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.ExecutorService;
020 import java.util.concurrent.RejectedExecutionException;
021 import java.util.concurrent.atomic.AtomicBoolean;
022
023 import org.apache.camel.AsyncCallback;
024 import org.apache.camel.AsyncProcessor;
025 import org.apache.camel.CamelContext;
026 import org.apache.camel.Exchange;
027 import org.apache.camel.Rejectable;
028 import org.apache.camel.ThreadPoolRejectedPolicy;
029 import org.apache.camel.support.ServiceSupport;
030 import org.apache.camel.util.AsyncProcessorHelper;
031 import org.apache.camel.util.ObjectHelper;
032 import org.slf4j.Logger;
033 import org.slf4j.LoggerFactory;
034
035 /**
036 * Threads processor that leverage a thread pool for continue processing the {@link Exchange}s
037 * using the asynchronous routing engine.
038 * <p/>
039 * Pay attention to how this processor handles rejected tasks.
040 * <ul>
041 * <li>Abort - The current exchange will be set with a {@link RejectedExecutionException} exception,
042 * and marked to stop continue routing.
043 * The {@link org.apache.camel.spi.UnitOfWork} will be regarded as <b>failed</b>, due the exception.</li>
044 * <li>Discard - The current exchange will be marked to stop continue routing (notice no exception is set).
045 * The {@link org.apache.camel.spi.UnitOfWork} will be regarded as <b>successful</b>, due no exception being set.</li>
046 * <li>DiscardOldest - The oldest exchange will be marked to stop continue routing (notice no exception is set).
047 * The {@link org.apache.camel.spi.UnitOfWork} will be regarded as <b>successful</b>, due no exception being set.
048 * And the current exchange will be added to the task queue.</li>
049 * <li>CallerRuns - The current exchange will be processed by the current thread. Which mean the current thread
050 * will not be free to process a new exchange, as its processing the current exchange.</li>
051 * </ul>
052 */
053 public class ThreadsProcessor extends ServiceSupport implements AsyncProcessor {
054
055 private static final Logger LOG = LoggerFactory.getLogger(ThreadsProcessor.class);
056 private final CamelContext camelContext;
057 private final ExecutorService executorService;
058 private volatile boolean shutdownExecutorService;
059 private final AtomicBoolean shutdown = new AtomicBoolean(true);
060 private boolean callerRunsWhenRejected = true;
061 private ThreadPoolRejectedPolicy rejectedPolicy;
062
063 private final class ProcessCall implements Runnable, Rejectable {
064 private final Exchange exchange;
065 private final AsyncCallback callback;
066
067 public ProcessCall(Exchange exchange, AsyncCallback callback) {
068 this.exchange = exchange;
069 this.callback = callback;
070 }
071
072 @Override
073 public void run() {
074 LOG.trace("Continue routing exchange {} ", exchange);
075 if (shutdown.get()) {
076 exchange.setException(new RejectedExecutionException("ThreadsProcessor is not running."));
077 }
078 callback.done(false);
079 }
080
081 @Override
082 public void reject() {
083 // abort should mark the exchange with an rejected exception
084 boolean abort = ThreadPoolRejectedPolicy.Abort == rejectedPolicy;
085 if (abort) {
086 exchange.setException(new RejectedExecutionException());
087 }
088
089 LOG.trace("{} routing exchange {} ", abort ? "Aborted" : "Rejected", exchange);
090 // we should not continue routing, and no redelivery should be performed
091 exchange.setProperty(Exchange.ROUTE_STOP, true);
092 exchange.setProperty(Exchange.REDELIVERY_EXHAUSTED, true);
093
094 if (shutdown.get()) {
095 exchange.setException(new RejectedExecutionException("ThreadsProcessor is not running."));
096 }
097 callback.done(false);
098 }
099
100 @Override
101 public String toString() {
102 return "ProcessCall[" + exchange + "]";
103 }
104 }
105
106 public ThreadsProcessor(CamelContext camelContext, ExecutorService executorService, boolean shutdownExecutorService) {
107 ObjectHelper.notNull(camelContext, "camelContext");
108 ObjectHelper.notNull(executorService, "executorService");
109 this.camelContext = camelContext;
110 this.executorService = executorService;
111 this.shutdownExecutorService = shutdownExecutorService;
112 }
113
114 public void process(final Exchange exchange) throws Exception {
115 AsyncProcessorHelper.process(this, exchange);
116 }
117
118 public boolean process(Exchange exchange, AsyncCallback callback) {
119 if (shutdown.get()) {
120 throw new IllegalStateException("ThreadsProcessor is not running.");
121 }
122
123 ProcessCall call = new ProcessCall(exchange, callback);
124 try {
125 LOG.trace("Submitting task {}", call);
126 executorService.submit(call);
127 // tell Camel routing engine we continue routing asynchronous
128 return false;
129 } catch (RejectedExecutionException e) {
130 boolean callerRuns = isCallerRunsWhenRejected();
131 if (!callerRuns) {
132 exchange.setException(e);
133 }
134
135 LOG.trace("{} executing task {}", callerRuns ? "CallerRuns" : "Aborted", call);
136 if (shutdown.get()) {
137 exchange.setException(new RejectedExecutionException());
138 }
139 callback.done(true);
140 return true;
141 }
142 }
143
144 public boolean isCallerRunsWhenRejected() {
145 return callerRunsWhenRejected;
146 }
147
148 public void setCallerRunsWhenRejected(boolean callerRunsWhenRejected) {
149 this.callerRunsWhenRejected = callerRunsWhenRejected;
150 }
151
152 public ThreadPoolRejectedPolicy getRejectedPolicy() {
153 return rejectedPolicy;
154 }
155
156 public void setRejectedPolicy(ThreadPoolRejectedPolicy rejectedPolicy) {
157 this.rejectedPolicy = rejectedPolicy;
158 }
159
160 public String toString() {
161 return "Threads";
162 }
163
164 protected void doStart() throws Exception {
165 shutdown.set(false);
166 }
167
168 protected void doStop() throws Exception {
169 shutdown.set(true);
170 }
171
172 protected void doShutdown() throws Exception {
173 if (shutdownExecutorService) {
174 camelContext.getExecutorServiceManager().shutdownNow(executorService);
175 }
176 super.doShutdown();
177 }
178
179 }