@Beta public class ErrorAwarePolicy extends Object implements ChainableLoadBalancingPolicy
ErrorAwarePolicy.ErrorFilter
to customize that logic.
The policy follows the builder pattern to be created, the ErrorAwarePolicy.Builder
class can be created with
builder(com.datastax.driver.core.policies.LoadBalancingPolicy)
method.
This policy is currently in BETA mode and its behavior might be changing throughout different driver versions.Modifier and Type | Class and Description |
---|---|
static class |
ErrorAwarePolicy.Builder
Utility class to create a
ErrorAwarePolicy . |
static interface |
ErrorAwarePolicy.ErrorFilter
A filter for the errors considered by
ErrorAwarePolicy . |
Modifier and Type | Method and Description |
---|---|
static ErrorAwarePolicy.Builder |
builder(LoadBalancingPolicy childPolicy)
Creates a new error aware policy builder given the child policy
that the resulting policy should wrap.
|
void |
close()
Gets invoked at cluster shutdown.
|
HostDistance |
distance(Host host)
Returns the distance assigned by this policy to the provided host.
|
LoadBalancingPolicy |
getChildPolicy()
Returns the child policy.
|
void |
init(Cluster cluster,
Collection<Host> hosts)
Initialize this load balancing policy.
|
Iterator<Host> |
newQueryPlan(String loggedKeyspace,
Statement statement)
Returns the hosts to use for a new query.
|
void |
onAdd(Host host)
Called when a new node is added to the cluster.
|
void |
onDown(Host host)
Called when a node is determined to be down.
|
void |
onRemove(Host host)
Called when a node is removed from the cluster.
|
void |
onUp(Host host)
Called when a node is determined to be up.
|
public LoadBalancingPolicy getChildPolicy()
ChainableLoadBalancingPolicy
getChildPolicy
in interface ChainableLoadBalancingPolicy
public void init(Cluster cluster, Collection<Host> hosts)
LoadBalancingPolicy
init
in interface LoadBalancingPolicy
cluster
- the Cluster
instance for which the policy is created.hosts
- the initial hosts to use.public HostDistance distance(Host host)
LoadBalancingPolicy
HostDistance
). A policy should assign a LOCAL
distance to nodes that are susceptible to be returned first by
newQueryPlan
and it is useless for newQueryPlan
to
return hosts to which it assigns an IGNORED
distance.
The host distance is primarily used to prevent keeping too many
connections to host in remote datacenters when the policy itself always
picks host in the local datacenter first.distance
in interface LoadBalancingPolicy
host
- the host of which to return the distance of.host
.public Iterator<Host> newQueryPlan(String loggedKeyspace, Statement statement)
LoadBalancingPolicy
Iterator
are down, the query
will fail.newQueryPlan
in interface LoadBalancingPolicy
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.public void onAdd(Host host)
LoadBalancingPolicy
onAdd
in interface LoadBalancingPolicy
host
- the host that has been newly added.public void onUp(Host host)
LoadBalancingPolicy
onUp
in interface LoadBalancingPolicy
host
- the host that has been detected up.public void onDown(Host host)
LoadBalancingPolicy
onDown
in interface LoadBalancingPolicy
host
- the host that has been detected down.public void onRemove(Host host)
LoadBalancingPolicy
onRemove
in interface LoadBalancingPolicy
host
- the removed host.public static ErrorAwarePolicy.Builder builder(LoadBalancingPolicy childPolicy)
childPolicy
- the load balancing policy to wrap with error
awareness.public void close()
LoadBalancingPolicy
close
in interface LoadBalancingPolicy
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