org.elasticsearch.cluster

Class ClusterState

java.lang.Object

org.elasticsearch.cluster.ClusterState

All Implemented Interfaces:

Diffable<ClusterState>, Writeable, ToXContent

public class ClusterState
extends java.lang.Object
implements ToXContent, Diffable<ClusterState>

Represents the current state of the cluster.

The cluster state object is immutable with the exception of the RoutingNodes structure, which is built on demand from the RoutingTable. The cluster state can be updated only on the master node. All updates are performed by on a single thread and controlled by the ClusterService. After every update the Discovery.publish(org.elasticsearch.cluster.ClusterChangedEvent, org.elasticsearch.discovery.Discovery.AckListener) method publishes a new version of the cluster state to all other nodes in the cluster. The actual publishing mechanism is delegated to the Discovery.publish(org.elasticsearch.cluster.ClusterChangedEvent, org.elasticsearch.discovery.Discovery.AckListener) method and depends on the type of discovery. In the Zen Discovery it is handled in the PublishClusterStateAction.publish(org.elasticsearch.cluster.ClusterChangedEvent, int, org.elasticsearch.discovery.Discovery.AckListener) method. The publishing mechanism can be overridden by other discovery.

The cluster state implements the Diffable interface in order to support publishing of cluster state differences instead of the entire state on each change. The publishing mechanism should only send differences to a node if this node was present in the previous version of the cluster state. If a node was not present in the previous version of the cluster state, this node is unlikely to have the previous cluster state version and should be sent a complete version. In order to make sure that the differences are applied to the correct version of the cluster state, each cluster state version update generates stateUUID that uniquely identifies this version of the state. This uuid is verified by the ClusterStateDiff#apply method to make sure that the correct diffs are applied. If uuids don’t match, the ClusterStateDiff#apply method throws the IncompatibleClusterStateVersionException, which causes the publishing mechanism to send a full version of the cluster state to the node on which this exception was thrown.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ClusterState.Builder
static interface	ClusterState.Custom
static class	ClusterState.Metric

Nested classes/interfaces inherited from interface org.elasticsearch.common.xcontent.ToXContent

ToXContent.DelegatingMapParams, ToXContent.MapParams, ToXContent.Params

Nested classes/interfaces inherited from interface org.elasticsearch.common.io.stream.Writeable

Writeable.Reader<V>, Writeable.Writer<V>

Field Summary

Fields

Modifier and Type	Field and Description
static ClusterState	EMPTY_STATE
static java.lang.String	UNKNOWN_UUID
static long	UNKNOWN_VERSION

Fields inherited from interface org.elasticsearch.common.xcontent.ToXContent

EMPTY_PARAMS

Constructor Summary

Constructors

Constructor and Description
ClusterState(ClusterName clusterName, long version, java.lang.String stateUUID, MetaData metaData, RoutingTable routingTable, DiscoveryNodes nodes, ClusterBlocks blocks, ImmutableOpenMap<java.lang.String,ClusterState.Custom> customs, boolean wasReadFromDiff)
ClusterState(long version, java.lang.String stateUUID, ClusterState state)

Method Summary

Modifier and Type	Method and Description
ClusterBlocks	blocks()
static ClusterState.Builder	builder(ClusterName clusterName)
static ClusterState.Builder	builder(ClusterState state)
<T extends ClusterState.Custom> T	custom(java.lang.String type)
ImmutableOpenMap<java.lang.String,ClusterState.Custom>	customs()
Diff<ClusterState>	diff(ClusterState previousState) Returns serializable object representing differences between this and previousState
ClusterBlocks	getBlocks()
ClusterName	getClusterName()
ImmutableOpenMap<java.lang.String,ClusterState.Custom>	getCustoms()
MetaData	getMetaData()
DiscoveryNodes	getNodes()
RoutingNodes	getRoutingNodes() Returns a built (on demand) routing nodes view of the routing table.
RoutingTable	getRoutingTable()
long	getVersion()
MetaData	metaData()
DiscoveryNodes	nodes()
static Diff<ClusterState>	readDiffFrom(StreamInput in, DiscoveryNode localNode)
static ClusterState	readFrom(StreamInput in, DiscoveryNode localNode)
RoutingTable	routingTable()
java.lang.String	stateUUID() This stateUUID is automatically generated for for each version of cluster state.
boolean	supersedes(ClusterState other) a cluster state supersedes another state if they are from the same master and the version of this state is higher than that of the other state.
java.lang.String	toString()
XContentBuilder	toXContent(XContentBuilder builder, ToXContent.Params params)
long	version()
boolean	wasReadFromDiff()
void	writeTo(StreamOutput out) Write this into the StreamOutput.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.elasticsearch.common.xcontent.ToXContent

