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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.filter.query;
21  
22  import java.util.Map;
23  import java.util.concurrent.ConcurrentHashMap;
24  import java.util.concurrent.Executors;
25  import java.util.concurrent.ScheduledExecutorService;
26  import java.util.concurrent.TimeUnit;
27  
28  import org.apache.mina.api.AbstractIoFilter;
29  import org.apache.mina.api.IoFuture;
30  import org.apache.mina.api.IoSession;
31  import org.apache.mina.filterchain.ReadFilterChainController;
32  import org.apache.mina.session.AttributeKey;
33  
34  /**
35   * A filter providing {@link IoFuture} for request/response protocol.
36   * 
37   * You send a request to the connected end-point and a {@link IoFuture} is provided for handling the received request
38   * response.
39   * 
40   * The filter find the received message matching the request, using {@link Request#requestId()} and
41   * {@link Response#requestId()}.
42   * 
43   * <pre>
44   * RequestFilter rq = new RequestFilter();
45   * 
46   * service.setFilters(.., rq);
47   * 
48   * IoFuture&lt;Response&gt; future = rq.request(session, message, 10000);
49   * 
50   * response.register(new AbstractIoFutureListener&lt;Response&gt;() {
51   *     &#064;Override
52   *     public void completed(Response result) {
53   *         System.err.println(&quot;request completed ! response : &quot; + result);
54   *     }
55   * });
56   * </pre>
57   * 
58   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
59   */
60  public class RequestFilter<REQUEST extends Request, RESPONSE extends Response> extends AbstractIoFilter {
61  
62      /**
63       * Send a request message and provide a {@link IoFuture} for handling the response. WARNING : for now timeout
64       * doesn't work (WIP).
65       * 
66       * @param session the session where to write the request
67       * @param request the request to be issued
68       * @param timeoutInMs the timeout in milli-seconds (doesn't work Work-in-progress).
69       * @return the {@link IoFuture} for waiting or listening the completion of this request.
70       */
71      @SuppressWarnings({ "rawtypes", "unchecked" })
72      public IoFuture<RESPONSE> request(IoSession session, REQUEST request, long timeoutInMs) {
73          Map inFlight = session.getAttribute(IN_FLIGHT_REQUESTS);
74          RequestFuture<REQUEST, RESPONSE> future = new RequestFuture<REQUEST, RESPONSE>(session, request.requestId());
75  
76          // schedule a timeout task
77          future.setTimeoutFuture(schedExec.schedule(future.timeout, timeoutInMs, TimeUnit.MILLISECONDS));
78  
79          // save the future for completion
80          inFlight.put(request.requestId(), future);
81          session.write(request);
82          return future;
83      }
84  
85      @SuppressWarnings("rawtypes")
86      static final AttributeKey<Map> IN_FLIGHT_REQUESTS = new AttributeKey<Map>(Map.class, "request.in.flight");
87  
88      private ScheduledExecutorService schedExec = Executors.newScheduledThreadPool(1);
89  
90      @SuppressWarnings("rawtypes")
91      @Override
92      public void sessionOpened(IoSession session) {
93          session.setAttribute(IN_FLIGHT_REQUESTS, new ConcurrentHashMap());
94      }
95  
96      @SuppressWarnings("unchecked")
97      @Override
98      public void messageReceived(IoSession session, Object message, ReadFilterChainController controller) {
99          if (message instanceof Response) {
100             Object id = ((Response) message).requestId();
101             if (id != null) {
102                 // got a response, let's find the query
103                 Map<?, ?> inFlight = session.getAttribute(IN_FLIGHT_REQUESTS);
104                 RequestFuture<REQUEST, RESPONSE> future = (RequestFuture<REQUEST, RESPONSE>) inFlight.remove(id);
105                 if (future != null) {
106                     future.complete((RESPONSE) message);
107                 }
108             }
109         }
110 
111         super.messageReceived(session, message, controller);
112     }
113 
114     /**
115      * {@inheritDoc} cancel remaining requests
116      */
117     @Override
118     public void sessionClosed(IoSession session) {
119         Map<?, ?> inFlight = session.getAttribute(IN_FLIGHT_REQUESTS);
120         for (Object v : inFlight.values()) {
121             ((RequestFuture<?, ?>) v).cancel(true);
122         }
123     }
124 }