ovsdb/server.h

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