Refactor internal engine

This commit is a minor refactoring of internal engine to move hooks for
generating sequence numbers into the engine itself. As such, we refactor
tests that relied on this hook to use the new hook, and remove the hook
from the sequence number service itself.

Relates #27082

core/src/main/java/org/elasticsearch/index/engine/Engine.java

@@ -572,7 +572,11 @@ public CommitStats commitStats() {
         return new CommitStats(getLastCommittedSegmentInfos());
     }
 
-    /** get the sequence number service */
+    /**
+     * The sequence number service for this engine.
+     *
+     * @return the sequence number service
+     */
     public abstract SequenceNumbersService seqNoService();
 
     /**

core/src/main/java/org/elasticsearch/index/seqno/SequenceNumbersService.java

@@ -66,7 +66,7 @@ public SequenceNumbersService(
      *
      * @return the next assigned sequence number
      */
-    public long generateSeqNo() {
+    public final long generateSeqNo() {
         return localCheckpointTracker.generateSeqNo();
     }
 

core/src/test/java/org/elasticsearch/index/replication/IndexLevelReplicationTests.java

@@ -316,7 +316,7 @@ public long addDocument(Iterable<? extends IndexableField> doc) throws IOExcepti
                             assert documentFailureMessage != null;
                             throw new IOException(documentFailureMessage);
                         }
-                    }, null, config);
+                    }, null, null, config);
         }
     }
 

core/src/test/java/org/elasticsearch/index/replication/RecoveryDuringReplicationTests.java

@@ -637,6 +637,7 @@ public long addDocument(final Iterable<? extends IndexableField> doc) throws IOE
                                 }
                             },
                     null,
+                    null,
                     config);
         }
 

test/framework/src/main/java/org/elasticsearch/index/engine/TranslogHandler.java

@@ -0,0 +1,145 @@
+/*
+ * 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.engine;
+
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.elasticsearch.common.xcontent.NamedXContentRegistry;
+import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.analysis.AnalyzerScope;
+import org.elasticsearch.index.analysis.IndexAnalyzers;
+import org.elasticsearch.index.analysis.NamedAnalyzer;
+import org.elasticsearch.index.mapper.DocumentMapper;
+import org.elasticsearch.index.mapper.DocumentMapperForType;
+import org.elasticsearch.index.mapper.MapperService;
+import org.elasticsearch.index.mapper.Mapping;
+import org.elasticsearch.index.mapper.RootObjectMapper;
+import org.elasticsearch.index.shard.IndexShard;
+import org.elasticsearch.index.similarity.SimilarityService;
+import org.elasticsearch.index.translog.Translog;
+import org.elasticsearch.indices.IndicesModule;
+import org.elasticsearch.indices.mapper.MapperRegistry;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptyMap;
+import static org.elasticsearch.index.mapper.SourceToParse.source;
+
+public class TranslogHandler implements EngineConfig.TranslogRecoveryRunner {
+
+    private final MapperService mapperService;
+    public Mapping mappingUpdate = null;
+    private final Map<String, Mapping> recoveredTypes = new HashMap<>();
+
+    private final AtomicLong appliedOperations = new AtomicLong();
+
+    long appliedOperations() {
+        return appliedOperations.get();
+    }
+
+    public TranslogHandler(NamedXContentRegistry xContentRegistry, IndexSettings indexSettings) {
+        NamedAnalyzer defaultAnalyzer = new NamedAnalyzer("default", AnalyzerScope.INDEX, new StandardAnalyzer());
+        IndexAnalyzers indexAnalyzers =
+                new IndexAnalyzers(indexSettings, defaultAnalyzer, defaultAnalyzer, defaultAnalyzer, emptyMap(), emptyMap());
+        SimilarityService similarityService = new SimilarityService(indexSettings, null, emptyMap());
+        MapperRegistry mapperRegistry = new IndicesModule(emptyList()).getMapperRegistry();
+        mapperService = new MapperService(indexSettings, indexAnalyzers, xContentRegistry, similarityService, mapperRegistry,
+                () -> null);
+    }
+
+    private DocumentMapperForType docMapper(String type) {
+        RootObjectMapper.Builder rootBuilder = new RootObjectMapper.Builder(type);
+        DocumentMapper.Builder b = new DocumentMapper.Builder(rootBuilder, mapperService);
+        return new DocumentMapperForType(b.build(mapperService), mappingUpdate);
+    }
+
+    private void applyOperation(Engine engine, Engine.Operation operation) throws IOException {
+        switch (operation.operationType()) {
+            case INDEX:
+                Engine.Index engineIndex = (Engine.Index) operation;
+                Mapping update = engineIndex.parsedDoc().dynamicMappingsUpdate();
+                if (engineIndex.parsedDoc().dynamicMappingsUpdate() != null) {
+                    recoveredTypes.compute(engineIndex.type(), (k, mapping) -> mapping == null ? update : mapping.merge(update, false));
+                }
+                engine.index(engineIndex);
+                break;
+            case DELETE:
+                engine.delete((Engine.Delete) operation);
+                break;
+            case NO_OP:
+                engine.noOp((Engine.NoOp) operation);
+                break;
+            default:
+                throw new IllegalStateException("No operation defined for [" + operation + "]");
+        }
+    }
+
+    /**
+     * Returns the recovered types modifying the mapping during the recovery
+     */
+    public Map<String, Mapping> getRecoveredTypes() {
+        return recoveredTypes;
+    }
+
+    @Override
+    public int run(Engine engine, Translog.Snapshot snapshot) throws IOException {
+        int opsRecovered = 0;
+        Translog.Operation operation;
+        while ((operation = snapshot.next()) != null) {
+            applyOperation(engine, convertToEngineOp(operation, Engine.Operation.Origin.LOCAL_TRANSLOG_RECOVERY));
+            opsRecovered++;
+            appliedOperations.incrementAndGet();
+        }
+        return opsRecovered;
+    }
+
+    private Engine.Operation convertToEngineOp(Translog.Operation operation, Engine.Operation.Origin origin) {
+        switch (operation.opType()) {
+            case INDEX:
+                final Translog.Index index = (Translog.Index) operation;
+                final String indexName = mapperService.index().getName();
+                final Engine.Index engineIndex = IndexShard.prepareIndex(docMapper(index.type()),
+                        mapperService.getIndexSettings().getIndexVersionCreated(),
+                        source(indexName, index.type(), index.id(), index.source(), XContentFactory.xContentType(index.source()))
+                                .routing(index.routing()).parent(index.parent()), index.seqNo(), index.primaryTerm(),
+                        index.version(), index.versionType().versionTypeForReplicationAndRecovery(), origin,
+                        index.getAutoGeneratedIdTimestamp(), true);
+                return engineIndex;
+            case DELETE:
+                final Translog.Delete delete = (Translog.Delete) operation;
+                final Engine.Delete engineDelete = new Engine.Delete(delete.type(), delete.id(), delete.uid(), delete.seqNo(),
+                        delete.primaryTerm(), delete.version(), delete.versionType().versionTypeForReplicationAndRecovery(),
+                        origin, System.nanoTime());
+                return engineDelete;
+            case NO_OP:
+                final Translog.NoOp noOp = (Translog.NoOp) operation;
+                final Engine.NoOp engineNoOp =
+                        new Engine.NoOp(noOp.seqNo(), noOp.primaryTerm(), origin, System.nanoTime(), noOp.reason());
+                return engineNoOp;
+            default:
+                throw new IllegalStateException("No operation defined for [" + operation + "]");
+        }
+    }
+
+}