(&waiter->lock_node);
+ waiter->lock = NULL;
+
+ if (list_is_empty(&lock->waiters)) {
+ hmap_remove(&lock->server->locks, &lock->hmap_node);
+ free(lock->name);
+ free(lock);
+ return NULL;
+ }
+
+ return ovsdb_lock_get_owner(lock)->session;
+}
+
+/* Destroys 'waiter', which must have already been removed from its lock's
+ * waiting list with ovsdb_lock_waiter_remove().
+ *
+ * Removing and destroying locks are decoupled because a lock initially created
+ * by the "steal" request, that is later stolen by another client, remains in
+ * the database session until the database client sends an "unlock" request. */
+void
+ovsdb_lock_waiter_destroy(struct ovsdb_lock_waiter *waiter)
+{
+ ovs_assert(!waiter->lock);
+ hmap_remove(&waiter->session->waiters, &waiter->session_node);
+ free(waiter->lock_name);
+ free(waiter);
+}
+
+/* Returns true if 'waiter' owns its associated lock. */
+bool
+ovsdb_lock_waiter_is_owner(const struct ovsdb_lock_waiter *waiter)
{
+ return waiter->lock && waiter == ovsdb_lock_get_owner(waiter->lock);
}
-/* Initializes 'server' as a server that operates on 'db'. */
+/* Initializes 'server'.
+ *
+ * The caller must call ovsdb_server_add_db() for each database to which
+ * 'server' should provide access. */
void
-ovsdb_server_init(struct ovsdb_server *server, struct ovsdb *db)
+ovsdb_server_init(struct ovsdb_server *server)
+{
+ shash_init(&server->dbs);
+ hmap_init(&server->locks);
+}
+
+/* Adds 'db' to the set of databases served out by 'server'. Returns true if
+ * successful, false if 'db''s name is the same as some database already in
+ * 'server'. */
+bool
+ovsdb_server_add_db(struct ovsdb_server *server, struct ovsdb *db)
+{
+ return shash_add_once(&server->dbs, db->schema->name, db);
+}
+
+/* Removes 'db' from the set of databases served out by 'server'. Returns
+ * true if successful, false if there is no db associated with
+ * db->schema->name. */
+bool
+ovsdb_server_remove_db(struct ovsdb_server *server, struct ovsdb *db)
{
- server->db = db;
+ void *data = shash_find_and_delete(&server->dbs, db->schema->name);
+ if (data) {
+ return true;
+ }
+ return false;
}
/* Destroys 'server'. */
void
-ovsdb_server_destroy(struct ovsdb_server *server OVS_UNUSED)
+ovsdb_server_destroy(struct ovsdb_server *server)
+{
+ shash_destroy(&server->dbs);
+ hmap_destroy(&server->locks);
+}
+
+static struct ovsdb_lock *
+ovsdb_server_create_lock__(struct ovsdb_server *server, const char *lock_name,
+ uint32_t hash)
{
+ struct ovsdb_lock *lock;
+
+ HMAP_FOR_EACH_WITH_HASH (lock, hmap_node, hash, &server->locks) {
+ if (!strcmp(lock->name, lock_name)) {
+ return lock;
+ }
+ }
+
+ lock = xzalloc(sizeof *lock);
+ lock->server = server;
+ lock->name = xstrdup(lock_name);
+ hmap_insert(&server->locks, &lock->hmap_node, hash);
+ list_init(&lock->waiters);
+
+ return lock;
+}
+
+/* Attempts to acquire the lock named 'lock_name' for 'session' within
+ * 'server'. Returns the new lock waiter.
+ *
+ * If 'mode' is OVSDB_LOCK_STEAL, then the new lock waiter is always the owner
+ * of the lock. '*victimp' receives the session of the previous owner or NULL
+ * if the lock was previously unowned. (If the victim itself originally
+ * obtained the lock through a "steal" operation, then this function also
+ * removes the victim from the lock's waiting list.)
+ *
+ * If 'mode' is OVSDB_LOCK_WAIT, then the new lock waiter is the owner of the
+ * lock only if this lock had no existing owner. '*victimp' is set to NULL. */
+struct ovsdb_lock_waiter *
+ovsdb_server_lock(struct ovsdb_server *server,
+ struct ovsdb_session *session,
+ const char *lock_name,
+ enum ovsdb_lock_mode mode,
+ struct ovsdb_session **victimp)
+{
+ uint32_t hash = hash_string(lock_name, 0);
+ struct ovsdb_lock_waiter *waiter, *victim;
+ struct ovsdb_lock *lock;
+
+ lock = ovsdb_server_create_lock__(server, lock_name, hash);
+ victim = (mode == OVSDB_LOCK_STEAL && !list_is_empty(&lock->waiters)
+ ? ovsdb_lock_get_owner(lock)
+ : NULL);
+
+ waiter = xmalloc(sizeof *waiter);
+ waiter->mode = mode;
+ waiter->lock_name = xstrdup(lock_name);
+ waiter->lock = lock;
+ if (mode == OVSDB_LOCK_STEAL) {
+ list_push_front(&lock->waiters, &waiter->lock_node);
+ } else {
+ list_push_back(&lock->waiters, &waiter->lock_node);
+ }
+ waiter->session = session;
+ hmap_insert(&waiter->session->waiters, &waiter->session_node, hash);
+
+ if (victim && victim->mode == OVSDB_LOCK_STEAL) {
+ ovsdb_lock_waiter_remove(victim);
+ }
+ *victimp = victim ? victim->session : NULL;
+
+ return waiter;
}
projects / cascardo / ovs.git / blobdiff