org.mule.tck.junit4.rule.FreePortFinder.java Source code

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Here is the source code for org.mule.tck.junit4.rule.FreePortFinder.java

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/*
 * $Id$
 * --------------------------------------------------------------------------------------
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 *
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */

package org.mule.tck.junit4.rule;

import java.io.IOException;
import java.net.ServerSocket;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Finds available port numbers in a specified range.
 */
public class FreePortFinder {

    protected final Log logger = LogFactory.getLog(getClass());

    private final int minPortNumber;
    private final int portRange;
    private final Set<Integer> selectedPorts = new HashSet<Integer>();
    private final Random random = new Random();

    public FreePortFinder(int minPortNumber, int maxPortNumber) {
        this.minPortNumber = minPortNumber;
        this.portRange = maxPortNumber - minPortNumber;
    }

    public synchronized Integer find() {
        for (int i = 0; i < portRange; i++) {
            int port = minPortNumber + random.nextInt(portRange);

            if (selectedPorts.contains(port)) {
                continue;
            }

            if (isPortFree(port)) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Found free port: " + port);
                }

                selectedPorts.add(port);

                return port;
            }
        }

        throw new IllegalStateException("Unable to find an available port");
    }

    /**
     * Indicates that the port is free from the point of view of the caller.
     * <p/>
     * Checks that the port was released, if it was not, then it would be
     * marked as in use, so no other client receives the same port again.
     *
     * @param port the port number to release.
     */
    public synchronized void releasePort(int port) {
        if (isPortFree(port)) {
            selectedPorts.remove(port);
        } else {
            if (logger.isInfoEnabled()) {
                logger.info(String.format("Port %d was is not correctly released", port));
            }
        }
    }

    /**
     * Check and log is a given port is available
     *
     * @param port the port number to check
     * @return true if the port is available, false otherwise
     */
    public boolean isPortFree(int port) {
        boolean portIsFree = true;

        ServerSocket server = null;
        try {
            server = new ServerSocket(port);
            server.setReuseAddress(true);
        } catch (IOException e) {
            portIsFree = false;
        } finally {
            if (server != null) {
                try {
                    server.close();
                } catch (IOException e) {
                    // ignore
                }
            }
        }

        return portIsFree;
    }
}