/*
* Copyright 2011 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.jboss.netty.channel.socket.nio;
import java.nio.channels.Selector;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelSink;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.socket.ServerSocketChannel;
import org.jboss.netty.channel.socket.ServerSocketChannelFactory;
import org.jboss.netty.util.ExternalResourceReleasable;
import org.jboss.netty.util.internal.ExecutorUtil;
/**
* A {@link ServerSocketChannelFactory} which creates a server-side NIO-based
* {@link ServerSocketChannel}. It utilizes the non-blocking I/O mode which
* was introduced with NIO to serve many number of concurrent connections
* efficiently.
*
* <h3>How threads work</h3>
* <p>
* There are two types of threads in a {@link NioServerSocketChannelFactory};
* one is boss thread and the other is worker thread.
*
* <h4>Boss threads</h4>
* <p>
* Each bound {@link ServerSocketChannel} has its own boss thread.
* For example, if you opened two server ports such as 80 and 443, you will
* have two boss threads. A boss thread accepts incoming connections until
* the port is unbound. Once a connection is accepted successfully, the boss
* thread passes the accepted {@link Channel} to one of the worker
* threads that the {@link NioServerSocketChannelFactory} manages.
*
* <h4>Worker threads</h4>
* <p>
* One {@link NioServerSocketChannelFactory} can have one or more worker
* threads. A worker thread performs non-blocking read and write for one or
* more {@link Channel}s in a non-blocking mode.
*
* <h3>Life cycle of threads and graceful shutdown</h3>
* <p>
* All threads are acquired from the {@link Executor}s which were specified
* when a {@link NioServerSocketChannelFactory} was created. Boss threads are
* acquired from the {@code bossExecutor}, and worker threads are acquired from
* the {@code workerExecutor}. Therefore, you should make sure the specified
* {@link Executor}s are able to lend the sufficient number of threads.
* It is the best bet to specify {@linkplain Executors#newCachedThreadPool() a cached thread pool}.
* <p>
* Both boss and worker threads are acquired lazily, and then released when
* there's nothing left to process. All the related resources such as
* {@link Selector} are also released when the boss and worker threads are
* released. Therefore, to shut down a service gracefully, you should do the
* following:
*
* <ol>
* <li>unbind all channels created by the factory,
* <li>close all child channels accepted by the unbound channels, and
* (these two steps so far is usually done using {@link ChannelGroup#close()})</li>
* <li>call {@link #releaseExternalResources()}.</li>
* </ol>
*
* Please make sure not to shut down the executor until all channels are
* closed. Otherwise, you will end up with a {@link RejectedExecutionException}
* and the related resources might not be released properly.
*
* @apiviz.landmark
*/
public class NioServerSocketChannelFactory implements ServerSocketChannelFactory {
final Executor bossExecutor;
private final WorkerPool<NioWorker> workerPool;
private final ChannelSink sink;
/**
* Create a new {@link NioServerSocketChannelFactory} using {@link Executors#newCachedThreadPool()} for the boss and worker.
*
* See {@link #NioServerSocketChannelFactory(Executor, Executor)}
*/
public NioServerSocketChannelFactory() {
this(Executors.newCachedThreadPool(), Executors.newCachedThreadPool());
}
/**
* Creates a new instance. Calling this constructor is same with calling
* {@link #NioServerSocketChannelFactory(Executor, Executor, int)} with 2 *
* the number of available processors in the machine. The number of
* available processors is obtained by {@link Runtime#availableProcessors()}.
*
* @param bossExecutor
* the {@link Executor} which will execute the boss threads
* @param workerExecutor
* the {@link Executor} which will execute the I/O worker threads
*/
public NioServerSocketChannelFactory(
Executor bossExecutor, Executor workerExecutor) {
this(bossExecutor, workerExecutor, SelectorUtil.DEFAULT_IO_THREADS);
}
/**
* Creates a new instance.
*
* @param bossExecutor
* the {@link Executor} which will execute the boss threads
* @param workerExecutor
* the {@link Executor} which will execute the I/O worker threads
* @param workerCount
* the maximum number of I/O worker threads
*/
public NioServerSocketChannelFactory(
Executor bossExecutor, Executor workerExecutor,
int workerCount) {
this(bossExecutor, new NioWorkerPool(workerExecutor, workerCount, true));
}
/**
* Creates a new instance.
*
* @param bossExecutor
* the {@link Executor} which will execute the boss threads
* @param workerPool
* the {@link WorkerPool} which will be used to obtain the {@link NioWorker} that execute the I/O worker threads
*/
public NioServerSocketChannelFactory(
Executor bossExecutor, WorkerPool<NioWorker> workerPool) {
if (bossExecutor == null) {
throw new NullPointerException("bossExecutor");
}
if (workerPool == null) {
throw new NullPointerException("workerPool");
}
this.bossExecutor = bossExecutor;
this.workerPool = workerPool;
sink = new NioServerSocketPipelineSink(workerPool);
}
public ServerSocketChannel newChannel(ChannelPipeline pipeline) {
return new NioServerSocketChannel(this, pipeline, sink);
}
public void releaseExternalResources() {
ExecutorUtil.terminate(bossExecutor);
if (workerPool instanceof ExternalResourceReleasable) {
((ExternalResourceReleasable) workerPool).releaseExternalResources();
}
}
}