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