|
|||||||||||||||||||
| 30 day Evaluation Version distributed via the Maven Jar Repository. Clover is not free. You have 30 days to evaluate it. Please visit http://www.thecortex.net/clover to obtain a licensed version of Clover | |||||||||||||||||||
| Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
| Task.java | 0% | 0% | 0% | 0% |
|
||||||||||||||
| 1 |
/**
|
|
| 2 |
* @(#)Task.java
|
|
| 3 |
*
|
|
| 4 |
* JFoxSOAF, Service-Oriented Application Framework
|
|
| 5 |
*
|
|
| 6 |
* Copyright(c) JFoxSOAF Team
|
|
| 7 |
*
|
|
| 8 |
* Licensed under the GNU LGPL, Version 2.1 (the "License");
|
|
| 9 |
* you may not use this file except in compliance with the License.
|
|
| 10 |
* You may obtain a copy of the License at
|
|
| 11 |
*
|
|
| 12 |
* http://www.gnu.org/copyleft/lesser.html
|
|
| 13 |
*
|
|
| 14 |
* Unless required by applicable law or agreed to in writing, software
|
|
| 15 |
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
| 16 |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
| 17 |
* See the License for the specific language governing permissions and
|
|
| 18 |
* limitations under the License.
|
|
| 19 |
*
|
|
| 20 |
* For more information, please visit:
|
|
| 21 |
* http://www.jfox.cn/confluence/display/JFoxSOAF/Home
|
|
| 22 |
* http://www.huihoo.org/jfox/jfoxsoaf
|
|
| 23 |
*/
|
|
| 24 |
|
|
| 25 |
package org.huihoo.jfox.soaf.services.timer;
|
|
| 26 |
|
|
| 27 |
import java.io.Externalizable;
|
|
| 28 |
import java.io.ObjectOutput;
|
|
| 29 |
import java.io.ObjectInput;
|
|
| 30 |
import java.io.IOException;
|
|
| 31 |
|
|
| 32 |
/**
|
|
| 33 |
* <p>
|
|
| 34 |
* A task which can be scheduled to run at specified times by the TaskScheduler
|
|
| 35 |
* <br>
|
|
| 36 |
* </p>
|
|
| 37 |
* <p>
|
|
| 38 |
* The user should extend this class and override the required methods (e.g.
|
|
| 39 |
* run() method).
|
|
| 40 |
* </p>
|
|
| 41 |
*
|
|
| 42 |
* @author <a href="mailto:founder_chen@yahoo.com.cn">Peter Cheng </a>
|
|
| 43 |
* @author <a href="mailto:berkovichnyc@hotmail.com">Efraim Berkovich </a>
|
|
| 44 |
* @version $Revision: 1.1 $ $Date: 2005/05/22 06:52:07 $
|
|
| 45 |
* @version Revision: 1.0
|
|
| 46 |
*/
|
|
| 47 |
|
|
| 48 |
public abstract class Task implements Runnable, Externalizable { |
|
| 49 |
|
|
| 50 |
// instance variables
|
|
| 51 |
/** has the cancel() method been called? */
|
|
| 52 |
protected boolean isCancelled = false; |
|
| 53 |
|
|
| 54 |
/** The name of the task (for display purposes) */
|
|
| 55 |
protected String name = null; |
|
| 56 |
|
|
| 57 |
private transient long ID; |
|
| 58 |
|
|
| 59 |
private boolean hasBeenScheduled = false; |
|
| 60 |
|
|
| 61 |
private long scheduledInitialTime = 0; |
|
| 62 |
|
|
| 63 |
private long scheduledInterval = 0; // if <=0 -- means one-time execution |
|
| 64 |
|
|
| 65 |
private long lastRunTime = 0; |
|
| 66 |
|
|
| 67 |
// package view -- the task scheduler sets this when the task is scheduled
|
|
| 68 |
// with it
|
|
| 69 |
SimpleTimerServiceImpl scheduler = null;
|
|
| 70 |
|
|
| 71 |
// static variables
|
|
| 72 |
private static Boolean mutex = new Boolean(true); |
|
| 73 |
|
|
| 74 |
private static long nextID = 0; |
|
| 75 |
|
|
| 76 |
/**
|
|
| 77 |
* Creates a new task and assigns it a unique ID.
