com.datastax.driver.core.policies

Interface SpeculativeExecutionPolicy

All Known Implementing Classes:

ConstantSpeculativeExecutionPolicy, NoSpeculativeExecutionPolicy, PercentileSpeculativeExecutionPolicy

public interface SpeculativeExecutionPolicy

The policy that decides if the driver will send speculative queries to the next hosts when the current host takes too long to respond.

Note that only idempotent statements will be speculatively retried, see Statement.isIdempotent() for more information.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	SpeculativeExecutionPolicy.SpeculativeExecutionPlan A plan that governs speculative executions for a given query.

Method Summary

Modifier and Type	Method and Description
void	close() Gets invoked at cluster shutdown.
void	init(Cluster cluster) Gets invoked at cluster startup.
SpeculativeExecutionPolicy.SpeculativeExecutionPlan	newPlan(String loggedKeyspace, Statement statement) Returns the plan to use for a new query.

Method Detail

init

void init(Cluster cluster)

Gets invoked at cluster startup.

Parameters:

cluster - the cluster that this policy is associated with.

newPlan

SpeculativeExecutionPolicy.SpeculativeExecutionPlan newPlan(String loggedKeyspace,
                                                            Statement statement)

Returns the plan to use for a new query.

Parameters:

loggedKeyspace - the currently logged keyspace (the one set through either Cluster.connect(String) or by manually doing a USE query) for the session on which this plan need to be built. This can be null if the corresponding session has no keyspace logged in.

statement - the query for which to build a plan.

Returns:

the plan.

close

void close()

Gets invoked at cluster shutdown.

This gives the policy the opportunity to perform some cleanup, for instance stop threads that it might have started.