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() {









Nested Class Summary




static interface
AbstractBatchDecoder.Cumulator



          Cumulate ByteBufs.


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



Field Summary




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
AbstractBatchDecoder()



           
 



Method Summary




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 - 
msg - 
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