Class TokenAwarePolicy

A wrapper load balancing policy that adds token awareness to a child policy.

This policy encapsulates another policy. The resulting policy works in the following way:

The Distance(Host) method is inherited from the child policy.
The host yielded by the NewQueryPlan(string, IStatement) method will first return the Local replicas for the statement, based on the RoutingKey.

Inheritance

object

TokenAwarePolicy

Implements

ILoadBalancingPolicy

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Cassandra

Assembly: Cassandra.dll

Syntax

public class TokenAwarePolicy : ILoadBalancingPolicy

Constructors

TokenAwarePolicy(ILoadBalancingPolicy)

Creates a new TokenAware policy that wraps the provided child load balancing policy.

Declaration

public TokenAwarePolicy(ILoadBalancingPolicy childPolicy)

Parameters

Type	Name	Description
ILoadBalancingPolicy	childPolicy	the load balancing policy to wrap with token awareness.

Properties

ChildPolicy

Declaration

public ILoadBalancingPolicy ChildPolicy { get; }

Property Value

Type	Description
ILoadBalancingPolicy

Methods

Distance(Host)

Return the HostDistance for the provided host.

Declaration

public HostDistance Distance(Host host)

Parameters

Type	Name	Description
Host	host	the host of which to return the distance of.

Returns

Type	Description
HostDistance	the HostDistance to `host` as returned by the wrapped policy.

Initialize(ICluster)

Initialize this load balancing policy.

Note that the driver guarantees that it will call this method exactly once per policy object and will do so before any call to another of the methods of the policy.

Declaration

public void Initialize(ICluster cluster)

Parameters

Type	Name	Description
ICluster	cluster	The information about the session instance for which the policy is created.

NewQueryPlan(string, IStatement)

Returns the hosts to use for a new query.

The returned plan will first return replicas (whose HostDistance for the child policy is Local) for the query if it can determine them (i.e. mainly if IStatement.RoutingKey is not null). Following what it will return the plan of the child policy.

Declaration

public IEnumerable<Host> NewQueryPlan(string loggedKeyspace, IStatement query)

Parameters

Type	Name	Description
string	loggedKeyspace	Keyspace on which the query is going to be executed
IStatement	query	the query for which to build the plan.

Returns

Type	Description
IEnumerable<Host>	the new query plan.

Implements

ILoadBalancingPolicy