001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.camel.processor; 018 019 import java.util.concurrent.CountDownLatch; 020 import java.util.concurrent.TimeUnit; 021 022 import org.apache.camel.AlreadyStoppedException; 023 import org.apache.camel.Exchange; 024 import org.apache.camel.Processor; 025 import org.apache.commons.logging.Log; 026 import org.apache.commons.logging.LogFactory; 027 028 /** 029 * A useful base class for any processor which provides some kind of throttling 030 * or delayed processing 031 * 032 * @version $Revision: 51829 $ 033 */ 034 public abstract class DelayProcessorSupport extends DelegateProcessor { 035 private static final transient Log LOG = LogFactory.getLog(Delayer.class); 036 private CountDownLatch stoppedLatch = new CountDownLatch(1); 037 private boolean fastStop = true; 038 039 public DelayProcessorSupport(Processor processor) { 040 super(processor); 041 } 042 043 public void process(Exchange exchange) throws Exception { 044 delay(exchange); 045 super.process(exchange); 046 } 047 048 public boolean isFastStop() { 049 return fastStop; 050 } 051 052 /** 053 * Enables & disables a fast stop; basically to avoid waiting a possibly 054 * long time for delays to complete before the context shuts down; instead 055 * the current processing method throws 056 * {@link org.apache.camel.AlreadyStoppedException} to terminate processing. 057 */ 058 public void setFastStop(boolean fastStop) { 059 this.fastStop = fastStop; 060 } 061 062 protected void doStop() throws Exception { 063 stoppedLatch.countDown(); 064 super.doStop(); 065 } 066 067 protected abstract void delay(Exchange exchange) throws Exception; 068 069 /** 070 * Wait until the given system time before continuing 071 * 072 * @param time the system time to wait for 073 * @param exchange the exchange being processed 074 */ 075 protected void waitUntil(long time, Exchange exchange) throws Exception { 076 while (true) { 077 long delay = time - currentSystemTime(); 078 if (delay < 0) { 079 return; 080 } else { 081 if (isFastStop() && !isRunAllowed()) { 082 throw new AlreadyStoppedException(); 083 } 084 try { 085 sleep(delay); 086 } catch (InterruptedException e) { 087 handleSleepInteruptedException(e); 088 } 089 } 090 } 091 } 092 093 protected void sleep(long delay) throws InterruptedException { 094 if (delay <= 0) { 095 return; 096 } 097 if (LOG.isTraceEnabled()) { 098 LOG.trace("Sleeping for: " + delay + " millis"); 099 } 100 if (isFastStop()) { 101 stoppedLatch.await(delay, TimeUnit.MILLISECONDS); 102 } else { 103 Thread.sleep(delay); 104 } 105 } 106 107 /** 108 * Called when a sleep is interupted; allows derived classes to handle this 109 * case differently 110 */ 111 protected void handleSleepInteruptedException(InterruptedException e) { 112 LOG.debug("Sleep interupted: " + e, e); 113 } 114 115 protected long currentSystemTime() { 116 return System.currentTimeMillis(); 117 } 118 }