ovsdb/server.h

   1 /* Copyright (c) 2011, 2012 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 SERVER_H
  17 #define SERVER_H 1
  18
  19 #include "openvswitch/hmap.h"
  20 #include "openvswitch/list.h"
  21 #include "openvswitch/shash.h"
  22 #include "openvswitch/uuid.h"
  23
  24 struct ovsdb;
  25 struct ovsdb_server;
  26
  27 /* Abstract representation of an OVSDB client connection, not tied to any
  28  * particular network protocol.  Protocol implementations
  29  * (e.g. jsonrpc-server.c) embed this in a larger data structure.  */
  30 struct ovsdb_session {
  31     struct ovsdb_server *server;
  32     struct ovs_list completions;/* Completed triggers. */
  33     struct hmap waiters;        /* "ovsdb_lock_waiter *"s by lock name. */
  34 };
  35
  36 void ovsdb_session_init(struct ovsdb_session *, struct ovsdb_server *);
  37 void ovsdb_session_destroy(struct ovsdb_session *);
  38
  39 struct ovsdb_lock_waiter *ovsdb_session_get_lock_waiter(
  40     const struct ovsdb_session *, const char *lock_name);
  41
  42 /* A database lock.
  43  *
  44  * A lock always has one or more "lock waiters" kept on a list.  The waiter at
  45  * the head of the list owns the lock. */
  46 struct ovsdb_lock {
  47     struct hmap_node hmap_node;  /* In ovsdb_server's "locks" hmap. */
  48     struct ovsdb_server *server; /* The containing server. */
  49     char *name;                  /* Unique name. */
  50     struct ovs_list waiters;     /* Contains "struct ovsdb_lock_waiter"s. */
  51 };
  52
  53 struct ovsdb_lock_waiter *ovsdb_lock_get_owner(const struct ovsdb_lock *);
  54
  55 /* How to obtain a lock. */
  56 enum ovsdb_lock_mode {
  57     OVSDB_LOCK_WAIT,            /* By waiting for it to become available. */
  58     OVSDB_LOCK_STEAL            /* By stealing it from the owner. */
  59 };
  60
  61 /* A session's request for a database lock. */
  62 struct ovsdb_lock_waiter {
  63     struct hmap_node session_node; /* In ->session->locks's hmap. */
  64     struct ovsdb_lock *lock;    /* The lock being waited for. */
  65
  66     enum ovsdb_lock_mode mode;
  67     char *lock_name;
  68
  69     struct ovsdb_session *session;
  70     struct ovs_list lock_node;  /* In ->lock->waiters's list. */
  71 };
  72
  73 struct ovsdb_session *ovsdb_lock_waiter_remove(struct ovsdb_lock_waiter *);
  74 void ovsdb_lock_waiter_destroy(struct ovsdb_lock_waiter *);
  75 bool ovsdb_lock_waiter_is_owner(const struct ovsdb_lock_waiter *);
  76
  77 /* Abstract representation of an OVSDB server not tied to any particular
  78  * network protocol.  Protocol implementations (e.g. jsonrpc-server.c) embed
  79  * this in a larger data structure.  */
  80 struct ovsdb_server {
  81     struct shash dbs;      /* Maps from a db name to a "struct ovsdb *". */
  82     struct hmap locks;     /* Contains "struct ovsdb_lock"s indexed by name. */
  83     struct uuid uuid;      /* Server ID. Generated every time a server is
  84                               launched.  */
  85 };
  86
  87 void ovsdb_server_init(struct ovsdb_server *);
  88 bool ovsdb_server_add_db(struct ovsdb_server *, struct ovsdb *);
  89 void ovsdb_server_remove_db(struct ovsdb_server *, struct ovsdb *);
  90 void ovsdb_server_destroy(struct ovsdb_server *);
  91
  92 struct ovsdb_lock_waiter *ovsdb_server_lock(struct ovsdb_server *,
  93                                             struct ovsdb_session *,
  94                                             const char *lock_name,
  95                                             enum ovsdb_lock_mode,
  96                                             struct ovsdb_session **victimp);
  97
  98 #endif /* ovsdb/server.h */