Interface IRetryPolicy

A policy that defines a default behavior to adopt when a request returns a TimeoutException or an UnavailableException. Such policy allows to centralize the handling of query retries, allowing to minimize the need for exception catching/handling in business code.

Namespace: Cassandra

Assembly: Cassandra.dll

Syntax

public interface IRetryPolicy

Methods

OnReadTimeout(IStatement, ConsistencyLevel, int, int, bool, int)

Defines whether to retry and at which consistency level on a read timeout.

Note that this method may be called even if requiredResponses >= receivedResponses if dataPresent is false (see com.datastax.driver.core.exceptions.ReadTimeoutException#WasDataRetrieved).

Declaration

RetryDecision OnReadTimeout(IStatement query, ConsistencyLevel cl, int requiredResponses, int receivedResponses, bool dataRetrieved, int nbRetry)

Parameters

Type	Name	Description
IStatement	query	the original query that timeouted.
ConsistencyLevel	cl	the original consistency level of the read that timeouted.
int	requiredResponses	the number of responses that were required to achieve the requested consistency level.
int	receivedResponses	the number of responses that had been received by the time the timeout exception was raised.
bool	dataRetrieved	whether actual data (by opposition to data checksum) was present in the received responses.
int	nbRetry	the number of retry already performed for this operation.

Returns

Type	Description
RetryDecision	the retry decision. If RetryDecision.Rethrow is returned, a com.datastax.driver.core.exceptions.ReadTimeoutException will be thrown for the operation.

OnUnavailable(IStatement, ConsistencyLevel, int, int, int)

Defines whether to retry and at which consistency level on an unavailable exception.

Declaration

RetryDecision OnUnavailable(IStatement query, ConsistencyLevel cl, int requiredReplica, int aliveReplica, int nbRetry)

Parameters

Type	Name	Description
IStatement	query	the original query for which the consistency level cannot be achieved.
ConsistencyLevel	cl	the original consistency level for the operation.
int	requiredReplica	the number of replica that should have been (known) alive for the operation to be attempted.
int	aliveReplica	the number of replica that were know to be alive by the coordinator of the operation.
int	nbRetry	the number of retry already performed for this operation.

Returns

Type	Description
RetryDecision	the retry decision. If RetryDecision.Rethrow is returned, an com.datastax.driver.core.exceptions.UnavailableException will be thrown for the operation.

OnWriteTimeout(IStatement, ConsistencyLevel, string, int, int, int)

Defines whether to retry and at which consistency level on a write timeout.

Declaration

RetryDecision OnWriteTimeout(IStatement query, ConsistencyLevel cl, string writeType, int requiredAcks, int receivedAcks, int nbRetry)

Parameters

Type	Name	Description
IStatement	query	the original query that timeouted.
ConsistencyLevel	cl	the original consistency level of the write that timeouted.
string	writeType	the type of the write that timeouted.
int	requiredAcks	the number of acknowledgments that were required to achieve the requested consistency level.
int	receivedAcks	the number of acknowledgments that had been received by the time the timeout exception was raised.
int	nbRetry	the number of retry already performed for this operation.

Returns

Type	Description
RetryDecision	the retry decision. If RetryDecision.Rethrow is returned, a com.datastax.driver.core.exceptions.WriteTimeoutException will be thrown for the operation.