Netty/Handler 4.1.107.Final · io.netty.handler.flush.FlushConsolidationHandler

ChannelDuplexHandler which consolidates Channel#flush() / ChannelHandlerContext#flush() operations (which also includes Channel#writeAndFlush(Object) / Channel#writeAndFlush(Object, ChannelPromise) and ChannelOutboundInvoker#writeAndFlush(Object) / ChannelOutboundInvoker#writeAndFlush(Object, ChannelPromise)).

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, flush(ChannelHandlerContext) will not be passed on to the next ChannelOutboundHandler 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.

Modifier and Type	Field and Description
private final boolean	consolidateWhenNoReadInProgress
private ChannelHandlerContext	ctx
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).
private final int	explicitFlushAfterFlushes
private int	flushPendingCount
private final Runnable	flushTask
private Future<?>	nextScheduledFlush
private boolean	readInProgress

Access	Constructor and Description
public	FlushConsolidationHandler() Create new instance which explicit flush after 256 pending flush operations at the latest.
public	FlushConsolidationHandler(int the number of flushes after which an explicit flush will be done. explicitFlushAfterFlushes) Create new instance which doesn't consolidate flushes when no read is in progress.
public	FlushConsolidationHandler(int the number of flushes after which an explicit flush will be done. explicitFlushAfterFlushes, boolean whether to consolidate flushes even when no read loop is currently ongoing. consolidateWhenNoReadInProgress) Create new instance.

Modifier and Type	Method and Description
private void	cancelScheduledFlush()
public void	channelRead(ChannelHandlerContext ctx, Object msg) Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelRead. Implements io.netty.channel.ChannelInboundHandler.channelRead. Calls `ChannelHandlerContext#fireChannelRead(Object)` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`.
public void	channelReadComplete(ChannelHandlerContext ctx) Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelReadComplete. Implements io.netty.channel.ChannelInboundHandler.channelReadComplete. Calls `ChannelHandlerContext#fireChannelReadComplete()` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`.
public void	channelWritabilityChanged(ChannelHandlerContext ctx) Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelWritabilityChanged. Implements io.netty.channel.ChannelInboundHandler.channelWritabilityChanged. Calls `ChannelHandlerContext#fireChannelWritabilityChanged()` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`.
public void	close(ChannelHandlerContext the `ChannelHandlerContext` for which the close operation is made ctx, ChannelPromise the `ChannelPromise` to notify once the operation completes promise) Overrides io.netty.channel.ChannelDuplexHandler.close. Implements io.netty.channel.ChannelOutboundHandler.close. Calls `ChannelHandlerContext#close(ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`.
public void	disconnect(ChannelHandlerContext the `ChannelHandlerContext` for which the disconnect operation is made ctx, ChannelPromise the `ChannelPromise` to notify once the operation completes promise) Overrides io.netty.channel.ChannelDuplexHandler.disconnect. Implements io.netty.channel.ChannelOutboundHandler.disconnect. Calls `ChannelHandlerContext#disconnect(ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`.
public void	exceptionCaught(ChannelHandlerContext ctx, Throwable cause) Overrides io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught. Implements io.netty.channel.ChannelHandler.exceptionCaught, io.netty.channel.ChannelInboundHandler.exceptionCaught. Gets called if a `Throwable` was thrown.
public void	flush(ChannelHandlerContext the `ChannelHandlerContext` for which the flush operation is made ctx) Overrides io.netty.channel.ChannelDuplexHandler.flush. Implements io.netty.channel.ChannelOutboundHandler.flush. Calls `ChannelHandlerContext#flush()` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`.
private void	flushIfNeeded(ChannelHandlerContext ctx)
private void	flushNow(ChannelHandlerContext ctx)
public void	handlerAdded(ChannelHandlerContext ctx) Overrides io.netty.channel.ChannelHandlerAdapter.handlerAdded. Implements io.netty.channel.ChannelHandler.handlerAdded. Gets called after the `ChannelHandler` was added to the actual context and it's ready to handle events.
public void	handlerRemoved(ChannelHandlerContext ctx) Overrides io.netty.channel.ChannelHandlerAdapter.handlerRemoved. Implements io.netty.channel.ChannelHandler.handlerRemoved. Gets called after the `ChannelHandler` was removed from the actual context and it doesn't handle events anymore.
private void	resetReadAndFlushIfNeeded(ChannelHandlerContext ctx)
private void	scheduleFlush(final ChannelHandlerContext ctx)

consolidateWhenNoReadInProgress	back to summary
private final boolean consolidateWhenNoReadInProgress

ctx	back to summary
private ChannelHandlerContext ctx

DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES	back to summary
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).

explicitFlushAfterFlushes	back to summary
private final int explicitFlushAfterFlushes

flushPendingCount	back to summary
private int flushPendingCount

flushTask	back to summary
private final Runnable flushTask

nextScheduledFlush	back to summary
private Future<?> nextScheduledFlush

readInProgress	back to summary
private boolean readInProgress

FlushConsolidationHandler	back to summary
public FlushConsolidationHandler() Create new instance which explicit flush after 256 pending flush operations at the latest.

