| TokenAwarePolicy Class |
This policy encapsulates another policy. The resulting policy works in the following way:
- the distance method is inherited from the child policy.
- the iterator return by the newQueryPlan method will first return the LOCAL replicas for the query (based on Statement.GetRoutingKey) if possible (i.e. if the query getRoutingKey method doesn't return null and if GetReplicas(String, Byte) returns a non empty set of replicas for that partition key). If no local replica can be either found or successfully contacted, the rest of the query plan will fallback to one of the child policy.
Do note that only replica for which the child policy distance method returns HostDistance.Local will be considered having priority. For example, if you wrap DCAwareRoundRobinPolicy with this token aware policy, replicas from remote data centers may only be returned after all the host of the local data center.
Inheritance HierarchyCassandraTokenAwarePolicy
Namespace: Cassandra
Assembly: Cassandra (in Cassandra.dll) Version: 3.0.9 (git 5ca22bb)
Syntaxpublic class TokenAwarePolicy : ILoadBalancingPolicy
The TokenAwarePolicy type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | TokenAwarePolicy |
Creates a new TokenAware policy that wraps the provided child
load balancing policy.
|
Methods| Name | Description | |
|---|---|---|
| Distance |
Return the HostDistance for the provided host.
|
| Initialize | |
| NewQueryPlan |
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. |
See Also