CompositeTransportChannel 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  package org.codehaus.activemq.transport.composite;
    19
    20  import EDU.oswego.cs.dl.util.concurrent.SynchronizedBoolean;
    21  import org.apache.commons.logging.Log;
    22  import org.apache.commons.logging.LogFactory;
    23  import org.codehaus.activemq.TimeoutExpiredException;
    24  import org.codehaus.activemq.message.Packet;
    25  import org.codehaus.activemq.message.PacketListener;
    26  import org.codehaus.activemq.message.Receipt;
    27  import org.codehaus.activemq.message.WireFormat;
    28  import org.codehaus.activemq.transport.TransportChannel;
    29  import org.codehaus.activemq.transport.TransportChannelProvider;
    30  import org.codehaus.activemq.transport.TransportChannelSupport;
    31
    32  import javax.jms.ExceptionListener;
    33  import javax.jms.JMSException;
    34  import java.net.URI;
    35  import java.util.ArrayList;
    36  import java.util.Collections;
    37  import java.util.List;
    38
    39  /***
    40   * A Compsite implementation of a TransportChannel
    41   *
    42   * @version $Revision: 1.20 $
    43   */
    44  public class CompositeTransportChannel extends TransportChannelSupport {
    45      private static final Log log = LogFactory.getLog(CompositeTransportChannel.class);
    46
    47      protected WireFormat wireFormat;
    48      protected List uris;
    49      protected TransportChannel channel;
    50      protected SynchronizedBoolean closed;
    51      protected SynchronizedBoolean started;
    52      protected int maximumRetries = 10;
    53      protected long failureSleepTime = 500L;
    54      protected URI currentURI;
    55      private long establishConnectionTimeout = 30000L;
    56
    57
    58      public CompositeTransportChannel(WireFormat wireFormat) {
    59          this.wireFormat = wireFormat;
    60          this.uris = Collections.synchronizedList(new ArrayList());
    61          closed = new SynchronizedBoolean(false);
    62          started = new SynchronizedBoolean(false);
    63      }
    64
    65      public CompositeTransportChannel(WireFormat wireFormat, List uris) {
    66          this(wireFormat);
    67          this.uris.addAll(uris);
    68      }
    69
    70      public String toString() {
    71          return "CompositeTransportChannel: " + channel;
    72      }
    73
    74      public void start() throws JMSException {
    75          if (started.commit(false, true)) {
    76              establishConnection(establishConnectionTimeout);
    77          }
    78      }
    79
    80      /***
    81       * close the channel
    82       */
    83      public void stop() {
    84          if (closed.commit(false, true)) {
    85              if (channel != null) {
    86                  try {
    87                      channel.stop();
    88                  }
    89                  catch (Exception e) {
    90                      log.warn("Caught while closing: " + e + ". Now Closed", e);
    91                  }
    92                  finally {
    93                      channel = null;
    94                      super.stop();
    95                  }
    96              }
    97          }
    98      }
    99
    100     public Receipt send(Packet packet) throws JMSException {
    101         return getChannel().send(packet);
    102     }
    103
    104
    105     public Receipt send(Packet packet, int timeout) throws JMSException {
    106         return getChannel().send(packet, timeout);
    107     }
    108
    109
    110     public void asyncSend(Packet packet) throws JMSException {
    111         getChannel().asyncSend(packet);
    112     }
    113
    114     public void setPacketListener(PacketListener listener) {
    115         super.setPacketListener(listener);
    116         if (channel != null) {
    117             channel.setPacketListener(listener);
    118         }
    119     }
    120
    121
    122     public void setExceptionListener(ExceptionListener listener) {
    123         super.setExceptionListener(listener);
    124         if (channel != null) {
    125             channel.setExceptionListener(listener);
    126         }
    127     }
    128
    129
    130     public boolean isMulticast() {
    131         return false;
    132     }
    133
    134     // Properties
    135     //-------------------------------------------------------------------------
    136
    137
    138     /***
    139      * Return the maximum amount of time spent trying to establish a connection
    140      * or a negative number to keep going forever
    141      *
    142      * @return
    143      */
    144     public long getEstablishConnectionTimeout() {
    145         return establishConnectionTimeout;
    146     }
    147
    148     public void setEstablishConnectionTimeout(long establishConnectionTimeout) {
    149         this.establishConnectionTimeout = establishConnectionTimeout;
    150     }
    151
    152     public int getMaximumRetries() {
    153         return maximumRetries;
    154     }
    155
    156     public void setMaximumRetries(int maximumRetries) {
    157         this.maximumRetries = maximumRetries;
    158     }
    159
    160     public long getFailureSleepTime() {
    161         return failureSleepTime;
    162     }
    163
    164     public void setFailureSleepTime(long failureSleepTime) {
