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 */ 017package org.apache.camel.util.concurrent; 018 019import java.util.concurrent.Callable; 020import java.util.concurrent.RejectedExecutionHandler; 021import java.util.concurrent.RunnableFuture; 022import java.util.concurrent.ScheduledThreadPoolExecutor; 023import java.util.concurrent.ThreadFactory; 024 025import org.apache.camel.Rejectable; 026 027/** 028 * Scheduled thread pool executor that creates {@link RejectableFutureTask} instead of 029 * {@link java.util.concurrent.FutureTask} when registering new tasks for execution. 030 * <p/> 031 * Instances of {@link RejectableFutureTask} are required to handle {@link org.apache.camel.ThreadPoolRejectedPolicy#Discard} 032 * and {@link org.apache.camel.ThreadPoolRejectedPolicy#DiscardOldest} policies correctly, e.g. notify 033 * {@link Callable} and {@link Runnable} tasks when they are rejected. 034 * To be notified of rejection tasks have to implement {@link org.apache.camel.Rejectable} interface: <br/> 035 * <code><pre> 036 * public class RejectableTask implements Runnable, Rejectable { 037 * @Override 038 * public void run() { 039 * // execute task 040 * } 041 * @Override 042 * public void reject() { 043 * // do something useful on rejection 044 * } 045 * } 046 * </pre></code> 047 * <p/> 048 * If the task does not implement {@link org.apache.camel.Rejectable} interface the behavior is exactly the same as with 049 * ordinary {@link ScheduledThreadPoolExecutor}. 050 * 051 * @see RejectableFutureTask 052 * @see org.apache.camel.Rejectable 053 * @see RejectableThreadPoolExecutor 054 */ 055public class RejectableScheduledThreadPoolExecutor extends ScheduledThreadPoolExecutor { 056 057 public RejectableScheduledThreadPoolExecutor(int corePoolSize) { 058 super(corePoolSize); 059 } 060 061 public RejectableScheduledThreadPoolExecutor(int corePoolSize, ThreadFactory threadFactory) { 062 super(corePoolSize, threadFactory); 063 } 064 065 public RejectableScheduledThreadPoolExecutor(int corePoolSize, RejectedExecutionHandler handler) { 066 super(corePoolSize, handler); 067 } 068 069 public RejectableScheduledThreadPoolExecutor(int corePoolSize, ThreadFactory threadFactory, RejectedExecutionHandler handler) { 070 super(corePoolSize, threadFactory, handler); 071 } 072 073 @Override 074 protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { 075 if (runnable instanceof Rejectable) { 076 return new RejectableFutureTask<T>(runnable, value); 077 } else { 078 return super.newTaskFor(runnable, value); 079 } 080 } 081 082 @Override 083 protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { 084 if (callable instanceof Rejectable) { 085 return new RejectableFutureTask<T>(callable); 086 } else { 087 return super.newTaskFor(callable); 088 } 089 } 090 091 @Override 092 public String toString() { 093 // the thread factory often have more precise details what the thread pool is used for 094 if (getThreadFactory() instanceof CamelThreadFactory) { 095 String name = ((CamelThreadFactory) getThreadFactory()).getName(); 096 return super.toString() + "[" + name + "]"; 097 } else { 098 return super.toString(); 099 } 100 } 101 102}