1 /**
2 * Copyright 2005-2014 The Kuali Foundation
3 *
4 * Licensed under the Educational Community License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.opensource.org/licenses/ecl2.php
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.kuali.rice.test.remote;
17
18 import java.io.IOException;
19 import java.net.DatagramSocket;
20 import java.net.ServerSocket;
21 import java.util.NoSuchElementException;
22 import java.util.concurrent.atomic.AtomicInteger;
23
24
25 /**
26 * <p>Finds currently available server ports.</p>
27 *
28 * <p>This class is a verbatim copy of AvailablePortFinder from the camel-test component of the Apache Camel project.
29 * </p>
30 *
31 * @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>
32 */
33 public final class AvailablePortFinder {
34 /**
35 * The minimum server currentMinPort number. Set at 1024 to avoid returning privileged
36 * currentMinPort numbers.
37 */
38 public static final int MIN_PORT_NUMBER = 1024;
39
40 /**
41 * The maximum server currentMinPort number.
42 */
43 public static final int MAX_PORT_NUMBER = 49151;
44
45
46 /**
47 * Incremented to the next lowest available port when getNextAvailable() is called.
48 */
49 private static AtomicInteger currentMinPort = new AtomicInteger(MIN_PORT_NUMBER);
50
51 /**
52 * Creates a new instance.
53 */
54 private AvailablePortFinder() {
55 // Do nothing
56 }
57
58 /**
59 * Gets the next available currentMinPort starting at the lowest currentMinPort number. This is the preferred
60 * method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening
61 * the port.
62 *
63 * @throws NoSuchElementException if there are no ports available
64 */
65 public static synchronized int getNextAvailable() {
66 int next = getNextAvailable(currentMinPort.get());
67 currentMinPort.set(next + 1);
68 return next;
69 }
70
71 /**
72 * Gets the next available currentMinPort starting at a currentMinPort.
73 *
74 * @param fromPort the currentMinPort to scan for availability
75 * @throws NoSuchElementException if there are no ports available
76 */
77 public static synchronized int getNextAvailable(int fromPort) {
78 if (fromPort < currentMinPort.get() || fromPort > MAX_PORT_NUMBER) {
79 throw new IllegalArgumentException("Invalid start currentMinPort: " + fromPort);
80 }
81
82 for (int i = fromPort; i <= MAX_PORT_NUMBER; i++) {
83 if (available(i)) {
84 return i;
85 }
86 }
87
88 throw new NoSuchElementException("Could not find an available currentMinPort above " + fromPort);
89 }
90
91 /**
92 * Checks to see if a specific currentMinPort is available.
93 *
94 * @param port the currentMinPort to check for availability
95 */
96 public static boolean available(int port) {
97 if (port < currentMinPort.get() || port > MAX_PORT_NUMBER) {
98 throw new IllegalArgumentException("Invalid start currentMinPort: " + port);
99 }
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 }