Example usage for org.apache.zookeeper.recipes.lock LockListener LockListener

Introduction

In this page you can find the example usage for org.apache.zookeeper.recipes.lock LockListener LockListener.

Prototype

LockListener

Source Link

Usage

From source file:io.teknek.daemon.TeknekDaemon.java

License:Apache License

private void considerStarting(String child) throws WorkerDaoException {
    Plan plan = WorkerDao.findPlanByName(reKeeper.getZooKeeper(), child);
    if (plan == null) {
        logger.warn(String.format("Did not find a valid plan under node name %s", child));
        return;//from   w  ww.  ja v a 2s  . c  o m
    }
    if (!child.equals(plan.getName())) {
        logger.warn(String.format("Node name %s is not the same is the json value %s will not start", child,
                plan.getName()));
        return;
    }
    List<String> workerUuidsWorkingOnPlan = WorkerDao.findWorkersWorkingOnPlan(reKeeper.getZooKeeper(), plan);
    if (alreadyAtMaxWorkersPerNode(plan, workerUuidsWorkingOnPlan, workerThreads.get(plan))) {
        return;
    }
    if (!isPlanSane(plan)) {
        return;
    }
    logger.debug("trying to acqure lock on " + WorkerDao.LOCKS_ZK + "/" + plan.getName());
    WorkerDao.maybeCreatePlanLockDir(reKeeper.getZooKeeper(), plan);
    final CountDownLatch c = new CountDownLatch(1);
    WriteLock l = new WriteLock(reKeeper.getZooKeeper(), WorkerDao.LOCKS_ZK + "/" + plan.getName(), null);
    l.setLockListener(new LockListener() {

        @Override
        public void lockAcquired() {
            logger.debug(myId + " counting down");
            c.countDown();
        }

        @Override
        public void lockReleased() {
            logger.debug(myId + " released");
        }

    });
    boolean hasLatch = false;
    try {
        boolean gotLock = l.lock();
        if (!gotLock) {
            logger.debug("did not get lock");
            return;
        }
        hasLatch = c.await(3000, TimeUnit.MILLISECONDS);
        if (hasLatch) {
            plan = WorkerDao.findPlanByName(reKeeper.getZooKeeper(), child);
            if (plan.isDisabled()) {
                logger.debug("disabled " + plan.getName());
                return;
            }
            List<String> workerUuids = WorkerDao.findWorkersWorkingOnPlan(reKeeper.getZooKeeper(), plan);
            if (workerUuids.size() >= plan.getMaxWorkers()) {
                logger.debug("already running max children:" + workerUuids.size() + " planmax:"
                        + plan.getMaxWorkers() + " running:" + workerUuids);
                return;
            }
            logger.debug("starting worker");
            try {
                Worker worker = new Worker(plan, workerUuids, this);
                worker.init();
                worker.start();
                addWorkerToList(plan, worker);
            } catch (RuntimeException e) {
                throw new WorkerStartException(e);
            }
        }
    } catch (KeeperException | InterruptedException | WorkerDaoException | WorkerStartException e) {
        logger.warn("getting lock", e);
    } finally {
        try {
            l.unlock();
        } catch (RuntimeException ex) {
            logger.warn("Unable to unlock/cleanup. hadlock?" + hasLatch, ex);
        }
    }
}

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