Source Code Cross Referenced for ControllerWatcher.java in  » Database-JDBC-Connection-Pool » sequoia-2.10.9 » org » continuent » sequoia » driver » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Database JDBC Connection Pool » sequoia 2.10.9 » org.continuent.sequoia.driver 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /**
002:         * Sequoia: Database clustering technology.
003:         * Copyright (C) 2006 Continuent, Inc.
004:         * Contact: sequoia@continuent.org
005:         * 
006:         * Licensed under the Apache License, Version 2.0 (the "License");
007:         * you may not use this file except in compliance with the License.
008:         * You may obtain a copy of the License at
009:         * 
010:         * http://www.apache.org/licenses/LICENSE-2.0
011:         * 
012:         * Unless required by applicable law or agreed to in writing, software
013:         * distributed under the License is distributed on an "AS IS" BASIS,
014:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015:         * See the License for the specific language governing permissions and
016:         * limitations under the License. 
017:         *
018:         * Initial developer(s): Gilles Rayrat.
019:         * Contributor(s): Marc Herbert
020:         */package org.continuent.sequoia.driver;
021:
022:        import java.io.IOException;
023:        import java.net.InetSocketAddress;
024:        import java.nio.ByteBuffer;
025:        import java.nio.channels.DatagramChannel;
026:        import java.nio.channels.SelectionKey;
027:        import java.nio.channels.Selector;
028:        import java.util.Date;
029:        import java.util.Iterator;
030:
031:        import org.continuent.sequoia.common.util.Constants;
032:
033:        /**
034:         * Main class for controller ping monitoring.<br>
035:         * Launches a controller pinger thread and creates a list of controllers with
036:         * their states. Reads controllers responses (pongs) and updates state
037:         * accordingly
038:         * 
039:         * @author <a href="mailto:gilles.rayrat@continuent.com">Gilles Rayrat</a>
040:         * @author <a href="mailto:marc.herbert@continuent.com">Marc Herbert</a>
041:         * @version 1.0
042:         */
043:        public class ControllerWatcher extends Thread {
044:            /** List of controllers to send pings to */
045:            final WatchedControllers controllers;
046:            /** Thread that sends pings */
047:            final ControllerPingSender pinger;
048:            /** Selector for incomming pings */
049:            final Selector selector;
050:            /** Level of logging (logs are printed to stdout, see {@link SequoiaUrl}) */
051:            final int logLevel;
052:            /**
053:             * Time to wait between 2 successive pings to a controller, also used for
054:             * select timeout
055:             */
056:            final int pingDelayInMs;
057:            /**
058:             * Delay after which a controller will be considered as failing if it did not
059:             * respond to pings. Used here as a timeout for select()
060:             */
061:            final int controllerTimeout;
062:
063:            private boolean terminated = false;
064:
065:            /**
066:             * Creates a controller watcher with the given controllers to watch.<br>
067:             * Pings will be sent to all given controllers
068:             * 
069:             * @param controllerList controllers to ping
070:             * @param callback Callback implementation to call when a controller state
071:             *          changes
072:             * @param pingDelayInMs time to wait between two successive pings
073:             * @param controllerTimeout delay after which a controller will be considered
074:             *          as failing if it did not respond to pings
075:             * @param logLevel level of logging to use (logs are printed to stdout)
076:             * @exception IOException if the socket selector could not be opened
077:             */
078:            public ControllerWatcher(ControllerInfo[] controllerList,
079:                    ControllerStateChangedCallback callback, int pingDelayInMs,
080:                    int controllerTimeout, int logLevel) throws IOException {
081:                this (new WatchedControllers(controllerList, System
082:                        .currentTimeMillis(), controllerTimeout, callback),
083:                        pingDelayInMs, controllerTimeout, logLevel);
084:            }
085:
086:            private ControllerWatcher(WatchedControllers watchedControllers,
087:                    int pingDelayInMs, int controllerTimeout, int logLevel)
088:                    throws IOException
089:
090:            {
091:                super ("ControllerWatcher");
092:
093:                this .controllers = watchedControllers;
094:                this .pingDelayInMs = pingDelayInMs;
095:                this .controllerTimeout = controllerTimeout;
096:                this .logLevel = logLevel;
097:                this .selector = Selector.open();
098:
099:                this .pinger = new ControllerPingSender(this , this .controllers,
100:                        newRegisteredChannel(), pingDelayInMs, logLevel);
101:                this .pinger.setDaemon(true);
102:
103:            }
104:
105:            /**
106:             * @return a new DatagramChannel configured and registered at this.selector
107:             */
108:            private DatagramChannel newRegisteredChannel() throws IOException {
109:                // Register channel
110:                // Open the channel, set it to non-blocking, initiate connect
111:                DatagramChannel channel = DatagramChannel.open();
112:                channel.configureBlocking(false);
113:                channel.register(this .selector, SelectionKey.OP_READ);
114:                return channel;
115:
116:            }
117:
118:            private void processAnswers() throws IOException {
119:                long timeAnswerWasReceived = System.currentTimeMillis();
120:                for (Iterator i = selector.selectedKeys().iterator(); i
121:                        .hasNext();) {
122:                    // Retrieve the next key and remove it from the set
123:                    SelectionKey sk = (SelectionKey) i.next();
124:                    i.remove();
125:                    DatagramChannel channel = (DatagramChannel) sk.channel();
126:                    ByteBuffer buf = ByteBuffer.allocate(1);
127:
128:                    InetSocketAddress addr = (InetSocketAddress) channel
129:                            .receive(buf);
130:                    if (addr != null) {
131:                        // creates the controller info from the received SocketAddress
132:                        ControllerInfo from = new ControllerInfo(addr);
133:                        byte data[] = buf.array();
134:                        if (data[0] == Constants.CONTROLLER_PING_VERSION) {
135:                            controllers.setControllerResponsed(from,
136:                                    timeAnswerWasReceived);
137:                        } else if (logLevel >= SequoiaUrl.DEBUG_LEVEL_DEBUG) {
138:                            System.out
139:                                    .println(new Date()
140:                                            + " "
141:                                            + this 
142:                                            + ": controller "
143:                                            + from
144:                                            + " ping protocol does not match ours, was: "
145:                                            + data[0] + ", expected:"
146:                                            + Constants.CONTROLLER_PING_VERSION);
147:                        }
148:                    }
149:                }
150:            }
151:
152:            /**
153:             * Starts watching controllers.<br>
154:             * Reads ping responses from controllers and updates corresponding controller
155:             * data in the <code>ControllerList</code>.
