org.apache.flink.runtime.io.network.bufferprovider

Class LocalBufferPool

java.lang.Object

org.apache.flink.runtime.io.network.bufferprovider.LocalBufferPool

All Implemented Interfaces:

BufferProvider

public final class LocalBufferPool
extends Object
implements BufferProvider

A buffer pool used to manage a designated number of buffers from a GlobalBufferPool.

A local buffer pool mediates buffer requests to the global buffer pool to ensure dead-lock free operation of the network stack by limiting the number of designated buffers per local buffer pool. It also implements the default mechanism for buffer recycling, which ensures that every buffer is ultimately returned to the global buffer pool.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.runtime.io.network.bufferprovider.BufferProvider

BufferProvider.BufferAvailabilityRegistration

Constructor Summary

Constructors

Constructor and Description
LocalBufferPool(GlobalBufferPool globalBufferPool, int numDesignatedBuffers)

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() Destroys this local buffer pool and immediately returns all available buffers to the global buffer pool.
int	getBufferSize() Returns the size of buffers (in bytes) available at this buffer provider.
int	numAvailableBuffers() Returns the number of buffers available in the local buffer pool.
int	numDesignatedBuffers() Returns the designated number of buffers for this local buffer pool.
int	numRequestedBuffers() Returns the number of buffers, which have been requested from the global buffer pool.
BufferProvider.BufferAvailabilityRegistration	registerBufferAvailabilityListener(BufferAvailabilityListener listener) Registers the given BufferAvailabilityListener with an empty buffer pool.
void	reportAsynchronousEvent() Reports an asynchronous event and interrupts each blocking method of this buffer provider in order to allow the blocked thread to respond to the event.
Buffer	requestBuffer(int minBufferSize) Requests a buffer with a minimum size of minBufferSize.
Buffer	requestBufferBlocking(int minBufferSize) Requests a buffer with a minimum size of minBufferSize.
void	setNumDesignatedBuffers(int numDesignatedBuffers) Sets the designated number of buffers for this local buffer pool and returns excess buffers to the global buffer pool.

Methods inherited from class java.lang.Object

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

Constructor Detail

LocalBufferPool

public LocalBufferPool(GlobalBufferPool globalBufferPool,
               int numDesignatedBuffers)

Method Detail

requestBuffer

public Buffer requestBuffer(int minBufferSize)
                     throws IOException

Description copied from interface: BufferProvider

Requests a buffer with a minimum size of minBufferSize. The method returns immediately, even if the request could not be fulfilled.

Specified by:

requestBuffer in interface BufferProvider

Parameters:

minBufferSize - minimum size of the requested buffer (in bytes)

Returns:

buffer with at least the requested size or null if no such buffer is currently available

Throws:

IOException

requestBufferBlocking

public Buffer requestBufferBlocking(int minBufferSize)
                             throws IOException,
                                    InterruptedException

Description copied from interface: BufferProvider

Requests a buffer with a minimum size of minBufferSize. The method blocks until the request has been fulfilled or BufferProvider.reportAsynchronousEvent() has been called.

Specified by:

requestBufferBlocking in interface BufferProvider

Parameters:

minBufferSize - minimum size of the requested buffer (in bytes)

Returns:

buffer with at least the requested size

Throws:

IOException

InterruptedException

getBufferSize

public int getBufferSize()

Description copied from interface: BufferProvider

Returns the size of buffers (in bytes) available at this buffer provider.

Specified by:

getBufferSize in interface BufferProvider

Returns:

size of buffers (in bytes) available at this buffer provider

reportAsynchronousEvent

public void reportAsynchronousEvent()

Description copied from interface: BufferProvider

Reports an asynchronous event and interrupts each blocking method of this buffer provider in order to allow the blocked thread to respond to the event.

Specified by:

reportAsynchronousEvent in interface BufferProvider

registerBufferAvailabilityListener

public BufferProvider.BufferAvailabilityRegistration registerBufferAvailabilityListener(BufferAvailabilityListener listener)

Description copied from interface: BufferProvider

Registers the given BufferAvailabilityListener with an empty buffer pool.

The registration only succeeds, if the buffer pool is empty and has not been destroyed yet.

The registered listener will receive a notification when at least one buffer has become available again. After the notification, the listener will be unregistered.

Specified by:

registerBufferAvailabilityListener in interface BufferProvider

Parameters:

listener - the listener to be registered

Returns:

true if the registration has been successful; false if the registration failed, because the buffer pool was not empty or has already been destroyed

setNumDesignatedBuffers

public void setNumDesignatedBuffers(int numDesignatedBuffers)

Sets the designated number of buffers for this local buffer pool and returns excess buffers to the global buffer pool.

The designated number of buffers determines how many buffers this buffer pool is allowed to manage. New buffers can only be requested, if the requested number of buffers is less than the designated number. If possible, excess buffers will be returned to the global buffer pool.

Parameters:

numDesignatedBuffers - number of buffers designated for this local buffer pool

numAvailableBuffers

public int numAvailableBuffers()

Returns the number of buffers available in the local buffer pool.

Returns:

number of available buffers

numRequestedBuffers

public int numRequestedBuffers()

Returns the number of buffers, which have been requested from the global buffer pool.

Returns:

number of buffers requested from the global buffer pool

numDesignatedBuffers

public int numDesignatedBuffers()

Returns the designated number of buffers for this local buffer pool.

Returns:

number of designated buffers for this buffer pool

destroy

public void destroy()

Destroys this local buffer pool and immediately returns all available buffers to the global buffer pool.

Buffers, which have been requested from this local buffer pool via requestBuffer cannot be returned immediately and will be returned when the respective buffer is recycled (see recycleBuffer(MemorySegment)).