Mercurial > hg > blitz_condensed
comparison src/com/go/trove/net/InetAddressResolver.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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-1:000000000000 | 0:3dc0c5604566 |
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1 /* ==================================================================== | |
2 * Trove - Copyright (c) 1997-2000 Walt Disney Internet Group | |
3 * ==================================================================== | |
4 * The Tea Software License, Version 1.1 | |
5 * | |
6 * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved. | |
7 * | |
8 * Redistribution and use in source and binary forms, with or without | |
9 * modification, are permitted provided that the following conditions | |
10 * are met: | |
11 * | |
12 * 1. Redistributions of source code must retain the above copyright | |
13 * notice, this list of conditions and the following disclaimer. | |
14 * | |
15 * 2. Redistributions in binary form must reproduce the above copyright | |
16 * notice, this list of conditions and the following disclaimer in | |
17 * the documentation and/or other materials provided with the | |
18 * distribution. | |
19 * | |
20 * 3. The end-user documentation included with the redistribution, | |
21 * if any, must include the following acknowledgment: | |
22 * "This product includes software developed by the | |
23 * Walt Disney Internet Group (http://opensource.go.com/)." | |
24 * Alternately, this acknowledgment may appear in the software itself, | |
25 * if and wherever such third-party acknowledgments normally appear. | |
26 * | |
27 * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must | |
28 * not be used to endorse or promote products derived from this | |
29 * software without prior written permission. For written | |
30 * permission, please contact opensource@dig.com. | |
31 * | |
32 * 5. Products derived from this software may not be called "Tea", | |
33 * "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet", | |
34 * "Kettle", "Trove" or "BeanDoc" appear in their name, without prior | |
35 * written permission of the Walt Disney Internet Group. | |
36 * | |
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED | |
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
40 * DISCLAIMED. IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS | |
41 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
42 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
43 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
44 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY | |
45 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
46 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
47 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
48 * ==================================================================== | |
49 * | |
50 * For more information about Tea, please see http://opensource.go.com/. | |
51 */ | |
52 | |
53 package com.go.trove.net; | |
54 | |
55 import java.net.*; | |
56 import java.util.*; | |
57 import java.lang.ref.*; | |
58 import com.go.trove.util.SoftHashMap; | |
59 | |
60 /****************************************************************************** | |
61 * Allows network host names to resolve to inet addresses via event | |
62 * notification. | |
63 * <p> | |
64 * Note: This class makes use of the java.util.Timer class, available only in | |
65 * Java 2, version 1.3. | |
66 * | |
67 * @author Brian S O'Neill | |
68 * @version | |
69 * <!--$$Revision: 1.1 $-->, <!--$$JustDate:--> 01/01/23 <!-- $--> | |
70 */ | |
71 public class InetAddressResolver { | |
72 // Wait for 10 minutes before trying to resolve again. | |
73 private static final long RESOLVE_PERIOD = 10 * 60 * 1000; | |
74 private static Timer cResolveTimer; | |
75 | |
76 private static Map cResolvers = new SoftHashMap(); | |
77 | |
78 private static Timer getResolveTimer() { | |
79 Timer timer = cResolveTimer; | |
80 if (timer == null) { | |
81 timer = new Timer(true); | |
82 timer.schedule(new TimerTask() { | |
83 public void run() { | |
84 Thread.currentThread().setName("InetAddressResolver"); | |