156:             * 
157:             * @see java.lang.Thread#run()
158:             */
159:            public void run() {
160:                if (logLevel >= SequoiaUrl.DEBUG_LEVEL_DEBUG)
161:                    System.out.println(new Date() + " " + this  + " started.");
162:
163:                // Start ping
164:                pinger.start();
165:                while (!terminated) {
166:                    try {
167:                        int nbOfAnswers = selector.select(2 * pingDelayInMs);
168:                        if (nbOfAnswers > 0)
169:                            processAnswers();
170:                        // This will start callbacks according to new states
171:                        controllers.lookForDeadControllers(System
172:                                .currentTimeMillis());
173:                    } catch (IOException ioe) {
174:                        System.err
175:                                .println(new Date()
176:                                        + " "
177:                                        + this 
178:                                        + ": Error while reading controller answers to ping");
179:                        ioe.printStackTrace(System.err);
180:
181:                        restartBothDaemons();
182:                    } // try
183:                } // while (!terminated)
184:
185:                if (logLevel >= SequoiaUrl.DEBUG_LEVEL_DEBUG)
186:                    System.out.println(new Date() + " " + this  + " terminated");
187:
188:            }
189:
190:            /**
191:             * Forces a given controller to be considered as not responding
192:             * 
193:             * @see WatchedControllers#setControllerDown(ControllerInfo)
194:             */
195:            public void forceControllerDown(ControllerInfo c) {
196:                controllers.setControllerDown(c);
197:            }
198:
199:            /**
200:             * Returns the given controllers index in the original list
201:             * 
202:             * @param controller the controller to get index of
203:             * @return original index of the given controller
204:             */
205:            public int getOriginalIndexOf(ControllerInfo controller) {
206:                return controllers.getOriginalIndexOf(controller);
207:            }
208:
209:            /**
210:             * Terminates both pinger and watcher thread TODO: terminateBoth definition.
211:             */
212:            public void terminateBoth() {
213:                pinger.terminate();
214:                terminated = true;
215:                try {
216:                    // workaround for SEQUOIA-942 (Selector.open() leaks file descriptors)
217:                    selector.close();
218:                } catch (IOException e) {
219:                    e.printStackTrace(System.err); // ignore
220:                }
221:            }
222:
223:            void restartBothDaemons() {
224:                synchronized (this ) {
225:                    // don't restart multiple times
226:                    if (terminated)
227:                        return;
228:
229:                    // tell old threads (including Thread.this!) to die ASAP
230:                    this .terminateBoth();
231:                }
232:
233:                boolean failed = true;
234:
235:                // just for logging
236:                ControllerWatcher newWatcher = null; // compiler is not clever enough
237:
238:                while (failed) {
239:                    try
240:                    // to start over with 2 brand new threads (and thus a brand new,
241:                    // non-interrupted, non-closed channel)
242:                    {
243:                        Thread.sleep(pingDelayInMs);
244:                        newWatcher = new ControllerWatcher(controllers,
245:                                pingDelayInMs, controllerTimeout, logLevel);
246:                        newWatcher.start();
247:                        failed = false; // success, exit try loop
248:                    } catch (InterruptedException ie) {
249:                        // loop over
250:                        ie.printStackTrace(System.err);
251:                    } catch (IOException e) {
252:                        // loop over
253:                        e.printStackTrace(System.err);
254:                    }
255:                }
256:
257:                System.err.println(new Date() + " " + this 
258:                        + " successfully restarted both daemons.");
259:                System.err.println("New watcher = " + newWatcher);
260:
261:            }
262:
263:            public String toString() {
264:                // Add our address, useful as an ID. Stolen from Object.toString()
265:                return super .toString() + "@" + Integer.toHexString(hashCode())
266:                        + " " + " " + controllers;
267:            }
268:
269:        }
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