How to use

ReentrantDistributedLock

in

org.apache.twill.internal.zookeeper

@Override
public Lock createLock(String name) {
 return new ReentrantDistributedLock(zkClient, "/lock/" + name);
}

/**
 * Acquires a distributed lock through ZooKeeper. It's the same as calling
 * {@link #acquire(boolean, boolean, long, TimeUnit)} with {@link Long#MAX_VALUE} as timeout.
 */
private boolean acquire(boolean interruptible, boolean waitForLock) throws InterruptedException, ExecutionException {
 try {
  return acquire(interruptible, waitForLock, Long.MAX_VALUE, TimeUnit.SECONDS);
 } catch (TimeoutException e) {
  // Should never happen
  throw Throwables.propagate(e);
 }
}

@Override
public Lock createLock(String name) {
 return new ReentrantDistributedLock(zkClient, "/lock/" + name);
}

/**
 * Acquires a distributed lock through ZooKeeper. It's the same as calling
 * {@link #acquire(boolean, boolean, long, TimeUnit)} with {@link Long#MAX_VALUE} as timeout.
 */
private boolean acquire(boolean interruptible, boolean waitForLock) throws InterruptedException, ExecutionException {
 try {
  return acquire(interruptible, waitForLock, Long.MAX_VALUE, TimeUnit.SECONDS);
 } catch (TimeoutException e) {
  // Should never happen
  throw Throwables.propagate(e);
 }
}

@Override
protected Lock getLock(StreamId streamId) {
 // It's ok to create new locks every time as it's backed by ZK for distributed lock
 ZKClient lockZKClient = ZKClients.namespace(zkClient, "/" + Constants.Service.STREAMS + "/locks");
 return new ReentrantDistributedLock(lockZKClient, streamId.toString());
}

@Override
public void lock() {
 lock.lock();
 try {
  acquire(false, true);
 } catch (Exception e) {
  lock.unlock();
  throw Throwables.propagate(e);
 }
}

this.logAppenderInitializer = injector.getInstance(LogAppenderInitializer.class);
this.zkClient = injector.getInstance(ZKClientService.class);
this.shutdownLock = new ReentrantDistributedLock(zkClient, "/lock/" + Constants.Service.MASTER_SERVICES);

@Override
public void lock() {
 lock.lock();
 try {
  acquire(false, true);
 } catch (Exception e) {
  lock.unlock();
  throw Throwables.propagate(e);
 }
}

@Override
public boolean tryLock() {
 if (!lock.tryLock()) {
  return false;
 }
 try {
  if (acquire(false, false)) {
   return true;
  }
  lock.unlock();
  return false;
 } catch (Exception e) {
  lock.unlock();
  throw Throwables.propagate(e);
 }
}

@Override
public boolean tryLock() {
 if (!lock.tryLock()) {
  return false;
 }
 try {
  if (acquire(false, false)) {
   return true;
  }
  lock.unlock();
  return false;
 } catch (Exception e) {
  lock.unlock();
  throw Throwables.propagate(e);
 }
}

@Override
public void lockInterruptibly() throws InterruptedException {
 lock.lockInterruptibly();
 try {
  acquire(true, true);
 } catch (Exception e) {
  lock.unlock();
  Throwables.propagateIfInstanceOf(e, InterruptedException.class);
  throw Throwables.propagate(e);
 }
}

@Override
public void lockInterruptibly() throws InterruptedException {
 lock.lockInterruptibly();
 try {
  acquire(true, true);
 } catch (Exception e) {
  lock.unlock();
  Throwables.propagateIfInstanceOf(e, InterruptedException.class);
  throw Throwables.propagate(e);
 }
}

@Override
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
 long startTime = System.nanoTime();
 if (!lock.tryLock(time, unit)) {
  return false;
 }
 long timeoutNano = unit.toNanos(time) - (System.nanoTime() - startTime);
 try {
  if (acquire(true, true, timeoutNano, TimeUnit.NANOSECONDS)) {
   return true;
  }
  lock.unlock();
  return false;
 } catch (ExecutionException e) {
  lock.unlock();
  throw Throwables.propagate(e.getCause());
 } catch (TimeoutException e) {
  lock.unlock();
  return false;
 }
}

@Override
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
 long startTime = System.nanoTime();
 if (!lock.tryLock(time, unit)) {
  return false;
 }
 long timeoutNano = unit.toNanos(time) - (System.nanoTime() - startTime);
 try {
  if (acquire(true, true, timeoutNano, TimeUnit.NANOSECONDS)) {
   return true;
  }
  lock.unlock();
  return false;
 } catch (ExecutionException e) {
  lock.unlock();
  throw Throwables.propagate(e.getCause());
 } catch (TimeoutException e) {
  lock.unlock();
  return false;
 }
}