|
|
| 78 |
*/
|
|
| 79 | 0 |
protected Task() {
|
| 80 | 0 |
synchronized (mutex) {
|
| 81 | 0 |
this.ID = nextID;
|
| 82 | 0 |
nextID++; |
| 83 | 0 |
if (nextID == Long.MAX_VALUE)
|
| 84 | 0 |
nextID = 0; |
| 85 |
} |
|
| 86 |
|
|
| 87 |
} |
|
| 88 |
|
|
| 89 |
/**
|
|
| 90 |
* Schedules the specified task for execution at the specified time. If the
|
|
| 91 |
* time is in the past, the task is scheduled for immediate execution.
|
|
| 92 |
* <p>
|
|
| 93 |
* There are two types of scheduling: one time and periodic.
|
|
| 94 |
* <p>
|
|
| 95 |
* <b>One time </b> <br>
|
|
| 96 |
* The task will execute exactly once.
|
|
| 97 |
* <p>
|
|
| 98 |
* <b>Periodic </b> <br>
|
|
| 99 |
* The task is scheduled for repeated periodic execution, beginning at the
|
|
| 100 |
* specified time. Once a task starts running, the next occurrence of the
|
|
| 101 |
* task will start running <i>interval </i> time later. It is possible for
|
|
| 102 |
* one event-firing of the task (if it runs too long) will overlap another
|
|
| 103 |
* event-firing of that same task. If this is not desired, then the task
|
|
| 104 |
* should synchronize within its run() method.
|
|
| 105 |
* <p>
|
|
| 106 |
* This method can only be called once. Calling it more than once will cause
|
|
| 107 |
* an exception.
|
|
| 108 |
* <p>
|
|
| 109 |
*
|
|
| 110 |
* @param firstTime long system time at which to run the task.
|
|
| 111 |
* @param interval long number of millis between executions of the task,
|
|
| 112 |
* passing <=0 will cause the task to be executed once.
|
|
| 113 |
* @exception IllegalStateException On calling this method more than once.
|
|
| 114 |
*/
|
|
| 115 | 0 |
public synchronized final void setSchedule(long firstTime, long interval) |
| 116 |
throws IllegalStateException {
|
|
| 117 | 0 |
if (hasBeenScheduled)
|
| 118 | 0 |
throw new IllegalStateException( |
| 119 |
"Cannot set schedule for the task more than once.");
|
|
| 120 |
|
|
| 121 | 0 |
hasBeenScheduled = true;
|
| 122 | 0 |
this.scheduledInitialTime = firstTime;
|
| 123 | 0 |
this.scheduledInterval = interval;
|
| 124 |
} |
|
| 125 |
|
|
| 126 |
/**
|
|
| 127 |
* Get the task ID.
|
|
| 128 |
*
|
|
| 129 |
* @return unique Task ID.
|
|
| 130 |
*/
|
|
| 131 | 0 |
public long getID() { |
| 132 | 0 |
return ID;
|
| 133 |
} |
|
| 134 |
|
|
| 135 |
/**
|
|
| 136 |
* Get the first scheduled time for the task.
|
|
| 137 |
*
|
|
| 138 |
* @return the time the task was first scheduled to run (as long, millis)
|
|
| 139 |
*/
|
|
| 140 | 0 |
public long getScheduledFirstTime() { |
| 141 | 0 |
return scheduledInitialTime;
|
| 142 |
} |
|
| 143 |
|
|
| 144 |
/**
|
|
| 145 |
* Get the interval scheduled for the task.
|
|
| 146 |
*
|
|
| 147 |
* @return the interval scheduled for the task. (as long, millis)
|
|
| 148 |
*/
|
|
| 149 | 0 |
public long getScheduledInterval() { |
| 150 | 0 |
return scheduledInterval;
|
| 151 |
} |
|
| 152 |
|
|
| 153 |
/**
|
|
| 154 |
* Was the cancel method called for this task?
|
|
| 155 |
*
|
|
| 156 |
* @return true if cancel was called, false if not
|
|
| 157 |
*/
|
|
| 158 | 0 |
public boolean isCancelled() { |
| 159 | 0 |
return isCancelled;
|
| 160 |
} |
|
| 161 |
|
|
| 162 |
/**
|
|
| 163 |
* Get the name for the task
|
|
| 164 |
*
|
|
| 165 |
* @return the task name
|
|
| 166 |
*/
|
|
| 167 | 0 |
public String getName() {
|
| 168 | 0 |
if (name == null) |
| 169 | 0 |
return this.getClass().toString(); |
| 170 |
|
|
| 171 | 0 |
return name;
|
| 172 |
} |
|
| 173 |
|
|
| 174 |
/**
|
|
| 175 |
* Calling this method notifies the TaskScheduler (if the task has been
|
|
| 176 |
* scheduled) and forces it to persist this task's data.
