001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.reef.io.network.group.impl.utils; 020 021import java.util.concurrent.atomic.AtomicInteger; 022import java.util.logging.Logger; 023 024public class CountingSemaphore { 025 026 private static final Logger LOG = Logger.getLogger(CountingSemaphore.class.getName()); 027 028 private final AtomicInteger counter; 029 030 private final String name; 031 032 private final Object lock; 033 034 private final int initCount; 035 036 public CountingSemaphore(final int initCount, final String name, final Object lock) { 037 super(); 038 this.initCount = initCount; 039 this.name = name; 040 this.lock = lock; 041 this.counter = new AtomicInteger(initCount); 042 LOG.finest("Counter initialized to " + initCount); 043 } 044 045 public int getInitialCount() { 046 return initCount; 047 } 048 049 public int increment() { 050 synchronized (lock) { 051 final int retVal = counter.incrementAndGet(); 052 LOG.finest(name + "Incremented counter to " + retVal); 053 logStatus(); 054 return retVal; 055 } 056 } 057 058 private void logStatus() { 059 final int yetToRun = counter.get(); 060 final int curRunning = initCount - yetToRun; 061 LOG.fine(name + curRunning + " workers are running & " + yetToRun + " workers are yet to run"); 062 } 063 064 public int decrement() { 065 synchronized (lock) { 066 final int retVal = counter.decrementAndGet(); 067 LOG.finest(name + "Decremented counter to " + retVal); 068 if (retVal < 0) { 069 LOG.warning("Counter negative. More workers exist than you expected"); 070 } 071 if (retVal <= 0) { 072 LOG.finest(name + "All workers are done with their task. Notifying waiting threads"); 073 lock.notifyAll(); 074 } else { 075 LOG.finest(name + "Some workers are not done yet"); 076 } 077 logStatus(); 078 return retVal; 079 } 080 } 081 082 public int get() { 083 synchronized (lock) { 084 return counter.get(); 085 } 086 } 087 088 public void await() { 089 synchronized (lock) { 090 LOG.finest(name + "Waiting for workers to be done"); 091 while (counter.get() > 0) { 092 try { 093 lock.wait(); 094 LOG.finest(name + "Notified with counter=" + counter.get()); 095 } catch (final InterruptedException e) { 096 throw new RuntimeException("InterruptedException while waiting for counting semaphore counter", e); 097 } 098 } 099 LOG.finest(name + "Returning from wait"); 100 } 101 } 102 103}