001 /** 002 * 003 * Licensed to the Apache Software Foundation (ASF) under one or more 004 * contributor license agreements. See the NOTICE file distributed with 005 * this work for additional information regarding copyright ownership. 006 * The ASF licenses this file to You under the Apache License, Version 2.0 007 * (the "License"); you may not use this file except in compliance with 008 * 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, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 package org.apache.camel.impl; 019 020 import java.util.concurrent.atomic.AtomicBoolean; 021 022 import org.apache.camel.Service; 023 024 /** 025 * A useful base class which ensures that a service is only initialized once and provides some helper methods for 026 * enquiring of its status 027 * 028 * @version $Revision: 534063 $ 029 */ 030 public abstract class ServiceSupport implements Service { 031 private AtomicBoolean started = new AtomicBoolean(false); 032 private AtomicBoolean stopping = new AtomicBoolean(false); 033 private AtomicBoolean stopped = new AtomicBoolean(false); 034 035 public void start() throws Exception { 036 if (started.compareAndSet(false, true)) { 037 doStart(); 038 } 039 } 040 041 public void stop() throws Exception { 042 if (stopped.compareAndSet(false, true)) { 043 stopping.set(true); 044 try { 045 doStop(); 046 } 047 finally { 048 stopped.set(true); 049 started.set(false); 050 stopping.set(false); 051 } 052 } 053 } 054 055 /** 056 * @return true if this service has been started 057 */ 058 public boolean isStarted() { 059 return started.get(); 060 } 061 062 /** 063 * @return true if this service is in the process of closing 064 */ 065 public boolean isStopping() { 066 return stopping.get(); 067 } 068 069 070 /** 071 * @return true if this service is closed 072 */ 073 public boolean isStopped() { 074 return stopped.get(); 075 } 076 077 protected abstract void doStart() throws Exception; 078 079 protected abstract void doStop() throws Exception; 080 081 }