Remove MergeScheduler pluggability

Nobody should really plug in a different merge scheduler for elasticsearch.
This is too expert and might cause catastrophic failures.

core/src/main/java/org/elasticsearch/index/IndexService.java

@@ -36,37 +36,23 @@ import org.elasticsearch.index.aliases.IndexAliasesService;
 import org.elasticsearch.index.analysis.AnalysisService;
 import org.elasticsearch.index.cache.IndexCache;
 import org.elasticsearch.index.cache.bitset.BitsetFilterCache;
-import org.elasticsearch.index.cache.bitset.ShardBitsetFilterCache;
 import org.elasticsearch.index.cache.filter.ShardFilterCache;
-import org.elasticsearch.index.cache.query.ShardQueryCache;
 import org.elasticsearch.index.deletionpolicy.DeletionPolicyModule;
 import org.elasticsearch.index.fielddata.IndexFieldDataService;
-import org.elasticsearch.index.fielddata.ShardFieldData;
-import org.elasticsearch.index.gateway.IndexShardGateway;
 import org.elasticsearch.index.gateway.IndexShardGatewayService;
-import org.elasticsearch.index.get.ShardGetService;
-import org.elasticsearch.index.indexing.ShardIndexingService;
-import org.elasticsearch.index.indexing.slowlog.ShardSlowLogIndexingService;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.merge.policy.MergePolicyModule;
 import org.elasticsearch.index.merge.policy.MergePolicyProvider;
-import org.elasticsearch.index.merge.scheduler.MergeSchedulerModule;
 import org.elasticsearch.index.merge.scheduler.MergeSchedulerProvider;
 import org.elasticsearch.index.percolator.PercolatorQueriesRegistry;
-import org.elasticsearch.index.percolator.stats.ShardPercolateService;
 import org.elasticsearch.index.query.IndexQueryParserService;
-import org.elasticsearch.index.search.slowlog.ShardSlowLogSearchService;
-import org.elasticsearch.index.search.stats.ShardSearchService;
 import org.elasticsearch.index.settings.IndexSettings;
 import org.elasticsearch.index.settings.IndexSettingsService;
 import org.elasticsearch.index.shard.*;
 import org.elasticsearch.index.similarity.SimilarityService;
-import org.elasticsearch.index.snapshots.IndexShardSnapshotAndRestoreService;
 import org.elasticsearch.index.store.IndexStore;
 import org.elasticsearch.index.store.Store;
 import org.elasticsearch.index.store.StoreModule;
-import org.elasticsearch.index.suggest.stats.ShardSuggestService;
-import org.elasticsearch.index.termvectors.ShardTermVectorsService;
 import org.elasticsearch.index.translog.TranslogService;
 import org.elasticsearch.indices.IndicesLifecycle;
 import org.elasticsearch.indices.IndicesService;
@@ -313,7 +299,6 @@ public class IndexService extends AbstractIndexComponent implements IndexCompone
                     new StoreCloseListener(shardId, canDeleteShardContent, shardFilterCache), path));
             modules.add(new DeletionPolicyModule(indexSettings));
             modules.add(new MergePolicyModule(indexSettings));
-            modules.add(new MergeSchedulerModule(indexSettings));
             try {
                 shardInjector = modules.createChildInjector(injector);
             } catch (CreationException e) {

core/src/main/java/org/elasticsearch/index/merge/scheduler/MergeSchedulerModule.java

@@ -1,45 +0,0 @@
-/*
- * 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.index.merge.scheduler;
-
-import org.elasticsearch.common.inject.AbstractModule;
-import org.elasticsearch.common.settings.Settings;
-
-/**
- *
- */
-public class MergeSchedulerModule extends AbstractModule {
-
-    public static final String MERGE_SCHEDULER_TYPE_KEY = "index.merge.scheduler.type";
-    public static final Class<? extends MergeSchedulerProvider> DEFAULT = ConcurrentMergeSchedulerProvider.class;
-
-    private final Settings settings;
-
-    public MergeSchedulerModule(Settings settings) {
-        this.settings = settings;
-    }
-
-    @Override
-    protected void configure() {
-        bind(MergeSchedulerProvider.class)
-                .to(settings.getAsClass(MERGE_SCHEDULER_TYPE_KEY, DEFAULT, "org.elasticsearch.index.merge.scheduler.", "MergeSchedulerProvider"))
-                .asEagerSingleton();
-    }
-}

