X-Git-Url: http://git.cascardo.eti.br/?a=blobdiff_plain;f=ovsdb%2Fserver.c;h=82f55cb1954c8c94846894491b6aa3c29de891d7;hb=HEAD;hp=ad9454dfbaaca9c102c1539e127c2afe4441b4bf;hpb=e317253b1391c7b0a84c8dd51eaf1f3cc16eff56;p=cascardo%2Fovs.git

diff --git a/ovsdb/server.c b/ovsdb/server.c
index ad9454dfb..82f55cb19 100644
--- a/ovsdb/server.c
+++ b/ovsdb/server.c
@@ -1,4 +1,4 @@
-/* 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.
@@ -17,29 +17,206 @@
 
 #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;
 }