com.sun.identity.common

Class HeadTaskRunnable

java.lang.Object

com.sun.identity.common.HeadTaskRunnable

All Implemented Interfaces:

TaskRunnable, Runnable

public class HeadTaskRunnable
extends Object
implements TaskRunnable

HeadTaskRunnable is designed to be the head of the linked-list when TaskRunnable needs to be linked together. Whenever there is an insertion or deletion, HeadTaskRunnable must be locked to guarantee correct synchronization. Besides, when last element of the linked-list is removed (setNext(null)), HeadTaskRunnable should use Triggerable to remove or destroy the linked-list.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	acquireCount
protected boolean	expired
protected TaskRunnable	nextTask
protected Thread	owner
protected Triggerable	parent
protected TaskRunnable	tailTask
protected Date	time
protected boolean	timeout
protected int	waitCount

Constructor Summary

Constructors

Constructor and Description
HeadTaskRunnable(Triggerable parent, TaskRunnable nextTask, Date time) Constructor of HeadTaskRunnable.

Method Summary

Modifier and Type	Method and Description
boolean	acquireValidLock() Tries to acquire a valid (non-expired) lock.
boolean	addElement(Object key) Implements for TaskRunnable interface, always return false.
void	cancel() Implements for TaskRunnable interface.
protected void	expire() Sets the status of the HeadTask to expired.
Thread	getCurrentOwner() Returns the thread which currently holding this lock.
HeadTaskRunnable	getHeadTask() Implements for TaskRunnable interface, no actual use for HeadTaskRunnable.
long	getRunPeriod() Implements for TaskRunnable interface, HeadTaskRunnable doesn't have a run period.
boolean	isEmpty() Implements for TaskRunnable interface, always return false.
boolean	isExpired() Returns a boolean to indicate whether the HeadTask is expired already.
boolean	isTimedOut() Returns a boolean to indicate whether the HeadTask is timeout already.
TaskRunnable	next() Returns the TaskRunnable next to this TaskRunnable in the linked-list.
TaskRunnable	previous() Implements for TaskRunnable interface, there is no previous element for HeadTaskRunnable.
void	releaseLockAndNotify() Releases the currently holding lock.
boolean	removeElement(Object key) Implements for TaskRunnable interface, always return false.
void	run() Implements for TaskRunnable interface, just run the next TaskRunnable.
long	scheduledExecutionTime() Returns the time which this HeadTaskRunnable is scheduled.
void	setHeadTask(HeadTaskRunnable headTask) Implements for TaskRunnable interface, no actual use for HeadTaskRunnable.
void	setNext(TaskRunnable task) Sets the TaskRunnable next to this TaskRunnable in the linked-list.
void	setPrevious(TaskRunnable task) Implements for TaskRunnable interface, There is no previous element for HeadTaskRunnable.
void	setTail(TaskRunnable task) Sets the task which is the tail of the list.
void	setTrigger(Triggerable parent) Sets the Triggerable interface which will be run when the linked-list is empty.
TaskRunnable	tail() Returns the Task which is at the tail of the list.
protected void	timeout() Sets the status of the HeadTask to timeout.

Methods inherited from class java.lang.Object

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

Field Detail

time

protected Date time

nextTask

protected volatile TaskRunnable nextTask

tailTask

protected volatile TaskRunnable tailTask

expired

protected volatile boolean expired

timeout

protected volatile boolean timeout

waitCount

protected int waitCount

acquireCount

protected int acquireCount

owner

protected volatile Thread owner

parent

protected Triggerable parent

Constructor Detail

HeadTaskRunnable

public HeadTaskRunnable(Triggerable parent,
                        TaskRunnable nextTask,
                        Date time)
                 throws IllegalArgumentException

Constructor of HeadTaskRunnable.

Parameters:

parent - The Triggerable interface to be run when the linked-list is empty

nextTask - The TaskRunnable next to this TaskRunnable

time - The time this TaskRunnable is scheduled

Throws:

IllegalArgumentException

Method Detail

expire

protected void expire()
               throws IllegalMonitorStateException

Sets the status of the HeadTask to expired.

Throws:

IllegalMonitorStateException

timeout

protected void timeout()
                throws IllegalMonitorStateException

Sets the status of the HeadTask to timeout.