isFragment

Field Detail

EMPTY_STATE

public static final ClusterState EMPTY_STATE

UNKNOWN_UUID

public static final java.lang.String UNKNOWN_UUID

See Also:

Constant Field Values

UNKNOWN_VERSION

public static final long UNKNOWN_VERSION

See Also:

Constant Field Values

Constructor Detail

ClusterState

public ClusterState(long version,
                    java.lang.String stateUUID,
                    ClusterState state)

ClusterState

public ClusterState(ClusterName clusterName,
                    long version,
                    java.lang.String stateUUID,
                    MetaData metaData,
                    RoutingTable routingTable,
                    DiscoveryNodes nodes,
                    ClusterBlocks blocks,
                    ImmutableOpenMap<java.lang.String,ClusterState.Custom> customs,
                    boolean wasReadFromDiff)

Method Detail

version

public long version()

getVersion

public long getVersion()

stateUUID

public java.lang.String stateUUID()

This stateUUID is automatically generated for for each version of cluster state. It is used to make sure that we are applying diffs to the right previous state.

nodes

public DiscoveryNodes nodes()

getNodes

public DiscoveryNodes getNodes()

metaData

public MetaData metaData()

getMetaData

public MetaData getMetaData()

routingTable

public RoutingTable routingTable()

getRoutingTable

public RoutingTable getRoutingTable()

blocks

public ClusterBlocks blocks()

getBlocks

public ClusterBlocks getBlocks()

customs

public ImmutableOpenMap<java.lang.String,ClusterState.Custom> customs()

getCustoms

public ImmutableOpenMap<java.lang.String,ClusterState.Custom> getCustoms()

custom

public <T extends ClusterState.Custom> T custom(java.lang.String type)

getClusterName

public ClusterName getClusterName()

wasReadFromDiff

public boolean wasReadFromDiff()

getRoutingNodes

public RoutingNodes getRoutingNodes()

Returns a built (on demand) routing nodes view of the routing table.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

supersedes

public boolean supersedes(ClusterState other)

a cluster state supersedes another state if they are from the same master and the version of this state is higher than that of the other state.

In essence that means that all the changes from the other cluster state are also reflected by the current one

toXContent

public XContentBuilder toXContent(XContentBuilder builder,
                                  ToXContent.Params params)
                           throws java.io.IOException

Specified by:

toXContent in interface ToXContent

Throws:

java.io.IOException

builder

public static ClusterState.Builder builder(ClusterName clusterName)

builder

public static ClusterState.Builder builder(ClusterState state)

diff

public Diff<ClusterState> diff(ClusterState previousState)

Description copied from interface: Diffable

Returns serializable object representing differences between this and previousState

Specified by:

diff in interface Diffable<ClusterState>

readDiffFrom

public static Diff<ClusterState> readDiffFrom(StreamInput in,
                                              DiscoveryNode localNode)
                                       throws java.io.IOException

Throws:

java.io.IOException

readFrom

public static ClusterState readFrom(StreamInput in,
                                    DiscoveryNode localNode)
                             throws java.io.IOException

Throws:

java.io.IOException

writeTo

public void writeTo(StreamOutput out)
             throws java.io.IOException

Description copied from interface: Writeable

Write this into the StreamOutput.

Specified by:

writeTo in interface Writeable

Throws:

java.io.IOException