1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package com.sun.jmx.remote.internal;
27
28 import java.io.IOException;
29 import java.io.InterruptedIOException;
30
31 import com.sun.jmx.remote.util.ClassLogger;
32 import com.sun.jmx.remote.util.EnvHelp;
33 import sun.misc.ManagedLocalsThread;
34
35 public abstract class ClientCommunicatorAdmin {
36 private static volatile long threadNo = 1;
37
38 public ClientCommunicatorAdmin(long period) {
39 this.period = period;
40
41 if (period > 0) {
42 checker = new Checker();
43
44 Thread t = new ManagedLocalsThread(
45 checker,
46 "JMX client heartbeat " + (++threadNo)
47 );
48
49 t.setDaemon(true);
50 t.start();
51 } else
52 checker = null;
53 }
54
55 /**
56 * Called by a client to inform of getting an IOException.
57 */
58 public void gotIOException (IOException ioe) throws IOException {
59 restart(ioe);
60 }
61
62 /**
63 * Called by this class to check a client connection.
64 */
65 protected abstract void checkConnection() throws IOException;
66
67 /**
68 * Tells a client to re-start again.
69 */
70 protected abstract void doStart() throws IOException;
71
72 /**
73 * Tells a client to stop because failing to call checkConnection.
74 */
75 protected abstract void doStop();
76
77 /**
78 * Terminates this object.
79 */
80 public void terminate() {
81 synchronized(lock) {
82 if (state == TERMINATED) {
83 return;
84 }
85
86 state = TERMINATED;
87
88 lock.notifyAll();
89
90 if (checker != null)
91 checker.stop();
92 }
93 }
94
95 private void restart(IOException ioe) throws IOException {
96 // check state
97 synchronized(lock) {
98 if (state == TERMINATED) {
99 throw new IOException("The client has been closed.");
100 } else if (state == FAILED) { // already failed to re-start by another thread
101 throw ioe;
102 } else if (state == RE_CONNECTING) {
103 // restart process has been called by another thread
104 // we need to wait
105 while(state == RE_CONNECTING) {
106 try {
107 lock.wait();
108 } catch (InterruptedException ire) {
109 // be asked to give up
110 InterruptedIOException iioe = new InterruptedIOException(ire.toString());
111 EnvHelp.initCause(iioe, ire);
112
113 throw iioe;
114 }
115 }
116
117 if (state == TERMINATED) {
118 throw new IOException("The client has been closed.");
119 } else if (state != CONNECTED) {
120 // restarted is failed by another thread
121 throw ioe;
122 }
123 return;
124 } else {
125 state = RE_CONNECTING;
126 lock.notifyAll();
127 }
128 }
129
130 // re-starting
131 try {
132 doStart();
133 synchronized(lock) {
134 if (state == TERMINATED) {
135 throw new IOException("The client has been closed.");
136 }
137
138 state = CONNECTED;
139
140 lock.notifyAll();
141 }
142
143 return;
144 } catch (Exception e) {
145 logger.warning("restart", "Failed to restart: " + e);
146 logger.debug("restart",e);
147
148 synchronized(lock) {
149 if (state == TERMINATED) {
150 throw new IOException("The client has been closed.");
151 }
152
153 state = FAILED;
154
155 lock.notifyAll();
156 }
157
158 try {
159 doStop();
160 } catch (Exception eee) {
161 // OK.
162 // We know there is a problem.
163 }
164
165 terminate();
166
167 throw ioe;
168 }
169 }
170
171 // --------------------------------------------------------------
172 // private varaibles
173 // --------------------------------------------------------------
174 private class Checker implements Runnable {
175 public void run() {
176 myThread = Thread.currentThread();
177
178 while (state != TERMINATED && !myThread.isInterrupted()) {
179 try {
180 Thread.sleep(period);
181 } catch (InterruptedException ire) {
182 // OK.
183 // We will check the state at the following steps
184 }
185
186 if (state == TERMINATED || myThread.isInterrupted()) {
187 break;
188 }
189
190 try {
191 checkConnection();
192 } catch (Exception e) {
193 synchronized(lock) {
194 if (state == TERMINATED || myThread.isInterrupted()) {
195 break;
196 }
197 }
198
199 e = (Exception)EnvHelp.getCause(e);
200
201 if (e instanceof IOException &&
202 !(e instanceof InterruptedIOException)) {
203 try {
204 gotIOException((IOException)e);
205 } catch (Exception ee) {
206 logger.warning("Checker-run",
207 "Failed to check connection: "+ e);
208 logger.warning("Checker-run", "stopping");
209 logger.debug("Checker-run",e);
210
211 break;
212 }
213 } else {
214 logger.warning("Checker-run",
215 "Failed to check the connection: " + e);
216 logger.debug("Checker-run",e);
217
218 // XXX stop checking?
219
220 break;
221 }
222 }
223 }
224
225 if (logger.traceOn()) {
226 logger.trace("Checker-run", "Finished.");
227 }
228 }
229
230 private void stop() {
231 if (myThread != null && myThread != Thread.currentThread()) {
232 myThread.interrupt();
233 }
234 }
235
236 private Thread myThread;
237 }
238
239 // --------------------------------------------------------------
240 // private variables
241 // --------------------------------------------------------------
242 private final Checker checker;
243 private long period;
244
245 // state
246 private final static int CONNECTED = 0;
247 private final static int RE_CONNECTING = 1;
248 private final static int FAILED = 2;
249 private final static int TERMINATED = 3;
250
251 private int state = CONNECTED;
252
253 private final int[] lock = new int[0];
254
255 private static final ClassLogger logger =
256 new ClassLogger("javax.management.remote.misc",
257 "ClientCommunicatorAdmin");
258 }