FlushConsolidationHandler	back to summary
public FlushConsolidationHandler(int explicitFlushAfterFlushes) Create new instance which doesn't consolidate flushes when no read is in progress. Parameters explicitFlushAfterFlushes:int the number of flushes after which an explicit flush will be done.

FlushConsolidationHandler	back to summary
public FlushConsolidationHandler(int explicitFlushAfterFlushes, boolean consolidateWhenNoReadInProgress) Create new instance. Parameters explicitFlushAfterFlushes:int the number of flushes after which an explicit flush will be done. consolidateWhenNoReadInProgress:boolean whether to consolidate flushes even when no read loop is currently ongoing.

Method Detail

cancelScheduledFlush	back to summary
private void cancelScheduledFlush()

channelRead back to summary

channelRead	back to summary
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelRead. Implements io.netty.channel.ChannelInboundHandler.channelRead. Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelRead. Calls `ChannelHandlerContext#fireChannelRead(Object)` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Annotations @Override

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

Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelRead.

Implements io.netty.channel.ChannelInboundHandler.channelRead.

Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelRead.

Calls ChannelHandlerContext#fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Annotations

@Override

channelReadComplete back to summary

channelReadComplete	back to summary
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelReadComplete. Implements io.netty.channel.ChannelInboundHandler.channelReadComplete. Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelReadComplete. Calls `ChannelHandlerContext#fireChannelReadComplete()` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Annotations @Override

public void channelReadComplete(ChannelHandlerContext ctx) throws Exception

Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelReadComplete.

Implements io.netty.channel.ChannelInboundHandler.channelReadComplete.

Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelReadComplete.

Calls ChannelHandlerContext#fireChannelReadComplete() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Annotations

@Override

channelWritabilityChanged back to summary

channelWritabilityChanged	back to summary
public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelWritabilityChanged. Implements io.netty.channel.ChannelInboundHandler.channelWritabilityChanged. Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelWritabilityChanged. Calls `ChannelHandlerContext#fireChannelWritabilityChanged()` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Annotations @Override

public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception

Overrides io.netty.channel.ChannelInboundHandlerAdapter.channelWritabilityChanged.

Implements io.netty.channel.ChannelInboundHandler.channelWritabilityChanged.

Doc from io.netty.channel.ChannelInboundHandlerAdapter.channelWritabilityChanged.

Calls ChannelHandlerContext#fireChannelWritabilityChanged() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Annotations

@Override

close back to summary

close	back to summary
public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception Overrides io.netty.channel.ChannelDuplexHandler.close. Implements io.netty.channel.ChannelOutboundHandler.close. Doc from io.netty.channel.ChannelDuplexHandler.close. Calls `ChannelHandlerContext#close(ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Parameters ctx:ChannelHandlerContext Doc from io.netty.channel.ChannelOutboundHandler.close. the `ChannelHandlerContext` for which the close operation is made promise:ChannelPromise Doc from io.netty.channel.ChannelOutboundHandler.close. the `ChannelPromise` to notify once the operation completes Annotations @Override Exceptions Exception: Doc from io.netty.channel.ChannelOutboundHandler.close. thrown if an error occurs

public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception

Overrides io.netty.channel.ChannelDuplexHandler.close.

Implements io.netty.channel.ChannelOutboundHandler.close.

Doc from io.netty.channel.ChannelDuplexHandler.close.

Calls ChannelHandlerContext#close(ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Parameters

ctx:ChannelHandlerContext

Doc from io.netty.channel.ChannelOutboundHandler.close.

the ChannelHandlerContext for which the close operation is made

promise:ChannelPromise

Doc from io.netty.channel.ChannelOutboundHandler.close.

the ChannelPromise to notify once the operation completes

Annotations

@Override

Exceptions

Exception:

Doc from io.netty.channel.ChannelOutboundHandler.close.

thrown if an error occurs

disconnect back to summary

disconnect	back to summary
public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception Overrides io.netty.channel.ChannelDuplexHandler.disconnect. Implements io.netty.channel.ChannelOutboundHandler.disconnect. Doc from io.netty.channel.ChannelDuplexHandler.disconnect. Calls `ChannelHandlerContext#disconnect(ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Parameters ctx:ChannelHandlerContext Doc from io.netty.channel.ChannelOutboundHandler.disconnect. the `ChannelHandlerContext` for which the disconnect operation is made promise:ChannelPromise Doc from io.netty.channel.ChannelOutboundHandler.disconnect. the `ChannelPromise` to notify once the operation completes Annotations @Override Exceptions Exception: Doc from io.netty.channel.ChannelOutboundHandler.disconnect. thrown if an error occurs

public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception

Overrides io.netty.channel.ChannelDuplexHandler.disconnect.

