org.apache.curator.framework.recipes.locks

Class InterProcessMutex

java.lang.Object

org.apache.curator.framework.recipes.locks.InterProcessMutex

All Implemented Interfaces:

InterProcessLock, Revocable<InterProcessMutex>

Direct Known Subclasses:

InterProcessReadWriteLock.ReadLock, InterProcessReadWriteLock.WriteLock

public class InterProcessMutex
extends Object
implements InterProcessLock, Revocable<InterProcessMutex>

A re-entrant mutex that works across JVMs. Uses Zookeeper to hold the lock. All processes in all JVMs that use the same lock path will achieve an inter-process critical section. Further, this mutex is "fair" - each user will get the mutex in the order requested (from ZK's point of view)

Constructor Summary

Constructors

Constructor and Description
InterProcessMutex(CuratorFramework client, String path)
InterProcessMutex(CuratorFramework client, String path, LockInternalsDriver driver)

Method Summary

Modifier and Type	Method and Description
void	acquire() Acquire the mutex - blocking until it's available.
boolean	acquire(long time, TimeUnit unit) Acquire the mutex - blocks until it's available or the given time expires.
protected byte[]	getLockNodeBytes()
protected String	getLockPath()
Collection<String>	getParticipantNodes() Return a sorted list of all current nodes participating in the lock
boolean	isAcquiredInThisProcess() Returns true if the mutex is acquired by a thread in this JVM
boolean	isOwnedByCurrentThread() Returns true if the mutex is acquired by the calling thread
void	makeRevocable(RevocationListener<InterProcessMutex> listener) Make the lock revocable.
void	makeRevocable(RevocationListener<InterProcessMutex> listener, Executor executor) Make the lock revocable.
void	release() Perform one release of the mutex if the calling thread is the same thread that acquired it.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

InterProcessMutex

public InterProcessMutex(CuratorFramework client,
                         String path)

Parameters:

client - client

path - the path to lock

InterProcessMutex

public InterProcessMutex(CuratorFramework client,
                         String path,
                         LockInternalsDriver driver)

Parameters:

client - client

path - the path to lock

driver - lock driver

Method Detail

acquire

public void acquire()
             throws Exception

Acquire the mutex - blocking until it's available. Note: the same thread can call acquire re-entrantly. Each call to acquire must be balanced by a call to release()

Specified by:

acquire in interface InterProcessLock

Throws:

Exception - ZK errors, connection interruptions

acquire

public boolean acquire(long time,
                       TimeUnit unit)
                throws Exception

Acquire the mutex - blocks until it's available or the given time expires. Note: the same thread can call acquire re-entrantly. Each call to acquire that returns true must be balanced by a call to release()

Specified by:

acquire in interface InterProcessLock

Parameters:

time - time to wait

unit - time unit

Returns:

true if the mutex was acquired, false if not

Throws:

Exception - ZK errors, connection interruptions

isAcquiredInThisProcess

public boolean isAcquiredInThisProcess()

Returns true if the mutex is acquired by a thread in this JVM

Specified by:

isAcquiredInThisProcess in interface InterProcessLock

Returns:

true/false

release

public void release()
             throws Exception

Perform one release of the mutex if the calling thread is the same thread that acquired it. If the thread had made multiple calls to acquire, the mutex will still be held when this method returns.

Specified by:

release in interface InterProcessLock

Throws:

Exception - ZK errors, interruptions, current thread does not own the lock

getParticipantNodes

public Collection<String> getParticipantNodes()
                                       throws Exception

Return a sorted list of all current nodes participating in the lock

Returns:

list of nodes

Throws:

Exception - ZK errors, interruptions, etc.

makeRevocable

public void makeRevocable(RevocationListener<InterProcessMutex> listener)

Description copied from interface: Revocable

Make the lock revocable. Your listener will get called when another process/thread wants you to release the lock. Revocation is cooperative.

Specified by:

makeRevocable in interface Revocable<InterProcessMutex>

Parameters:

listener - the listener

makeRevocable

public void makeRevocable(RevocationListener<InterProcessMutex> listener,
                          Executor executor)

Description copied from interface: Revocable

Make the lock revocable. Your listener will get called when another process/thread wants you to release the lock. Revocation is cooperative.

Specified by:

makeRevocable in interface Revocable<InterProcessMutex>

Parameters:

listener - the listener

executor - executor for the listener

isOwnedByCurrentThread

public boolean isOwnedByCurrentThread()

Returns true if the mutex is acquired by the calling thread

Returns:

true/false

getLockNodeBytes

protected byte[] getLockNodeBytes()

getLockPath

protected String getLockPath()