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.RejectedExecutionException; 020import java.util.concurrent.RejectedExecutionHandler; 021import java.util.concurrent.ThreadPoolExecutor; 022 023/** 024 * Represent the kinds of options for rejection handlers for thread pools. 025 * <p/> 026 * These options are used for fine grained thread pool settings, where you want to control which handler to use when a 027 * thread pool cannot execute a new task. 028 * <p/> 029 * Camel will by default use <tt>CallerRuns</tt>. 030 */ 031public enum ThreadPoolRejectedPolicy { 032 033 Abort, 034 CallerRuns, 035 DiscardOldest, 036 Discard; 037 038 public RejectedExecutionHandler asRejectedExecutionHandler() { 039 if (this == Abort) { 040 return new RejectedExecutionHandler() { 041 @Override 042 public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) { 043 if (r instanceof Rejectable) { 044 ((Rejectable) r).reject(); 045 } else { 046 throw new RejectedExecutionException("Task " + r.toString() + " rejected from " + executor.toString()); 047 } 048 } 049 050 @Override 051 public String toString() { 052 return "Abort"; 053 } 054 }; 055 } else if (this == CallerRuns) { 056 return new ThreadPoolExecutor.CallerRunsPolicy() { 057 @Override 058 public String toString() { 059 return "CallerRuns"; 060 } 061 }; 062 } else if (this == DiscardOldest) { 063 return new RejectedExecutionHandler() { 064 @Override 065 public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) { 066 if (!executor.isShutdown()) { 067 Runnable rejected = executor.getQueue().poll(); 068 if (rejected instanceof Rejectable) { 069 ((Rejectable) rejected).reject(); 070 } 071 executor.execute(r); 072 } 073 } 074 075 @Override 076 public String toString() { 077 return "DiscardOldest"; 078 } 079 }; 080 } else if (this == Discard) { 081 return new RejectedExecutionHandler() { 082 @Override 083 public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) { 084 if (r instanceof Rejectable) { 085 ((Rejectable) r).reject(); 086 } 087 } 088 089 @Override 090 public String toString() { 091 return "Discard"; 092 } 093 }; 094 } 095 throw new IllegalArgumentException("Unknown ThreadPoolRejectedPolicy: " + this); 096 } 097 098}