org.apache.wiki
Class WikiBackgroundThread

java.lang.Object
  java.lang.Thread
      org.apache.wiki.WikiBackgroundThread

All Implemented Interfaces:

Runnable, EventListener, WikiEventListener

Direct Known Subclasses:

RSSThread

public abstract class WikiBackgroundThread
extends Thread
implements WikiEventListener

Abstract Thread subclass that operates in the background; when it detects the WikiEngineEvent.SHUTDOWN event, it terminates itself. Subclasses of this method need only implement the method backgroundTask(), instead of the normal Thread.run(), and provide a constructor that passes the WikiEngine and sleep interval. This class is thread-safe.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

WikiBackgroundThread(WikiEngine engine, int sleepInterval)
Constructs a new instance of this background thread with a specified sleep interval, and adds the new instance to the wiki engine's event listeners.

Method Summary

void	actionPerformed(WikiEvent event) Listens for WikiEngineEvent.SHUTDOWN and, if detected, marks the thread for death.
abstract void	backgroundTask() Abstract method that performs the actual work for this background thread; subclasses must implement this method.
WikiEngine	getEngine() Returns the WikiEngine that created this background thread.
void	run() Runs the background thread's backgroundTask() method at the interval specified at construction.
void	shutdown() Requests the shutdown of this background thread.
void	shutdownTask() Executes a task after shutdown signal was detected.
void	startupTask() Executes a task just after the thread's Thread.run() method starts, but before the backgroundTask() task executes.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

WikiBackgroundThread

public WikiBackgroundThread(WikiEngine engine,
                            int sleepInterval)

Constructs a new instance of this background thread with a specified sleep interval, and adds the new instance to the wiki engine's event listeners.

Parameters:

engine - the wiki engine

sleepInterval - the interval between invocations of the thread's Thread.run() method, in seconds

Method Detail

actionPerformed

public final void actionPerformed(WikiEvent event)

Listens for WikiEngineEvent.SHUTDOWN and, if detected, marks the thread for death.

Specified by:

actionPerformed in interface WikiEventListener

Parameters:

event - a WikiEvent object

See Also:

WikiEventListener.actionPerformed(org.apache.wiki.event.WikiEvent)

backgroundTask

public abstract void backgroundTask()
                             throws Exception

Abstract method that performs the actual work for this background thread; subclasses must implement this method.

Throws:

Exception - Any exception can be thrown

getEngine

public WikiEngine getEngine()

Returns the WikiEngine that created this background thread.

Returns:

the wiki engine

shutdown

public void shutdown()

Requests the shutdown of this background thread. Note that the shutdown is not immediate.

Since:

2.4.92

run

public final void run()

Runs the background thread's backgroundTask() method at the interval specified at construction. The thread will initially pause for a full sleep interval before starting, after which it will execute startupTask(). This method will cleanly terminate the thread if it has previously been marked as dead, before which it will execute shutdownTask(). If any of the three methods return an exception, it will be re-thrown as a InternalWikiException.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

See Also:

Thread.run()

shutdownTask

public void shutdownTask()
                  throws Exception

Executes a task after shutdown signal was detected. By default, this method does nothing; override it to implement custom functionality.

Throws:

Exception - Any exception can be thrown.

startupTask

public void startupTask()
                 throws Exception

Executes a task just after the thread's Thread.run() method starts, but before the backgroundTask() task executes. By default, this method does nothing; override it to implement custom functionality.

Throws:

Exception - Any exception can be thrown.