@Test
public void test() throws Exception {
Timing timing = new Timing();
LeaderSelector leaderSelector = null;
CuratorFramework client =
CuratorFrameworkFactory.builder()
.retryPolicy(new ExponentialBackoffRetry(100, 3))
.connectString(server.getConnectString())
.sessionTimeoutMs(timing.session())
.connectionTimeoutMs(timing.connection())
.build();
try {
client.start();
MyLeaderSelectorListener listener = new MyLeaderSelectorListener();
ExecutorService executorPool = Executors.newFixedThreadPool(20);
leaderSelector = new LeaderSelector(client, "/test", threadFactory, executorPool, listener);
leaderSelector.autoRequeue();
leaderSelector.start();
timing.sleepABit();
Assert.assertEquals(listener.getLeaderCount(), 1);
} finally {
CloseableUtils.closeQuietly(leaderSelector);
CloseableUtils.closeQuietly(client);
}
}
@VisibleForTesting
void reset() throws Exception {
setLeadership(false);
setNode(null);
BackgroundCallback callback =
new BackgroundCallback() {
@Override
public void processResult(CuratorFramework client, CuratorEvent event) throws Exception {
if (debugResetWaitLatch != null) {
debugResetWaitLatch.await();
debugResetWaitLatch = null;
}
if (event.getResultCode() == KeeperException.Code.OK.intValue()) {
setNode(event.getName());
getChildren();
} else {
log.error("getChildren() failed. rc = " + event.getResultCode());
}
}
};
client
.create()
.creatingParentsIfNeeded()
.withProtection()
.withMode(CreateMode.EPHEMERAL_SEQUENTIAL)
.inBackground(callback)
.forPath(ZKPaths.makePath(latchPath, LOCK_NAME), LeaderSelector.getIdBytes(id));
}
private void internalStart() throws Exception {
hasLeadership.set(false);
if (ourPath != null) {
client.delete().guaranteed().inBackground().forPath(ourPath);
}
ourPath =
client
.create()
.withProtection()
.withMode(CreateMode.EPHEMERAL_SEQUENTIAL)
.forPath(ZKPaths.makePath(latchPath, LOCK_NAME), LeaderSelector.getIdBytes(id));
checkForLeadership();
}
/**
* Return the id for the current leader. If for some reason there is no current leader, a dummy
* participant is returned.
*
* <p><B>NOTE</B> - this method polls the ZK server. Therefore it can possibly return a value that
* does not match {@link #hasLeadership()} as hasLeadership uses a local field of the class.
*
* @return leader
* @throws Exception ZK errors, interruptions, etc.
*/
public Participant getLeader() throws Exception {
Collection<String> participantNodes =
LockInternals.getParticipantNodes(client, latchPath, LOCK_NAME, sorter);
return LeaderSelector.getLeader(client, participantNodes);
}
