oracle.jdeveloper.usage.util

Class AbstractBackgroundTask

java.lang.Object

oracle.javatools.parser.util.AsyncTask

oracle.jdeveloper.usage.util.AbstractBackgroundTask

All Implemented Interfaces:

java.lang.Runnable, BackgroundTask

Direct Known Subclasses:

TaskMultiplexer.TaskWrapper

public abstract class AbstractBackgroundTask
extends AsyncTask
implements BackgroundTask

The AbstractBackgroundTask takes care of the common code for a BackgroundTask based on the AsyncTask API. The cancellation contained here is for a polling-based cancel mechanism.

Nested Class Summary

Nested classes/interfaces inherited from class oracle.javatools.parser.util.AsyncTask

AsyncTask.CancelledException

Field Summary

Fields inherited from class oracle.javatools.parser.util.AsyncTask

CANCELLED_RESULT, STATUS_CANCELLED, STATUS_COMPLETED, STATUS_FAILED, STATUS_READY, STATUS_RUNNING

Constructor Summary

Constructors

Constructor and Description
AbstractBackgroundTask()

Method Summary

Modifier and Type	Method and Description
void	cancel() Attempts to cancel the current task in progress.
protected void	cancelTaskImpl() Implementation-specific work to cancel this running task should go here.
int	getProgress() Fetches the current progress of the query task.
java.lang.String	getProgressText() Fetches a human-readable (translated) descriptive text that describes what the task is currently doing.
protected abstract AsyncScheduler	getSchedulerImpl() Requests the scheduler that this task was scheduled with.
protected boolean	isCancelledImpl() Return whether the task is marked for cancellation, to be implemented by the implementation.
protected void	requestCancelImpl() Request to cancel the task in-progress.
protected java.lang.Object	runImpl() Wrapper for the task implementation to catch and report task failures in the form of RuntimeExceptions.
protected abstract java.lang.Object	runTaskImpl() Implementation of this task.
void	setProgress(int value) Sets the current progress value.
protected void	setProgressFromSubTask(BackgroundTask task, int rangeStart, int rangeEnd) Utility routine to update the task progress based on a subtask's progress.
protected void	setProgressFromSubTask(int subValue, int rangeStart, int rangeEnd) Utility routine to update our task's progress based on a subtask.
void	setProgressText(java.lang.String text) Sets the human-readable descriptive text describing what the task is currently doing.

Methods inherited from class oracle.javatools.parser.util.AsyncTask

bailIfCancelled, getResult, getStatus, isFinished, requestCancel, run, sleep, waitUntilFinished, waitUntilFinished

Methods inherited from class java.lang.Object

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

Methods inherited from interface oracle.jdeveloper.usage.util.BackgroundTask

isFinished, waitUntilFinished

Constructor Detail

AbstractBackgroundTask

public AbstractBackgroundTask()

Method Detail

cancel

public final void cancel()

Attempts to cancel the current task in progress. This does not guarantee the task will be cancelled immediately, as it is implementation dependent, though implementations are strongly encouraged to ensure a speedy cancellation. Clients should not fetch or use the query results when a cancel is issued, as the results are unpredictable.

Specified by:

cancel in interface BackgroundTask

getSchedulerImpl

protected abstract AsyncScheduler getSchedulerImpl()

Requests the scheduler that this task was scheduled with. This is up to the implementation to fill in with the scheduler it uses for tasks. This will only be used for the purposes of cancelling the task. If your task is cancellable, you should return the scheduler here.

Returns:

the scheduler of this task, or null if the task is not cancellable

runTaskImpl

protected abstract java.lang.Object runTaskImpl()
                                         throws AsyncTask.CancelledException

Implementation of this task. Subclasses should override this.

Returns:

the implementation-specific return result (if any), or CANCELLED_RESULT if the operation is cancelled

Throws:

CancelledException - if the task has been cancelled

AsyncTask.CancelledException

cancelTaskImpl

protected void cancelTaskImpl()

Implementation-specific work to cancel this running task should go here. A default NOP implementation is provided for convenience.

runImpl

protected final java.lang.Object runImpl()
                                  throws AsyncTask.CancelledException

Wrapper for the task implementation to catch and report task failures in the form of RuntimeExceptions.

Specified by:

runImpl in class AsyncTask

Returns:

the implementation-specific return result (if any), or CANCELLED_RESULT if the operation is cancelled

Throws:

CancelledException - if the task has been cancelled

AsyncTask.CancelledException

requestCancelImpl

protected final void requestCancelImpl()

Request to cancel the task in-progress.

Specified by:

requestCancelImpl in class AsyncTask

isCancelledImpl

protected final boolean isCancelledImpl()

Return whether the task is marked for cancellation, to be implemented by the implementation.

Specified by:

isCancelledImpl in class AsyncTask

Returns:

whether the task is marked for cancellation

setProgressFromSubTask

protected void setProgressFromSubTask(int subValue,
                                      int rangeStart,
                                      int rangeEnd)

Utility routine to update our task's progress based on a subtask. The value provided is the progress (0 to 100) of the subtask, while the portion of our progress that is assigned to the subtask is bounded by rangeStart and rangeEnd. So this utility routine just assigns our progress based on these three values.

Parameters:

subValue - the sub-task's progress (0-100)

rangeStart - the range start of the main task's progress

rangeEnd - the range end of the main task's progress

setProgressFromSubTask

protected void setProgressFromSubTask(BackgroundTask task,
                                      int rangeStart,
                                      int rangeEnd)

Utility routine to update the task progress based on a subtask's progress.

Parameters:

task - the sub-task

rangeStart - the range start of the main task's progress

rangeEnd - the range end of the main task's progress

getProgress

public final int getProgress()

Fetches the current progress of the query task. This will return an integer between 0 (just started) and 100 (finished). This is solely an estimate, and is not guaranteed to be accurate, though implementations are encouraged to try to provide an accurate number. This can be used by clients to display a progress bar for example.

Specified by:

getProgress in interface BackgroundTask

Returns:

a progress value between 0 and 100 to denote the running status of this task

setProgress

public final void setProgress(int value)

Sets the current progress value. This is used by implementations to provide an estimate of the current progress of the task.

Parameters:

value - the current value, as a value between 0 and 100

getProgressText

public final java.lang.String getProgressText()

Fetches a human-readable (translated) descriptive text that describes what the task is currently doing. Implementations should try to make this information actually usable and informative for users. This can be used by clients to display with a progress bar for example.

Specified by:

getProgressText in interface BackgroundTask

Returns:

a human-readable description of the current task's progress

setProgressText

public final void setProgressText(java.lang.String text)

Sets the human-readable descriptive text describing what the task is currently doing.

Parameters:

text - the descriptive progress text