core/src/main/java/org/elasticsearch/index/shard/IndexShardModule.java

@@ -34,6 +34,8 @@ import org.elasticsearch.index.gateway.IndexShardGatewayService;
 import org.elasticsearch.index.get.ShardGetService;
 import org.elasticsearch.index.indexing.ShardIndexingService;
 import org.elasticsearch.index.indexing.slowlog.ShardSlowLogIndexingService;
+import org.elasticsearch.index.merge.scheduler.ConcurrentMergeSchedulerProvider;
+import org.elasticsearch.index.merge.scheduler.MergeSchedulerProvider;
 import org.elasticsearch.index.percolator.PercolatorQueriesRegistry;
 import org.elasticsearch.index.percolator.stats.ShardPercolateService;
 import org.elasticsearch.index.search.slowlog.ShardSlowLogSearchService;
@@ -90,7 +92,7 @@ public class IndexShardModule extends AbstractModule {
         }
 
         bind(EngineFactory.class).to(settings.getAsClass(ENGINE_FACTORY, DEFAULT_ENGINE_FACTORY_CLASS, ENGINE_PREFIX, ENGINE_SUFFIX));
-
+        bind(MergeSchedulerProvider.class).to(ConcurrentMergeSchedulerProvider.class).asEagerSingleton();
         bind(ShardIndexWarmerService.class).asEagerSingleton();
         bind(ShardIndexingService.class).asEagerSingleton();
         bind(ShardSlowLogIndexingService.class).asEagerSingleton();

core/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsTests.java

@@ -33,7 +33,6 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.engine.VersionConflictEngineException;
 import org.elasticsearch.index.merge.policy.TieredMergePolicyProvider;
 import org.elasticsearch.index.merge.scheduler.ConcurrentMergeSchedulerProvider;
-import org.elasticsearch.index.merge.scheduler.MergeSchedulerModule;
 import org.elasticsearch.index.store.IndexStore;
 import org.elasticsearch.index.store.Store;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
@@ -366,7 +365,6 @@ public class UpdateSettingsTests extends ElasticsearchIntegrationTest {
                                      .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, "0")
                                      .put(TieredMergePolicyProvider.INDEX_MERGE_POLICY_MAX_MERGE_AT_ONCE, "2")
                                      .put(TieredMergePolicyProvider.INDEX_MERGE_POLICY_SEGMENTS_PER_TIER, "2")
-                                     .put(MergeSchedulerModule.MERGE_SCHEDULER_TYPE_KEY, ConcurrentMergeSchedulerProvider.class)
                                      .put(ConcurrentMergeSchedulerProvider.MAX_THREAD_COUNT, "10000")
                                      .put(ConcurrentMergeSchedulerProvider.MAX_MERGE_COUNT, "10000")
                                      ));

core/src/test/java/org/elasticsearch/test/ElasticsearchIntegrationTest.java

@@ -103,7 +103,6 @@ import org.elasticsearch.index.mapper.internal.SizeFieldMapper;
 import org.elasticsearch.index.mapper.internal.TimestampFieldMapper;
 import org.elasticsearch.index.merge.policy.*;
 import org.elasticsearch.index.merge.scheduler.ConcurrentMergeSchedulerProvider;
-import org.elasticsearch.index.merge.scheduler.MergeSchedulerModule;
 import org.elasticsearch.index.translog.Translog;
 import org.elasticsearch.index.translog.TranslogConfig;
 import org.elasticsearch.index.translog.TranslogService;
@@ -545,7 +544,6 @@ public abstract class ElasticsearchIntegrationTest extends ElasticsearchTestCase
 
         switch (random.nextInt(4)) {
             case 3:
-                builder.put(MergeSchedulerModule.MERGE_SCHEDULER_TYPE_KEY, ConcurrentMergeSchedulerProvider.class);
                 final int maxThreadCount = RandomInts.randomIntBetween(random, 1, 4);
                 final int maxMergeCount = RandomInts.randomIntBetween(random, maxThreadCount, maxThreadCount + 4);
                 builder.put(ConcurrentMergeSchedulerProvider.MAX_MERGE_COUNT, maxMergeCount);

docs/reference/index-modules/merge.asciidoc

@@ -199,9 +199,3 @@ indexing will see the throttle move higher to allow merges to keep up
 with ongoing indexing.  This is a dynamic setting (you can <<indices-update-settings,change it
 at any time on a running index>>).
 
-[float]
-==== SerialMergeScheduler
-
-This is accepted for backwards compatibility, but just uses
-ConcurrentMergeScheduler with index.merge.scheduler.max_thread_count
-set to 1 so that only 1 merge may run at a time.