org.apache.flink.runtime.io

Interface AvailabilityProvider

All Known Subinterfaces:

BufferPool, BufferProvider, PullingAsyncDataInput<T>, PushingAsyncDataInput<T>, RecordWriterDelegate<T>, RecoverableStreamTaskInput<T>, ResultPartitionWriter, StreamInputProcessor, StreamTaskInput<T>

All Known Implementing Classes:

AbstractStreamTaskNetworkInput, AvailabilityProvider.AvailabilityHelper, BoundedBlockingResultPartition, BroadcastRecordWriter, BufferWritingResultPartition, ChannelSelectorRecordWriter, CheckpointedInputGate, HsResultPartition, IndexedInputGate, InputGate, InputGateWithMetrics, LocalBufferPool, MultiInputSortingDataInput, MultipleRecordWriters, NetworkBufferPool, NonRecordWriter, PipelinedResultPartition, RecordWriter, RescalingStreamTaskNetworkInput, ResultPartition, SingleInputGate, SingleRecordWriter, SortingDataInput, SortMergeResultPartition, SourceOperator, StreamMultipleInputProcessor, StreamOneInputProcessor, StreamTaskExternallyInducedSourceInput, StreamTaskFinishedOnRestoreSourceInput, StreamTaskNetworkInput, StreamTaskSourceInput, TieredResultPartition, UnionInputGate

@Internal
public interface AvailabilityProvider

Interface defining couple of essential methods for listening on data availability using CompletableFuture. For usage check out for example PullingAsyncDataInput.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	AvailabilityProvider.AvailabilityHelper A availability implementation for providing the helpful functions of resetting the available/unavailable states.

Field Summary

Fields

Modifier and Type	Field and Description
static CompletableFuture<?>	AVAILABLE Constant that allows to avoid volatile checks CompletableFuture.isDone().

Method Summary

Modifier and Type	Method and Description
static CompletableFuture<?>	and(CompletableFuture<?> first, CompletableFuture<?> second)
CompletableFuture<?>	getAvailableFuture()
default boolean	isApproximatelyAvailable() Checks whether this instance is available only via constant AVAILABLE to avoid performance concern caused by volatile access in CompletableFuture.isDone().
default boolean	isAvailable() In order to best-effort avoid volatile access in CompletableFuture.isDone(), we check the condition of future == AVAILABLE firstly for getting probable performance benefits while hot looping.
static CompletableFuture<?>	or(CompletableFuture<?> first, CompletableFuture<?> second)

Field Detail

AVAILABLE

static final CompletableFuture<?> AVAILABLE

Constant that allows to avoid volatile checks CompletableFuture.isDone(). Check isAvailable() and isApproximatelyAvailable() for more explanation.

Method Detail

getAvailableFuture

CompletableFuture<?> getAvailableFuture()

Returns:

a future that is completed if the respective provider is available.

isAvailable

default boolean isAvailable()

In order to best-effort avoid volatile access in CompletableFuture.isDone(), we check the condition of future == AVAILABLE firstly for getting probable performance benefits while hot looping.

It is always safe to use this method in performance nonsensitive scenarios to get the precise state.

Returns:

true if this instance is available for further processing.

isApproximatelyAvailable

default boolean isApproximatelyAvailable()

Checks whether this instance is available only via constant AVAILABLE to avoid performance concern caused by volatile access in CompletableFuture.isDone(). So it is mainly used in the performance sensitive scenarios which do not always need the precise state.

This method is still safe to get the precise state if getAvailableFuture() was touched via (.get(), .wait(), .isDone(), ...) before, which also has a "happen-before" relationship with this call.

Returns:

true if this instance is available for further processing.

and

static CompletableFuture<?> and(CompletableFuture<?> first,
                                CompletableFuture<?> second)

or

static CompletableFuture<?> or(CompletableFuture<?> first,
                               CompletableFuture<?> second)