lib/connectivity.c

   1 /*
   2  * Copyright (c) 2013 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "connectivity.h"
  19 #include "ovs-thread.h"
  20 #include "seq.h"
  21
  22 static struct seq *connectivity_seq;
  23
  24 /* Provides a global seq for connectivity changes.
  25  *
  26  * Connectivity monitoring modules should call seq_change() on the returned
  27  * object whenever the status of a port changes, whether the cause is local or
  28  * remote.
  29  *
  30  * Clients can seq_wait() on this object for changes to netdev flags, features,
  31  * ethernet addresses, carrier changes, and bfd/cfm/lacp/stp status. */
  32 struct seq *
  33 connectivity_seq_get(void)
  34 {
  35     static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
  36
  37     if (ovsthread_once_start(&once)) {
  38         connectivity_seq = seq_create();
  39         ovsthread_once_done(&once);
  40     }
  41
  42     return connectivity_seq;
  43 }