Implements io.netty.channel.ChannelOutboundHandler.disconnect.

Doc from io.netty.channel.ChannelDuplexHandler.disconnect.

Calls ChannelHandlerContext#disconnect(ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Parameters

ctx:ChannelHandlerContext

Doc from io.netty.channel.ChannelOutboundHandler.disconnect.

the ChannelHandlerContext for which the disconnect operation is made

promise:ChannelPromise

Doc from io.netty.channel.ChannelOutboundHandler.disconnect.

the ChannelPromise to notify once the operation completes

Annotations

@Override

Exceptions

Exception:

Doc from io.netty.channel.ChannelOutboundHandler.disconnect.

thrown if an error occurs

exceptionCaught back to summary

exceptionCaught	back to summary
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception Overrides io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught. Implements io.netty.channel.ChannelHandler.exceptionCaught, io.netty.channel.ChannelInboundHandler.exceptionCaught. Doc from io.netty.channel.ChannelHandler.exceptionCaught. Gets called if a `Throwable` was thrown. Annotations @Override

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

Overrides io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught.

Implements io.netty.channel.ChannelHandler.exceptionCaught, io.netty.channel.ChannelInboundHandler.exceptionCaught.

Doc from io.netty.channel.ChannelHandler.exceptionCaught.

Gets called if a Throwable was thrown.

Annotations

@Override

flush back to summary

flush	back to summary
public void flush(ChannelHandlerContext ctx) throws Exception Overrides io.netty.channel.ChannelDuplexHandler.flush. Implements io.netty.channel.ChannelOutboundHandler.flush. Doc from io.netty.channel.ChannelDuplexHandler.flush. Calls `ChannelHandlerContext#flush()` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Parameters ctx:ChannelHandlerContext Doc from io.netty.channel.ChannelOutboundHandler.flush. the `ChannelHandlerContext` for which the flush operation is made Annotations @Override Exceptions Exception: Doc from io.netty.channel.ChannelOutboundHandler.flush. thrown if an error occurs

public void flush(ChannelHandlerContext ctx) throws Exception

Overrides io.netty.channel.ChannelDuplexHandler.flush.

Implements io.netty.channel.ChannelOutboundHandler.flush.

Doc from io.netty.channel.ChannelDuplexHandler.flush.

Calls ChannelHandlerContext#flush() to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Parameters

ctx:ChannelHandlerContext

Doc from io.netty.channel.ChannelOutboundHandler.flush.

the ChannelHandlerContext for which the flush operation is made

Annotations

@Override

Exceptions

Exception:

Doc from io.netty.channel.ChannelOutboundHandler.flush.

thrown if an error occurs

flushIfNeeded	back to summary
private void flushIfNeeded(ChannelHandlerContext ctx)

flushNow	back to summary
private void flushNow(ChannelHandlerContext ctx)

handlerAdded back to summary

handlerAdded	back to summary
public void handlerAdded(ChannelHandlerContext ctx) throws Exception Overrides io.netty.channel.ChannelHandlerAdapter.handlerAdded. Implements io.netty.channel.ChannelHandler.handlerAdded. Doc from io.netty.channel.ChannelHandler.handlerAdded. Gets called after the `ChannelHandler` was added to the actual context and it's ready to handle events. Annotations @Override

public void handlerAdded(ChannelHandlerContext ctx) throws Exception

Overrides io.netty.channel.ChannelHandlerAdapter.handlerAdded.

Implements io.netty.channel.ChannelHandler.handlerAdded.

Doc from io.netty.channel.ChannelHandler.handlerAdded.

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

Annotations

@Override

handlerRemoved back to summary

handlerRemoved	back to summary
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception Overrides io.netty.channel.ChannelHandlerAdapter.handlerRemoved. Implements io.netty.channel.ChannelHandler.handlerRemoved. Doc from io.netty.channel.ChannelHandler.handlerRemoved. Gets called after the `ChannelHandler` was removed from the actual context and it doesn't handle events anymore. Annotations @Override

public void handlerRemoved(ChannelHandlerContext ctx) throws Exception

Overrides io.netty.channel.ChannelHandlerAdapter.handlerRemoved.

Implements io.netty.channel.ChannelHandler.handlerRemoved.

Doc from io.netty.channel.ChannelHandler.handlerRemoved.

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

Annotations

@Override

resetReadAndFlushIfNeeded	back to summary
private void resetReadAndFlushIfNeeded(ChannelHandlerContext ctx)

scheduleFlush	back to summary
private void scheduleFlush(final ChannelHandlerContext ctx)

public Class FlushConsolidationHandler

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail