Module io.netty5.handler

Package io.netty5.handler.stream

Class ChunkedWriteHandler

java.lang.Object

io.netty5.handler.stream.ChunkedWriteHandler

All Implemented Interfaces:

ChannelHandler

public class ChunkedWriteHandler
extends Object
implements ChannelHandler

A ChannelHandler that adds support for writing a large data stream asynchronously neither spending a lot of memory nor getting OutOfMemoryError. Large data streaming such as file transfer requires complicated state management in a ChannelHandler implementation. ChunkedWriteHandler manages such complicated states so that you can send a large data stream without difficulties.

To use ChunkedWriteHandler in your application, you have to insert a new ChunkedWriteHandler instance:

 ChannelPipeline p = ...;
 p.addLast("streamer", new ChunkedWriteHandler());
 p.addLast("handler", new MyHandler());
 

Once inserted, you can write a ChunkedInput so that the ChunkedWriteHandler can pick it up and fetch the content of the stream chunk by chunk and write the fetched chunk downstream:

 Channel ch = ...;
 ch.write(new ChunkedFile(new File("video.mkv"));
 

Sending a stream which generates a chunk intermittently

Some ChunkedInput generates a chunk on a certain event or timing. Such ChunkedInput implementation often returns null on ChunkedInput.readChunk(BufferAllocator), resulting in the indefinitely suspended transfer. To resume the transfer when a new chunk is available, you have to call resumeTransfer().

Constructor Summary

Constructors

Constructor	Description
ChunkedWriteHandler()
ChunkedWriteHandler(int maxPendingWrites)	Deprecated. use ChunkedWriteHandler()

Method Summary

Modifier and Type	Method	Description
void	channelInactive(ChannelHandlerContext ctx)	The Channel of the ChannelHandlerContext was registered is now inactive and reached its end of lifetime.
void	channelWritabilityChanged(ChannelHandlerContext ctx)	Gets called once the writable state of a Channel changed.
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	resumeTransfer()	Continues to fetch the chunks from the input.
Future<Void>	write(ChannelHandlerContext ctx, Object msg)	Called once a write operation is made.

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, channelExceptionCaught, channelInboundEvent, channelRead, channelReadComplete, channelRegistered, channelShutdown, channelUnregistered, close, connect, deregister, disconnect, handlerRemoved, isSharable, pendingOutboundBytes, read, register, sendOutboundEvent, shutdown

Constructor Detail

ChunkedWriteHandler

public ChunkedWriteHandler()

ChunkedWriteHandler

@Deprecated
public ChunkedWriteHandler(int maxPendingWrites)

Deprecated.

use ChunkedWriteHandler()

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

resumeTransfer

public void resumeTransfer()

Continues to fetch the chunks from the input.

write

public Future<Void> write(ChannelHandlerContext ctx,
                          Object msg)

Description copied from interface: ChannelHandler

Called once a write operation is made. The write operation will write the messages through the ChannelPipeline. Those are then ready to be flushed to the actual Channel once Channel.flush() is called.

Specified by:

write in interface ChannelHandler

Parameters:

ctx - the ChannelHandlerContext for which the write operation is made

msg - the message to write

Returns:

the Future which will be notified once the operation completes.

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

channelInactive

public void channelInactive(ChannelHandlerContext ctx)
                     throws Exception

Description copied from interface: ChannelHandler

The Channel of the ChannelHandlerContext was registered is now inactive and reached its end of lifetime.

Specified by:

channelInactive in interface ChannelHandler

Throws:

Exception

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