SynchToAsynchChannelServerAdapter xref

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    1   /***
    2    *
    3    * Copyright 2004 Protique Ltd
    4    *
    5    * Licensed under the Apache License, Version 2.0 (the "License");
    6    * you may not use this file except in compliance with the License.
    7    * You may obtain a copy of the License at
    8    *
    9    * http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   **/
    18
    19  package org.activeio.adapter;
    20
    21  import java.io.IOException;
    22  import java.io.InterruptedIOException;
    23  import java.net.URI;
    24
    25  import org.activeio.AcceptListener;
    26  import org.activeio.AsynchChannelServer;
    27  import org.activeio.Channel;
    28  import org.activeio.ChannelFactory;
    29  import org.activeio.ChannelServer;
    30  import org.activeio.Disposable;
    31  import org.activeio.Service;
    32  import org.activeio.SynchChannelServer;
    33
    34  import EDU.oswego.cs.dl.util.concurrent.Executor;
    35  import EDU.oswego.cs.dl.util.concurrent.Latch;
    36  import EDU.oswego.cs.dl.util.concurrent.SynchronizedBoolean;
    37
    38  /***
    39   * Adapts a {@see org.activeio,SynchChannelServer} so that it provides an
    40   * {@see org.activeio.AsynchChannelServer} interface.  When this channel
    41   * is started, a background thread is used to poll the (@see org.activeio.SynchChannelServer}
    42   * for accepted channel connections which are then delivered to the {@see org.activeio.AcceptConsumer}.
    43   *
    44   * @version $Revision$
    45   */
    46  final public class SynchToAsynchChannelServerAdapter implements AsynchChannelServer, Runnable {
    47
    48      private final SynchChannelServer synchChannelServer;
    49      private final SynchronizedBoolean running = new SynchronizedBoolean(false);
    50      private final Executor executor;
    51      private AcceptListener acceptListener;
    52      private Latch doneLatch;
    53
    54
    55      static public AsynchChannelServer adapt(ChannelServer channel) {
    56          return adapt(channel, ChannelFactory.DEFAULT_EXECUTOR);
    57      }
    58
    59      static public AsynchChannelServer adapt(ChannelServer channel, Executor executor) {
    60
    61          // It might not need adapting
    62          if( channel instanceof AsynchChannelServer ) {
    63              return (AsynchChannelServer) channel;
    64          }
    65
    66          // Can we just just undo the adaptor
    67          if( channel.getClass() == SynchToAsynchChannelAdapter.class ) {
    68              return ((AsynchToSynchChannelServerAdapter)channel).getAsynchChannelServer();
    69          }
    70
    71          return new SynchToAsynchChannelServerAdapter((SynchChannelServer)channel, executor);
    72      }
    73
    74      public SynchToAsynchChannelServerAdapter(SynchChannelServer synchServer) {
    75          this(synchServer, ChannelFactory.DEFAULT_EXECUTOR);
    76      }
    77
    78      public SynchToAsynchChannelServerAdapter(SynchChannelServer synchServer, Executor executor) {
    79          this.synchChannelServer = synchServer;
    80          this.executor=executor;
    81      }
    82
    83      synchronized public void start() throws IOException {
    84          if (running.commit(false, true)) {
    85
    86              if( acceptListener == null )
    87                  throw new IllegalStateException("AcceptListener must be set before object can be started.");
    88
    89              synchChannelServer.start();
    90
    91              try {
    92                  doneLatch = new Latch();
    93                  executor.execute(this);
    94              } catch (InterruptedException e) {
    95                  throw new InterruptedIOException(e.getMessage());
    96              }
    97          }
    98      }
    99
    100     synchronized public void stop(long timeout) throws IOException {
    101         if (running.commit(true, false)) {
    102             try {
    103
    104                 if( timeout == NO_WAIT_TIMEOUT ) {
    105                     synchChannelServer.stop(NO_WAIT_TIMEOUT);
    106                 } else if( timeout == WAIT_FOREVER_TIMEOUT ) {
    107                     doneLatch.acquire();
    108                     synchChannelServer.stop(WAIT_FOREVER_TIMEOUT);
    109                 } else {
    110
    111                     long start = System.currentTimeMillis();
    112                     if( doneLatch.attempt(timeout) ) {
    113                         timeout -= (System.currentTimeMillis() - start);
    114                     } else {
    115                         timeout=0;
    116                     }
    117
    118                     if( timeout <= 0 ) {
    119                         synchChannelServer.stop(NO_WAIT_TIMEOUT);
    120                     } else {
    121                         synchChannelServer.stop(timeout);
    122                     }
    123                 }
    124
    125             } catch (IOException e) {
    126                 throw e;
    127             } catch (Throwable e) {
    128                 throw (IOException)new IOException("stop failed: " + e.getMessage()).initCause(e);
    129             }
    130         }
    131     }
    132
    133     public void run() {
    134         // Change the thread name.
    135         String oldName = Thread.currentThread().getName();
    136         Thread.currentThread().setName( synchChannelServer.toString() );
    137         try {
    138 	        while (running.get()) {
    139 	            try {
    140 	                Channel channel = synchChannelServer.accept(500);
    141 	                if( channel == null )
    142 	                    continue;
    143 	                acceptListener.onAccept(channel);
    144 	            } catch (IOException e) {
    145 	                if( running.get() )
    146 	                    acceptListener.onAcceptError(e);
    147 	        	} catch (Throwable e) {
    148 	                if( running.get() )
    149 	                    acceptListener.onAcceptError((IOException)new IOException("Unexpected Error: "+e).initCause(e));
    150 	        	}
    151 	        }
    152         } finally {
    153             if( doneLatch!=null )
    154                 doneLatch.release();
    155             Thread.currentThread().setName(oldName);
    156         }
    157     }
    158
    159     /***
    160      * @see org.activeio.AsynchChannelServer#setAcceptListener(org.activeio.AcceptListener)
    161      */
    162     public void setAcceptListener(AcceptListener acceptListener) {
    163         if(running.get())
    164             throw new IllegalStateException("Cannot change the AcceptListener while the object is running.");
    165         this.acceptListener = acceptListener;
    166     }
    167
    168     /***
    169      * @see org.activeio.Disposable#dispose()
    170      */
    171     public void dispose() {
    172         try {
    173             stop(Service.NO_WAIT_TIMEOUT);
    174         } catch ( IOException ignore) {
    175         }
    176         if( synchChannelServer instanceof Disposable ) {
    177             ((Disposable)synchChannelServer).dispose();
    178         }
    179     }
    180
    181     public URI getBindURI() {
    182         return synchChannelServer.getBindURI();
    183     }
    184
    185     public URI getConnectURI() {
    186         return synchChannelServer.getConnectURI();
    187     }
    188
    189     public SynchChannelServer getSynchChannelServer() {
    190         return synchChannelServer;
    191     }
    192
    193     public Object narrow(Class target) {
    194         if( target.isAssignableFrom(getClass()) ) {
    195             return this;
    196         }
    197         return synchChannelServer.narrow(target);
    198     }
    199
    200     public String toString() {
    201         return synchChannelServer.toString();
    202     }
    203 }