org.apache.cassandra.transport

Class CQLMessageHandler<M extends Message>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

org.apache.cassandra.net.AbstractMessageHandler

org.apache.cassandra.transport.CQLMessageHandler<M>

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundHandler, FrameDecoder.FrameProcessor

public class CQLMessageHandler<M extends Message>
extends AbstractMessageHandler

Implementation of AbstractMessageHandler for processing CQL messages which comprise a Message wrapped in an Envelope. This class is parameterized by a Message subtype, expected to be either Message.Request or Message.Response. Most commonly, an instance for handling Message.Request is created for each inbound CQL client connection. # Small vs large messages Small messages are deserialized in place, and then handed off to a consumer for processing. Large messages accumulate frames until all bytes for the envelope are received, then concatenate and deserialize the frames on the event loop thread and pass them on to the same consumer. # Flow control (backpressure) The size of an incoming message is explicit in the Envelope.Header. By default, every connection has 1MiB of exlusive permits available before needing to access the per-endpoint and global reserves. By default, those reserves are sized proportionally to the heap - 2.5% of heap per-endpoint and a 10% for the global reserve. Permits are held while CQL messages are processed and released after the response has been encoded into the buffers of the response frame. A connection level option (THROW_ON_OVERLOAD) allows clients to choose the backpressure strategy when a connection has exceeded the maximum number of allowed permits. The choices are to either pause reads from the incoming socket and allow TCP backpressure to do the work, or to throw an explict exception and rely on the client to back off.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.cassandra.net.AbstractMessageHandler

AbstractMessageHandler.OnHandlerClosed, AbstractMessageHandler.WaitQueue

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 int	LARGE_MESSAGE_THRESHOLD

Fields inherited from class org.apache.cassandra.net.AbstractMessageHandler

channel, corruptFramesRecovered, corruptFramesUnrecovered, decoder, endpointReserveCapacity, endpointWaitQueue, globalReserveCapacity, globalWaitQueue, largeMessage, largeThreshold, onClosed, queueCapacity, receivedBytes, receivedCount, throttledCount, throttledNanos

Method Summary

Modifier and Type	Method and Description
protected void	fatalExceptionCaught(java.lang.Throwable cause)
protected java.lang.String	id()
boolean	process(FrameDecoder.Frame frame) Frame processor that the frames should be handed off to.
protected void	processCorruptFrame(FrameDecoder.CorruptFrame frame)
protected boolean	processFirstFrameOfLargeMessage(FrameDecoder.IntactFrame frame, ResourceLimits.Limit endpointReserve, ResourceLimits.Limit globalReserve)
protected boolean	processOneContainedMessage(ShareableBytes bytes, ResourceLimits.Limit endpointReserve, ResourceLimits.Limit globalReserve)
protected boolean	processRequest(Envelope request)

Methods inherited from class org.apache.cassandra.net.AbstractMessageHandler

acquireCapacity, acquireCapacity, channelInactive, channelRead, handlerAdded, processSubsequentFrameOfLargeMessage, releaseCapacity, releaseProcessedCapacity

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelReadComplete, 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

LARGE_MESSAGE_THRESHOLD

public static final int LARGE_MESSAGE_THRESHOLD

See Also:

Constant Field Values

Method Detail

process

public boolean process(FrameDecoder.Frame frame)
                throws java.io.IOException

Description copied from interface: FrameDecoder.FrameProcessor

Frame processor that the frames should be handed off to.

Specified by:

process in interface FrameDecoder.FrameProcessor

Overrides:

process in class AbstractMessageHandler

Returns:

true if more frames can be taken by the processor, false if the decoder should pause until it's explicitly resumed.

Throws:

java.io.IOException

processOneContainedMessage

protected boolean processOneContainedMessage(ShareableBytes bytes,
                                             ResourceLimits.Limit endpointReserve,
                                             ResourceLimits.Limit globalReserve)

Specified by:

processOneContainedMessage in class AbstractMessageHandler

processRequest

protected boolean processRequest(Envelope request)

processFirstFrameOfLargeMessage

protected boolean processFirstFrameOfLargeMessage(FrameDecoder.IntactFrame frame,
                                                  ResourceLimits.Limit endpointReserve,
                                                  ResourceLimits.Limit globalReserve)
                                           throws java.io.IOException

Specified by:

processFirstFrameOfLargeMessage in class AbstractMessageHandler

Throws:

java.io.IOException

id

protected java.lang.String id()

Specified by:

id in class AbstractMessageHandler

processCorruptFrame

protected void processCorruptFrame(FrameDecoder.CorruptFrame frame)

Specified by:

processCorruptFrame in class AbstractMessageHandler

fatalExceptionCaught

protected void fatalExceptionCaught(java.lang.Throwable cause)

Specified by:

fatalExceptionCaught in class AbstractMessageHandler