Package org.jivesoftware.util

Class AutoCloseableReentrantLock

java.lang.Object

org.jivesoftware.util.AutoCloseableReentrantLock

public class AutoCloseableReentrantLock
extends Object

A ReentrantLock lock that can be unlocked using an AutoCloseable. This allows for easy locking of resources, using a specific class as a namespace. Typical usage:

     try (final AutoCloseableReentrantLock.AutoCloseableLock ignored = new AutoCloseableReentrantLock(Clazz.class, user.getUsername()).lock()) {
         user.performNonThreadSafeTask();
     }
 

This essentially has the same effect as:

     synchronised ((Clazz.class.getName() + user.getUsername()).intern()) {
         user.performNonThreadSafeTask();
     }
 

but has advantages in that the current status of the lock can interrogated, the lock can be acquired interruptibly, etc.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	AutoCloseableReentrantLock.AutoCloseableLock

Constructor Summary

Constructors

Constructor	Description
AutoCloseableReentrantLock(Class clazz, String resource)	Create a class and resource specific lock.

Method Summary

Modifier and Type	Method	Description
boolean	isHeldByCurrentThread()	Queries if this lock is held by the current thread.
boolean	isLocked()	Queries if this lock is held by any thread.
AutoCloseableReentrantLock.AutoCloseableLock	lock()	Acquires the lock, blocking indefinitely.
AutoCloseableReentrantLock.AutoCloseableLock	lockInterruptibly()	Acquires the lock, blocking until the lock is acquired or the thread is interrupted.
Optional<AutoCloseableReentrantLock.AutoCloseableLock>	tryLock()	Tries to acquire the lock, returning immediately.

Methods inherited from class java.lang.Object

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

Constructor Details

AutoCloseableReentrantLock

public AutoCloseableReentrantLock(Class clazz,
 String resource)

Create a class and resource specific lock. If another thread has not closed another AutoCloseableReentrantLock with the same class and resource then this will block until it is closed.

Parameters:

clazz - The class for which the lock should be created.

resource - The resource for which the lock should be created.

Method Details

lock

public AutoCloseableReentrantLock.AutoCloseableLock lock()
                                                  throws IllegalStateException

Acquires the lock, blocking indefinitely.

Returns:

An AutoCloseableLock

Throws:

IllegalStateException - if this lock has already been released by the last thread to hold it

tryLock

public Optional<AutoCloseableReentrantLock.AutoCloseableLock> tryLock()

Tries to acquire the lock, returning immediately.

Returns:

An AutoCloseableLock if the lock was required, otherwise empty.

Throws:

IllegalStateException - if this lock has already been released by the last thread to hold it

lockInterruptibly

public AutoCloseableReentrantLock.AutoCloseableLock lockInterruptibly()
                                                               throws InterruptedException,
IllegalStateException

Acquires the lock, blocking until the lock is acquired or the thread is interrupted.

Returns:

An AutoCloseableLock

Throws:

InterruptedException - if the thread was interrupted before the lock could be acquired

IllegalStateException - if this lock has already been released by the last thread to hold it

isHeldByCurrentThread

public boolean isHeldByCurrentThread()

Queries if this lock is held by the current thread.

Returns:

true if current thread holds this lock and false otherwise

See Also:

• ReentrantLock.isHeldByCurrentThread()

isLocked

public boolean isLocked()

Queries if this lock is held by any thread. This method is designed for use in monitoring of the system state, not for synchronization control.

Returns:

true if any thread holds this lock and false otherwise

See Also:

• ReentrantLock.isLocked()