/*
 *
 * 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.bookkeeper.util;

import java.net.ServerSocket;

/**
 * Port manager provides free ports to allows multiple instances
 * of the bookkeeper tests to run at once.
 */
public class PortManager {

    /**
     * Return an available port.
     *
     * @return available port.
     */
    public static synchronized int nextFreePort() {
        int exceptionCount = 0;
        while (true) {
            try (ServerSocket ss = new ServerSocket(0)) {
                return ss.getLocalPort();
            } catch (Exception e) {
                exceptionCount++;
                if (exceptionCount > 100) {
                    throw new RuntimeException("Unable to allocate socket port", e);
                }
            }
        }
    }
}
