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Java > Open Source Codes > org > apache > tools > ant > util > RetryHandler


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. 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.apache.tools.ant.util;
19
20 import java.io.IOException JavaDoc;
21
22 import org.apache.tools.ant.Project;
23 import org.apache.tools.ant.Task;
24
25 /**
26  * A simple utility class to take a piece of code (that implements
27  * <code>Retryable</code> interface) and executes that with possibility to
28  * retry the execution in case of IOException.
29  */
30 public class RetryHandler {
31
32     private int retriesAllowed = 0;
33     private Task task;
34
35     /**
36      * Create a new RetryingHandler.
37      *
38      * @param retriesAllowed how many times to retry
39      * @param task the Ant task that is is executed from, used for logging only
40      */
41     public RetryHandler(int retriesAllowed, Task task) {
42         this.retriesAllowed = retriesAllowed;
43         this.task = task;
44     }
45
46     /**
47      * Execute the <code>Retryable</code> code with specified number of retries.
48      *
49      * @param exe the code to execute
50      * @param desc some descriptive text for this piece of code, used for logging
51      * @throws IOException if the number of retries has exceeded the allowed limit
52      */
53     public void execute(Retryable exe, String JavaDoc desc) throws IOException JavaDoc {
54         int retries = 0;
55         while (true) {
56             try {
57                 exe.execute();
58                 break;
59             } catch (IOException JavaDoc e) {
60                 retries++;
61                 if (retries > this.retriesAllowed && this.retriesAllowed > -1) {
62                     task.log("try #" + retries + ": IO error ("
63                             + desc + "), number of maximum retries reached ("
64                             + this.retriesAllowed + "), giving up", Project.MSG_WARN);
65                     throw e;
66                 } else {
67                     task.log("try #" + retries + ": IO error (" + desc
68                              + "), retrying", Project.MSG_WARN);
69                 }
70             }
71         }
72     }
73
74 }
75
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