org.apache.cassandra.service.reads

Class AbstractReadExecutor

java.lang.Object

org.apache.cassandra.service.reads.AbstractReadExecutor

Direct Known Subclasses:

AbstractReadExecutor.NeverSpeculatingReadExecutor

public abstract class AbstractReadExecutor
extends java.lang.Object

Sends a read request to the replicas needed to satisfy a given ConsistencyLevel. Optionally, may perform additional requests to provide redundancy against replica failure: AlwaysSpeculatingReadExecutor will always send a request to one extra replica, while SpeculatingReadExecutor will wait until it looks like the original request is in danger of timing out before performing extra reads.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractReadExecutor.NeverSpeculatingReadExecutor

Field Summary

Fields

Modifier and Type	Field and Description
protected ColumnFamilyStore	cfs
protected ReadCommand	command
protected DigestResolver<EndpointsForToken,ReplicaPlan.ForTokenRead>	digestResolver
protected ReadCallback<EndpointsForToken,ReplicaPlan.ForTokenRead>	handler
protected long	queryStartNanoTime
protected ReadRepair<EndpointsForToken,ReplicaPlan.ForTokenRead>	readRepair
protected PartitionIterator	result
protected TraceState	traceState

Method Summary

Modifier and Type	Method and Description
void	awaitReadRepair()
void	awaitResponses() Wait for the CL to be satisfied by responses
void	executeAsync() send the initial set of requests
DecoratedKey	getKey()
static AbstractReadExecutor	getReadExecutor(SinglePartitionReadCommand command, ConsistencyLevel consistencyLevel, long queryStartNanoTime)
ReadRepair<EndpointsForToken,ReplicaPlan.ForTokenRead>	getReadRepair()
PartitionIterator	getResult()
protected void	makeDigestRequests(java.lang.Iterable<Replica> replicas)
protected void	makeFullDataRequests(ReplicaCollection<?> replicas)
protected void	makeTransientDataRequests(java.lang.Iterable<Replica> replicas)
void	maybeSendAdditionalDataRequests()
abstract void	maybeTryAdditionalReplicas() Perform additional requests if it looks like the original will time out.
void	setResult(PartitionIterator result)

Methods inherited from class java.lang.Object

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

Field Detail

command

protected final ReadCommand command

readRepair

protected final ReadRepair<EndpointsForToken,ReplicaPlan.ForTokenRead> readRepair

digestResolver

protected final DigestResolver<EndpointsForToken,ReplicaPlan.ForTokenRead> digestResolver

handler

protected final ReadCallback<EndpointsForToken,ReplicaPlan.ForTokenRead> handler

traceState

protected final TraceState traceState

cfs

protected final ColumnFamilyStore cfs

queryStartNanoTime

protected final long queryStartNanoTime

result

protected volatile PartitionIterator result

Method Detail

getKey

public DecoratedKey getKey()

getReadRepair

public ReadRepair<EndpointsForToken,ReplicaPlan.ForTokenRead> getReadRepair()

makeFullDataRequests

protected void makeFullDataRequests(ReplicaCollection<?> replicas)

makeTransientDataRequests

protected void makeTransientDataRequests(java.lang.Iterable<Replica> replicas)

makeDigestRequests

protected void makeDigestRequests(java.lang.Iterable<Replica> replicas)

maybeTryAdditionalReplicas

public abstract void maybeTryAdditionalReplicas()

Perform additional requests if it looks like the original will time out. May block while it waits to see if the original requests are answered first.

executeAsync

public void executeAsync()

send the initial set of requests

getReadExecutor

public static AbstractReadExecutor getReadExecutor(SinglePartitionReadCommand command,
                                                   ConsistencyLevel consistencyLevel,
                                                   long queryStartNanoTime)
                                            throws UnavailableException

Returns:

an executor appropriate for the configured speculative read policy

Throws:

UnavailableException

setResult

public void setResult(PartitionIterator result)

awaitResponses

public void awaitResponses()
                    throws ReadTimeoutException

Wait for the CL to be satisfied by responses

Throws:

ReadTimeoutException

awaitReadRepair

public void awaitReadRepair()
                     throws ReadTimeoutException

Throws:

ReadTimeoutException

maybeSendAdditionalDataRequests

public void maybeSendAdditionalDataRequests()

getResult

public PartitionIterator getResult()
                            throws ReadFailureException,
                                   ReadTimeoutException

Throws:

ReadFailureException

ReadTimeoutException