Ant example source code file (RetryHandler.java)

This example Ant source code file (RetryHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

io, io, ioexception, ioexception, retryhandler, retryhandler, string, task, task

The RetryHandler.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.tools.ant.util;

import java.io.IOException;

import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;

/**
 * A simple utility class to take a piece of code (that implements
 * <code>Retryable interface) and executes that with possibility to
 * retry the execution in case of IOException.
 */
public class RetryHandler {

    private int retriesAllowed = 0;
    private Task task;

    /**
     * Create a new RetryingHandler.
     *
     * @param retriesAllowed how many times to retry
     * @param task the Ant task that is is executed from, used for logging only
     */
    public RetryHandler(int retriesAllowed, Task task) {
        this.retriesAllowed = retriesAllowed;
        this.task = task;
    }

    /**
     * Execute the <code>Retryable code with specified number of retries.
     *
     * @param exe the code to execute
     * @param desc some descriptive text for this piece of code, used for logging
     * @throws IOException if the number of retries has exceeded the allowed limit
     */
    public void execute(Retryable exe, String desc) throws IOException {
        int retries = 0;
        while (true) {
            try {
                exe.execute();
                break;
            } catch (IOException e) {
                retries++;
                if (retries > this.retriesAllowed && this.retriesAllowed > -1) {
                    task.log("try #" + retries + ": IO error ("
                            + desc + "), number of maximum retries reached ("
                            + this.retriesAllowed + "), giving up", Project.MSG_WARN);
                    throw e;
                } else {
                    task.log("try #" + retries + ": IO error (" + desc
                             + "), retrying", Project.MSG_WARN);
                }
            }
        }
    }

}