1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.kuali.rice.test.remote;
18
19 import java.io.IOException;
20 import java.net.DatagramSocket;
21 import java.net.ServerSocket;
22 import java.util.NoSuchElementException;
23 import java.util.concurrent.atomic.AtomicInteger;
24
25
26 /**
27 * <p>Finds currently available server ports.</p>
28 *
29 * <p>This class is a verbatim copy of AvailablePortFinder from the camel-test component of the Apache Camel project.
30 * </p>
31 *
32 * @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>
33 */
34 public final class AvailablePortFinder {
35 /**
36 * The minimum server currentMinPort number. Set at 1024 to avoid returning privileged
37 * currentMinPort numbers.
38 */
39 public static final int MIN_PORT_NUMBER = 1024;
40
41 /**
42 * The maximum server currentMinPort number.
43 */
44 public static final int MAX_PORT_NUMBER = 49151;
45
46
47 /**
48 * Incremented to the next lowest available port when getNextAvailable() is called.
49 */
50 private static AtomicInteger currentMinPort = new AtomicInteger(MIN_PORT_NUMBER);
51
52 /**
53 * Creates a new instance.
54 */
55 private AvailablePortFinder() {
56 // Do nothing
57 }
58
59 /**
60 * Gets the next available currentMinPort starting at the lowest currentMinPort number. This is the preferred
61 * method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening
62 * the port.
63 *
64 * @throws NoSuchElementException if there are no ports available
65 */
66 public static synchronized int getNextAvailable() {
67 int next = getNextAvailable(currentMinPort.get());
68 currentMinPort.set(next + 1);
69 return next;
70 }
71
72 /**
73 * Gets the next available currentMinPort starting at a currentMinPort.
74 *
75 * @param fromPort the currentMinPort to scan for availability
76 * @throws NoSuchElementException if there are no ports available
77 */
78 public static synchronized int getNextAvailable(int fromPort) {
79 if (fromPort < currentMinPort.get() || fromPort > MAX_PORT_NUMBER) {
80 throw new IllegalArgumentException("Invalid start currentMinPort: " + fromPort);
81 }
82
83 for (int i = fromPort; i <= MAX_PORT_NUMBER; i++) {
84 if (available(i)) {
85 return i;
86 }
87 }
88
89 throw new NoSuchElementException("Could not find an available currentMinPort above " + fromPort);
90 }
91
92 /**
93 * Checks to see if a specific currentMinPort is available.
94 *
95 * @param port the currentMinPort to check for availability
96 */
97 public static boolean available(int port) {
98 if (port < currentMinPort.get() || port > MAX_PORT_NUMBER) {
99 throw new IllegalArgumentException("Invalid start currentMinPort: " + port);
100 }
101
102 ServerSocket ss = null;
103 DatagramSocket ds = null;
104 try {
105 ss = new ServerSocket(port);
106 ss.setReuseAddress(true);
107 ds = new DatagramSocket(port);
108 ds.setReuseAddress(true);
109 return true;
110 } catch (IOException e) {
111 // Do nothing
112 } finally {
113 if (ds != null) {
114 ds.close();
115 }
116
117 if (ss != null) {
118 try {
119 ss.close();
120 } catch (IOException e) {
121 /* should not be thrown */
122 }
123 }
124 }
125
126 return false;
127 }
128 }