VMPipeAsynchChannelFactory xref

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    1   /***
    2    *
    3    * Copyright 2004 Hiram Chirino
    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.activeio.net;
    19
    20  import java.io.IOException;
    21  import java.lang.reflect.InvocationHandler;
    22  import java.lang.reflect.InvocationTargetException;
    23  import java.lang.reflect.Method;
    24  import java.lang.reflect.Proxy;
    25  import java.net.URI;
    26  import java.util.Collections;
    27  import java.util.HashMap;
    28  import java.util.Map;
    29
    30  import org.activeio.AsynchChannel;
    31  import org.activeio.AsynchChannelFactory;
    32  import org.activeio.AsynchChannelListener;
    33  import org.activeio.AsynchChannelServer;
    34  import org.activeio.Packet;
    35
    36  /***
    37   *
    38   * @version $Revision$
    39   */
    40  final public class VMPipeAsynchChannelFactory implements AsynchChannelFactory {
    41
    42      //
    43      // We do all this crazy stuff of looking the server map using System
    44      // properties
    45      // because this class could be loaded multiple times in different
    46      // classloaders.
    47      //
    48      private static final String SERVER_MAP_LOCATION = VMPipeAsynchChannelFactory.class.getName() + ".SERVER_MAP";
    49
    50      private static final Map SERVER_MAP;
    51      static {
    52          Map m = null;
    53          m = (Map) System.getProperties().get(SERVER_MAP_LOCATION);
    54          if (m == null) {
    55              m = Collections.synchronizedMap(new HashMap());
    56              System.getProperties().put(SERVER_MAP_LOCATION, m);
    57          }
    58          SERVER_MAP = m;
    59      }
    60
    61      private final static ClassLoader MY_CLASSLOADER = Packet.class.getClassLoader();
    62
    63
    64      /***
    65       * Used to marshal calls to a PipeChannel in a different classloader.
    66       */
    67      static public class ClassloaderAsynchChannelAdapter implements AsynchChannel {
    68
    69          private final ClassLoader cl;
    70          private final Object channel;
    71          private final Method writeMethod;
    72          private final Method setListenerMethod;
    73          private final Class listenerClazz;
    74          private final Class packetClazz;
    75          private final Object listenerProxy;
    76          private final Method duplicateMethod;
    77          private final Method startMethod;
    78          private final Method stopMethod;
    79          private final Method disposeMethod;
    80
    81          private AsynchChannelListener channelListener;
    82
    83          public class ListenerProxyHandler implements InvocationHandler {
    84              public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    85                  switch (method.getName().length()) {
    86                  case 8: // onPacket
    87                      Object packet = duplicateMethod.invoke(args[0], new Object[]{MY_CLASSLOADER});
    88                      channelListener.onPacket((Packet) packet);
    89                      break;
    90                  case 13: // onPacketError
    91                      channelListener.onPacketError((IOException) args[0]);
    92                      break;
    93                  default:
    94                      channelListener.onPacketError(new IOException("Unknown proxy method invocation: "+method.getName()));
    95                  }
    96                  return null;
    97              }
    98          }
    99
    100         public ClassloaderAsynchChannelAdapter(Object channel) throws SecurityException, NoSuchMethodException,
    101                 ClassNotFoundException {
    102             this.channel = channel;
    103             Class clazz = channel.getClass();
    104             cl = clazz.getClassLoader();
    105
    106             listenerClazz = cl.loadClass(AsynchChannelListener.class.getName());
    107             packetClazz = cl.loadClass(Packet.class.getName());
    108             writeMethod = clazz.getMethod("write", new Class[] { packetClazz });
    109             startMethod = clazz.getMethod("start", new Class[] { });
    110             stopMethod = clazz.getMethod("stop", new Class[] { long.class });
    111             disposeMethod = clazz.getMethod("dispose", new Class[] { });
    112
    113             setListenerMethod = clazz.getMethod("setAsynchChannelListener", new Class[] { listenerClazz });
    114             duplicateMethod = packetClazz.getMethod("duplicate", new Class[] { ClassLoader.class });
    115
    116             ListenerProxyHandler handler = new ListenerProxyHandler();
    117             listenerProxy = Proxy.newProxyInstance(cl, new Class[] { listenerClazz }, handler);
    118         }
    119
    120         public void write(Packet packet) throws IOException {
    121             callIOExceptionMethod(writeMethod, new Object[] { packet.duplicate(cl) });
    122         }
    123
    124         public void setAsynchChannelListener(AsynchChannelListener channelListener) {
    125             this.channelListener = channelListener;
    126             callMethod(setListenerMethod, new Object[] { channelListener == null ? null : listenerProxy });
