com.datastax.driver.core

Class DelegatingCluster

java.lang.Object

com.datastax.driver.core.Cluster

com.datastax.driver.core.DelegatingCluster

All Implemented Interfaces:

Closeable, AutoCloseable

public abstract class DelegatingCluster
extends Cluster

Base class for custom Cluster implementations that wrap another instance (delegate / decorator pattern).

Nested Class Summary

Nested classes/interfaces inherited from class com.datastax.driver.core.Cluster

Cluster.Builder, Cluster.Initializer

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DelegatingCluster() Builds a new instance.

Method Summary

Modifier and Type	Method and Description
void	close() Initiates a shutdown of this cluster instance and blocks until that shutdown completes.
CloseFuture	closeAsync() Initiates a shutdown of this cluster instance.
Session	connect() Creates a new session on this cluster and initialize it.
Session	connect(String keyspace) Creates a new session on this cluster, initialize it and sets the keyspace to the provided one.
protected abstract Cluster	delegate() Returns the delegate instance where all calls will be forwarded.
Configuration	getConfiguration() The cluster configuration.
Metadata	getMetadata() Returns read-only metadata on the connected cluster.
Metrics	getMetrics() The cluster metrics.
Cluster	init() Initialize this Cluster instance.
boolean	isClosed() Whether this Cluster instance has been closed.
Session	newSession() Creates a new session on this cluster but does not initialize it.
Cluster	register(Host.StateListener listener) Registers the provided listener to be notified on hosts up/down/added/removed events.
Cluster	register(LatencyTracker tracker) Registers the provided tracker to be updated with hosts read latencies.
Cluster	unregister(Host.StateListener listener) Unregisters the provided listener from being notified on hosts events.
Cluster	unregister(LatencyTracker tracker) Unregisters the provided latency tracking from being updated with host read latencies.

Methods inherited from class com.datastax.driver.core.Cluster

builder, buildFrom, getClusterName, getDriverVersion

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DelegatingCluster

protected DelegatingCluster()

Builds a new instance.

Method Detail

delegate

protected abstract Cluster delegate()

Returns the delegate instance where all calls will be forwarded.

Returns:

the delegate.

init

public Cluster init()

Description copied from class: Cluster

Initialize this Cluster instance. This method creates an initial connection to one of the contact points used to construct the Cluster instance. That connection is then used to populate the cluster Metadata.

Calling this method is optional in the sense that any call to one of the connect methods of this object will automatically trigger a call to this method beforehand. It is thus only useful to call this method if for some reason you want to populate the metadata (or test that at least one contact point can be reached) without creating a first Session.

Please note that this method only creates one control connection for gathering cluster metadata. In particular, it doesn't create any connection pools. Those are created when a new Session is created through connect.

This method has no effect if the cluster is already initialized.

Overrides:

init in class Cluster

Returns:

this Cluster object.

newSession

public Session newSession()

Description copied from class: Cluster

Creates a new session on this cluster but does not initialize it.

Because this method does not perform any initialization, it cannot fail. The initialization of the session (the connection of the Session to the Cassandra nodes) will occur if either the Session.init() method is called explicitly, or whenever the returned session object is used.

Once a session returned by this method gets initialized (see above), it will be set to no keyspace. If you want to set such session to a keyspace, you will have to explicitly execute a 'USE mykeyspace' query.

Note that if you do not particularly need to defer initialization, it is simpler to use one of the connect() method of this class.

Overrides:

newSession in class Cluster

Returns:

a new, non-initialized session on this cluster.

connect

public Session connect()

Description copied from class: Cluster

Creates a new session on this cluster and initialize it.

Note that this method will initialize the newly created session, trying to connect to the Cassandra nodes before returning. If you only want to create a Session object without initializing it right away, see Cluster.newSession().

Overrides:

connect in class Cluster

Returns:

a new session on this cluster sets to no keyspace.

connect

public Session connect(String keyspace)

Description copied from class: Cluster

Creates a new session on this cluster, initialize it and sets the keyspace to the provided one.

Note that this method will initialize the newly created session, trying to connect to the Cassandra nodes before returning. If you only want to create a Session object without initializing it right away, see Cluster.newSession().

