public void start() throws Exception {
m_leaderLatch =
new LeaderLatch(
m_client.get(),
m_config.getMetaServerLeaderElectionZkPath(),
m_config.getMetaServerName());
m_leaderLatch.addListener(
new LeaderLatchListener() {
@Override
public void notLeader() {
log.info("Become follower");
m_hasLeadership.set(false);
m_leader.set(fetcheLeaderInfoFromZk());
m_listenerContainer.notLeader(ClusterStateHolder.this);
}
@Override
public void isLeader() {
log.info("Become leader");
m_hasLeadership.set(true);
m_leader.set(fetcheLeaderInfoFromZk());
m_listenerContainer.isLeader(ClusterStateHolder.this);
}
},
Executors.newSingleThreadExecutor(
HermesThreadFactory.create("LeaderLatchListenerPool", true)));
// call notLeader before start, since if this is not leader, it won't trigger notLeader on start
m_listenerContainer.notLeader(this);
m_leaderLatch.start();
}
public static void main(String[] args) throws Exception {
List<LeaderLatch> leaders = new ArrayList<LeaderLatch>();
List<CuratorFramework> clients = new ArrayList<CuratorFramework>();
TestingServer server = new TestingServer();
try {
for (int i = 0; i < 10; i++) {
CuratorFramework client =
CuratorFrameworkFactory.newClient(
"192.168.50.202:2181,192.168.50.203:2181,192.168.50.204:2181",
new ExponentialBackoffRetry(20000, 3));
clients.add(client);
LeaderLatch leader = new LeaderLatch(client, "/francis/leader");
leader.addListener(
new LeaderLatchListener() {
@Override
public void isLeader() {
// TODO Auto-generated method stub
System.out.println("I am Leader");
}
@Override
public void notLeader() {
// TODO Auto-generated method stub
System.out.println("I am not Leader");
}
});
leaders.add(leader);
client.start();
leader.start();
}
Thread.sleep(Integer.MAX_VALUE);
} finally {
for (CuratorFramework client : clients) {
CloseableUtils.closeQuietly(client);
}
for (LeaderLatch leader : leaders) {
CloseableUtils.closeQuietly(leader);
}
// CloseableUtils.closeQuietly(server);
}
Thread.sleep(Integer.MAX_VALUE);
}
public void registerLeaderLatchListener(LeaderLatchListener... leaderListener) {
try {
leaderLatch.start();
Arrays.stream(leaderListener).forEach(leaderLatch::addListener);
} catch (Exception e) {
throw new InternalProcessingException(e);
}
}
public String getCurrentLeader() {
try {
final LeaderLatch latch = leaderLatch.get();
if (latch == null) {
return null;
}
Participant participant = latch.getLeader();
if (participant.isLeader()) {
return participant.getId();
}
return null;
} catch (Exception e) {
throw Throwables.propagate(e);
}
}
private HostPort fetcheLeaderInfoFromZk() {
try {
Participant leader = m_leaderLatch.getLeader();
return JSON.parseObject(leader.getId(), HostPort.class);
} catch (Exception e) {
log.error("Failed to fetch leader info from zk.", e);
}
return null;
}
@Override
public void run() {
try {
synchronized (lock) {
final LeaderLatch latch = leaderLatch.get();
if (latch == null || !latch.hasLeadership()) {
log.info(
"LEGGO MY EGGO. [%s] is leader.", latch == null ? null : latch.getLeader().getId());
stopBeingLeader();
return;
}
}
List<Boolean> allStarted =
Arrays.asList(databaseSegmentManager.isStarted(), serverInventoryView.isStarted());
for (Boolean aBoolean : allStarted) {
if (!aBoolean) {
log.error("InventoryManagers not started[%s]", allStarted);
stopBeingLeader();
return;
}
}
// Do coordinator stuff.
DruidCoordinatorRuntimeParams params =
DruidCoordinatorRuntimeParams.newBuilder()
.withStartTime(startTime)
.withDatasources(databaseSegmentManager.getInventory())
.withDynamicConfigs(dynamicConfigs.get())
.withEmitter(emitter)
.build();
for (DruidCoordinatorHelper helper : helpers) {
params = helper.run(params);
}
} catch (Exception e) {
log.makeAlert(e, "Caught exception, ignoring so that schedule keeps going.").emit();
}
}
private LeaderLatch createNewLeaderLatch() {
final LeaderLatch newLeaderLatch =
new LeaderLatch(
curator,
ZKPaths.makePath(zkPaths.getCoordinatorPath(), COORDINATOR_OWNER_NODE),
config.getHost());
newLeaderLatch.addListener(
new LeaderLatchListener() {
@Override
public void isLeader() {
DruidCoordinator.this.becomeLeader();
}
@Override
public void notLeader() {
DruidCoordinator.this.stopBeingLeader();
}
},
Execs.singleThreaded("CoordinatorLeader-%s"));
return leaderLatch.getAndSet(newLeaderLatch);
}
public boolean isLeader() {
return curatorClient.getZookeeperClient().isConnected() && leaderLatch.hasLeadership();
}
public void close() throws Exception {
m_leaderLatch.close();
}
