/**
* try to grab a 'lock' on the task zk node to own and execute the task.
*
* <p>
*
* @param path zk node for the task
*/
private void grabTask(String path) {
Stat stat = new Stat();
byte[] data;
synchronized (grabTaskLock) {
currentTask = path;
workerInGrabTask = true;
if (Thread.interrupted()) {
return;
}
}
try {
try {
if ((data = ZKUtil.getDataNoWatch(watcher, path, stat)) == null) {
SplitLogCounters.tot_wkr_failed_to_grab_task_no_data.incrementAndGet();
return;
}
} catch (KeeperException e) {
LOG.warn("Failed to get data for znode " + path, e);
SplitLogCounters.tot_wkr_failed_to_grab_task_exception.incrementAndGet();
return;
}
SplitLogTask slt;
try {
slt = SplitLogTask.parseFrom(data);
} catch (DeserializationException e) {
LOG.warn("Failed parse data for znode " + path, e);
SplitLogCounters.tot_wkr_failed_to_grab_task_exception.incrementAndGet();
return;
}
if (!slt.isUnassigned()) {
SplitLogCounters.tot_wkr_failed_to_grab_task_owned.incrementAndGet();
return;
}
currentVersion =
attemptToOwnTask(
true, watcher, server.getServerName(), path, slt.getMode(), stat.getVersion());
if (currentVersion < 0) {
SplitLogCounters.tot_wkr_failed_to_grab_task_lost_race.incrementAndGet();
return;
}
if (ZKSplitLog.isRescanNode(watcher, currentTask)) {
ZkSplitLogWorkerCoordination.ZkSplitTaskDetails splitTaskDetails =
new ZkSplitLogWorkerCoordination.ZkSplitTaskDetails();
splitTaskDetails.setTaskNode(currentTask);
splitTaskDetails.setCurTaskZKVersion(new MutableInt(currentVersion));
endTask(
new SplitLogTask.Done(server.getServerName(), slt.getMode()),
SplitLogCounters.tot_wkr_task_acquired_rescan,
splitTaskDetails);
return;
}
LOG.info("worker " + server.getServerName() + " acquired task " + path);
SplitLogCounters.tot_wkr_task_acquired.incrementAndGet();
getDataSetWatchAsync();
submitTask(path, slt.getMode(), currentVersion, reportPeriod);
// after a successful submit, sleep a little bit to allow other RSs to grab the rest tasks
try {
int sleepTime = RandomUtils.nextInt(500) + 500;
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
LOG.warn("Interrupted while yielding for other region servers", e);
Thread.currentThread().interrupt();
}
} finally {
synchronized (grabTaskLock) {
workerInGrabTask = false;
// clear the interrupt from stopTask() otherwise the next task will
// suffer
Thread.interrupted();
}
}
}
