001/** 002 * 003 * Copyright (c) 2014, the Railo Company Ltd. All rights reserved. 004 * 005 * This library is free software; you can redistribute it and/or 006 * modify it under the terms of the GNU Lesser General Public 007 * License as published by the Free Software Foundation; either 008 * version 2.1 of the License, or (at your option) any later version. 009 * 010 * This library is distributed in the hope that it will be useful, 011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013 * Lesser General Public License for more details. 014 * 015 * You should have received a copy of the GNU Lesser General Public 016 * License along with this library. If not, see <http://www.gnu.org/licenses/>. 017 * 018 **/ 019package lucee.commons.lock; 020 021import java.util.concurrent.TimeUnit; 022import java.util.concurrent.locks.ReentrantLock; 023 024public class SimpleLock<L> implements Lock { 025 026 private ReentrantLock lock; 027 private L label; 028 029 public SimpleLock(L label) { 030 this.lock=new ReentrantLock(true); 031 this.label=label; 032 } 033 034 035 @Override 036 public void lock(long timeout) throws LockException { 037 if(timeout<=0) throw new LockException("timeout must be a postive number"); 038 long initialTimeout=timeout; 039 long start=System.currentTimeMillis(); 040 do{ 041 try { 042 if(!lock.tryLock(timeout, TimeUnit.MILLISECONDS)){ 043 throw new LockException(initialTimeout); 044 } 045 break; // exit loop 046 } 047 catch (InterruptedException e) { 048 timeout-=System.currentTimeMillis()-start; 049 } 050 if(timeout<=0) { 051 // Lucee was not able to aquire lock in time 052 throw new LockException(initialTimeout); 053 } 054 } 055 while(true); 056 057 } 058 059 @Override 060 public void unlock() { 061 lock.unlock(); 062 } 063 064 /** 065 * Returns an estimate of the number of threads waiting to 066 * acquire this lock. The value is only an estimate because the number of 067 * threads may change dynamically while this method traverses 068 * internal data structures. This method is designed for use in 069 * monitoring of the system state, not for synchronization 070 * control. 071 * 072 * @return the estimated number of threads waiting for this lock 073 */ 074 public int getQueueLength() { 075 return lock.getQueueLength(); 076 } 077 078 079 public L getLabel(){ 080 return label; 081 } 082}