    127         }
    128
    129         public AsynchChannelListener getAsynchChannelListener() {
    130             return channelListener;
    131         }
    132
    133         public void dispose() {
    134             callMethod(disposeMethod, new Object[] { });
    135         }
    136
    137         public void start() throws IOException {
    138             callIOExceptionMethod(startMethod, new Object[] {});
    139         }
    140
    141         public void stop(long timeout) throws IOException {
    142             callIOExceptionMethod(stopMethod, new Object[] {new Long(timeout)});
    143         }
    144
    145         private void callMethod(Method method, Object[] args) {
    146             try {
    147                 method.invoke(channel, args);
    148             } catch (InvocationTargetException e) {
    149                 if (e.getTargetException() instanceof RuntimeException) {
    150                     throw (RuntimeException) e.getTargetException();
    151                 }
    152                 throw new RuntimeException(e.getTargetException());
    153             } catch (Throwable e) {
    154                 throw new RuntimeException("Reflexive invocation failed: " + e, e);
    155             }
    156         }
    157
    158         private void callIOExceptionMethod(Method method, Object[] args) throws IOException {
    159             try {
    160                 method.invoke(channel, args);
    161             } catch (InvocationTargetException e) {
    162                 if (e.getTargetException() instanceof IOException) {
    163                     throw (IOException) e.getTargetException();
    164                 }
    165                 if (e.getTargetException() instanceof RuntimeException) {
    166                     throw (RuntimeException) e.getTargetException();
    167                 }
    168                 throw new RuntimeException(e.getTargetException());
    169             } catch (Throwable e) {
    170                 throw (IOException) new IOException("Reflexive invocation failed: " + e).initCause(e);
    171             }
    172         }
    173
    174         //
    175         // The following methods do not need to delegate since they
    176         // are implemented as noops in the PipeChannel
    177         //
    178         public Object narrow(Class target) {
    179             if (target.isAssignableFrom(getClass())) {
    180                 return this;
    181             }
    182             return null;
    183         }
    184
    185         public void flush() throws IOException {
    186         }
    187
    188     }
    189
    190     private boolean forceRefelection;
    191
    192     public AsynchChannel openAsynchChannel(URI location) throws IOException {
    193
    194         Object server = lookupServer(location);
    195         if (!forceRefelection && server.getClass() == VMPipeAsynchChannelServer.class) {
    196             return ((VMPipeAsynchChannelServer) server).connect();
    197         }
    198
    199         // Asume server is in a different classloader.
    200         // Use reflection to connect.
    201         try {
    202             Method method = server.getClass().getMethod("connect", new Class[] {});
    203             Object channel = method.invoke(server, new Object[] {});
    204             return new ClassloaderAsynchChannelAdapter(channel);
    205         } catch (Throwable e) {
    206             throw (IOException) new IOException("Connection could not be established: " + e).initCause(e);
    207         }
    208     }
    209
    210     public AsynchChannelServer bindAsynchChannel(URI bindURI) throws IOException {
    211         VMPipeAsynchChannelServer server = new VMPipeAsynchChannelServer(bindURI);
    212         bindServer(bindURI, server);
    213         return server;
    214     }
    215
    216     private static Map getServerMap() {
    217         return SERVER_MAP;
    218     }
    219
    220     static public String getServerKeyForURI(URI location) {
    221         return location.getHost();
    222     }
    223
    224     public static void bindServer(URI bindURI, VMPipeAsynchChannelServer server) throws IOException {
    225         String key = getServerKeyForURI(bindURI);
    226         if (getServerMap().get(key) != null)
    227             throw new IOException("Server is allready bound at: " + bindURI);
    228         getServerMap().put(key, server);
    229     }
    230
    231     public static Object lookupServer(URI location) throws IOException {
    232         String key = getServerKeyForURI(location);
    233         Object server = getServerMap().get(key);
    234         if (server == null) {
    235             throw new IOException("Connection refused.");
    236         }
    237         return server;
    238     }
    239
    240     public static void unbindServer(URI bindURI) {
    241         String key = getServerKeyForURI(bindURI);
    242         getServerMap().remove(key);
    243     }
    244
    245     public boolean isForceRefelection() {
    246         return forceRefelection;
    247     }
    248
    249     public void setForceRefelection(boolean forceRefelection) {
    250         this.forceRefelection = forceRefelection;
    251     }
    252
    253 }