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    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.oio;
    17
    18  import java.util.concurrent.Executor;
    19  import java.util.concurrent.RejectedExecutionException;
    20
    21  import org.jboss.netty.channel.Channel;
    22  import org.jboss.netty.channel.ChannelPipeline;
    23  import org.jboss.netty.channel.group.ChannelGroup;
    24  import org.jboss.netty.channel.socket.ClientSocketChannelFactory;
    25  import org.jboss.netty.channel.socket.SocketChannel;
    26  import org.jboss.netty.util.internal.ExecutorUtil;
    27
    28  /**
    29   * A {@link ClientSocketChannelFactory} which creates a client-side blocking
    30   * I/O based {@link SocketChannel}.  It utilizes the good old blocking I/O API
    31   * which is known to yield better throughput and latency when there are
    32   * relatively small number of connections to serve.
    33   *
    34   * <h3>How threads work</h3>
    35   * <p>
    36   * There is only one type of threads in {@link OioClientSocketChannelFactory};
    37   * worker threads.
    38   *
    39   * <h4>Worker threads</h4>
    40   * <p>
    41   * Each connected {@link Channel} has a dedicated worker thread, just like a
    42   * traditional blocking I/O thread model.
    43   *
    44   * <h3>Life cycle of threads and graceful shutdown</h3>
    45   * <p>
    46   * Worker threads are acquired from the {@link Executor} which was specified
    47   * when a {@link OioClientSocketChannelFactory} was created (i.e. {@code workerExecutor}.)
    48   * Therefore, you should make sure the specified {@link Executor} is able to
    49   * lend the sufficient number of threads.
    50   * <p>
    51   * Worker threads are acquired lazily, and then released when there's nothing
    52   * left to process.  All the related resources are also released when the
    53   * worker threads are released.  Therefore, to shut down a service gracefully,
    54   * you should do the following:
    55   *
    56   * <ol>
    57   * <li>close all channels created by the factory usually using
    58   *     {@link ChannelGroup#close()}, and</li>
    59   * <li>call {@link #releaseExternalResources()}.</li>
    60   * </ol>
    61   *
    62   * Please make sure not to shut down the executor until all channels are
    63   * closed.  Otherwise, you will end up with a {@link RejectedExecutionException}
    64   * and the related resources might not be released properly.
    65   *
    66   * <h3>Limitation</h3>
    67   * <p>
    68   * A {@link SocketChannel} created by this factory does not support asynchronous
    69   * operations.  Any I/O requests such as {@code "connect"} and {@code "write"}
    70   * will be performed in a blocking manner.
    71   *
    72   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    73   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    74   *
    75   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
    76   *
    77   * @apiviz.landmark
    78   */
    79  public class OioClientSocketChannelFactory implements ClientSocketChannelFactory {
    80
    81      private final Executor workerExecutor;
    82      final OioClientSocketPipelineSink sink;
    83
    84      /**
    85       * Creates a new instance.
    86       *
    87       * @param workerExecutor
    88       *        the {@link Executor} which will execute the I/O worker threads
    89       */
    90      public OioClientSocketChannelFactory(Executor workerExecutor) {
    91          if (workerExecutor == null) {
    92              throw new NullPointerException("workerExecutor");
    93          }
    94          this.workerExecutor = workerExecutor;
    95          sink = new OioClientSocketPipelineSink(workerExecutor);
    96      }
    97
    98      public SocketChannel newChannel(ChannelPipeline pipeline) {
    99          return new OioClientSocketChannel(this, pipeline, sink);
    100     }
    101
    102     public void releaseExternalResources() {
    103         ExecutorUtil.terminate(workerExecutor);
    104     }
    105 }