com.alipay.remoting.codec

Class AbstractBatchDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

com.alipay.remoting.codec.AbstractBatchDecoder

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundHandler

Direct Known Subclasses:

ProtocolCodeBasedDecoder

public abstract class AbstractBatchDecoder
extends io.netty.channel.ChannelInboundHandlerAdapter

This class mainly hack the ByteToMessageDecoder to provide batch submission capability. This can be used the same way as ByteToMessageDecoder except the case your following inbound handler may get a decoded msg, which actually is an array list, then you can submit the list of msgs to an executor to process. For example

   if (msg instanceof List) {
       processorManager.getDefaultExecutor().execute(new Runnable() {
           public void run() {
               // batch submit to an executor
               for (Object m : (List) msg) {
                   RpcCommandHandler.this.process(ctx, m);
               }
           }
       });
   } else {
       process(ctx, msg);
   }
 

You can check the method channelRead(ChannelHandlerContext, Object) ()} to know the detail modification.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AbstractBatchDecoder.Cumulator Cumulate ByteBufs.

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

io.netty.channel.ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
static AbstractBatchDecoder.Cumulator	COMPOSITE_CUMULATOR Cumulate ByteBufs by add them to a CompositeByteBuf and so do no memory copy whenever possible.
static AbstractBatchDecoder.Cumulator	MERGE_CUMULATOR Cumulate ByteBufs by merge them into one ByteBuf's, using memory copies.

Constructor Summary

Constructors

Constructor and Description
AbstractBatchDecoder()

Method Summary

Modifier and Type	Method and Description
protected int	actualReadableBytes() Returns the actual number of readable bytes in the internal cumulative buffer of this decoder.
protected void	callDecode(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in, List<Object> out) Called once data should be decoded from the given ByteBuf.
void	channelInactive(io.netty.channel.ChannelHandlerContext ctx)
void	channelRead(io.netty.channel.ChannelHandlerContext ctx, Object msg) This method has been modified to check the size of decoded msgs, which is represented by the local variable RecyclableArrayList out.
void	channelReadComplete(io.netty.channel.ChannelHandlerContext ctx)
protected abstract void	decode(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in, List<Object> out) Decode the from one ByteBuf to an other.
protected void	decodeLast(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in, List<Object> out) Is called one last time when the ChannelHandlerContext goes in-active.
protected void	discardSomeReadBytes()
void	handlerRemoved(io.netty.channel.ChannelHandlerContext ctx)
protected void	handlerRemoved0(io.netty.channel.ChannelHandlerContext ctx) Gets called after the ByteToMessageDecoder was removed from the actual context and it doesn't handle events anymore.
protected io.netty.buffer.ByteBuf	internalBuffer() Returns the internal cumulative buffer of this decoder.
boolean	isSingleDecode() If true then only one message is decoded on each channelRead(ChannelHandlerContext, Object) call.
void	setCumulator(AbstractBatchDecoder.Cumulator cumulator) Set the AbstractBatchDecoder.Cumulator to use for cumulate the received ByteBufs.
void	setDiscardAfterReads(int discardAfterReads) Set the number of reads after which ByteBuf.discardSomeReadBytes() are called and so free up memory.
void	setSingleDecode(boolean singleDecode) If set then only one message is decoded on each channelRead(ChannelHandlerContext, Object) call.

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.netty.channel.ChannelHandler

handlerAdded

Field Detail

MERGE_CUMULATOR

public static final AbstractBatchDecoder.Cumulator MERGE_CUMULATOR

Cumulate ByteBufs by merge them into one ByteBuf's, using memory copies.

COMPOSITE_CUMULATOR

public static final AbstractBatchDecoder.Cumulator COMPOSITE_CUMULATOR

Cumulate ByteBufs by add them to a CompositeByteBuf and so do no memory copy whenever possible. Be aware that CompositeByteBuf use a more complex indexing implementation so depending on your use-case and the decoder implementation this may be slower then just use the MERGE_CUMULATOR.

