org.apache.cassandra.net

Class FrameDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

org.apache.cassandra.net.FrameDecoder

All Implemented Interfaces:

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

Direct Known Subclasses:

FrameDecoderCrc, FrameDecoderLZ4

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

A Netty inbound handler that decodes incoming frames and passes them forward to InboundMessageHandler for processing. Handles work stashing, and together with InboundMessageHandler - flow control. Unlike most Netty inbound handlers, doesn't use the pipeline to talk to its upstream handler. Instead, a FrameDecoder.FrameProcessor must be registered with the frame decoder, to be invoked on new frames. See deliver(FrameProcessor). See activate(FrameProcessor), reactivate(), and FrameDecoder.FrameProcessor for flow control implementation. Five frame decoders currently exist, one used for each connection depending on flags and messaging version: 1. FrameDecoderCrc: no compression; payload is protected by CRC32 2. FrameDecoderLZ4: LZ4 compression with custom frame format; payload is protected by CRC32 3. FrameDecoderUnprotected: no compression; no integrity protection 4. FrameDecoderLegacy: no compression; no integrity protection; turns unframed streams of legacy messages (< 4.0) into frames 5. FrameDecoderLegacyLZ4 LZ4 compression using standard LZ4 frame format; groups legacy messages (< 4.0) into frames

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FrameDecoder.CorruptFrame A corrupted frame was encountered; this represents the knowledge we have about this frame, and whether or not the stream is recoverable.
static class	FrameDecoder.Frame
static interface	FrameDecoder.FrameProcessor
static class	FrameDecoder.IntactFrame The payload bytes of a complete frame, i.e.

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

io.netty.channel.ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
protected BufferPoolAllocator	allocator

Method Summary

Modifier and Type	Method and Description
void	activate(FrameDecoder.FrameProcessor processor) For use by InboundMessageHandler (or other upstream handlers) that want to start receiving frames.
void	channelInactive(io.netty.channel.ChannelHandlerContext ctx)
void	channelRead(io.netty.channel.ChannelHandlerContext ctx, java.lang.Object msg) Called by Netty pipeline when a new message arrives; we anticipate in normal operation this will receive messages of type BufferPoolAllocator.Wrapped or BufferPoolAllocator.Wrapped.
void	channelReadComplete(io.netty.channel.ChannelHandlerContext ctx)
void	discard() For use by InboundMessageHandler (or other upstream handlers) that want to permanently stop receiving frames, e.g.
void	handlerAdded(io.netty.channel.ChannelHandlerContext ctx)
boolean	isActive()
void	reactivate() For use by InboundMessageHandler (or other upstream handlers) that want to resume receiving frames after previously indicating that processing should be paused.

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerRemoved, 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

handlerRemoved

Field Detail

allocator

protected final BufferPoolAllocator allocator

Method Detail

isActive

public boolean isActive()

Returns:

true if we are actively decoding and processing frames

activate

public void activate(FrameDecoder.FrameProcessor processor)

For use by InboundMessageHandler (or other upstream handlers) that want to start receiving frames.

reactivate

public void reactivate()
                throws java.io.IOException

For use by InboundMessageHandler (or other upstream handlers) that want to resume receiving frames after previously indicating that processing should be paused.

Throws:

java.io.IOException

discard

public void discard()

For use by InboundMessageHandler (or other upstream handlers) that want to permanently stop receiving frames, e.g. because of an exception caught.

channelRead

public void channelRead(io.netty.channel.ChannelHandlerContext ctx,
                        java.lang.Object msg)
                 throws java.io.IOException

Called by Netty pipeline when a new message arrives; we anticipate in normal operation this will receive messages of type BufferPoolAllocator.Wrapped or BufferPoolAllocator.Wrapped. These buffers are unwrapped and passed to decode(Collection, ShareableBytes), which collects decoded frames into frames, which we send upstream in deliver(org.apache.cassandra.net.FrameDecoder.FrameProcessor)

Specified by:

channelRead in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelRead in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

java.io.IOException

channelReadComplete

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

Specified by:

channelReadComplete in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelReadComplete in class io.netty.channel.ChannelInboundHandlerAdapter

handlerAdded

public void handlerAdded(io.netty.channel.ChannelHandlerContext ctx)

Specified by:

handlerAdded in interface io.netty.channel.ChannelHandler

Overrides:

handlerAdded in class io.netty.channel.ChannelHandlerAdapter

channelInactive

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

Specified by:

channelInactive in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelInactive in class io.netty.channel.ChannelInboundHandlerAdapter