001 /**
002 * Copyright 2005-2011 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.kuali.rice.test.remote;
017
018 import java.io.IOException;
019 import java.net.DatagramSocket;
020 import java.net.ServerSocket;
021 import java.util.NoSuchElementException;
022 import java.util.concurrent.atomic.AtomicInteger;
023
024
025 /**
026 * <p>Finds currently available server ports.</p>
027 *
028 * <p>This class is a verbatim copy of AvailablePortFinder from the camel-test component of the Apache Camel project.
029 * </p>
030 *
031 * @see <a href="http://svn.apache.org/viewvc/camel/trunk/components/camel-test/src/main/java/org/apache/camel/test/AvailablePortFinder.java?revision=1137595&view=co">IANA.org</a>
032 */
033 public final class AvailablePortFinder {
034 /**
035 * The minimum server currentMinPort number. Set at 1024 to avoid returning privileged
036 * currentMinPort numbers.
037 */
038 public static final int MIN_PORT_NUMBER = 1024;
039
040 /**
041 * The maximum server currentMinPort number.
042 */
043 public static final int MAX_PORT_NUMBER = 49151;
044
045
046 /**
047 * Incremented to the next lowest available port when getNextAvailable() is called.
048 */
049 private static AtomicInteger currentMinPort = new AtomicInteger(MIN_PORT_NUMBER);
050
051 /**
052 * Creates a new instance.
053 */
054 private AvailablePortFinder() {
055 // Do nothing
056 }
057
058 /**
059 * Gets the next available currentMinPort starting at the lowest currentMinPort number. This is the preferred
060 * method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening
061 * the port.
062 *
063 * @throws NoSuchElementException if there are no ports available
064 */
065 public static synchronized int getNextAvailable() {
066 int next = getNextAvailable(currentMinPort.get());
067 currentMinPort.set(next + 1);
068 return next;
069 }
070
071 /**
072 * Gets the next available currentMinPort starting at a currentMinPort.
073 *
074 * @param fromPort the currentMinPort to scan for availability
075 * @throws NoSuchElementException if there are no ports available
076 */
077 public static synchronized int getNextAvailable(int fromPort) {
078 if (fromPort < currentMinPort.get() || fromPort > MAX_PORT_NUMBER) {
079 throw new IllegalArgumentException("Invalid start currentMinPort: " + fromPort);
080 }
081
082 for (int i = fromPort; i <= MAX_PORT_NUMBER; i++) {
083 if (available(i)) {
084 return i;
085 }
086 }
087
088 throw new NoSuchElementException("Could not find an available currentMinPort above " + fromPort);
089 }
090
091 /**
092 * Checks to see if a specific currentMinPort is available.
093 *
094 * @param port the currentMinPort to check for availability
095 */
096 public static boolean available(int port) {
097 if (port < currentMinPort.get() || port > MAX_PORT_NUMBER) {
098 throw new IllegalArgumentException("Invalid start currentMinPort: " + port);
099 }
100
101 ServerSocket ss = null;
102 DatagramSocket ds = null;
103 try {
104 ss = new ServerSocket(port);
105 ss.setReuseAddress(true);
106 ds = new DatagramSocket(port);
107 ds.setReuseAddress(true);
108 return true;
109 } catch (IOException e) {
110 // Do nothing
111 } finally {
112 if (ds != null) {
113 ds.close();
114 }
115
116 if (ss != null) {
117 try {
118 ss.close();
119 } catch (IOException e) {
120 /* should not be thrown */
121 }
122 }
123 }
124
125 return false;
126 }
127 }