Package org.elasticsearch.tasks

Class CancellableTask

java.lang.Object

org.elasticsearch.tasks.Task

org.elasticsearch.tasks.CancellableTask

Direct Known Subclasses:

AllocatedPersistentTask, BulkByScrollTask, SearchShardTask, SearchTask

public class CancellableTask
extends Task

A task that can be cancelled

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	CancellableTask.CancellationListener	This interface is implemented by any class that needs to react to the cancellation of this task.

Nested classes/interfaces inherited from class org.elasticsearch.tasks.Task

Task.Status

Field Summary

Fields inherited from class org.elasticsearch.tasks.Task

HEADERS_TO_COPY, TRACE_ID, TRACE_PARENT_HTTP_HEADER, X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER, X_OPAQUE_ID_HTTP_HEADER

Constructor Summary

Constructors

Constructor	Description
CancellableTask(long id, String type, String action, String description, TaskId parentTaskId, Map<String,String> headers)

Method Summary

Modifier and Type	Method	Description
final void	addListener(CancellableTask.CancellationListener listener)	This method adds a listener that needs to be notified if this task is cancelled.
final void	ensureNotCancelled()	Throws a TaskCancelledException if this task has been cancelled, otherwise does nothing.
final String	getReasonCancelled()	The reason the task was cancelled or null if it hasn't been cancelled.
final boolean	isCancelled()	Return whether the task is cancelled.
final <T> boolean	notifyIfCancelled(ActionListener<T> listener)	Notifies the listener of failure with a TaskCancelledException if this task has been cancelled, otherwise does nothing.
protected void	onCancelled()	Called after the task is cancelled so that it can take any actions that it has to take.
boolean	shouldCancelChildrenOnCancellation()	Returns whether this task's children need to be cancelled too.

Methods inherited from class org.elasticsearch.tasks.Task

getAction, getDescription, getHeader, getId, getParentTaskId, getStartTime, getStartTimeNanos, getStatus, getType, headers, result, result, taskInfo, taskInfo

Methods inherited from class java.lang.Object

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

Constructor Details

CancellableTask

public CancellableTask(long id,
 String type,
 String action,
 String description,
 TaskId parentTaskId,
 Map<String,String> headers)

Method Details

shouldCancelChildrenOnCancellation

public boolean shouldCancelChildrenOnCancellation()

Returns whether this task's children need to be cancelled too. true is a reasonable response even for tasks that have no children, since child tasks might be added in future and it'd be easy to forget to update this, but returning false saves a bit of computation in the task manager.

isCancelled

public final boolean isCancelled()

Return whether the task is cancelled. If testing this flag to decide whether to throw a TaskCancelledException, consider using ensureNotCancelled() or notifyIfCancelled(org.elasticsearch.action.ActionListener<T>) instead: these methods construct an exception that automatically includes the cancellation reason.

getReasonCancelled

@Nullable
public final String getReasonCancelled()

The reason the task was cancelled or null if it hasn't been cancelled. May also be null if the task was just cancelled since we don't set the reason and the cancellation flag atomically.

addListener

public final void addListener(CancellableTask.CancellationListener listener)

This method adds a listener that needs to be notified if this task is cancelled.

onCancelled

protected void onCancelled()

Called after the task is cancelled so that it can take any actions that it has to take.

ensureNotCancelled

public final void ensureNotCancelled()

Throws a TaskCancelledException if this task has been cancelled, otherwise does nothing.

notifyIfCancelled

public final <T> boolean notifyIfCancelled(ActionListener<T> listener)

Notifies the listener of failure with a TaskCancelledException if this task has been cancelled, otherwise does nothing.

Returns:

true if the task is cancelled and the listener was notified, otherwise false.