Throws:

IllegalMonitorStateException

isTimedOut

public boolean isTimedOut()

Returns a boolean to indicate whether the HeadTask is timeout already.

Returns:

a boolen to indicate whether the HeadTask is timeout.

isExpired

public boolean isExpired()

Returns a boolean to indicate whether the HeadTask is expired already.

Returns:

a boolean to indicate whether the HeadTask is expired.

getCurrentOwner

public Thread getCurrentOwner()

Returns the thread which currently holding this lock.

Returns:

the thread which currently own the lock or null.

acquireValidLock

public boolean acquireValidLock()

Tries to acquire a valid (non-expired) lock.

Returns:

a boolean to indicate whether it is succeed to acquire the lock.

releaseLockAndNotify

public void releaseLockAndNotify()
                          throws IllegalMonitorStateException

Releases the currently holding lock.

Throws:

IllegalMonitorStateException

setHeadTask

public void setHeadTask(HeadTaskRunnable headTask)

Implements for TaskRunnable interface, no actual use for HeadTaskRunnable.

Specified by:

setHeadTask in interface TaskRunnable

Parameters:

headTask - The HeadTaskRunnable

getHeadTask

public HeadTaskRunnable getHeadTask()

Implements for TaskRunnable interface, no actual use for HeadTaskRunnable.

Specified by:

getHeadTask in interface TaskRunnable

Returns:

The head task of this linkable TaskRunnable

addElement

public boolean addElement(Object key)

Implements for TaskRunnable interface, always return false.

Specified by:

addElement in interface TaskRunnable

Parameters:

key - Element to be added to this TaskRunnable

Returns:

false means nothing can be added to this TaskRunnable

removeElement

public boolean removeElement(Object key)

Implements for TaskRunnable interface, always return false.

Specified by:

removeElement in interface TaskRunnable

Parameters:

key - Element to be removed from this TaskRunnable

Returns:

false means nothing can be removed from this TaskRunnable

isEmpty

public boolean isEmpty()

Implements for TaskRunnable interface, always return false.

Specified by:

isEmpty in interface TaskRunnable

Returns:

true means this TaskRunnable is always empty

setNext

public void setNext(TaskRunnable task)

Sets the TaskRunnable next to this TaskRunnable in the linked-list.

Specified by:

setNext in interface TaskRunnable

Parameters:

task - The next TaskRunnable

setPrevious

public void setPrevious(TaskRunnable task)

Implements for TaskRunnable interface, There is no previous element for HeadTaskRunnable.

Specified by:

setPrevious in interface TaskRunnable

Parameters:

task - The previous TaskRunnable

next

public TaskRunnable next()

Returns the TaskRunnable next to this TaskRunnable in the linked-list.

Specified by:

next in interface TaskRunnable

Returns:

next TaskRunnable object or null if it is not set

previous

public TaskRunnable previous()

Implements for TaskRunnable interface, there is no previous element for HeadTaskRunnable.

Specified by:

previous in interface TaskRunnable

Returns:

null means there is no previous element

getRunPeriod

public long getRunPeriod()

Implements for TaskRunnable interface, HeadTaskRunnable doesn't have a run period.

Specified by:

getRunPeriod in interface TaskRunnable

Returns:

-1 means the task only will be run once

cancel

public void cancel()

Implements for TaskRunnable interface.

Specified by:

cancel in interface TaskRunnable

setTrigger

public void setTrigger(Triggerable parent)

Sets the Triggerable interface which will be run when the linked-list is empty.

Parameters:

parent - The Triggerable interface to be run when the linked-list is empty

setTail

public void setTail(TaskRunnable task)

Sets the task which is the tail of the list. It is for internal use only.

Parameters:

task - The task which is at the tail of the list.

tail

public TaskRunnable tail()

Returns the Task which is at the tail of the list.

Returns:

The task which is at the tail of the list.

scheduledExecutionTime

public long scheduledExecutionTime()

Returns the time which this HeadTaskRunnable is scheduled.

Specified by:

scheduledExecutionTime in interface TaskRunnable

Returns:

The long value which represents the time this task is scheduled

run

public void run()

Implements for TaskRunnable interface, just run the next TaskRunnable.

Specified by:

run in interface Runnable