Class CoalescingBufferQueue

java.lang.Object

io.netty.channel.AbstractCoalescingBufferQueue

io.netty.channel.CoalescingBufferQueue

public final class CoalescingBufferQueue
extends AbstractCoalescingBufferQueue

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, 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	Description
CoalescingBufferQueue(Channel channel)
CoalescingBufferQueue(Channel channel, int initSize)
CoalescingBufferQueue(Channel channel, int initSize, boolean updateWritability)

Method Summary

Modifier and Type	Method	Description
protected ByteBuf	compose(ByteBufAllocator alloc, ByteBuf cumulation, ByteBuf next)	Calculate the result of current + next.
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.
protected ByteBuf	removeEmptyValue()	The value to return when AbstractCoalescingBufferQueue.remove(ByteBufAllocator, int, ChannelPromise) is called but the queue is empty.

Methods inherited from class AbstractCoalescingBufferQueue

add, add, add, addFirst, composeFirst, composeFirst, composeIntoComposite, copyAndCompose, copyTo, isEmpty, readableBytes, releaseAndFailAll, remove, removeFirst, size, toString, writeAndRemoveAll

Methods inherited from class Object

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

Constructor Details

CoalescingBufferQueue

public CoalescingBufferQueue(Channel channel)

CoalescingBufferQueue

public CoalescingBufferQueue(Channel channel,
 int initSize)

CoalescingBufferQueue

public CoalescingBufferQueue(Channel channel,
 int initSize,
 boolean updateWritability)

Method Details

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 AbstractCoalescingBufferQueue.readableBytes then a buffer of length AbstractCoalescingBufferQueue.readableBytes is returned.

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

Returns:

a ByteBuf composed of the enqueued buffers.

releaseAndFailAll

public void releaseAndFailAll(Throwable cause)

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

compose

protected ByteBuf compose(ByteBufAllocator alloc,
 ByteBuf cumulation,
 ByteBuf next)

Description copied from class: AbstractCoalescingBufferQueue

Calculate the result of current + next.

Specified by:

compose in class AbstractCoalescingBufferQueue

removeEmptyValue

protected ByteBuf removeEmptyValue()

Description copied from class: AbstractCoalescingBufferQueue

The value to return when AbstractCoalescingBufferQueue.remove(ByteBufAllocator, int, ChannelPromise) is called but the queue is empty.

Specified by:

removeEmptyValue in class AbstractCoalescingBufferQueue

Returns:

the ByteBuf which represents an empty queue.