Introduce index store plugins

plugins/store-smb/src/main/java/org/elasticsearch/plugin/store/smb/SMBStorePlugin.java

@@ -19,16 +19,26 @@
 
 package org.elasticsearch.plugin.store.smb;
 
-import org.elasticsearch.index.IndexModule;
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.store.IndexStore;
 import org.elasticsearch.index.store.smbmmapfs.SmbMmapFsIndexStore;
 import org.elasticsearch.index.store.smbsimplefs.SmbSimpleFsIndexStore;
+import org.elasticsearch.plugins.IndexStorePlugin;
 import org.elasticsearch.plugins.Plugin;
 
-public class SMBStorePlugin extends Plugin {
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+public class SMBStorePlugin extends Plugin implements IndexStorePlugin {
 
     @Override
-    public void onIndexModule(IndexModule indexModule) {
-        indexModule.addIndexStore("smb_mmap_fs", SmbMmapFsIndexStore::new);
-        indexModule.addIndexStore("smb_simple_fs", SmbSimpleFsIndexStore::new);
+    public Map<String, Function<IndexSettings, IndexStore>> getIndexStoreFactories() {
+        final Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories = new HashMap<>(2);
+        indexStoreFactories.put("smb_mmap_fs", SmbMmapFsIndexStore::new);
+        indexStoreFactories.put("smb_simple_fs", SmbSimpleFsIndexStore::new);
+        return Collections.unmodifiableMap(indexStoreFactories);
     }
+
 }

server/src/main/java/org/elasticsearch/index/IndexModule.java

@@ -49,6 +49,7 @@
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.indices.fielddata.cache.IndicesFieldDataCache;
 import org.elasticsearch.indices.mapper.MapperRegistry;
+import org.elasticsearch.plugins.IndexStorePlugin;
 import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.threadpool.ThreadPool;
 
@@ -74,7 +75,7 @@
  *     {@link #addSimilarity(String, TriFunction)} while existing Providers can be referenced through Settings under the
  *     {@link IndexModule#SIMILARITY_SETTINGS_PREFIX} prefix along with the "type" value.  For example, to reference the
  *     {@link BM25Similarity}, the configuration {@code "index.similarity.my_similarity.type : "BM25"} can be used.</li>
- *      <li>{@link IndexStore} - Custom {@link IndexStore} instances can be registered via {@link #addIndexStore(String, Function)}</li>
+ *      <li>{@link IndexStore} - Custom {@link IndexStore} instances can be registered via {@link IndexStorePlugin}</li>
  *      <li>{@link IndexEventListener} - Custom {@link IndexEventListener} instances can be registered via
  *      {@link #addIndexEventListener(IndexEventListener)}</li>
  *      <li>Settings update listener - Custom settings update listener can be registered via
@@ -109,7 +110,7 @@ public final class IndexModule {
     private SetOnce<IndexSearcherWrapperFactory> indexSearcherWrapper = new SetOnce<>();
     private final Set<IndexEventListener> indexEventListeners = new HashSet<>();
     private final Map<String, TriFunction<Settings, Version, ScriptService, Similarity>> similarities = new HashMap<>();
-    private final Map<String, Function<IndexSettings, IndexStore>> storeTypes = new HashMap<>();
+    private final Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories;
     private final SetOnce<BiFunction<IndexSettings, IndicesQueryCache, QueryCache>> forceQueryCacheProvider = new SetOnce<>();
     private final List<SearchOperationListener> searchOperationListeners = new ArrayList<>();
     private final List<IndexingOperationListener> indexOperationListeners = new ArrayList<>();
@@ -119,16 +120,22 @@ public final class IndexModule {
      * Construct the index module for the index with the specified index settings. The index module contains extension points for plugins
      * via {@link org.elasticsearch.plugins.PluginsService#onIndexModule(IndexModule)}.
      *
-     * @param indexSettings    the index settings
-     * @param analysisRegistry the analysis registry
-     * @param engineFactory    the engine factory
+     * @param indexSettings       the index settings
+     * @param analysisRegistry    the analysis registry
+     * @param engineFactory       the engine factory
+     * @param indexStoreFactories the available store types
      */
-    public IndexModule(final IndexSettings indexSettings, final AnalysisRegistry analysisRegistry, final EngineFactory engineFactory) {
+    public IndexModule(
+            final IndexSettings indexSettings,
+            final AnalysisRegistry analysisRegistry,
+            final EngineFactory engineFactory,
+            final Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories) {
         this.indexSettings = indexSettings;
         this.analysisRegistry = analysisRegistry;
         this.engineFactory = Objects.requireNonNull(engineFactory);
         this.searchOperationListeners.add(new SearchSlowLog(indexSettings));
         this.indexOperationListeners.add(new IndexingSlowLog(indexSettings));
+        this.indexStoreFactories = Collections.unmodifiableMap(indexStoreFactories);
     }
 
     /**
@@ -245,25 +252,6 @@ public void addIndexOperationListener(IndexingOperationListener listener) {
         this.indexOperationListeners.add(listener);
     }
 
-    /**
-     * Adds an {@link IndexStore} type to this index module. Typically stores are registered with a reference to
-     * it's constructor:
-     * <pre>
-     *     indexModule.addIndexStore("my_store_type", MyStore::new);
-     * </pre>
-     *
-     * @param type the type to register
-     * @param provider the instance provider / factory method
-     */
-    public void addIndexStore(String type, Function<IndexSettings, IndexStore> provider) {
-        ensureNotFrozen();
-        if (storeTypes.containsKey(type)) {
-            throw new IllegalArgumentException("key [" + type +"] already registered");
-        }
-        storeTypes.put(type, provider);
-    }
-
-
     /**
      * Registers the given {@link Similarity} with the given name.
      * The function takes as parameters:<ul>
@@ -360,7 +348,7 @@ public IndexService newIndexService(
         if (Strings.isEmpty(storeType) || isBuiltinType(storeType)) {
             store = new IndexStore(indexSettings);
         } else {
-            Function<IndexSettings, IndexStore> factory = storeTypes.get(storeType);
+            Function<IndexSettings, IndexStore> factory = indexStoreFactories.get(storeType);
             if (factory == null) {
                 throw new IllegalArgumentException("Unknown store type [" + storeType + "]");
             }

server/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -100,6 +100,7 @@
 import org.elasticsearch.index.shard.IndexingOperationListener;
 import org.elasticsearch.index.shard.IndexingStats;
 import org.elasticsearch.index.shard.ShardId;
+import org.elasticsearch.index.store.IndexStore;
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.indices.cluster.IndicesClusterStateService;
 import org.elasticsearch.indices.fielddata.cache.IndicesFieldDataCache;
@@ -181,6 +182,7 @@ public class IndicesService extends AbstractLifecycleComponent
     private final IndicesQueryCache indicesQueryCache;
     private final MetaStateService metaStateService;
     private final Collection<Function<IndexSettings, Optional<EngineFactory>>> engineFactoryProviders;
+    private final Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories;
 
     @Override
     protected void doStart() {
@@ -193,7 +195,8 @@ public IndicesService(Settings settings, PluginsService pluginsService, NodeEnvi
                           MapperRegistry mapperRegistry, NamedWriteableRegistry namedWriteableRegistry, ThreadPool threadPool,
                           IndexScopedSettings indexScopedSettings, CircuitBreakerService circuitBreakerService, BigArrays bigArrays,
                           ScriptService scriptService, Client client, MetaStateService metaStateService,
-                          Collection<Function<IndexSettings, Optional<EngineFactory>>> engineFactoryProviders) {
+                          Collection<Function<IndexSettings, Optional<EngineFactory>>> engineFactoryProviders,
+                          Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories) {
         super(settings);
         this.threadPool = threadPool;
         this.pluginsService = pluginsService;
@@ -225,6 +228,7 @@ public void onRemoval(ShardId shardId, String fieldName, boolean wasEvicted, lon
         this.cacheCleaner = new CacheCleaner(indicesFieldDataCache, indicesRequestCache,  logger, threadPool, this.cleanInterval);
         this.metaStateService = metaStateService;
         this.engineFactoryProviders = engineFactoryProviders;
+        this.indexStoreFactories = indexStoreFactories;
     }
 
     @Override
@@ -464,7 +468,7 @@ private synchronized IndexService createIndexService(final String reason,
             idxSettings.getNumberOfReplicas(),
             reason);
 
-        final IndexModule indexModule = new IndexModule(idxSettings, analysisRegistry, getEngineFactory(idxSettings));
+        final IndexModule indexModule = new IndexModule(idxSettings, analysisRegistry, getEngineFactory(idxSettings), indexStoreFactories);
         for (IndexingOperationListener operationListener : indexingOperationListeners) {
             indexModule.addIndexOperationListener(operationListener);
         }
@@ -524,7 +528,7 @@ private EngineFactory getEngineFactory(final IndexSettings idxSettings) {
      */
     public synchronized MapperService createIndexMapperService(IndexMetaData indexMetaData) throws IOException {
         final IndexSettings idxSettings = new IndexSettings(indexMetaData, this.settings, indexScopedSettings);
-        final IndexModule indexModule = new IndexModule(idxSettings, analysisRegistry, getEngineFactory(idxSettings));
+        final IndexModule indexModule = new IndexModule(idxSettings, analysisRegistry, getEngineFactory(idxSettings), indexStoreFactories);
         pluginsService.onIndexModule(indexModule);
         return indexModule.newIndexMapperService(xContentRegistry, mapperRegistry, scriptService);
     }

server/src/main/java/org/elasticsearch/node/Node.java

@@ -26,8 +26,8 @@
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.ElasticsearchTimeoutException;
 import org.elasticsearch.Version;
-import org.elasticsearch.action.ActionModule;
 import org.elasticsearch.action.Action;
+import org.elasticsearch.action.ActionModule;
 import org.elasticsearch.action.search.SearchExecutionStatsCollector;
 import org.elasticsearch.action.search.SearchPhaseController;
 import org.elasticsearch.action.search.SearchTransportService;
@@ -94,6 +94,7 @@
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.EngineFactory;
+import org.elasticsearch.index.store.IndexStore;
 import org.elasticsearch.indices.IndicesModule;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.indices.analysis.AnalysisModule;
@@ -117,6 +118,7 @@
 import org.elasticsearch.plugins.ClusterPlugin;
 import org.elasticsearch.plugins.DiscoveryPlugin;
 import org.elasticsearch.plugins.EnginePlugin;
+import org.elasticsearch.plugins.IndexStorePlugin;
 import org.elasticsearch.plugins.IngestPlugin;
 import org.elasticsearch.plugins.MapperPlugin;
 import org.elasticsearch.plugins.MetaDataUpgrader;
@@ -407,11 +409,19 @@ protected Node(final Environment environment, Collection<Class<? extends Plugin>
                             enginePlugins.stream().map(plugin -> plugin::getEngineFactory))
                     .collect(Collectors.toList());
 
+
+            final Map<String, Function<IndexSettings, IndexStore>> indexStoreFactories =
+                    pluginsService.filterPlugins(IndexStorePlugin.class)
+                            .stream()
+                            .map(IndexStorePlugin::getIndexStoreFactories)
+                            .flatMap(m -> m.entrySet().stream())
+                            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
             final IndicesService indicesService =
                     new IndicesService(settings, pluginsService, nodeEnvironment, xContentRegistry, analysisModule.getAnalysisRegistry(),
                             clusterModule.getIndexNameExpressionResolver(), indicesModule.getMapperRegistry(), namedWriteableRegistry,
                             threadPool, settingsModule.getIndexScopedSettings(), circuitBreakerService, bigArrays,
-                            scriptModule.getScriptService(), client, metaStateService, engineFactoryProviders);
+                            scriptModule.getScriptService(), client, metaStateService, engineFactoryProviders, indexStoreFactories);
 
 
             Collection<Object> pluginComponents = pluginsService.filterPlugins(Plugin.class).stream()

server/src/main/java/org/elasticsearch/plugins/IndexStorePlugin.java

@@ -0,0 +1,42 @@
+/*
+ * 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.plugins;
+
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.store.IndexStore;
+
+import java.util.Map;
+import java.util.function.Function;
+
+/**
+ * A plugin that provides alternative index store implementations.
+ */
+public interface IndexStorePlugin {
+
+    /**
+     * The index store factories for this plugin. When an index is created the store type setting
+     * {@link org.elasticsearch.index.IndexModule#INDEX_STORE_TYPE_SETTING} on the index will be examined and either use the default or a
+     * built-in type, or looked up among all the index store factories from {@link IndexStore} plugins.
+     *
+     * @return a map from store type to an index store factory
+     */
+    Map<String, Function<IndexSettings, IndexStore>> getIndexStoreFactories();
+
+}