|
|
| 177 |
* <p>
|
|
| 178 |
*
|
|
| 179 |
* @exception various possible depending on persist strategy of the
|
|
| 180 |
* scheduler
|
|
| 181 |
*/
|
|
| 182 | 0 |
public void persist() throws Exception { |
| 183 | 0 |
if (scheduler != null) |
| 184 | 0 |
scheduler.persist(this);
|
| 185 |
} |
|
| 186 |
|
|
| 187 |
/**
|
|
| 188 |
* Cancels this timer task. If the task has been scheduled for one-time
|
|
| 189 |
* execution and has not yet run, or has not yet been scheduled, it will
|
|
| 190 |
* never run. If the task has been scheduled for repeated execution, it will
|
|
| 191 |
* never run again. (If the task is running when this call occurs, the task
|
|
| 192 |
* will run to completion, but will never run again.)
|
|
| 193 |
* <p>
|
|
| 194 |
* Note that calling this method from within the run method of a repeating
|
|
| 195 |
* timer task absolutely guarantees that the timer task will not run again.
|
|
| 196 |
* <p>
|
|
| 197 |
* This method may be called repeatedly; the second and subsequent calls
|
|
| 198 |
* have no effect.
|
|
| 199 |
*/
|
|
| 200 | 0 |
public void cancel() { |
| 201 | 0 |
isCancelled = true;
|
| 202 | 0 |
if (scheduler != null) { |
| 203 | 0 |
scheduler.cleanup(this);
|
| 204 |
} |
|
| 205 |
} |
|
| 206 |
|
|
| 207 |
/**
|
|
| 208 |
* Returns the scheduled execution time of the most recent actual execution
|
|
| 209 |
* of this task. (If this method is invoked while task execution is in
|
|
| 210 |
* progress, the return value is the scheduled execution time of the ongoing
|
|
| 211 |
* task execution.)
|
|
| 212 |
* <p>
|
|
| 213 |
* This method is typically invoked from within a task's run method, to
|
|
| 214 |
* determine whether the current execution of the task is sufficiently
|
|
| 215 |
* timely to warrant performing the scheduled activity:
|
|
| 216 |
* <p>
|
|
| 217 |
*
|
|
| 218 |
* <pre>
|
|
| 219 |
* public void run() {
|
|
| 220 |
* if (System.currentTimeMillis() - lastExecutionTime() >= MAX_TARDINESS)
|
|
| 221 |
* return; // Too late; skip this execution.
|
|
| 222 |
* // Perform the task
|
|
| 223 |
* }
|
|
| 224 |
* </pre>
|
|
| 225 |
*
|
|
| 226 |
* <p>
|
|
| 227 |
*
|
|
| 228 |
* @return the time at which the most recent execution of this task was
|
|
| 229 |
* scheduled to occur, in the format returned by Date.getTime(). The
|
|
| 230 |
* return value is undefined if the task has yet to commence its
|
|
| 231 |
* first execution.
|
|
| 232 |
*/
|
|
| 233 | 0 |
public long lastExecutionTime() { |
| 234 | 0 |
return lastRunTime;
|
| 235 |
} |
|
| 236 |
|
|
| 237 |
/**
|
|
| 238 |
* Set the last run time. This is only called by the TaskScheduler
|
|
| 239 |
*
|
|
| 240 |
* @param lastRunTime. The last run time
|
|
| 241 |
*/
|
|
| 242 | 0 |
void setLastRunTime(long lastRunTime) { |
| 243 | 0 |
this.lastRunTime = lastRunTime;
|
| 244 |
} |
|
| 245 |
|
|
| 246 |
/**
|
|
| 247 |
* This method persists the task. Tasks should override this method if they
|
|
| 248 |
* carry instance data. (Make sure to call super.writeExternal() if you
|
|
| 249 |
* override).
