Module io.netty5.handler

Package io.netty5.handler.flush

Class FlushConsolidationHandler

java.lang.Object

io.netty5.handler.flush.FlushConsolidationHandler

All Implemented Interfaces:

ChannelHandler

public class FlushConsolidationHandler
extends Object
implements ChannelHandler

ChannelHandler which consolidates Channel.flush() / ChannelHandlerContext.flush() operations (which also includes Channel.writeAndFlush(Object) and ChannelOutboundInvoker.writeAndFlush(Object).

Flush operations are generally speaking expensive as these may trigger a syscall on the transport level. Thus it is in most cases (where write latency can be traded with throughput) a good idea to try to minimize flush operations as much as possible.

If a read loop is currently ongoing, ChannelHandler.flush(ChannelHandlerContext) will not be passed on to the next ChannelHandler in the ChannelPipeline, as it will pick up any pending flushes when channelReadComplete(ChannelHandlerContext) is triggered. If no read loop is ongoing, the behavior depends on the consolidateWhenNoReadInProgress constructor argument:

• if false, flushes are passed on to the next handler directly;
• if true, the invocation of the next handler is submitted as a separate task on the event loop. Under high throughput, this gives the opportunity to process other flushes before the task gets executed, thus batching multiple flushes into one.

If explicitFlushAfterFlushes is reached the flush will be forwarded as well (whether while in a read loop, or while batching outside of a read loop).

If the Channel becomes non-writable it will also try to execute any pending flush operations.

The FlushConsolidationHandler should be put as first ChannelHandler in the ChannelPipeline to have the best effect.

Field Summary

Fields

Modifier and Type	Field	Description
static int	DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES	The default number of flushes after which a flush will be forwarded to downstream handlers (whether while in a read loop, or while batching outside of a read loop).

Constructor Summary

Constructors

Constructor	Description
FlushConsolidationHandler()	Create new instance which explicit flush after 256 pending flush operations at the latest.
FlushConsolidationHandler(int explicitFlushAfterFlushes)	Create new instance which doesn't consolidate flushes when no read is in progress.
FlushConsolidationHandler(int explicitFlushAfterFlushes, boolean consolidateWhenNoReadInProgress)	Create new instance.

Method Summary

Modifier and Type	Method	Description
void	channelExceptionCaught(ChannelHandlerContext ctx, Throwable cause)	Gets called if a Throwable was thrown when handling inbound events.
void	channelRead(ChannelHandlerContext ctx, Object msg)	Invoked when the current Channel has read a message from the peer.
void	channelReadComplete(ChannelHandlerContext ctx)	Invoked when the last message read by the current read operation has been consumed by ChannelHandler.channelRead(ChannelHandlerContext, Object).
void	channelWritabilityChanged(ChannelHandlerContext ctx)	Gets called once the writable state of a Channel changed.
Future<Void>	close(ChannelHandlerContext ctx)	Called once a close operation is made.
Future<Void>	disconnect(ChannelHandlerContext ctx)	Called once a disconnect operation is made.
void	flush(ChannelHandlerContext ctx)	Called once a flush operation is made.
void	handlerAdded(ChannelHandlerContext ctx)	Gets called after the ChannelHandler was added to the actual context and it's ready to handle events.
void	handlerRemoved(ChannelHandlerContext ctx)	Gets called after the ChannelHandler was removed from the actual context and it doesn't handle events anymore.

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.netty5.channel.ChannelHandler

bind, channelActive, channelInactive, channelInboundEvent, channelRegistered, channelShutdown, channelUnregistered, connect, deregister, isSharable, pendingOutboundBytes, read, register, sendOutboundEvent, shutdown, write

Field Detail

DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES

public static final int DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES

The default number of flushes after which a flush will be forwarded to downstream handlers (whether while in a read loop, or while batching outside of a read loop).

See Also:

Constant Field Values

Constructor Detail

FlushConsolidationHandler

public FlushConsolidationHandler()

Create new instance which explicit flush after 256 pending flush operations at the latest.

FlushConsolidationHandler

public FlushConsolidationHandler(int explicitFlushAfterFlushes)

Create new instance which doesn't consolidate flushes when no read is in progress.

Parameters:

explicitFlushAfterFlushes - the number of flushes after which an explicit flush will be done.

FlushConsolidationHandler

public FlushConsolidationHandler(int explicitFlushAfterFlushes,
                                 boolean consolidateWhenNoReadInProgress)

Create new instance.

Parameters:

explicitFlushAfterFlushes - the number of flushes after which an explicit flush will be done.

consolidateWhenNoReadInProgress - whether to consolidate flushes even when no read loop is currently ongoing.

Method Detail

handlerAdded

public void handlerAdded(ChannelHandlerContext ctx)
                  throws Exception

Description copied from interface: ChannelHandler

Gets called after the ChannelHandler was added to the actual context and it's ready to handle events.

Specified by:

handlerAdded in interface ChannelHandler

Throws:

Exception

flush

public void flush(ChannelHandlerContext ctx)

Description copied from interface: ChannelHandler

Called once a flush operation is made. The flush operation will try to flush out all previous written messages that are pending.

Specified by:

flush in interface ChannelHandler

Parameters:

ctx - the ChannelHandlerContext for which the flush operation is made

channelReadComplete

public void channelReadComplete(ChannelHandlerContext ctx)
                         throws Exception

Description copied from interface: ChannelHandler

Invoked when the last message read by the current read operation has been consumed by ChannelHandler.channelRead(ChannelHandlerContext, Object). If ChannelOption.AUTO_READ is off, no further attempt to read an inbound data from the current Channel will be made until ChannelHandlerContext.read() is called.

Specified by:

channelReadComplete in interface ChannelHandler

Throws:

Exception

channelRead

public void channelRead(ChannelHandlerContext ctx,
                        Object msg)
                 throws Exception

Description copied from interface: ChannelHandler

Invoked when the current Channel has read a message from the peer.

Specified by:

channelRead in interface ChannelHandler

Throws:

Exception

channelExceptionCaught

public void channelExceptionCaught(ChannelHandlerContext ctx,
                                   Throwable cause)
                            throws Exception

Description copied from interface: ChannelHandler

Gets called if a Throwable was thrown when handling inbound events.

Specified by:

channelExceptionCaught in interface ChannelHandler

Throws:

Exception

disconnect

public Future<Void> disconnect(ChannelHandlerContext ctx)

Description copied from interface: ChannelHandler

Called once a disconnect operation is made.

Specified by:

disconnect in interface ChannelHandler

Parameters:

ctx - the ChannelHandlerContext for which the disconnect operation is made

Returns:

the Future which will be notified once the operation completes.

close

public Future<Void> close(ChannelHandlerContext ctx)

Description copied from interface: ChannelHandler

Called once a close operation is made.

Specified by:

close in interface ChannelHandler

Parameters:

ctx - the ChannelHandlerContext for which the close operation is made

Returns:

the Future which will be notified once the operation completes.

channelWritabilityChanged

public void channelWritabilityChanged(ChannelHandlerContext ctx)
                               throws Exception

Description copied from interface: ChannelHandler

Gets called once the writable state of a Channel changed. You can check the state with Channel.writableBytes() or Channel.isWritable().

Specified by:

channelWritabilityChanged in interface ChannelHandler

Throws:

Exception

handlerRemoved

public void handlerRemoved(ChannelHandlerContext ctx)
                    throws Exception

Description copied from interface: ChannelHandler

Gets called after the ChannelHandler was removed from the actual context and it doesn't handle events anymore.

Specified by:

handlerRemoved in interface ChannelHandler

Throws:

Exception