Package org.elasticsearch.cluster

Class ClusterState

java.lang.Object

org.elasticsearch.cluster.ClusterState

All Implemented Interfaces:

Diffable<ClusterState>, Writeable, ToXContent, ToXContentFragment

public class ClusterState
extends Object
implements ToXContentFragment, 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 ClusterStatePublisher.publish(org.elasticsearch.cluster.ClusterStatePublicationEvent, org.elasticsearch.action.ActionListener<java.lang.Void>, org.elasticsearch.cluster.coordination.ClusterStatePublisher.AckListener) method publishes a new version of the cluster state to all other nodes in the cluster.

Implements the Diffable interface in order to support publishing of cluster state differences instead of the entire state on each change. The publishing mechanism only sends 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 Diff.apply(org.elasticsearch.cluster.ClusterState) method to make sure that the correct diffs are applied. If uuids don’t match, the Diff.apply(org.elasticsearch.cluster.ClusterState) 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.

Implements ToXContentFragment to be exposed in REST APIs (e.g. GET _cluster/state and POST _cluster/reroute) and to be indexed by monitoring, mostly just for diagnostics purposes. The XContent representation does not need to be 100% faithful since we never reconstruct a cluster state from its XContent representation, but the more faithful it is the more useful it is for diagnostics.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ClusterState.Builder
static interface	ClusterState.Custom
static interface	ClusterState.FeatureAware	An interface that implementors use when a class requires a client to maybe have a feature.
static enum	ClusterState.Metric

Nested classes/interfaces inherited from interface org.elasticsearch.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	Description
static final ClusterState	EMPTY_STATE
static final String	UNKNOWN_UUID
static final long	UNKNOWN_VERSION

Fields inherited from interface org.elasticsearch.xcontent.ToXContent

EMPTY_PARAMS

Constructor Summary

Constructors

Constructor	Description
ClusterState(long version, String stateUUID, ClusterState state)
ClusterState(ClusterName clusterName, long version, String stateUUID, Metadata metadata, RoutingTable routingTable, DiscoveryNodes nodes, ClusterBlocks blocks, ImmutableOpenMap<String,ClusterState.Custom> customs, int minimumMasterNodesOnPublishingMaster, boolean wasReadFromDiff, RoutingNodes routingNodes)

Method Summary

Modifier and Type	Method	Description
ClusterBlocks	blocks()
static ClusterState.Builder	builder(ClusterName clusterName)
static ClusterState.Builder	builder(ClusterState state)
CoordinationMetadata	coordinationMetadata()
<T extends ClusterState.Custom> T	custom(String type)
<T extends ClusterState.Custom> T	custom(String type, T defaultValue)
ImmutableOpenMap<String,ClusterState.Custom>	customs()
Diff<ClusterState>	diff(ClusterState previousState)	Returns serializable object representing differences between this and previousState
ClusterBlocks	getBlocks()
ClusterName	getClusterName()
ImmutableOpenMap<String,ClusterState.Custom>	getCustoms()
CoordinationMetadata.VotingConfiguration	getLastAcceptedConfiguration()
CoordinationMetadata.VotingConfiguration	getLastCommittedConfiguration()
Metadata	getMetadata()
int	getMinimumMasterNodesOnPublishingMaster()	The node-level `discovery.zen.minimum_master_nodes` setting on the master node that published this cluster state, for use in rolling upgrades from 6.x to 7.x.
DiscoveryNodes	getNodes()
RoutingNodes	getRoutingNodes()	Returns a built (on demand) routing nodes view of the routing table.
RoutingTable	getRoutingTable()
long	getVersion()
long	getVersionOrMetadataVersion()
Set<CoordinationMetadata.VotingConfigExclusion>	getVotingConfigExclusions()
Metadata	metadata()
DiscoveryNodes	nodes()
static Diff<ClusterState>	readDiffFrom(StreamInput in, DiscoveryNode localNode)
static ClusterState	readFrom(StreamInput in, DiscoveryNode localNode)
RoutingTable	routingTable()
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.
long	term()
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.xcontent.ToXContentFragment

isFragment

Field Details

EMPTY_STATE

public static final ClusterState EMPTY_STATE

UNKNOWN_UUID

public static final String UNKNOWN_UUID

See Also:

• Constant Field Values

UNKNOWN_VERSION

public static final long UNKNOWN_VERSION

See Also:

• Constant Field Values

Constructor Details

ClusterState

public ClusterState(long version,
 String stateUUID,
 ClusterState state)

ClusterState

public ClusterState(ClusterName clusterName,
 long version,
 String stateUUID,
 Metadata metadata,
 RoutingTable routingTable,
 DiscoveryNodes nodes,
 ClusterBlocks blocks,
 ImmutableOpenMap<String,ClusterState.Custom> customs,
 int minimumMasterNodesOnPublishingMaster,
 boolean wasReadFromDiff,
 @Nullable
 RoutingNodes routingNodes)

Method Details

term

public long term()

version

public long version()

getVersion

public long getVersion()

getVersionOrMetadataVersion

public long getVersionOrMetadataVersion()

stateUUID

public 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()

coordinationMetadata

public CoordinationMetadata coordinationMetadata()

routingTable

public RoutingTable routingTable()

getRoutingTable

public RoutingTable getRoutingTable()

blocks

public ClusterBlocks blocks()

getBlocks

public ClusterBlocks getBlocks()

customs

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

getCustoms

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

custom

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

custom

public <T extends ClusterState.Custom> T custom(String type,
 T defaultValue)

getClusterName

public ClusterName getClusterName()

getLastAcceptedConfiguration

public CoordinationMetadata.VotingConfiguration getLastAcceptedConfiguration()

getLastCommittedConfiguration

public CoordinationMetadata.VotingConfiguration getLastCommittedConfiguration()

getVotingConfigExclusions

public Set<CoordinationMetadata.VotingConfigExclusion> getVotingConfigExclusions()

getMinimumMasterNodesOnPublishingMaster

public int getMinimumMasterNodesOnPublishingMaster()

The node-level `discovery.zen.minimum_master_nodes` setting on the master node that published this cluster state, for use in rolling upgrades from 6.x to 7.x. Once all the 6.x master-eligible nodes have left the cluster, the 7.x nodes use this value to determine how many master-eligible nodes must be discovered before the cluster can be bootstrapped. Note that this method returns the node-level value of this setting, and ignores any cluster-level override that was set via the API. Callers are expected to combine this value with any value set in the cluster-level settings. This should be removed once we no longer need support for Version.V_6_7_0.

wasReadFromDiff

public boolean wasReadFromDiff()

getRoutingNodes

public RoutingNodes getRoutingNodes()

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

toString

public String toString()

Overrides:

toString in class 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 IOException

Specified by:

toXContent in interface ToXContent

Throws:

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 IOException

Throws:

IOException

readFrom

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

Throws:

IOException

writeTo

public void writeTo(StreamOutput out)
             throws IOException

Description copied from interface: Writeable

Write this into the StreamOutput.

Specified by:

writeTo in interface Writeable

Throws:

IOException