oracle.ifs.utils.common

Class Mutex

java.lang.Object

oracle.ifs.utils.common.Mutex

public final class Mutex
extends Object

This class implements a mutual exclusion lock (mutex). Threads will block trying to acquire the lock if the lock is already owned by another thread. The same thread can acquire the lock multiple times but then it needs to release it the same number of times by calling releaseLock() or call releaseAllLocks() before the mutex can be acquired by a different thread.

The owner thread must explicitly release the lock before the thread is disposed of, otherwise it will leave a locked mutex behind.

Constructor Summary

Constructors

Constructor and Description
Mutex()

Method Summary

Modifier and Type	Method and Description
boolean	acquireLock() Waits indefintely to acquire the lock and it is equivalent to calling acquireLock(0).
boolean	acquireLock(long timeout) Acquires a lock on this mutex.
int	getLockCount() Returns the number of locks the calling thread has on this mutex.
boolean	isLockedByCurrentThread() Returns true if the current calling thread has at least one lock on this mutex.
void	releaseAllLocks() Releases all locks that the calling thread holds on this mutex.
int	releaseLock() Releases one lock on this mutex.

Methods inherited from class java.lang.Object

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

Constructor Detail

Mutex

public Mutex()

Method Detail

acquireLock

public final boolean acquireLock()

Waits indefintely to acquire the lock and it is equivalent to calling acquireLock(0).

See Also:

acquireLock(long)

acquireLock

public final boolean acquireLock(long timeout)

Acquires a lock on this mutex. A thread that already has the lock may call this method multiple times and the call will return right away but a count of how many locks were acquired is kept. The owner thread must release the lock an equal number of times by calling releaseLock() or by calling releaseAllLocks() once.

Parameters:

timeout - The time in milliseconds to wait to obtain the lock. If the timeout is 0, the thread will wait indefinitely to obtain the lock.

Returns:

true if the lock was successfully acquired or false if the lock could not be acquired.

releaseLock

public final int releaseLock()

Releases one lock on this mutex. If a different thread other than the lock owner threaed tries to release the lock a RuntimeException is thrown. The counter will be decremented by one. If the counter reaches zero, the mutex will be completely unlocked and other threads waiting on this mutex will be able to proceed.

Returns how many locks the calling thread still has left on this mutex, the same as calling getLockCount()

releaseAllLocks

public final void releaseAllLocks()

Releases all locks that the calling thread holds on this mutex. The mutex will be completely unlocked and other threads waiting on this mutex will be able to proceed.

isLockedByCurrentThread

public final boolean isLockedByCurrentThread()

Returns true if the current calling thread has at least one lock on this mutex. If a different thread other than the lock owner threaed tries to release the lock a RuntimeException is thrown.

getLockCount

public final int getLockCount()

Returns the number of locks the calling thread has on this mutex.