Overrides:

connect in class Cluster

Parameters:

keyspace - The name of the keyspace to use for the created Session.

Returns:

a new session on this cluster sets to keyspace keyspaceName.

getMetadata

public Metadata getMetadata()

Description copied from class: Cluster

Returns read-only metadata on the connected cluster.

This includes the known nodes with their status as seen by the driver, as well as the schema definitions. Since this return metadata on the connected cluster, this method may trigger the creation of a connection if none has been established yet (neither init() nor connect() has been called yet).

Overrides:

getMetadata in class Cluster

Returns:

the cluster metadata.

getConfiguration

public Configuration getConfiguration()

Description copied from class: Cluster

The cluster configuration.

Overrides:

getConfiguration in class Cluster

Returns:

the cluster configuration.

getMetrics

public Metrics getMetrics()

Description copied from class: Cluster

The cluster metrics.

Overrides:

getMetrics in class Cluster

Returns:

the cluster metrics, or null if metrics collection has been disabled (that is if Configuration.getMetricsOptions() returns null).

register

public Cluster register(Host.StateListener listener)

Description copied from class: Cluster

Registers the provided listener to be notified on hosts up/down/added/removed events.

Registering the same listener multiple times is a no-op.

Note that while LoadBalancingPolicy implements Host.StateListener, the configured load balancing does not need to (and should not) be registered through this method to received host related events.

Overrides:

register in class Cluster

Parameters:

listener - the new Host.StateListener to register.

Returns:

this Cluster object;

unregister

public Cluster unregister(Host.StateListener listener)

Description copied from class: Cluster

Unregisters the provided listener from being notified on hosts events.

This method is a no-op if listener hadn't previously be registered against this Cluster.

Overrides:

unregister in class Cluster

Parameters:

listener - the Host.StateListener to unregister.

Returns:

this Cluster object;

register

public Cluster register(LatencyTracker tracker)

Description copied from class: Cluster

Registers the provided tracker to be updated with hosts read latencies.

Registering the same listener multiple times is a no-op.

Be wary that the registered tracker update method will be call very frequently (at the end of every query to a Cassandra host) and should thus not be costly.

The main use case for a LatencyTracker is so LoadBalancingPolicy can implement latency awareness Typically, LatencyAwarePolicy registers it's own internal LatencyTracker (automatically, you don't have to call this method directly).

Overrides:

register in class Cluster

Parameters:

tracker - the new LatencyTracker to register.

Returns:

this Cluster object;

unregister

public Cluster unregister(LatencyTracker tracker)

Description copied from class: Cluster

Unregisters the provided latency tracking from being updated with host read latencies.

This method is a no-op if tracker hadn't previously be registered against this Cluster.

Overrides:

unregister in class Cluster

Parameters:

tracker - the LatencyTracker to unregister.

Returns:

this Cluster object;

closeAsync

public CloseFuture closeAsync()

Description copied from class: Cluster

Initiates a shutdown of this cluster instance.

This method is asynchronous and return a future on the completion of the shutdown process. As soon a the cluster is shutdown, no new request will be accepted, but already submitted queries are allowed to complete. This method closes all connections from all sessions and reclaims all resources used by this Cluster instance.

If for some reason you wish to expedite this process, the CloseFuture.force() can be called on the result future.

This method has no particular effect if the cluster was already closed (in which case the returned future will return immediately).

Overrides:

closeAsync in class Cluster

Returns:

a future on the completion of the shutdown process.

close

public void close()

Description copied from class: Cluster

Initiates a shutdown of this cluster instance and blocks until that shutdown completes.

This method is a shortcut for closeAsync().get().

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class Cluster

isClosed

public boolean isClosed()

Description copied from class: Cluster

Whether this Cluster instance has been closed.

Note that this method returns true as soon as one of the close methods (Cluster.closeAsync() or Cluster.close()) has been called, it does not guarantee that the closing is done. If you want to guarantee that the closing is done, you can call close() and wait until it returns (or call the get method on closeAsync() with a very short timeout and check this doesn't timeout).

Overrides:

isClosed in class Cluster

Returns:

true if this Cluster instance has been closed, false otherwise.