org.colombbus.tangara.net.HttpConnRetryHandler.java Source code

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Here is the source code for org.colombbus.tangara.net.HttpConnRetryHandler.java

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/**
 * Tangara is an educational platform to get started with programming.
 * Copyright (C) 2008 Colombbus (http://www.colombbus.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.colombbus.tangara.net;

import java.io.IOException;

import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpMethodRetryHandler;
import org.apache.commons.httpclient.NoHttpResponseException;
import org.apache.log4j.Logger;

/**
 * A simple handler of HTTP reconnection.
 * <p>
 * It is based on a simple retry count. If the number of retries is greater than
 * a specified value, the handler gives-up.
 * </p>
 * 
 * @author gwen
 */
public class HttpConnRetryHandler implements HttpMethodRetryHandler {

    /**
     * Create a new handler
     * 
     * @param maxRetries
     *            maximum number of tries. It shall be greater than 0
     */
    public HttpConnRetryHandler(int maxRetries) {
        super();
        if (maxRetries < 1) {
            LOG.error("Fail to create handler. The maxRetries parameter shall be greater than 0");
            throw new IllegalArgumentException("maxRetries parameter shall be greater than 0");
        }
        this.maxRetries = maxRetries;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.commons.httpclient.HttpMethodRetryHandler#retryMethod(org.apache.commons.httpclient.HttpMethod,
     *      java.io.IOException, int)
     */
    @Override
    public boolean retryMethod(final HttpMethod method, final IOException exception, int executionCount) {
        LOG.info("Try number " + executionCount);
        if (executionCount >= maxRetries) {
            LOG.warn("Too many tries (" + executionCount + ")", exception);
            // Do not retry if over max retry count
            return false;
        }
        if (exception instanceof NoHttpResponseException) {
            LOG.error("No response from the server. No more tries", exception);
            // Retry if the server dropped connection on us
            return true;
        }
        if (!method.isRequestSent()) {
            LOG.error("Request not sent. No more tries", exception);
            // Retry if the request has not been sent fully or
            // if it's OK to retry methods that have been sent
            return true;
        }

        // otherwise do not retry
        LOG.error("Source of the HTTP failure not identified. No more tries", exception);
        return false;
    }

    /** Number of retries */
    private int maxRetries;

    /** Class logger */
    private static Logger LOG = Logger.getLogger(HttpConnRetryHandler.class);
}