io.netty.channel

Class CoalescingBufferQueue

java.lang.Object

io.netty.channel.CoalescingBufferQueue

public final class CoalescingBufferQueue
extends Object

A FIFO queue of bytes where producers add bytes by repeatedly adding ByteBuf and consumers take bytes in arbitrary lengths. This allows producers to add lots of small buffers and the consumer to take all the bytes out in a single buffer. Conversely the producer may add larger buffers and the consumer could take the bytes in many small buffers.

Bytes are added and removed with promises. If the last byte of a buffer added with a promise is removed then that promise will complete when the promise passed to remove(int, io.netty.channel.ChannelPromise) completes.

This functionality is useful for aggregating or partitioning writes into fixed size buffers for framing protocols such as HTTP2.

Constructor Summary

Constructors

Constructor and Description
CoalescingBufferQueue(Channel channel)
CoalescingBufferQueue(Channel channel, int initSize)

Method Summary

Modifier and Type	Method and Description
void	add(ByteBuf buf) Add a buffer to the end of the queue.
void	add(ByteBuf buf, ChannelFutureListener listener) Add a buffer to the end of the queue and associate a listener with it that should be completed when all the buffers bytes have been consumed from the queue and written.
void	add(ByteBuf buf, ChannelPromise promise) Add a buffer to the end of the queue and associate a promise with it that should be completed when all the buffers bytes have been consumed from the queue and written.
void	copyTo(CoalescingBufferQueue dest) Copy all pending entries in this queue into the destination queue.
boolean	isEmpty() Are there pending buffers in the queue.
int	readableBytes() The number of readable bytes.
void	releaseAndFailAll(Throwable cause) Release all buffers in the queue and complete all listeners and promises.
ByteBuf	remove(int bytes, ChannelPromise aggregatePromise) Remove a ByteBuf from the queue with the specified number of bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

CoalescingBufferQueue

public CoalescingBufferQueue(Channel channel)

CoalescingBufferQueue

public CoalescingBufferQueue(Channel channel,
                             int initSize)

Method Detail

add

public void add(ByteBuf buf)

Add a buffer to the end of the queue.

add

public void add(ByteBuf buf,
                ChannelPromise promise)

Add a buffer to the end of the queue and associate a promise with it that should be completed when all the buffers bytes have been consumed from the queue and written.

Parameters:

buf - to add to the tail of the queue

promise - to complete when all the bytes have been consumed and written, can be void.

add

public void add(ByteBuf buf,
                ChannelFutureListener listener)

Add a buffer to the end of the queue and associate a listener with it that should be completed when all the buffers bytes have been consumed from the queue and written.

Parameters:

buf - to add to the tail of the queue

listener - to notify when all the bytes have been consumed and written, can be null.

remove

public ByteBuf remove(int bytes,
                      ChannelPromise aggregatePromise)

Remove a ByteBuf from the queue with the specified number of bytes. Any added buffer who's bytes are fully consumed during removal will have it's promise completed when the passed aggregate ChannelPromise completes.

Parameters:

bytes - the maximum number of readable bytes in the returned ByteBuf, if bytes is greater than readableBytes then a buffer of length readableBytes is returned.

aggregatePromise - used to aggregate the promises and listeners for the constituent buffers.

Returns:

a ByteBuf composed of the enqueued buffers.

readableBytes

public int readableBytes()

The number of readable bytes.

isEmpty

public boolean isEmpty()

Are there pending buffers in the queue.

releaseAndFailAll

public void releaseAndFailAll(Throwable cause)

Release all buffers in the queue and complete all listeners and promises.

copyTo

public void copyTo(CoalescingBufferQueue dest)

Copy all pending entries in this queue into the destination queue.

Parameters:

dest - to copy pending buffers to.