Constructor Detail

AbstractBatchDecoder

public AbstractBatchDecoder()

Method Detail

setSingleDecode

public void setSingleDecode(boolean singleDecode)

If set then only one message is decoded on each channelRead(ChannelHandlerContext, Object) call. This may be useful if you need to do some protocol upgrade and want to make sure nothing is mixed up. Default is false as this has performance impacts.

isSingleDecode

public boolean isSingleDecode()

If true then only one message is decoded on each channelRead(ChannelHandlerContext, Object) call. Default is false as this has performance impacts.

setCumulator

public void setCumulator(AbstractBatchDecoder.Cumulator cumulator)

Set the AbstractBatchDecoder.Cumulator to use for cumulate the received ByteBufs.

setDiscardAfterReads

public void setDiscardAfterReads(int discardAfterReads)

Set the number of reads after which ByteBuf.discardSomeReadBytes() are called and so free up memory. The default is 16.

actualReadableBytes

protected int actualReadableBytes()

Returns the actual number of readable bytes in the internal cumulative buffer of this decoder. You usually do not need to rely on this value to write a decoder. Use it only when you must use it at your own risk. This method is a shortcut to internalBuffer().readableBytes().

internalBuffer

protected io.netty.buffer.ByteBuf internalBuffer()

Returns the internal cumulative buffer of this decoder. You usually do not need to access the internal buffer directly to write a decoder. Use it only when you must use it at your own risk.

handlerRemoved

public final void handlerRemoved(io.netty.channel.ChannelHandlerContext ctx)
                          throws Exception

Specified by:

handlerRemoved in interface io.netty.channel.ChannelHandler

Overrides:

handlerRemoved in class io.netty.channel.ChannelHandlerAdapter

Throws:

Exception

handlerRemoved0

protected void handlerRemoved0(io.netty.channel.ChannelHandlerContext ctx)
                        throws Exception

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

Throws:

Exception

channelRead

public void channelRead(io.netty.channel.ChannelHandlerContext ctx,
                        Object msg)
                 throws Exception

This method has been modified to check the size of decoded msgs, which is represented by the local variable RecyclableArrayList out. If has decoded more than one msg, then construct an array list to submit all decoded msgs to the pipeline.

Specified by:

channelRead in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelRead in class io.netty.channel.ChannelInboundHandlerAdapter

Parameters:

ctx - channel handler context

msg - data

Throws:

Exception

channelReadComplete

public void channelReadComplete(io.netty.channel.ChannelHandlerContext ctx)
                         throws Exception

Specified by:

channelReadComplete in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelReadComplete in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

discardSomeReadBytes

protected final void discardSomeReadBytes()

channelInactive

public void channelInactive(io.netty.channel.ChannelHandlerContext ctx)
                     throws Exception

Specified by:

channelInactive in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelInactive in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

callDecode

protected void callDecode(io.netty.channel.ChannelHandlerContext ctx,
                          io.netty.buffer.ByteBuf in,
                          List<Object> out)

Called once data should be decoded from the given ByteBuf. This method will call decode(ChannelHandlerContext, ByteBuf, List) as long as decoding should take place.

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

out - the List to which decoded messages should be added

decodeLast

protected void decodeLast(io.netty.channel.ChannelHandlerContext ctx,
                          io.netty.buffer.ByteBuf in,
                          List<Object> out)
                   throws Exception

Is called one last time when the ChannelHandlerContext goes in-active. Which means the channelInactive(ChannelHandlerContext) was triggered. By default this will just call decode(ChannelHandlerContext, ByteBuf, List) but sub-classes may override this for some special cleanup operation.

Throws:

Exception

decode

protected abstract void decode(io.netty.channel.ChannelHandlerContext ctx,
                               io.netty.buffer.ByteBuf in,
                               List<Object> out)
                        throws Exception

Decode the from one ByteBuf to an other. This method will be called till either the input ByteBuf has nothing to read when return from this method or till nothing was read from the input ByteBuf.

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

out - the List to which decoded messages should be added

Throws:

Exception - is thrown if an error accour