85 } | |
86 }, 0); | |
87 cResolveTimer = timer; | |
88 } | |
89 return timer; | |
90 } | |
91 | |
92 /** | |
93 * Resolve the host name into InetAddresses and listen for changes. | |
94 * The caller must save a reference to the resolver to prevent it from | |
95 * being reclaimed by the garbage collector. | |
96 * | |
97 * @param host host to resolve into InetAddresses | |
98 * @param listener listens for InetAddresses | |
99 */ | |
100 public static InetAddressResolver listenFor(String host, | |
101 InetAddressListener listener) { | |
102 synchronized (cResolvers) { | |
103 InetAddressResolver resolver = | |
104 (InetAddressResolver)cResolvers.get(host); | |
105 if (resolver == null) { | |
106 resolver = new InetAddressResolver(host); | |
107 cResolvers.put(host, resolver); | |
108 } | |
109 resolver.addListener(listener); | |
110 return resolver; | |
111 } | |
112 } | |
113 | |
114 private final String mHost; | |
115 | |
116 private List mListeners = new ArrayList(); | |
117 | |
118 // Is either an instance of UnknownHostException or InetAddress[]. | |
119 private Object mResolutionResults; | |
120 | |
121 private InetAddressResolver(String host) { | |
122 mHost = host; | |
123 | |
124 // Initial delay is random so that requests against other hosts are | |
125 // staggered. | |
126 long delay = (long)(Math.random() * RESOLVE_PERIOD); | |
127 getResolveTimer().schedule(new Resolver(this), delay, RESOLVE_PERIOD); | |
128 } | |
129 | |
130 private synchronized void addListener(InetAddressListener listener) { | |
131 mListeners.add(listener); | |
132 if (!resolveAddresses()) { | |
133 // Ensure that new listener is called the first time. | |
134 notifyListener(listener); | |
135 } | |
136 } | |
137 | |
138 private synchronized void notifyListener(InetAddressListener listener) { | |
139 if (mResolutionResults instanceof UnknownHostException) { | |
140 listener.unknown((UnknownHostException)mResolutionResults); | |
141 } | |
142 else { | |
143 InetAddress[] addresses = (InetAddress[])mResolutionResults; | |
144 addresses = (InetAddress[])addresses.clone(); | |
145 listener.resolved(addresses); | |
146 } | |
147 } | |
148 | |
149 // Returns true if anything changed from the last time this was invoked. | |
150 private synchronized boolean resolveAddresses() { | |
151 boolean changed; | |
152 try { | |
153 InetAddress[] addresses = InetAddress.getAllByName(mHost); | |
154 if (mResolutionResults instanceof UnknownHostException) { | |
155 changed = true; | |
156 } | |
157 else { | |
158 // Results may be ordered differently, so keep them sorted. | |
159 Arrays.sort(addresses, new Comparator() { | |
160 public int compare(Object a, Object b) { | |
161 return ((InetAddress)a).getHostAddress() | |
162 .compareTo(((InetAddress)b).getHostAddress()); | |
163 } | |
164 }); | |
165 | |
166 changed = !Arrays.equals | |
167 (addresses, (InetAddress[])mResolutionResults); | |
168 } | |
169 mResolutionResults = addresses; | |
170 } | |
171 catch (UnknownHostException e) { | |
172 changed = !(mResolutionResults instanceof UnknownHostException); | |
173 mResolutionResults = e; | |
174 } | |
175 | |
176 if (changed) { | |
177 int size = mListeners.size(); | |
178 for (int i=0; i<size; i++) { | |
179 notifyListener((InetAddressListener)mListeners.get(i)); | |
180 } | |
181 } | |
182 | |
183 return changed; | |
184 } | |
185 | |
186 private class Resolver extends TimerTask { | |
187 // Weakly references owner so that the timer won't prevent it from | |
188 // being garbage collected. | |
189 private final Reference mOwner; | |
190 | |
191 public Resolver(InetAddressResolver owner) { | |
192 mOwner = new WeakReference(owner); | |
193 } | |
194 | |
195 public void run() { | |
196 InetAddressResolver owner = (InetAddressResolver)mOwner.get(); | |
197 if (owner == null) { | |
198 cancel(); | |
199 } | |
200 Thread t = Thread.currentThread(); | |
201 String originalName = t.getName(); | |
202 t.setName("InetAddressResolver:" + owner.mHost); | |
203 try { | |
204 owner.resolveAddresses(); | |
205 } | |
206 finally { | |
207 t.setName(originalName); | |
208 } | |
209 } | |
210 } | |
211 } |