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December 19, 2015 20:19
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final AtomicBoolean hasLeadership = new AtomicBoolean(false); | |
public LeaderSelector startParticipant(CuratorFramework client, int id) throws Exception { | |
LeaderSelector selector = null; | |
final int myid = id; | |
LeaderSelectorListener listener = new LeaderSelectorListener() | |
{ | |
volatile CountDownLatch holdLatch; | |
@Override | |
public void takeLeadership(CuratorFramework client) throws Exception | |
{ | |
holdLatch = new CountDownLatch(1); | |
if ( !hasLeadership.compareAndSet(false, true) ) | |
{ | |
log("Another process has leadership. Me:" + myid + " - Leader:" + leader.get()); | |
} | |
try | |
{ | |
int previous_leader = leader.getAndSet(myid); | |
log(myid + " takes leadership. Leader was:" + previous_leader); | |
holdLatch.await(); | |
} | |
finally | |
{ | |
holdLatch = null; | |
hasLeadership.set(false); | |
} | |
} | |
@Override | |
public void stateChanged(CuratorFramework client, ConnectionState newState) | |
{ | |
if ((newState == ConnectionState.LOST) || (newState == ConnectionState.SUSPENDED)) | |
{ | |
if ( holdLatch != null ) | |
{ | |
holdLatch.countDown(); | |
} | |
if (leader.get() == myid) | |
{ | |
try {log(myid + " looses leadership.");} catch (Exception e) {}; | |
leader.set(-1); | |
} | |
} | |
} | |
}; | |
selector = new LeaderSelector(client, "/leader", listener); | |
selector.setId("" + myid); | |
selector.autoRequeue(); | |
selector.start(); | |
return selector; | |
} |
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