    165         this.failureSleepTime = failureSleepTime;
    166     }
    167
    168     public List getUris() {
    169         return uris;
    170     }
    171
    172     public void setUris(List list) {
    173         synchronized (uris) {
    174             uris.clear();
    175             uris.addAll(list);
    176         }
    177     }
    178
    179     /***
    180      * Can this wireformat process packets of this version
    181      * @param version the version number to test
    182      * @return true if can accept the version
    183      */
    184     public boolean canProcessWireFormatVersion(int version){
    185         return channel != null ? channel.canProcessWireFormatVersion(version) : true;
    186     }
    187
    188     /***
    189      * @return the current version of this wire format
    190      */
    191     public int getCurrentWireFormatVersion(){
    192         return channel != null ? channel.getCurrentWireFormatVersion() : 1;
    193     }
    194
    195     // Implementation methods
    196     //-------------------------------------------------------------------------
    197
    198     protected void establishConnection(long timeout) throws JMSException {
    199
    200         // lets try connect
    201         boolean connected = false;
    202         long time = failureSleepTime;
    203         long startTime = System.currentTimeMillis();
    204
    205         for (int i = 0; !connected && (i < maximumRetries || maximumRetries <= 0) && !closed.get() && !isPendingStop(); i++) {
    206             List list = new ArrayList(getUris());
    207             if (i > 0) {
    208                 if (maximumRetries > 0 || timeout > 0) {
    209                     long current = System.currentTimeMillis();
    210                     if (timeout >= 0) {
    211                         if (current + time > startTime + timeout) {
    212                             time = startTime + timeout - current;
    213                         }
    214                     }
    215                     if (current > startTime + timeout || time <= 0) {
    216                         throw new TimeoutExpiredException("Could not connect to any of the URIs: " + list);
    217                     }
    218                 }
    219                 log.info("Could not connect; sleeping for: " + time + " millis and trying again");
    220                 try {
    221                     Thread.sleep(time);
    222                 }
    223                 catch (InterruptedException e) {
    224                     log.warn("Sleep interupted: " + e, e);
    225                 }
    226                 if (maximumRetries > 0) {
    227                     time *= 2;
    228                 }
    229             }
    230
    231             while (!connected && !list.isEmpty() && !closed.get() && !isPendingStop()) {
    232                 URI uri = extractURI(list);
    233                 try {
    234                     attemptToConnect(uri);
    235                     configureChannel();
    236                     connected = true;
    237                     currentURI = uri;
    238                 }
    239                 catch (JMSException e) {
    240                     log.info("Could not connect to: " + uri + ". Reason: " + e);
    241                 }
    242             }
    243
    244         }
    245         if (!connected && !closed.get()) {
    246             StringBuffer buffer = new StringBuffer("");
    247             Object[] uriArray = getUris().toArray();
    248             for (int i = 0; i < uriArray.length; i++) {
    249                 buffer.append(uriArray[i]);
    250                 if (i < (uriArray.length - 1)) {
    251                     buffer.append(",");
    252                 }
    253             }
    254             JMSException jmsEx = new JMSException("Failed to connect to resource(s): " + buffer.toString());
    255             throw jmsEx;
    256         }
    257
    258     }
    259
    260
    261     protected TransportChannel getChannel() throws JMSException {
    262         if (channel == null) {
    263             throw new JMSException("No TransportChannel connection available");
    264         }
    265         return channel;
    266     }
    267
    268     protected void configureChannel() {
    269         ExceptionListener exceptionListener = getExceptionListener();
    270         if (exceptionListener != null) {
    271             channel.setExceptionListener(exceptionListener);
    272         }
    273         PacketListener packetListener = getPacketListener();
    274         if (packetListener != null) {
    275             channel.setPacketListener(packetListener);
    276         }
    277     }
    278
    279
    280     protected URI extractURI(List list) throws JMSException {
    281         int idx = 0;
    282         if (list.size() > 1) {
    283             do {
    284                 idx = (int) (Math.random() * list.size());
    285             }
    286             while (idx < 0 || idx >= list.size());
    287         }
    288         return (URI) list.remove(idx);
    289     }
    290
    291     protected void attemptToConnect(URI uri) throws JMSException {
    292         channel = TransportChannelProvider.create(wireFormat, uri);
    293         if (started.get()) {
    294             channel.start();
    295         }
    296     }
    297 }