org.apache.flink.streaming.runtime.io

Class BarrierBuffer

java.lang.Object

org.apache.flink.streaming.runtime.io.BarrierBuffer

All Implemented Interfaces:

CheckpointBarrierHandler

@Internal
public class BarrierBuffer
extends Object
implements CheckpointBarrierHandler

The barrier buffer is CheckpointBarrierHandler that blocks inputs with barriers until all inputs have received the barrier for a given checkpoint.

To avoid back-pressuring the input streams (which may cause distributed deadlocks), the BarrierBuffer continues receiving buffers from the blocked channels and stores them internally until the blocks are released.

Constructor Summary

Constructors

Constructor and Description
BarrierBuffer(InputGate inputGate, IOManager ioManager)

Method Summary

Modifier and Type	Method and Description
void	cleanup() Cleans up all internally held resources.
long	getCurrentCheckpointId() Gets the ID defining the current pending, or just completed, checkpoint.
BufferOrEvent	getNextNonBlocked() Returns the next BufferOrEvent that the operator may consume.
boolean	isEmpty() Checks if the barrier handler has buffered any data internally.
void	registerCheckpointEventHandler(EventListener<CheckpointBarrier> checkpointHandler) Registers the given event handler to be notified on successful checkpoints.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

BarrierBuffer

public BarrierBuffer(InputGate inputGate,
                     IOManager ioManager)
              throws IOException

Parameters:

inputGate - The input gate to draw the buffers and events from.

ioManager - The I/O manager that gives access to the temp directories.

Throws:

IOException - Thrown, when the spilling to temp files cannot be initialized.

Method Detail

getNextNonBlocked

public BufferOrEvent getNextNonBlocked()
                                throws IOException,
                                       InterruptedException

Description copied from interface: CheckpointBarrierHandler

Returns the next BufferOrEvent that the operator may consume. This call blocks until the next BufferOrEvent is available, ir until the stream has been determined to be finished.

Specified by:

getNextNonBlocked in interface CheckpointBarrierHandler

Returns:

The next BufferOrEvent, or null, if the stream is finished.

Throws:

IOException - Thrown, if the network or local disk I/O fails.

InterruptedException - Thrown, if the thread is interrupted while blocking during waiting for the next BufferOrEvent to become available.

registerCheckpointEventHandler

public void registerCheckpointEventHandler(EventListener<CheckpointBarrier> checkpointHandler)

Description copied from interface: CheckpointBarrierHandler

Registers the given event handler to be notified on successful checkpoints.

Specified by:

registerCheckpointEventHandler in interface CheckpointBarrierHandler

Parameters:

checkpointHandler - The handler to register.

isEmpty

public boolean isEmpty()

Description copied from interface: CheckpointBarrierHandler

Checks if the barrier handler has buffered any data internally.

Specified by:

isEmpty in interface CheckpointBarrierHandler

Returns:

True, if no data is buffered internally, false otherwise.

cleanup

public void cleanup()
             throws IOException

Description copied from interface: CheckpointBarrierHandler

Cleans up all internally held resources.

Specified by:

cleanup in interface CheckpointBarrierHandler

Throws:

IOException - Thrown, if the cleanup of I/O resources failed.

getCurrentCheckpointId

public long getCurrentCheckpointId()

Gets the ID defining the current pending, or just completed, checkpoint.

Returns:

The ID of the pending of completed checkpoint.

toString

public String toString()

Overrides:

toString in class Object