org.apache.cassandra.service
Class ReadCallback<T>

java.lang.Object
  org.apache.cassandra.service.ReadCallback<T>

All Implemented Interfaces:

IAsyncCallback, IMessageCallback

Direct Known Subclasses:

DatacenterReadCallback

public class ReadCallback<T>
extends java.lang.Object
implements IAsyncCallback

Field Summary

protected int	blockfor
protected SimpleCondition	condition
protected static java.lang.String	localdc
protected static org.slf4j.Logger	logger
protected java.util.concurrent.atomic.AtomicInteger	received
IResponseResolver<T>	resolver
protected static IEndpointSnitch	snitch

Constructor Summary

ReadCallback(IResponseResolver<T> resolver, org.apache.cassandra.thrift.ConsistencyLevel consistencyLevel, IReadCommand command, java.util.List<java.net.InetAddress> endpoints)
Constructor when response count has to be calculated and blocked for.

Method Summary

void	assureSufficientLiveNodes()
int	determineBlockFor(org.apache.cassandra.thrift.ConsistencyLevel consistencyLevel, java.lang.String table)
T	get()
boolean	isLatencyForSnitch()
protected void	maybeResolveForRepair() Check digests in the background on the Repair stage if we've received replies too all the requests we sent.
void	response(Message message)
void	response(ReadResponse result)
protected void	sortForConsistencyLevel(java.util.List<java.net.InetAddress> endpoints) Endpoints is already restricted to live replicas, sorted by snitch preference.
protected boolean	waitingFor(Message message)
protected boolean	waitingFor(ReadResponse response)

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final org.slf4j.Logger logger

snitch

protected static final IEndpointSnitch snitch

localdc

protected static final java.lang.String localdc

resolver

public final IResponseResolver<T> resolver

condition

protected final SimpleCondition condition

blockfor

protected final int blockfor

received

protected final java.util.concurrent.atomic.AtomicInteger received

Constructor Detail

ReadCallback

public ReadCallback(IResponseResolver<T> resolver,
                    org.apache.cassandra.thrift.ConsistencyLevel consistencyLevel,
                    IReadCommand command,
                    java.util.List<java.net.InetAddress> endpoints)

Constructor when response count has to be calculated and blocked for.

Method Detail

sortForConsistencyLevel

protected void sortForConsistencyLevel(java.util.List<java.net.InetAddress> endpoints)

Endpoints is already restricted to live replicas, sorted by snitch preference. This is a hook for DatacenterReadCallback to move local-DC replicas to the front of the list. We need this both when doing read repair (because the first replica gets the data read) and otherwise (because only the first 1..blockfor replicas will get digest reads).

get

public T get()
      throws java.util.concurrent.TimeoutException,
             DigestMismatchException,
             java.io.IOException

Throws:

java.util.concurrent.TimeoutException

DigestMismatchException

java.io.IOException

response

public void response(Message message)

Specified by:

response in interface IAsyncCallback

Parameters:

message - response received.

waitingFor

protected boolean waitingFor(Message message)

Returns:

true if the message counts towards the blockfor threshold TODO turn the Message into a response so we don't need two versions of this method

waitingFor

protected boolean waitingFor(ReadResponse response)

Returns:

true if the response counts towards the blockfor threshold

response

public void response(ReadResponse result)

maybeResolveForRepair

protected void maybeResolveForRepair()

Check digests in the background on the Repair stage if we've received replies too all the requests we sent.

determineBlockFor

public int determineBlockFor(org.apache.cassandra.thrift.ConsistencyLevel consistencyLevel,
                             java.lang.String table)

assureSufficientLiveNodes

public void assureSufficientLiveNodes()
                               throws org.apache.cassandra.thrift.UnavailableException

Throws:

org.apache.cassandra.thrift.UnavailableException

isLatencyForSnitch

public boolean isLatencyForSnitch()

Specified by:

isLatencyForSnitch in interface IMessageCallback

Returns:

true if this callback is on the read path and its latency should be given as input to the dynamic snitch.