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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.cluster;
import com.carrotsearch.hppc.cursors.ObjectCursor;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.metadata.MetaData;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
/**
* 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 iff 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) && !previousState.routingTable().hasIndex(index)) {
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 created in this event
*/
public List indicesCreated() {
if (!metaDataChanged()) {
return Collections.emptyList();
}
List created = null;
for (ObjectCursor cursor : state.metaData().indices().keys()) {
String index = cursor.value;
if (!previousState.metaData().hasIndex(index)) {
if (created == null) {
created = new ArrayList<>();
}
created.add(index);
}
}
return created == null ? Collections.emptyList() : created;
}
/**
* Returns the indices deleted in this event
*/
public List indicesDeleted() {
// 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();
}
List deleted = null;
for (ObjectCursor cursor : previousState.metaData().indices().keys()) {
String index = cursor.value;
if (!state.metaData().hasIndex(index)) {
if (deleted == null) {
deleted = new ArrayList<>();
}
deleted.add(index);
}
}
return deleted == null ? Collections.emptyList() : deleted;
}
/**
* 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 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 boolean indexMetaDataChanged(IndexMetaData current) {
MetaData previousMetaData = previousState.metaData();
if (previousMetaData == null) {
return true;
}
IndexMetaData previousIndexMetaData = previousMetaData.index(current.getIndex());
// no need to check on version, since disco modules will make sure to use the
// same instance if its a version match
if (previousIndexMetaData == current) {
return false;
}
return true;
}
/**
* 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 mater node of the cluster.
*/
public boolean localNodeMaster() {
return state.nodes().localNodeMaster();
}
/**
* 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
// different cluster from the previous cluster state, which will happen when a
// master node is elected that has never been part of the cluster before.
private boolean isNewCluster() {
final String prevClusterUUID = previousState.metaData().clusterUUID();
final String currClusterUUID = state.metaData().clusterUUID();
return prevClusterUUID.equals(currClusterUUID) == false;
}
}