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      1 /*
      2  * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/impl/client/DefaultHttpRequestRetryHandler.java $
      3  * $Revision: 652726 $
      4  * $Date: 2008-05-01 18:16:51 -0700 (Thu, 01 May 2008) $
      5  *
      6  * ====================================================================
      7  * Licensed to the Apache Software Foundation (ASF) under one
      8  * or more contributor license agreements.  See the NOTICE file
      9  * distributed with this work for additional information
     10  * regarding copyright ownership.  The ASF licenses this file
     11  * to you under the Apache License, Version 2.0 (the
     12  * "License"); you may not use this file except in compliance
     13  * with the License.  You may obtain a copy of the License at
     14  *
     15  *   http://www.apache.org/licenses/LICENSE-2.0
     16  *
     17  * Unless required by applicable law or agreed to in writing,
     18  * software distributed under the License is distributed on an
     19  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     20  * KIND, either express or implied.  See the License for the
     21  * specific language governing permissions and limitations
     22  * under the License.
     23  * ====================================================================
     24  *
     25  * This software consists of voluntary contributions made by many
     26  * individuals on behalf of the Apache Software Foundation.  For more
     27  * information on the Apache Software Foundation, please see
     28  * <http://www.apache.org/>.
     29  *
     30  */
     31 
     32 package org.apache.http.impl.client;
     33 
     34 import java.io.IOException;
     35 import java.io.InterruptedIOException;
     36 import java.net.UnknownHostException;
     37 
     38 import javax.net.ssl.SSLHandshakeException;
     39 
     40 import org.apache.http.NoHttpResponseException;
     41 import org.apache.http.client.HttpRequestRetryHandler;
     42 import org.apache.http.protocol.HttpContext;
     43 import org.apache.http.protocol.ExecutionContext;
     44 
     45 /**
     46  * The default {@link HttpRequestRetryHandler} used by request executors.
     47  *
     48  * @author Michael Becke
     49  * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
     50  */
     51 public class DefaultHttpRequestRetryHandler implements HttpRequestRetryHandler {
     52 
     53     /** the number of times a method will be retried */
     54     private final int retryCount;
     55 
     56     /** Whether or not methods that have successfully sent their request will be retried */
     57     private final boolean requestSentRetryEnabled;
     58 
     59     /**
     60      * Default constructor
     61      */
     62     public DefaultHttpRequestRetryHandler(int retryCount, boolean requestSentRetryEnabled) {
     63         super();
     64         this.retryCount = retryCount;
     65         this.requestSentRetryEnabled = requestSentRetryEnabled;
     66     }
     67 
     68     /**
     69      * Default constructor
     70      */
     71     public DefaultHttpRequestRetryHandler() {
     72         this(3, false);
     73     }
     74     /**
     75      * Used <code>retryCount</code> and <code>requestSentRetryEnabled</code> to determine
     76      * if the given method should be retried.
     77      */
     78     public boolean retryRequest(
     79             final IOException exception,
     80             int executionCount,
     81             final HttpContext context) {
     82         if (exception == null) {
     83             throw new IllegalArgumentException("Exception parameter may not be null");
     84         }
     85         if (context == null) {
     86             throw new IllegalArgumentException("HTTP context may not be null");
     87         }
     88         if (executionCount > this.retryCount) {
     89             // Do not retry if over max retry count
     90             return false;
     91         }
     92         if (exception instanceof NoHttpResponseException) {
     93             // Retry if the server dropped connection on us
     94             return true;
     95         }
     96         if (exception instanceof InterruptedIOException) {
     97             // Timeout
     98             return false;
     99         }
    100         if (exception instanceof UnknownHostException) {
    101             // Unknown host
    102             return false;
    103         }
    104         if (exception instanceof SSLHandshakeException) {
    105             // SSL handshake exception
    106             return false;
    107         }
    108         Boolean b = (Boolean)
    109             context.getAttribute(ExecutionContext.HTTP_REQ_SENT);
    110         boolean sent = (b != null && b.booleanValue());
    111         if (!sent || this.requestSentRetryEnabled) {
    112             // Retry if the request has not been sent fully or
    113             // if it's OK to retry methods that have been sent
    114             return true;
    115         }
    116         // otherwise do not retry
    117         return false;
    118     }
    119 
    120     /**
    121      * @return <code>true</code> if this handler will retry methods that have
    122      * successfully sent their request, <code>false</code> otherwise
    123      */
    124     public boolean isRequestSentRetryEnabled() {
    125         return requestSentRetryEnabled;
    126     }
    127 
    128     /**
    129      * @return the maximum number of times a method will be retried
    130      */
    131     public int getRetryCount() {
    132         return retryCount;
    133     }
    134 }
    135