/**
* Get the monitor lock in ZooKeeper
*
* @throws KeeperException
* @throws InterruptedException
*/
private void getMonitorLock() throws KeeperException, InterruptedException {
final String zRoot = ZooUtil.getRoot(instance);
final String monitorPath = zRoot + Constants.ZMONITOR;
final String monitorLockPath = zRoot + Constants.ZMONITOR_LOCK;
// Ensure that everything is kosher with ZK as this has changed.
ZooReaderWriter zoo = ZooReaderWriter.getInstance();
if (zoo.exists(monitorPath)) {
byte[] data = zoo.getData(monitorPath, null);
// If the node isn't empty, it's from a previous install (has hostname:port for HTTP server)
if (0 != data.length) {
// Recursively delete from that parent node
zoo.recursiveDelete(monitorPath, NodeMissingPolicy.SKIP);
// And then make the nodes that we expect for the incoming ephemeral nodes
zoo.putPersistentData(monitorPath, new byte[0], NodeExistsPolicy.FAIL);
zoo.putPersistentData(monitorLockPath, new byte[0], NodeExistsPolicy.FAIL);
} else if (!zoo.exists(monitorLockPath)) {
// monitor node in ZK exists and is empty as we expect
// but the monitor/lock node does not
zoo.putPersistentData(monitorLockPath, new byte[0], NodeExistsPolicy.FAIL);
}
} else {
// 1.5.0 and earlier
zoo.putPersistentData(zRoot + Constants.ZMONITOR, new byte[0], NodeExistsPolicy.FAIL);
if (!zoo.exists(monitorLockPath)) {
// Somehow the monitor node exists but not monitor/lock
zoo.putPersistentData(monitorLockPath, new byte[0], NodeExistsPolicy.FAIL);
}
}
// Get a ZooLock for the monitor
while (true) {
MoniterLockWatcher monitorLockWatcher = new MoniterLockWatcher();
monitorLock = new ZooLock(monitorLockPath);
monitorLock.lockAsync(monitorLockWatcher, new byte[0]);
monitorLockWatcher.waitForChange();
if (monitorLockWatcher.acquiredLock) {
break;
}
if (!monitorLockWatcher.failedToAcquireLock) {
throw new IllegalStateException("monitor lock in unknown state");
}
monitorLock.tryToCancelAsyncLockOrUnlock();
UtilWaitThread.sleep(
getSystemConfiguration().getTimeInMillis(Property.MONITOR_LOCK_CHECK_INTERVAL));
}
log.info("Got Monitor lock.");
}
