com.datastax.oss.driver.api.core.specex

Interface SpeculativeExecutionPolicy

All Superinterfaces:

AutoCloseable

public interface SpeculativeExecutionPolicy
extends AutoCloseable

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

Method Summary

Modifier and Type	Method and Description
void	close() Called when the cluster that this policy is associated with closes.
long	nextExecution(Node node, CqlIdentifier keyspace, Request request, int runningExecutions)

Method Detail

nextExecution

long nextExecution(@NonNull
                   Node node,
                   @Nullable
                   CqlIdentifier keyspace,
                   @NonNull
                   Request request,
                   int runningExecutions)

Parameters:

node - the node that caused the speculative execution (that is, the node that was queried previously but was too slow to answer)

keyspace - the CQL keyspace currently associated to the session. This is set either through the configuration, by calling SessionBuilder.withKeyspace(CqlIdentifier), or by manually executing a USE CQL statement. It can be null if the session has no keyspace.

request - the request to execute.

runningExecutions - the number of executions that are already running (including the initial, non-speculative request). For example, if this is 2 it means the initial attempt was sent, then the driver scheduled a first speculative execution, and it is now asking for the delay until the second speculative execution.

Returns:

the time (in milliseconds) until a speculative request is sent to the next node, or 0 to send it immediately, or a negative value to stop sending requests.

close

void close()

Called when the cluster that this policy is associated with closes.

Specified by:

close in interface AutoCloseable