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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.cluster;
import org.elasticsearch.cluster.metadata.IndexGraveyard;
import org.elasticsearch.cluster.metadata.IndexGraveyard.IndexGraveyardDiff;
import org.elasticsearch.cluster.metadata.IndexMetadata;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.gateway.GatewayService;
import org.elasticsearch.index.Index;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
/**
* An event received by the local node, signaling that the cluster state has changed.
*/
public class ClusterChangedEvent {
private final String source;
private final ClusterState previousState;
private final ClusterState state;
private final DiscoveryNodes.Delta nodesDelta;
public ClusterChangedEvent(String source, ClusterState state, ClusterState previousState) {
Objects.requireNonNull(source, "source must not be null");
Objects.requireNonNull(state, "state must not be null");
Objects.requireNonNull(previousState, "previousState must not be null");
this.source = source;
this.state = state;
this.previousState = previousState;
this.nodesDelta = state.nodes().delta(previousState.nodes());
}
/**
* The source that caused this cluster event to be raised.
*/
public String source() {
return this.source;
}
/**
* The new cluster state that caused this change event.
*/
public ClusterState state() {
return this.state;
}
/**
* The previous cluster state for this change event.
*/
public ClusterState previousState() {
return this.previousState;
}
/**
* Returns true if the routing tables (for all indices) have
* changed between the previous cluster state and the current cluster state.
* Note that this is an object reference equality test, not an equals test.
*/
public boolean routingTableChanged() {
return state.routingTable() != previousState.routingTable();
}
/**
* Returns true iff the routing table has changed for the given index.
* Note that this is an object reference equality test, not an equals test.
*/
public boolean indexRoutingTableChanged(String index) {
Objects.requireNonNull(index, "index must not be null");
if (state.routingTable().hasIndex(index) == false && previousState.routingTable().hasIndex(index) == false) {
return false;
}
if (state.routingTable().hasIndex(index) && previousState.routingTable().hasIndex(index)) {
return state.routingTable().index(index) != previousState.routingTable().index(index);
}
return true;
}
/**
* Returns the indices deleted in this event
*/
public List indicesDeleted() {
if (previousState.blocks().hasGlobalBlock(GatewayService.STATE_NOT_RECOVERED_BLOCK)) {
// working off of a non-initialized previous state, so use the tombstones for index deletions
return indicesDeletedFromTombstones();
} else {
// examine the diffs in index metadata between the previous and new cluster states to get the deleted indices
return indicesDeletedFromClusterState();
}
}
/**
* Returns true iff the metadata for the cluster has changed between
* the previous cluster state and the new cluster state. Note that this is an object
* reference equality test, not an equals test.
*/
public boolean metadataChanged() {
return state.metadata() != previousState.metadata();
}
/**
* Returns a set of custom meta data types when any custom metadata for the cluster has changed
* between the previous cluster state and the new cluster state. custom meta data types are
* returned iff they have been added, updated or removed between the previous and the current state
*/
public Set changedCustomMetadataSet() {
Set result = new HashSet<>();
Map currentCustoms = state.metadata().customs();
Map previousCustoms = previousState.metadata().customs();
if (currentCustoms.equals(previousCustoms) == false) {
for (Map.Entry currentCustomMetadata : currentCustoms.entrySet()) {
// new custom md added or existing custom md changed
if (previousCustoms.containsKey(currentCustomMetadata.getKey()) == false
|| currentCustomMetadata.getValue().equals(previousCustoms.get(currentCustomMetadata.getKey())) == false) {
result.add(currentCustomMetadata.getKey());
}
}
// existing custom md deleted
for (Map.Entry previousCustomMetadata : previousCustoms.entrySet()) {
if (currentCustoms.containsKey(previousCustomMetadata.getKey()) == false) {
result.add(previousCustomMetadata.getKey());
}
}
}
return result;
}
/**
* Returns true iff the {@link IndexMetadata} for a given index
* has changed between the previous cluster state and the new cluster state.
* Note that this is an object reference equality test, not an equals test.
*/
public static boolean indexMetadataChanged(IndexMetadata metadata1, IndexMetadata metadata2) {
assert metadata1 != null && metadata2 != null;
// no need to check on version, since disco modules will make sure to use the
// same instance if its a version match
return metadata1 != metadata2;
}
/**
* Returns true iff the cluster level blocks have changed between cluster states.
