Package org.apache.jackrabbit.oak.segment.file.cancel

Class Canceller

java.lang.Object

org.apache.jackrabbit.oak.segment.file.cancel.Canceller

public class Canceller
extends Object

Represents a way to check for a cancellation request. Users of this class (possibly cancelable, long-running operations) should periodically check whether a cancellation request has been received.

Method Summary

Modifier and Type	Method	Description
Cancellation	check()	Check if cancellation has been requested.
boolean	isCancelable()	Check if this instance can ever return anything other than NOPE.
static Canceller	newCanceller()	Create a new Canceller which is trivially empty.
Canceller	withCondition(String reason, BooleanSupplier condition)	Return a new Canceller based on a boolean predicate.
Canceller	withShortCircuit()	Create a new Canceller based on this Canceller.
Canceller	withTimeout(String reason, long duration, TimeUnit unit)	Return a new Canceller based on time duration.

Methods inherited from class java.lang.Object

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

Method Detail

newCanceller

public static Canceller newCanceller()

Create a new Canceller which is trivially empty. The returned Canceller will never relay a positive cancellation request.

Returns:

an instance of Canceller.

isCancelable

public boolean isCancelable()

Check if this instance can ever return anything other than NOPE. This will be only be false for ROOT and short circuits thereof.

check

public Cancellation check()

Check if cancellation has been requested. This method should be invoked periodically, and the returned Cancellation should be inspected and reacted upon.

Returns:

an instance of Cancellation.

withCondition

public Canceller withCondition(String reason,
                               BooleanSupplier condition)

Return a new Canceller based on a boolean predicate. The returned instance will relay a positive cancellation request when either the supplied boolean predicate is true or this Canceller is cancelled.

Parameters:

reason - The reason associated to the boolean condition.

condition - A boolean predicate.

Returns:

a new instance of Canceller.

withTimeout

public Canceller withTimeout(String reason,
                             long duration,
                             TimeUnit unit)

Return a new Canceller based on time duration. The returned instance will relay a positive cancellation request when either the duration expires or this Canceller is cancelled.

Parameters:

reason - The reason associated to the boolean condition.

duration - The duration for the timeout.

unit - The time unit for the duration.

Returns:

a new instance of Canceller.

withShortCircuit

public Canceller withShortCircuit()

Create a new Canceller based on this Canceller. The returned instance will be canceled when this instance is canceled, but will never transition back to an "uncanceled" state.

Returns:

a new instance of Canceller.