org.apache.batik.util
Class RunnableQueue

java.lang.Object
  |
  +--org.apache.batik.util.RunnableQueue

All Implemented Interfaces:

java.lang.Runnable

public class RunnableQueue

extends java.lang.Object

implements java.lang.Runnable

This class represents an object which queues Runnable objects for invocation in a single thread.

Inner Class Summary

protected static class	RunnableQueue.Link To store a Runnable.
protected static class	RunnableQueue.LockableLink To store a Runnable with an object waiting for him to be executed.
static interface	RunnableQueue.RunHandler This interface must be implemented by an object which wants to be notified of run events.
static class	RunnableQueue.RunnableQueueState Type-safe enumeration of queue states.

Field Summary

protected DoublyLinkedList	list The Runnable objects list, also used as synchoronization point for pushing/poping runables.
protected RunnableQueue.RunHandler	runHandler The object which handle run events.
protected java.lang.Thread	runnableQueueThread The current thread.
static RunnableQueue.RunnableQueueState	RUNNING The queue is in the processes of running tasks.
protected RunnableQueue.RunnableQueueState	state The Suspension state of this thread.
protected java.lang.Object	stateLock Object to synchronize/wait/notify for suspension issues.
static RunnableQueue.RunnableQueueState	SUSPENDED The queue is no longer running any tasks and will not run any tasks until resumeExecution is called.
static RunnableQueue.RunnableQueueState	SUSPENDING The queue may still be running tasks but as soon as possible will go to SUSPENDED state.

Constructor Summary

RunnableQueue()

Method Summary

static RunnableQueue	createRunnableQueue() Creates a new RunnableQueue started in a new thread.
protected void	executionResumed() Called when execution is being resumed.
protected void	executionSuspended() Called when execution is being suspended.
java.lang.Object	getIteratorLock() Returns iterator lock to use to work with the iterator returned by iterator().
RunnableQueue.RunnableQueueState	getQueueState()
RunnableQueue.RunHandler	getRunHandler() Returns the RunHandler or null.
java.lang.Thread	getThread() Returns the thread in which the RunnableQueue is currently running.
void	invokeAndWait(java.lang.Runnable r) Waits until the given Runnable's run() has returned.
void	invokeLater(java.lang.Runnable r) Schedules the given Runnable object for a later invocation, and returns.
java.util.Iterator	iterator() Returns an iterator over the runnables.
void	preemptAndWait(java.lang.Runnable r) Waits until the given Runnable's run() has returned.
void	preemptLater(java.lang.Runnable r) Schedules the given Runnable object for a later invocation, and returns.
void	resumeExecution() Resumes the execution of this queue.
void	run() Runs this queue.
protected void	runnableInvoked(java.lang.Runnable rable) Called when a Runnable completes.
void	setRunHandler(RunnableQueue.RunHandler rh) Sets the RunHandler for this queue.
void	suspendExecution(boolean waitTillSuspended) Suspends the execution of this queue after the current runnable completes.

Methods inherited from class java.lang.Object

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

Field Detail

RUNNING

public static final RunnableQueue.RunnableQueueState RUNNING

The queue is in the processes of running tasks.

SUSPENDING

public static final RunnableQueue.RunnableQueueState SUSPENDING

The queue may still be running tasks but as soon as possible will go to SUSPENDED state.

SUSPENDED

public static final RunnableQueue.RunnableQueueState SUSPENDED

The queue is no longer running any tasks and will not run any tasks until resumeExecution is called.

state

protected RunnableQueue.RunnableQueueState state

The Suspension state of this thread.

stateLock

protected java.lang.Object stateLock

Object to synchronize/wait/notify for suspension issues.

list

protected DoublyLinkedList list

The Runnable objects list, also used as synchoronization point for pushing/poping runables.

runHandler

protected RunnableQueue.RunHandler runHandler

The object which handle run events.

runnableQueueThread

protected java.lang.Thread runnableQueueThread

The current thread.

Constructor Detail

RunnableQueue

public RunnableQueue()

Method Detail

createRunnableQueue

public static RunnableQueue createRunnableQueue()

Creates a new RunnableQueue started in a new thread.

Returns:

a RunnableQueue which is garanteed to have entered its run() method.

run

public void run()

Runs this queue.

Specified by:

run in interface java.lang.Runnable

getThread

public java.lang.Thread getThread()

Returns the thread in which the RunnableQueue is currently running.

Returns:

null if the RunnableQueue has not entered his run() method.

invokeLater

public void invokeLater(java.lang.Runnable r)

Schedules the given Runnable object for a later invocation, and returns. An exception is thrown if the RunnableQueue was not started.

Throws:

java.lang.IllegalStateException - if getThread() is null.

invokeAndWait

public void invokeAndWait(java.lang.Runnable r)
                   throws java.lang.InterruptedException

Waits until the given Runnable's run() has returned. Note: invokeAndWait() must not be called from the current thread (for example from the run() method of the argument).

Throws:

java.lang.IllegalStateException - if getThread() is null or if the thread returned by getThread() is the current one.

preemptLater

public void preemptLater(java.lang.Runnable r)

Schedules the given Runnable object for a later invocation, and returns. The given runnable preempts any runnable that is not currently executing (ie the next runnable started will be the one given). An exception is thrown if the RunnableQueue was not started.

Throws:

java.lang.IllegalStateException - if getThread() is null.

preemptAndWait

public void preemptAndWait(java.lang.Runnable r)
                    throws java.lang.InterruptedException

Waits until the given Runnable's run() has returned. The given runnable preempts any runnable that is not currently executing (ie the next runnable started will be the one given). Note: preemptAndWait() must not be called from the current thread (for example from the run() method of the argument).

Throws:

java.lang.IllegalStateException - if getThread() is null or if the thread returned by getThread() is the current one.

getQueueState

public RunnableQueue.RunnableQueueState getQueueState()

suspendExecution

public void suspendExecution(boolean waitTillSuspended)

Suspends the execution of this queue after the current runnable completes.

Parameters:

waitTillSuspended - if true this method will not return until the queue has suspended (no runnable in progress or about to be in progress). If resumeExecution is called while waiting will simply return (this really indicates a race condition in your code). This may return before an associated RunHandler is notified.

Throws:

java.lang.IllegalStateException - if getThread() is null.

resumeExecution

public void resumeExecution()

Resumes the execution of this queue.

Throws:

java.lang.IllegalStateException - if getThread() is null.

getIteratorLock

public java.lang.Object getIteratorLock()

Returns iterator lock to use to work with the iterator returned by iterator().

iterator

public java.util.Iterator iterator()

Returns an iterator over the runnables.

setRunHandler

public void setRunHandler(RunnableQueue.RunHandler rh)

Sets the RunHandler for this queue.

getRunHandler

public RunnableQueue.RunHandler getRunHandler()

Returns the RunHandler or null.

executionSuspended

protected void executionSuspended()

Called when execution is being suspended. Currently just notifies runHandler

executionResumed

protected void executionResumed()

Called when execution is being resumed. Currently just notifies runHandler

runnableInvoked

protected void runnableInvoked(java.lang.Runnable rable)

Called when a Runnable completes. Currently just notifies runHandler

Parameters:

rable - The runnable that just completed.