|
|
| 250 |
*
|
|
| 251 |
* @param ObjectOutput The stream to write the object to
|
|
| 252 |
* @exception IOException On write problems
|
|
| 253 |
*/
|
|
| 254 | 0 |
public void writeExternal(ObjectOutput out) throws IOException { |
| 255 | 0 |
out.writeLong(this.scheduledInitialTime);
|
| 256 | 0 |
out.writeLong(this.scheduledInterval);
|
| 257 | 0 |
out.writeLong(this.lastRunTime);
|
| 258 | 0 |
out.writeObject(this.name);
|
| 259 |
} |
|
| 260 |
|
|
| 261 |
/**
|
|
| 262 |
* This method instantiates the task from persistent storage. Tasks should
|
|
| 263 |
* override this method if they carry instance data. (Make sure to call
|
|
| 264 |
* super.writeExternal() if you override).
|
|
| 265 |
* <p>
|
|
| 266 |
* When a Task is instantiated from deserialization, the
|
|
| 267 |
* scheduledInitialTime is set according to the following rules:
|
|
| 268 |
* <ul>
|
|
| 269 |
* <li>If the scheduledInitialTime is in the future, that time is kept.
|
|
| 270 |
* <li>If the scheduledInitialTime is in the past and the Task is a
|
|
| 271 |
* repeating task, then the scheduledInitialTime is set to the next time the
|
|
| 272 |
* task would run had the Task not been serialized. For example, if a Task
|
|
| 273 |
* runs once a day at 1pm, then the scheduledInitialTime will be set to the
|
|
| 274 |
* next 1pm running time. (The logic does not distinguish between fixed-rate
|
|
| 275 |
* vs. fixed-delay Tasks).
|
|
| 276 |
* </ul>
|
|
| 277 |
*
|
|
| 278 |
* @param ObjectInput The stream to write the object to
|
|
| 279 |
* @exception IOException On write problems
|
|
| 280 |
* @exception ClassNotFoundException On the class not being in the stream.
|
|
| 281 |
*/
|
|
| 282 | 0 |
public void readExternal(ObjectInput in) throws IOException, |
| 283 |
java.lang.ClassNotFoundException {
|
|
| 284 | 0 |
this.scheduledInitialTime = in.readLong();
|
| 285 | 0 |
this.scheduledInterval = in.readLong();
|
| 286 | 0 |
this.lastRunTime = in.readLong();
|
| 287 | 0 |
this.name = (String) in.readObject();
|
| 288 |
|
|
| 289 |
// set scheduledInitialTime to make it in the future
|
|
| 290 | 0 |
if (scheduledInitialTime < System.currentTimeMillis()) {
|
| 291 | 0 |
long n = System.currentTimeMillis() - scheduledInitialTime;
|
| 292 | 0 |
n = n % scheduledInterval; |
| 293 | 0 |
this.scheduledInitialTime = System.currentTimeMillis() + n;
|
| 294 |
} |
|
| 295 |
|
|
| 296 |
// assume all deserialized tasks had setSchedule() called
|
|
| 297 | 0 |
hasBeenScheduled = true;
|
| 298 |
} |
|
| 299 |
|
|
| 300 |
/**
|
|
| 301 |
* This method is the action to be performed. This method should be
|
|
| 302 |
* overriden. It will be called once at every time the task runs.
|
|
| 303 |
* <p>
|
|
| 304 |
* If a task encounters an error during run, it may call the cancel() method
|
|
| 305 |
* to prevent the task from running again.
|
|
| 306 |
* <p>
|
|
| 307 |
* If the task modifies its instance data during execution, then it should
|
|
| 308 |
* call the Task persist() method. This will notify the TaskScheduler to
|
|
| 309 |
* write the task to persistent storage by calling the writeExternal()
|
|
| 310 |
* method.
|
|
| 311 |
*/
|
|
| 312 |
public abstract void run(); |
|
| 313 |
|
|
| 314 |
/**
|
|
| 315 |
* This method should provide a status message regarding the task. Care
|
|
| 316 |
* should be taken to make sure the method is thread-safe, as code in the
|
|
| 317 |
* run() method and the caller of getStatus() will likely be in different
|
|
| 318 |
* threads.
|
|
| 319 |
*
|
|
| 320 |
* @return a task-specific status message
|
|
| 321 |
*/
|
|
| 322 |
public abstract String getStatus();
|
|
| 323 |
|
|
| 324 |
} |
|
||||||||||