private void handleStateChange(ConnectionState newState) {
switch (newState) {
default:
{
// NOP
break;
}
case RECONNECTED:
{
try {
reset();
} catch (Exception e) {
log.error("Could not reset leader latch", e);
setLeadership(false);
}
break;
}
case SUSPENDED:
case LOST:
{
setLeadership(false);
break;
}
}
}
@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));
}
/**
* Remove this instance from the leadership election. If this instance is the leader, leadership
* is released. IMPORTANT: the only way to release leadership is by calling close(). All
* LeaderLatch instances must eventually be closed.
*
* @throws IOException errors
*/
@Override
public void close() throws IOException {
Preconditions.checkState(state.compareAndSet(State.STARTED, State.CLOSED), "Not started");
try {
client.delete().guaranteed().inBackground().forPath(ourPath);
} catch (Exception e) {
throw new IOException(e);
} finally {
client.getConnectionStateListenable().removeListener(listener);
setLeadership(false);
}
}
/**
* Remove this instance from the leadership election. If this instance is the leader, leadership
* is released. IMPORTANT: the only way to release leadership is by calling close(). All
* LeaderLatch instances must eventually be closed.
*
* @throws IOException errors
*/
@Override
public void close() throws IOException {
Preconditions.checkState(
state.compareAndSet(State.STARTED, State.CLOSED), "Already closed or has not been started");
try {
setNode(null);
} catch (Exception e) {
throw new IOException(e);
} finally {
client.getConnectionStateListenable().removeListener(listener);
setLeadership(false);
}
}
private void handleStateChange(ConnectionState newState) {
if (newState == ConnectionState.RECONNECTED) {
newState = ConnectionState.CONNECTED;
}
ConnectionState previousState = connectionState.getAndSet(newState);
if ((previousState == ConnectionState.LOST) && (newState == ConnectionState.CONNECTED)) {
try {
internalStart();
} catch (Exception e) {
log.error("Could not restart leader latch", e);
connectionState.set(ConnectionState.LOST);
setLeadership(false);
}
}
}
private void checkLeadership(List<String> children) throws Exception {
final String localOurPath = ourPath.get();
List<String> sortedChildren = LockInternals.getSortedChildren(LOCK_NAME, sorter, children);
int ourIndex =
(localOurPath != null) ? sortedChildren.indexOf(ZKPaths.getNodeFromPath(localOurPath)) : -1;
if (ourIndex < 0) {
log.error("Can't find our node. Resetting. Index: " + ourIndex);
reset();
} else if (ourIndex == 0) {
setLeadership(true);
} else {
String watchPath = sortedChildren.get(ourIndex - 1);
Watcher watcher =
new Watcher() {
@Override
public void process(WatchedEvent event) {
if ((state.get() == State.STARTED)
&& (event.getType() == Event.EventType.NodeDeleted)
&& (localOurPath != null)) {
try {
getChildren();
} catch (Exception ex) {
log.error("An error occurred checking the leadership.", ex);
}
}
}
};
BackgroundCallback callback =
new BackgroundCallback() {
@Override
public void processResult(CuratorFramework client, CuratorEvent event)
throws Exception {
if (event.getResultCode() == KeeperException.Code.NONODE.intValue()) {
// previous node is gone - reset
reset();
}
}
};
client
.checkExists()
.usingWatcher(watcher)
.inBackground(callback)
.forPath(ZKPaths.makePath(latchPath, watchPath));
}
}
private void checkForLeadership() throws Exception {
List<String> sortedChildren =
LockInternals.getSortedChildren(client, latchPath, LOCK_NAME, sorter);
if (sortedChildren.size() == 0) {
throw new Exception("no children - unexpected state");
}
int ourIndex = sortedChildren.indexOf(ZKPaths.getNodeFromPath(ourPath));
if (ourIndex == 0) {
setLeadership(true);
} else {
final String ourPathWhenWatched =
ourPath; // protected against a lost/suspended connection and an old watcher - I'm not
// sure if this is possible but it can't hurt
String watchPath = sortedChildren.get(ourIndex - 1);
Watcher watcher =
new Watcher() {
@Override
public void process(WatchedEvent event) {
if ((event.getType() == Event.EventType.NodeDeleted)
&& (ourPath != null)
&& ourPath.equals(ourPathWhenWatched)) {
try {
checkForLeadership();
} catch (Exception ex) {
log.error("An error ocurred checking the leadership.", ex);
}
}
}
};
if (client.checkExists().usingWatcher(watcher).forPath(ZKPaths.makePath(latchPath, watchPath))
== null) {
// the previous Participant may be down, so we need to reevaluate the list
// to get the actual previous Participant or get the leadership
checkForLeadership();
}
}
}
