org.jboss.netty.channel.socket.nio

Class NioServerSocketChannelFactory

java.lang.Object

org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory

All Implemented Interfaces:

ChannelFactory, ServerChannelFactory, ServerSocketChannelFactory, ExternalResourceReleasable

public class NioServerSocketChannelFactory
extends Object
implements ServerSocketChannelFactory

A ServerSocketChannelFactory which creates a server-side NIO-based ServerSocketChannel. It utilizes the non-blocking I/O mode which was introduced with NIO to serve many number of concurrent connections efficiently.

How threads work

There are two types of threads in a NioServerSocketChannelFactory; one is boss thread and the other is worker thread.

Boss threads

Each bound 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 Channel to one of the worker threads that the NioServerSocketChannelFactory manages.

Worker threads

One NioServerSocketChannelFactory can have one or more worker threads. A worker thread performs non-blocking read and write for one or more Channels in a non-blocking mode.

Life cycle of threads and graceful shutdown

All threads are acquired from the Executors which were specified when a NioServerSocketChannelFactory was created. Boss threads are acquired from the bossExecutor, and worker threads are acquired from the workerExecutor. Therefore, you should make sure the specified Executors are able to lend the sufficient number of threads. It is the best bet to specify a cached thread pool.

Both boss and worker threads are acquired lazily, and then released when there's nothing left to process. All the related resources such as Selector are also released when the boss and worker threads are released. Therefore, to shut down a service gracefully, you should do the following:

1. unbind all channels created by the factory,
2. close all child channels accepted by the unbound channels, and (these two steps so far is usually done using ChannelGroup.close())
3. call releaseExternalResources().

Please make sure not to shut down the executor until all channels are closed. Otherwise, you will end up with a RejectedExecutionException and the related resources might not be released properly.

Constructor Summary

Constructors

Constructor and Description
NioServerSocketChannelFactory() Create a new NioServerSocketChannelFactory using Executors.newCachedThreadPool() for the boss and worker.
NioServerSocketChannelFactory(Executor bossExecutor, Executor workerExecutor) Creates a new instance.
NioServerSocketChannelFactory(Executor bossExecutor, Executor workerExecutor, int workerCount) Creates a new instance.
NioServerSocketChannelFactory(Executor bossExecutor, WorkerPool<NioWorker> workerPool) Creates a new instance.

Method Summary

Methods

Modifier and Type	Method and Description
ServerSocketChannel	newChannel(ChannelPipeline pipeline) Creates and opens a new Channel and attaches the specified ChannelPipeline to the new Channel.
void	releaseExternalResources() Releases the external resources that this factory depends on to function.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NioServerSocketChannelFactory

public NioServerSocketChannelFactory()

Create a new NioServerSocketChannelFactory using Executors.newCachedThreadPool() for the boss and worker. See NioServerSocketChannelFactory(Executor, Executor)

NioServerSocketChannelFactory

public NioServerSocketChannelFactory(Executor bossExecutor,
                             Executor workerExecutor)

Creates a new instance. Calling this constructor is same with calling NioServerSocketChannelFactory(Executor, Executor, int) with 2 * the number of available processors in the machine. The number of available processors is obtained by Runtime.availableProcessors().

Parameters:

bossExecutor - the Executor which will execute the boss threads

workerExecutor - the Executor which will execute the I/O worker threads

NioServerSocketChannelFactory

public NioServerSocketChannelFactory(Executor bossExecutor,
                             Executor workerExecutor,
                             int workerCount)

Creates a new instance.

Parameters:

bossExecutor - the Executor which will execute the boss threads

workerExecutor - the Executor which will execute the I/O worker threads

workerCount - the maximum number of I/O worker threads

NioServerSocketChannelFactory

public NioServerSocketChannelFactory(Executor bossExecutor,
                             WorkerPool<NioWorker> workerPool)

Creates a new instance.

Parameters:

bossExecutor - the Executor which will execute the boss threads

workerPool - the WorkerPool which will be used to obtain the NioWorker that execute the I/O worker threads

Method Detail

newChannel

public ServerSocketChannel newChannel(ChannelPipeline pipeline)

Description copied from interface: ChannelFactory

Creates and opens a new Channel and attaches the specified ChannelPipeline to the new Channel.

Specified by:

newChannel in interface ChannelFactory

Specified by:

newChannel in interface ServerChannelFactory

Specified by:

newChannel in interface ServerSocketChannelFactory

Parameters:

pipeline - the ChannelPipeline which is going to be attached to the new Channel

Returns:

the newly open channel

releaseExternalResources

public void releaseExternalResources()

Description copied from interface: ChannelFactory

Releases the external resources that this factory depends on to function. An external resource is a resource that this factory didn't create by itself. For example, Executors that you specified in the factory constructor are external resources. You can call this method to release all external resources conveniently when the resources are not used by this factory or any other part of your application. An unexpected behavior will be resulted in if the resources are released when there's an open channel which is managed by this factory.

Specified by:

releaseExternalResources in interface ChannelFactory

Specified by:

releaseExternalResources in interface ExternalResourceReleasable