View Javadoc

    1   /*
    2    * Copyright 2009 Red Hat, Inc.
    3    *
    4    * Red Hat licenses this file to you under the Apache License, version 2.0
    5    * (the "License"); you may not use this file except in compliance with the
    6    * License.  You may obtain a copy of the License at:
    7    *
    8    *    http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
    13   * License for the specific language governing permissions and limitations
    14   * under the License.
    15   */
    16  package org.jboss.netty.channel.socket.nio;
    17
    18  import java.nio.channels.Selector;
    19  import java.util.concurrent.Executor;
    20  import java.util.concurrent.Executors;
    21  import java.util.concurrent.RejectedExecutionException;
    22
    23  import org.jboss.netty.channel.Channel;
    24  import org.jboss.netty.channel.ChannelPipeline;
    25  import org.jboss.netty.channel.group.ChannelGroup;
    26  import org.jboss.netty.channel.socket.ClientSocketChannelFactory;
    27  import org.jboss.netty.channel.socket.SocketChannel;
    28  import org.jboss.netty.util.internal.ExecutorUtil;
    29
    30  /**
    31   * A {@link ClientSocketChannelFactory} which creates a client-side NIO-based
    32   * {@link SocketChannel}.  It utilizes the non-blocking I/O mode which was
    33   * introduced with NIO to serve many number of concurrent connections
    34   * efficiently.
    35   *
    36   * <h3>How threads work</h3>
    37   * <p>
    38   * There are two types of threads in a {@link NioClientSocketChannelFactory};
    39   * one is boss thread and the other is worker thread.
    40   *
    41   * <h4>Boss thread</h4>
    42   * <p>
    43   * One {@link NioClientSocketChannelFactory} has one boss thread.  It makes
    44   * a connection attempt on request.  Once a connection attempt succeeds,
    45   * the boss thread passes the connected {@link Channel} to one of the worker
    46   * threads that the {@link NioClientSocketChannelFactory} manages.
    47   *
    48   * <h4>Worker threads</h4>
    49   * <p>
    50   * One {@link NioClientSocketChannelFactory} can have one or more worker
    51   * threads.  A worker thread performs non-blocking read and write for one or
    52   * more {@link Channel}s in a non-blocking mode.
    53   *
    54   * <h3>Life cycle of threads and graceful shutdown</h3>
    55   * <p>
    56   * All threads are acquired from the {@link Executor}s which were specified
    57   * when a {@link NioClientSocketChannelFactory} was created.  A boss thread is
    58   * acquired from the {@code bossExecutor}, and worker threads are acquired from
    59   * the {@code workerExecutor}.  Therefore, you should make sure the specified
    60   * {@link Executor}s are able to lend the sufficient number of threads.
    61   * It is the best bet to specify {@linkplain Executors#newCachedThreadPool() a cached thread pool}.
    62   * <p>
    63   * Both boss and worker threads are acquired lazily, and then released when
    64   * there's nothing left to process.  All the related resources such as
    65   * {@link Selector} are also released when the boss and worker threads are
    66   * released.  Therefore, to shut down a service gracefully, you should do the
    67   * following:
    68   *
    69   * <ol>
    70   * <li>close all channels created by the factory usually using
    71   *     {@link ChannelGroup#close()}, and</li>
    72   * <li>call {@link #releaseExternalResources()}.</li>
    73   * </ol>
    74   *
    75   * Please make sure not to shut down the executor until all channels are
    76   * closed.  Otherwise, you will end up with a {@link RejectedExecutionException}
    77   * and the related resources might not be released properly.
    78   *
    79   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    80   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    81   *
    82   * @version $Rev: 2200 $, $Date: 2010-02-23 14:42:39 +0900 (Tue, 23 Feb 2010) $
    83   *
    84   * @apiviz.landmark
    85   */
    86  public class NioClientSocketChannelFactory implements ClientSocketChannelFactory {
    87
    88      private final Executor bossExecutor;
    89      private final Executor workerExecutor;
    90      private final NioClientSocketPipelineSink sink;
    91
    92      /**
    93       * Creates a new instance.  Calling this constructor is same with calling
    94       * {@link #NioClientSocketChannelFactory(Executor, Executor, int)} with 2 *
    95       * the number of available processors in the machine.  The number of
    96       * available processors is obtained by {@link Runtime#availableProcessors()}.
    97       *
    98       * @param bossExecutor
    99       *        the {@link Executor} which will execute the boss thread
    100      * @param workerExecutor
    101      *        the {@link Executor} which will execute the I/O worker threads
    102      */
    103     public NioClientSocketChannelFactory(
    104             Executor bossExecutor, Executor workerExecutor) {
    105         this(bossExecutor, workerExecutor, SelectorUtil.DEFAULT_IO_THREADS);
    106     }
    107
    108     /**
    109      * Creates a new instance.
    110      *
    111      * @param bossExecutor
    112      *        the {@link Executor} which will execute the boss thread
    113      * @param workerExecutor
    114      *        the {@link Executor} which will execute the I/O worker threads
    115      * @param workerCount
    116      *        the maximum number of I/O worker threads
    117      */
    118     public NioClientSocketChannelFactory(
    119             Executor bossExecutor, Executor workerExecutor,
    120             int workerCount) {
    121         if (bossExecutor == null) {
    122             throw new NullPointerException("bossExecutor");
    123         }
    124         if (workerExecutor == null) {
    125             throw new NullPointerException("workerExecutor");
    126         }
    127         if (workerCount <= 0) {
    128             throw new IllegalArgumentException(
    129                     "workerCount (" + workerCount + ") " +
    130                     "must be a positive integer.");
    131         }
    132
    133         this.bossExecutor = bossExecutor;
    134         this.workerExecutor = workerExecutor;
    135         sink = new NioClientSocketPipelineSink(bossExecutor, workerExecutor, workerCount);
    136     }
    137
    138     public SocketChannel newChannel(ChannelPipeline pipeline) {
    139         return new NioClientSocketChannel(this, pipeline, sink, sink.nextWorker());
    140     }
    141
    142     public void releaseExternalResources() {
    143         ExecutorUtil.terminate(bossExecutor, workerExecutor);
    144     }
    145 }