/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
package com.espertech.esper.util;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* Simple read-write lock based on {@link java.util.concurrent.locks.ReentrantReadWriteLock} that associates a
* name with the lock and traces read/write locking and unlocking.
*/
public class ManagedReadWriteLock {
private static final Logger log = LoggerFactory.getLogger(ManagedReadWriteLock.class);
/**
* Acquire text.
*/
public final static String ACQUIRE_TEXT = "Acquire ";
/**
* Acquired text.
*/
public final static String ACQUIRED_TEXT = "Got ";
/**
* Acquired text.
*/
public final static String TRY_TEXT = "Trying ";
/**
* Release text.
*/
public final static String RELEASE_TEXT = "Release ";
/**
* Released text.
*/
public final static String RELEASED_TEXT = "Freed ";
private final ReentrantReadWriteLock lock;
private final String name;
/**
* Ctor.
*
* @param name of lock
* @param isFair true if a fair lock, false if not
*/
public ManagedReadWriteLock(String name, boolean isFair) {
this.name = name;
this.lock = new ReentrantReadWriteLock(isFair);
}
/**
* Lock write lock.
*/
public void acquireWriteLock() {
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(ACQUIRE_TEXT + " write " + name, lock);
}
lock.writeLock().lock();
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(ACQUIRED_TEXT + " write " + name, lock);
}
}
/**
* Try write lock with timeout, returning an indicator whether the lock was acquired or not.
*
* @param msec number of milliseconds to wait for lock
* @return indicator whether the lock could be acquired or not
*/
public boolean tryWriteLock(long msec) {
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(TRY_TEXT + " write " + name, lock);
}
boolean result = false;
try {
result = lock.writeLock().tryLock(msec, TimeUnit.MILLISECONDS);
} catch (InterruptedException ex) {
log.warn("Lock wait interupted");
}
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(TRY_TEXT + " write " + name + " : " + result, lock);
}
return result;
}
/**
* Unlock write lock.
*/
public void releaseWriteLock() {
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(RELEASE_TEXT + " write " + name, lock);
}
lock.writeLock().unlock();
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(RELEASED_TEXT + " write " + name, lock);
}
}
/**
* Lock read lock.
*/
public void acquireReadLock() {
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(ACQUIRE_TEXT + " read " + name, lock);
}
lock.readLock().lock();
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(ACQUIRED_TEXT + " read " + name, lock);
}
}
/**
* Unlock read lock.
*/
public void releaseReadLock() {
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(RELEASE_TEXT + " read " + name, lock);
}
lock.readLock().unlock();
if (ThreadLogUtil.ENABLED_TRACE) {
ThreadLogUtil.traceLock(RELEASED_TEXT + " read " + name, lock);
}
}
public ReentrantReadWriteLock getLock() {
return lock;
}
}