/**
* Release the tryClaim of the coordinate. It means that nobody owns the coordinate anymore.
* Requires that that this instance owns the tryClaim to the coordinate.
*/
public void releaseClaim() throws CloudnameException {
scheduler.shutdown();
zkClient.deregisterListener(this);
while (true) {
final TrackedConfig config;
synchronized (trackedConfigList) {
if (trackedConfigList.isEmpty()) {
break;
}
config = trackedConfigList.remove(0);
}
config.stop();
}
sendEventToCoordinateListener(
CoordinateListener.Event.NOT_OWNER, "Released claim of coordinate");
synchronized (lastStatusVersionMonitor) {
try {
zkClient.getZookeeper().delete(path, lastStatusVersion);
} catch (InterruptedException e) {
throw new CloudnameException(e);
} catch (KeeperException e) {
throw new CloudnameException(e);
}
}
}
/**
* Creates the serialized value of the object and stores this in ZooKeeper under the path. It
* updates the lastStatusVersion. It does not set a watcher for the path.
*/
private void updateCoordinateData() throws CoordinateMissingException, CloudnameException {
if (!started.get()) {
throw new IllegalStateException("Not started.");
}
if (!zkClient.isConnected()) {
throw new CloudnameException("No proper connection with zookeeper.");
}
synchronized (lastStatusVersionMonitor) {
try {
Stat stat =
zkClient
.getZookeeper()
.setData(
path,
zkCoordinateData.snapshot().serialize().getBytes(Util.CHARSET_NAME),
lastStatusVersion);
LOG.fine("Updated coordinate, latest version is " + stat.getVersion());
lastStatusVersion = stat.getVersion();
} catch (KeeperException.NoNodeException e) {
throw new CoordinateMissingException("Coordinate does not exist " + path);
} catch (KeeperException e) {
throw new CloudnameException(
"ZooKeeper errror in updateCoordinateData: " + e.getMessage(), e);
} catch (UnsupportedEncodingException e) {
throw new CloudnameException(e);
} catch (InterruptedException e) {
throw new CloudnameException(e);
} catch (IOException e) {
throw new CloudnameException(e);
}
}
}
/** Register a watcher for the coordinate. */
private void registerWatcher() throws CloudnameException, InterruptedException {
LOG.fine("Register watcher for ZooKeeper..");
try {
zkClient.getZookeeper().exists(path, this);
} catch (KeeperException e) {
throw new CloudnameException(e);
}
}
/**
* Claims a coordinate. To know if it was successful or not you need to register a listener.
*
* @return this.
*/
public ClaimedCoordinate start() {
zkClient.registerListener(this);
started.set(true);
final long periodicDelayMs = 2000;
scheduler.scheduleWithFixedDelay(
new ResolveProblems(), 1 /* initial delay ms */, periodicDelayMs, TimeUnit.MILLISECONDS);
return this;
}
private void tryClaim() {
try {
zkClient
.getZookeeper()
.create(
path,
zkCoordinateData.snapshot().serialize().getBytes(Util.CHARSET_NAME),
ZooDefs.Ids.OPEN_ACL_UNSAFE,
CreateMode.EPHEMERAL,
new ClaimCallback(),
this);
} catch (IOException e) {
LOG.info("Got IO exception on claim with new ZooKeeper instance " + e.getMessage());
}
}
/**
* Handles event from ZooKeeper for this coordinate.
*
* @param event
*/
@Override
public void process(WatchedEvent event) {
LOG.info("Got an event from ZooKeeper " + event.toString());
synchronized (lastStatusVersionMonitor) {
switch (event.getType()) {
case None:
switch (event.getState()) {
case SyncConnected:
break;
case Disconnected:
case AuthFailed:
case Expired:
default:
// If we lost connection, we don't attempt to register another watcher as
// this might be blocking forever. Parent will try to reconnect (reclaim)
// later.
isSynchronizedWithZooKeeper.set(false);
sendEventToCoordinateListener(
CoordinateListener.Event.NO_CONNECTION_TO_STORAGE, event.toString());
return;
}
return;
case NodeDeleted:
// If node is deleted, we have no node to place a new watcher so we stop watching.
isSynchronizedWithZooKeeper.set(false);
sendEventToCoordinateListener(CoordinateListener.Event.NOT_OWNER, event.toString());
return;
case NodeDataChanged:
LOG.fine("Node data changed, check versions.");
boolean verifiedSynchronized = false;
try {
final Stat stat = zkClient.getZookeeper().exists(path, this);
if (stat == null) {
LOG.info("Could not stat path, setting out of synch, will retry claim");
} else {
LOG.fine("Previous version is " + lastStatusVersion + " now is " + stat.getVersion());
if (stat.getVersion() != lastStatusVersion) {
LOG.fine("Version mismatch, sending out of sync.");
} else {
verifiedSynchronized = true;
}
}
} catch (KeeperException e) {
LOG.fine(
"Problems with zookeeper, sending consistencyState out of sync: " + e.getMessage());
} catch (InterruptedException e) {
LOG.fine("Got interrupted: " + e.getMessage());
return;
} finally {
isSynchronizedWithZooKeeper.set(verifiedSynchronized);
}
if (verifiedSynchronized) {
sendEventToCoordinateListener(
CoordinateListener.Event.COORDINATE_OUT_OF_SYNC, event.toString());
}
return;
case NodeChildrenChanged:
case NodeCreated:
// This should not happen..
isSynchronizedWithZooKeeper.set(false);
sendEventToCoordinateListener(
CoordinateListener.Event.COORDINATE_OUT_OF_SYNC, event.toString());
return;
}
}
}
public CloudnameLock getCloudnameLock(CloudnameLock.Scope scope, String lockName) {
return new ZkCloudnameLock(zkClient.getZookeeper(), coordinate, scope, lockName);
}