Package com.intellij.openapi.progress.util

Class ReadTask

java.lang.Object

com.intellij.openapi.progress.util.ReadTask

public abstract class ReadTask
extends java.lang.Object

A computation that needs to be run in background and inside a read action, and canceled whenever a write action is about to occur.

See Also:

ProgressIndicatorUtils.scheduleWithWriteActionPriority(ReadTask)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReadTask.Continuation An object representing the action that should be done on Swing thread after the background computation is finished.

Constructor Summary

Constructors

Constructor and Description
ReadTask()

Method Summary

Modifier and Type	Method and Description
void	computeInReadAction(ProgressIndicator indicator) Performs the computation.
abstract void	onCanceled(ProgressIndicator indicator) Is invoked on Swing thread whenever the computation is canceled by a write action.
ReadTask.Continuation	performInReadAction(ProgressIndicator indicator) Performs the computation.
ReadTask.Continuation	runBackgroundProcess(ProgressIndicator indicator) Is invoked on a background thread.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadTask

public ReadTask()

Method Detail

computeInReadAction

public void computeInReadAction(ProgressIndicator indicator)
                         throws ProcessCanceledException

Performs the computation. Is invoked inside a read action and under a progress indicator that's canceled when a write action is about to occur. For tasks that have some Swing thread activity afterwards (e.g. applying changes, showing dialogs etc), use performInReadAction(ProgressIndicator) instead

Throws:

ProcessCanceledException

performInReadAction

public ReadTask.Continuation performInReadAction(ProgressIndicator indicator)
                                          throws ProcessCanceledException

Performs the computation. Is invoked inside a read action and under a progress indicator that's canceled when a write action is about to occur.

Returns:

an action that should be performed later on Swing thread if no write actions have happened before that

Throws:

ProcessCanceledException

onCanceled

public abstract void onCanceled(ProgressIndicator indicator)

Is invoked on Swing thread whenever the computation is canceled by a write action. A likely implementation is to restart the computation, maybe based on the new state of the system.

runBackgroundProcess

public ReadTask.Continuation runBackgroundProcess(ProgressIndicator indicator)
                                           throws ProcessCanceledException

Is invoked on a background thread. The responsibility of this method is to start a read action and call computeInReadAction(ProgressIndicator). Overriders might also do something else. For example, use DumbService.runReadActionInSmartMode(Runnable).

Parameters:

indicator - the progress indicator of the background thread

Throws:

ProcessCanceledException