thredds.util
Class Mutex

java.lang.Object
  thredds.util.Mutex

public class Mutex
extends java.lang.Object

A simple non-reentrant mutual exclusion lock. The lock is free upon construction. Each acquire gets the lock, and each release frees it. Releasing a lock that is already free has no effect.

This implementation makes no attempt to provide any fairness or ordering guarantees. If you need them, consider using one of the Semaphore implementations as a locking mechanism.

Sample usage

Mutex can be useful in constructions that cannot be expressed using java synchronized blocks because the acquire/release pairs do not occur in the same method or code block. For example, you can use them for hand-over-hand locking across the nodes of a linked list. This allows extremely fine-grained locking, and so increases potential concurrency, at the cost of additional complexity and overhead that would normally make this worthwhile only in cases of extreme contention.

JOHN CARON ADDITIONS: Track which Thread has acquired the mutex, throw RunTimeException if wrong Thread tries to release. You must match each release with exactly one acquire

[ Introduction to this package. ]

Constructor Summary

Mutex()

Method Summary

void	acquire()
boolean	attempt(long msecs)
int	getWho()
boolean	isLocked()
boolean	isLockedByMe()
void	release()

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

isLocked

public boolean isLocked()

getWho

public int getWho()

isLockedByMe

public boolean isLockedByMe()

acquire

public void acquire()
             throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

release

public void release()

attempt

public boolean attempt(long msecs)
                throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException