public static int?WaitUntilLeaderIsElectedOrChanged(
ZkClient zkClient, string topic, int partition, long timeoutMs, int?oldLeaderOpt = null)
{
var leaderLock = new ReentrantLock();
var leaderExistsOrChanged = leaderLock.NewCondition();
if (oldLeaderOpt.HasValue == false)
{
Logger.InfoFormat("Waiting for leader to be elected for partition [{0},{1}]", topic, partition);
}
else
{
Logger.InfoFormat("Waiting for leader for partition [{0},{1}] to be changed from old leader {2}", topic, partition, oldLeaderOpt.Value);
}
leaderLock.Lock();
try
{
zkClient.SubscribeDataChanges(ZkUtils.GetTopicPartitionLeaderAndIsrPath(topic, partition), new LeaderExistsOrChangedListener(topic, partition, leaderLock, leaderExistsOrChanged, oldLeaderOpt, zkClient));
leaderExistsOrChanged.Await(TimeSpan.FromMilliseconds(timeoutMs));
// check if leader is elected
var leader = ZkUtils.GetLeaderForPartition(zkClient, topic, partition);
if (leader != null)
{
if (oldLeaderOpt.HasValue == false)
{
Logger.InfoFormat("Leader {0} is elected for partition [{1},{2}]", leader, topic, partition);
}
else
{
Logger.InfoFormat(
"Leader for partition [{0},{1}] is changed from {2} to {3}",
topic,
partition,
oldLeaderOpt.Value,
leader);
}
}
else
{
Logger.ErrorFormat("Timing out after {0} ms since leader is not elected for partition [{1},{2}]", timeoutMs, topic, partition);
}
return(leader);
}
finally
{
leaderLock.Unlock();
}
}