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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.index.shard;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.IndexService;
import org.elasticsearch.index.IndexSettings;
import org.elasticsearch.indices.cluster.IndicesClusterStateService.AllocatedIndices.IndexRemovalReason;
/**
* An index event listener is the primary extension point for plugins and build-in services
* to react / listen to per-index and per-shard events. These listeners are registered per-index
* via {@link org.elasticsearch.index.IndexModule#addIndexEventListener(IndexEventListener)}. All listeners have the same
* lifecycle as the {@link IndexService} they are created for.
*
* An IndexEventListener can be used across multiple indices and shards since all callback methods receive sufficient
* local state via their arguments. Yet, if an instance is shared across indices they might be called concurrently and should not
* modify local state without sufficient synchronization.
*
*/
public interface IndexEventListener {
/**
* Called when the shard routing has changed state.
*
* @param indexShard The index shard
* @param oldRouting The old routing state (can be null)
* @param newRouting The new routing state
*/
default void shardRoutingChanged(IndexShard indexShard, @Nullable ShardRouting oldRouting, ShardRouting newRouting) {}
/**
* Called after the index shard has been created.
*/
default void afterIndexShardCreated(IndexShard indexShard) {}
/**
* Called after the index shard has been started.
*/
default void afterIndexShardStarted(IndexShard indexShard) {}
/**
* Called before the index shard gets closed.
*
* @param indexShard The index shard
*/
default void beforeIndexShardClosed(ShardId shardId, @Nullable IndexShard indexShard, Settings indexSettings) {}
/**
* Called after the index shard has been closed.
*
* @param shardId The shard id
*/
default void afterIndexShardClosed(ShardId shardId, @Nullable IndexShard indexShard, Settings indexSettings) {}
/**
* Called after a shard's {@link org.elasticsearch.index.shard.IndexShardState} changes.
* The order of concurrent events is preserved. The execution must be lightweight.
*
* @param indexShard the shard the new state was applied to
* @param previousState the previous index shard state if there was one, null otherwise
* @param currentState the new shard state
* @param reason the reason for the state change if there is one, null otherwise
*/
default void indexShardStateChanged(
IndexShard indexShard,
@Nullable IndexShardState previousState,
IndexShardState currentState,
@Nullable String reason
) {}
/**
* Called before the index gets created. Note that this is also called
* when the index is created on data nodes
*/
default void beforeIndexCreated(Index index, Settings indexSettings) {
}
/**
* Called after the index has been created.
*/
default void afterIndexCreated(IndexService indexService) {
}
/**
* Called before the index get closed.
*
* @param indexService The index service
* @param reason the reason for index removal
*/
default void beforeIndexRemoved(IndexService indexService, IndexRemovalReason reason) {
}
/**
* Called after the index has been removed.
*
* @param index The index
* @param reason the reason for index removal
*/
default void afterIndexRemoved(Index index, IndexSettings indexSettings, IndexRemovalReason reason) {
}
/**
* Called before the index shard gets created, before obtaining the shard lock.
* @param routing the routing entry that caused the shard to be created.
* @param indexSettings the shards index settings
*/
default void beforeIndexShardCreated(ShardRouting routing, Settings indexSettings) {}
/**
* Called before the index shard gets deleted from disk
* Note: this method is only executed on the first attempt of deleting the shard. Retries are will not invoke
* this method.
* @param shardId The shard id
* @param indexSettings the shards index settings
*/
default void beforeIndexShardDeleted(ShardId shardId, Settings indexSettings) {}
/**
* Called after the index shard has been deleted from disk.
*
* Note: this method is only called if the deletion of the shard did finish without an exception
*
* @param shardId The shard id
* @param indexSettings the shards index settings
*/
default void afterIndexShardDeleted(ShardId shardId, Settings indexSettings) {}
/**
* Called on the Master node only before the {@link IndexService} instances is created to simulate an index creation.
* This happens right before the index and it's metadata is registered in the cluster state
*/
default void beforeIndexAddedToCluster(Index index, Settings indexSettings) {}
/**
* Called when the given shards store is created. The shard store is created before the shard is created.
*
* @param shardId the shard ID the store belongs to
*/
default void onStoreCreated(ShardId shardId) {}
/**
* Called when the given shards store is closed. The store is closed once all resource have been released on the store.
* This implies that all index readers are closed and no recoveries are running.
*
* @param shardId the shard ID the store belongs to
*/
default void onStoreClosed(ShardId shardId) {}
/**
* Called before the index shard starts to recover.
* Note: unlike all other methods in this class, this method is not called using the cluster state update thread. When this method is
* called the shard already transitioned to the RECOVERING state.
*
* @param indexShard the shard that is about to recover
* @param indexSettings the shard's index settings
*/
default void beforeIndexShardRecovery(IndexShard indexShard, IndexSettings indexSettings) {}
/**
* Called after the raw files have been restored from the repository but any other recovery processing has happened
* @param indexShard the shard that is recovering
*/
default void afterFilesRestoredFromRepository(IndexShard indexShard) {}
}