Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.camel.impl; import java.util.ArrayList; import java.util.Collection; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ConcurrentHashMap; import org.apache.camel.spi.ServicePool; import org.apache.camel.util.ServiceHelper; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Default implementation to inherit for a basic service pool. * * @version $Revision$ */ public abstract class DefaultServicePool<Key, Service> extends ServiceSupport implements ServicePool<Key, Service> { protected final Log log = LogFactory.getLog(getClass()); protected final ConcurrentHashMap<Key, BlockingQueue<Service>> pool = new ConcurrentHashMap<Key, BlockingQueue<Service>>(); protected int capacity = 100; protected DefaultServicePool() { } public DefaultServicePool(int capacity) { this.capacity = capacity; } public int getCapacity() { return capacity; } public void setCapacity(int capacity) { this.capacity = capacity; } public synchronized int size() { int size = 0; for (BlockingQueue<Service> entry : pool.values()) { size += entry.size(); } return size; } public synchronized Service addAndAcquire(Key key, Service service) { BlockingQueue<Service> entry = pool.get(key); if (entry == null) { entry = new ArrayBlockingQueue<Service>(capacity); pool.put(key, entry); } if (log.isTraceEnabled()) { log.trace("AddAndAcquire key: " + key + " service: " + service); } // test if queue will be full if (entry.size() >= capacity) { throw new IllegalStateException("Queue full"); } return service; } public synchronized Service acquire(Key key) { BlockingQueue<Service> services = pool.get(key); if (services == null || services.isEmpty()) { if (log.isTraceEnabled()) { log.trace("No free services in pool to acquire for key: " + key); } return null; } Service answer = services.poll(); if (log.isTraceEnabled()) { log.trace("Acquire: " + key + " service: " + answer); } return answer; } public synchronized void release(Key key, Service service) { if (log.isTraceEnabled()) { log.trace("Release: " + key + " service: " + service); } BlockingQueue<Service> services = pool.get(key); if (services != null) { services.add(service); } } protected void doStart() throws Exception { if (log.isDebugEnabled()) { log.debug("Starting service pool: " + this); } } protected void doStop() throws Exception { if (log.isDebugEnabled()) { log.debug("Stopping service pool: " + this); } for (BlockingQueue<Service> entry : pool.values()) { Collection<Service> values = new ArrayList<Service>(); entry.drainTo(values); ServiceHelper.stopServices(values); entry.clear(); } pool.clear(); } }