* Note that this is an object reference equality test, not an equals test.
*/
public boolean blocksChanged() {
return state.blocks() != previousState.blocks();
}
/**
* Returns true iff the local node is the master node of the cluster.
*/
public boolean localNodeMaster() {
return state.nodes().isLocalNodeElectedMaster();
}
/**
* Returns the {@link org.elasticsearch.cluster.node.DiscoveryNodes.Delta} between
* the previous cluster state and the new cluster state.
*/
public DiscoveryNodes.Delta nodesDelta() {
return this.nodesDelta;
}
/**
* Returns true iff nodes have been removed from the cluster since the last cluster state.
*/
public boolean nodesRemoved() {
return nodesDelta.removed();
}
/**
* Returns true iff nodes have been added from the cluster since the last cluster state.
*/
public boolean nodesAdded() {
return nodesDelta.added();
}
/**
* Returns true iff nodes have been changed (added or removed) from the cluster since the last cluster state.
*/
public boolean nodesChanged() {
return nodesRemoved() || nodesAdded();
}
/**
* Determines whether or not the current cluster state represents an entirely
* new cluster, either when a node joins a cluster for the first time or when
* the node receives a cluster state update from a brand new cluster (different
* UUID from the previous cluster), which will happen when a master node is
* elected that has never been part of the cluster before.
*/
public boolean isNewCluster() {
final String prevClusterUUID = previousState.metadata().clusterUUID();
final String currClusterUUID = state.metadata().clusterUUID();
return prevClusterUUID.equals(currClusterUUID) == false;
}
// Get the deleted indices by comparing the index metadatas in the previous and new cluster states.
// If an index exists in the previous cluster state, but not in the new cluster state, it must have been deleted.
private List indicesDeletedFromClusterState() {
// If the new cluster state has a new cluster UUID, the likely scenario is that a node was elected
// master that has had its data directory wiped out, in which case we don't want to delete the indices and lose data;
// rather we want to import them as dangling indices instead. So we check here if the cluster UUID differs from the previous
// cluster UUID, in which case, we don't want to delete indices that the master erroneously believes shouldn't exist.
// See test DiscoveryWithServiceDisruptionsIT.testIndicesDeleted()
// See discussion on https://github.com/elastic/elasticsearch/pull/9952 and
// https://github.com/elastic/elasticsearch/issues/11665
if (metadataChanged() == false || isNewCluster()) {
return Collections.emptyList();
}
Set deleted = null;
final Metadata previousMetadata = previousState.metadata();
final Metadata currentMetadata = state.metadata();
if (currentMetadata.indices() != previousMetadata.indices()) {
for (IndexMetadata index : previousMetadata.indices().values()) {
IndexMetadata current = currentMetadata.index(index.getIndex());
if (current == null) {
if (deleted == null) {
deleted = new HashSet<>();
}
deleted.add(index.getIndex());
}
}
}
final IndexGraveyard currentGraveyard = currentMetadata.indexGraveyard();
final IndexGraveyard previousGraveyard = previousMetadata.indexGraveyard();
// Look for new entries in the index graveyard, where there's no corresponding index in the
// previous metadata. This indicates that a dangling index has been explicitly deleted, so
// each node should make sure to delete any related data.
if (currentGraveyard != previousGraveyard) {
final IndexGraveyardDiff indexGraveyardDiff = (IndexGraveyardDiff) currentGraveyard.diff(previousGraveyard);
final List added = indexGraveyardDiff.getAdded();
if (added.isEmpty() == false) {
if (deleted == null) {
deleted = new HashSet<>();
}
for (IndexGraveyard.Tombstone tombstone : added) {
deleted.add(tombstone.getIndex());
}
}
}
return deleted == null ? Collections.emptyList() : new ArrayList<>(deleted);
}
private List indicesDeletedFromTombstones() {
// We look at the full tombstones list to see which indices need to be deleted. In the case of
// a valid previous cluster state, indicesDeletedFromClusterState() will be used to get the deleted
// list, so a diff doesn't make sense here. When a node (re)joins the cluster, its possible for it
// to re-process the same deletes or process deletes about indices it never knew about. This is not
// an issue because there are safeguards in place in the delete store operation in case the index
// folder doesn't exist on the file system.
List tombstones = state.metadata().indexGraveyard().getTombstones();
return tombstones.stream().map(IndexGraveyard.Tombstone::getIndex).toList();
}
}