org.apache.flink.streaming.runtime.io

Class CachedBufferBlocker

java.lang.Object

org.apache.flink.streaming.runtime.io.CachedBufferBlocker

All Implemented Interfaces:

BufferBlocker

@Internal
public class CachedBufferBlocker
extends Object
implements BufferBlocker

The cached buffer blocker takes the buffers and events from a data stream and adds them to a memory queue. After a number of elements have been cached, the blocker can "roll over": It presents the cached elements as a readable sequence, and creates a new memory queue.

This buffer blocked can be used in credit-based flow control for better barrier alignment in exactly-once mode.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CachedBufferBlocker.CachedBufferOrEventSequence This class represents a sequence of cached buffers and events, created by the CachedBufferBlocker.

Constructor Summary

Constructors

Constructor and Description
CachedBufferBlocker(int pageSize) Creates a new buffer blocker, caching the buffers or events in memory queue.

Method Summary

Modifier and Type	Method and Description
void	add(BufferOrEvent boe) Adds a buffer or event to the blocker.
void	close() Cleans up all the resources in the current sequence.
long	getBytesBlocked() Gets the number of bytes blocked in the current sequence.
BufferOrEventSequence	rollOverReusingResources() It is never reusing resources and is defaulting to rollOverWithoutReusingResources().
BufferOrEventSequence	rollOverWithoutReusingResources() Starts a new sequence of buffers and event without reusing the same resources and returns the current sequence of buffers for reading.

Methods inherited from class java.lang.Object

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

Constructor Detail

CachedBufferBlocker

public CachedBufferBlocker(int pageSize)

Creates a new buffer blocker, caching the buffers or events in memory queue.

Parameters:

pageSize - The page size used to estimate the cached size.

Method Detail

add

public void add(BufferOrEvent boe)

Description copied from interface: BufferBlocker

Adds a buffer or event to the blocker.

Specified by:

add in interface BufferBlocker

Parameters:

boe - The buffer or event to be added into the blocker.

rollOverReusingResources

public BufferOrEventSequence rollOverReusingResources()

It is never reusing resources and is defaulting to rollOverWithoutReusingResources().

Specified by:

rollOverReusingResources in interface BufferBlocker

Returns:

The readable sequence of buffers and events, or 'null', if nothing was added.

rollOverWithoutReusingResources

public BufferOrEventSequence rollOverWithoutReusingResources()

Description copied from interface: BufferBlocker

Starts a new sequence of buffers and event without reusing the same resources and returns the current sequence of buffers for reading.

Specified by:

rollOverWithoutReusingResources in interface BufferBlocker

Returns:

The readable sequence of buffers and events, or 'null', if nothing was added.

close

public void close()

Description copied from interface: BufferBlocker

Cleans up all the resources in the current sequence.

Specified by:

close in interface BufferBlocker

getBytesBlocked

public long getBytesBlocked()

Description copied from interface: BufferBlocker

Gets the number of bytes blocked in the current sequence.

Specified by:

getBytesBlocked in interface BufferBlocker

Returns:

the number of bytes blocked in the current sequence.