Package org.wildfly.common.lock

Class SpinLock

java.lang.Object

org.wildfly.common.lock.SpinLock

All Implemented Interfaces:

Lock, ExtendedLock

public class SpinLock
extends Object
implements ExtendedLock

A spin lock. Such locks are designed to only be held for a very short time - for example, long enough to compare and swap two fields. The lock may degrade to yielding the thread after a certain number of spins if it is held for too long.

Spin locks do not support conditions, and they do not support timed waiting. Normally only the uninterruptible lock, tryLock, and unlock methods should be used to control the lock.

Constructor Summary

Constructors

Constructor	Description
SpinLock()	Construct a new instance.

Method Summary

Modifier and Type	Method	Description
boolean	isFair()	Determine if this lock is fair.
boolean	isHeldByCurrentThread()	Determine if this spin lock is held by the calling thread.
boolean	isLocked()	Determine if this spin lock is held.
void	lock()	Acquire the lock by spinning until it is held.
void	lockInterruptibly()	Acquire the lock by spinning until it is held or the thread is interrupted.
Condition	newCondition()	Unsupported.
boolean	tryLock()	Try to acquire the lock, returning immediately whether or not the lock was acquired.
boolean	tryLock(long time, TimeUnit unit)	Unsupported.
void	unlock()	Release the lock.

Methods inherited from class java.lang.Object

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

Constructor Detail

SpinLock

public SpinLock()

Construct a new instance.

Method Detail

isLocked

public boolean isLocked()

Determine if this spin lock is held. Useful for assertions.

Specified by:

isLocked in interface ExtendedLock

Returns:

true if the lock is held by any thread, false otherwise

isHeldByCurrentThread

public boolean isHeldByCurrentThread()

Determine if this spin lock is held by the calling thread. Useful for assertions.

Specified by:

isHeldByCurrentThread in interface ExtendedLock

Returns:

true if the lock is held by the calling thread, false otherwise

isFair

public boolean isFair()

Determine if this lock is fair.

Specified by:

isFair in interface ExtendedLock

Returns:

true; the lock is fair

lock

public void lock()

Acquire the lock by spinning until it is held.

Specified by:

lock in interface Lock

lockInterruptibly

public void lockInterruptibly()
                       throws InterruptedException

Acquire the lock by spinning until it is held or the thread is interrupted.

Specified by:

lockInterruptibly in interface Lock

Throws:

InterruptedException - if the thread is interrupted before the lock can be acquired

tryLock

public boolean tryLock()

Try to acquire the lock, returning immediately whether or not the lock was acquired.

Specified by:

tryLock in interface Lock

Returns:

true if the lock was acquired, false otherwise

unlock

public void unlock()

Release the lock.

Specified by:

unlock in interface Lock

Throws:

IllegalMonitorStateException - if the lock is not held by the current thread

tryLock

public boolean tryLock(long time,
                       TimeUnit unit)
                throws UnsupportedOperationException

Unsupported.

Specified by:

tryLock in interface Lock

Parameters:

time - ignored

unit - ignored

Returns:

nothing

Throws:

UnsupportedOperationException - always

newCondition

public Condition newCondition()
                       throws UnsupportedOperationException

Unsupported.

Specified by:

newCondition in interface Lock

Returns:

nothing

Throws:

UnsupportedOperationException - always