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Relax NoOpEngine constraints on translog #37413

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Jan 23, 2019
Merged

Relax NoOpEngine constraints on translog #37413

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68 changes: 4 additions & 64 deletions server/src/main/java/org/elasticsearch/index/engine/NoOpEngine.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,54 +24,20 @@
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.LeafReader;
import org.apache.lucene.store.Directory;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.core.internal.io.IOUtils;
import org.elasticsearch.index.translog.Translog;
import org.elasticsearch.index.translog.TranslogConfig;
import org.elasticsearch.index.translog.TranslogCorruptedException;
import org.elasticsearch.index.translog.TranslogDeletionPolicy;

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.function.LongSupplier;
import java.util.stream.Stream;
import java.util.function.Function;

/**
* NoOpEngine is an engine implementation that does nothing but the bare minimum
* required in order to have an engine. All attempts to do something (search,
* index, get), throw {@link UnsupportedOperationException}. This does maintain
* a translog with a deletion policy so that when flushing, no translog is
* retained on disk (setting a retention size and age of 0).
*
* It's also important to notice that this does list the commits of the Store's
* Directory so that the last commit's user data can be read for the historyUUID
* and last committed segment info.
* index, get), throw {@link UnsupportedOperationException}.
*/
public final class NoOpEngine extends ReadOnlyEngine {

public NoOpEngine(EngineConfig engineConfig) {
super(engineConfig, null, null, true, directoryReader -> directoryReader);
boolean success = false;
try {
// The deletion policy for the translog should not keep any translogs around, so the min age/size is set to -1
final TranslogDeletionPolicy translogDeletionPolicy = new TranslogDeletionPolicy(-1, -1);

// The translog is opened and closed to validate that the translog UUID from lucene is the same as the one in the translog
try (Translog translog = openTranslog(engineConfig, translogDeletionPolicy, engineConfig.getGlobalCheckpointSupplier())) {
final int nbOperations = translog.totalOperations();
if (nbOperations != 0) {
throw new IllegalArgumentException("Expected 0 translog operations but there were " + nbOperations);
}
}
success = true;
} catch (IOException | TranslogCorruptedException e) {
throw new EngineCreationFailureException(shardId, "failed to create engine", e);
} finally {
if (success == false) {
IOUtils.closeWhileHandlingException(this);
}
}
public NoOpEngine(EngineConfig config) {
super(config, null, null, true, Function.identity());
}

@Override
Expand Down Expand Up @@ -121,30 +87,4 @@ public CacheHelper getReaderCacheHelper() {
}
};
}

private Translog openTranslog(EngineConfig engineConfig, TranslogDeletionPolicy translogDeletionPolicy,
LongSupplier globalCheckpointSupplier) throws IOException {
final TranslogConfig translogConfig = engineConfig.getTranslogConfig();
final String translogUUID = loadTranslogUUIDFromLastCommit();
// We expect that this shard already exists, so it must already have an existing translog else something is badly wrong!
return new Translog(translogConfig, translogUUID, translogDeletionPolicy, globalCheckpointSupplier,
engineConfig.getPrimaryTermSupplier());
}

/**
* Reads the current stored translog ID from the last commit data.
*/
@Nullable
private String loadTranslogUUIDFromLastCommit() {
final Map<String, String> commitUserData = getLastCommittedSegmentInfos().getUserData();
if (commitUserData.containsKey(Translog.TRANSLOG_GENERATION_KEY) == false) {
throw new IllegalStateException("Commit doesn't contain translog generation id");
}
return commitUserData.get(Translog.TRANSLOG_UUID_KEY);
}

@Override
public boolean ensureTranslogSynced(Stream<Translog.Location> locations) {
throw new UnsupportedOperationException("Translog synchronization should never be needed");
}
}
54 changes: 54 additions & 0 deletions server/src/test/java/org/elasticsearch/index/engine/NoOpEngineRecoveryTests.java
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@@ -0,0 +1,54 @@
/*
* 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.elasticsearch.cluster.routing.RecoverySource.ExistingStoreRecoverySource;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.index.shard.IndexShard;
import org.elasticsearch.index.shard.IndexShardTestCase;

import java.io.IOException;

import static org.elasticsearch.cluster.routing.ShardRoutingHelper.initWithSameId;

public class NoOpEngineRecoveryTests extends IndexShardTestCase {

public void testRecoverFromNoOp() throws IOException {
final int nbDocs = scaledRandomIntBetween(1, 100);

final IndexShard indexShard = newStartedShard(true);
for (int i = 0; i < nbDocs; i++) {
indexDoc(indexShard, "_doc", String.valueOf(i));
}
indexShard.close("test", true);

final ShardRouting shardRouting = indexShard.routingEntry();
IndexShard primary = reinitShard(indexShard, initWithSameId(shardRouting, ExistingStoreRecoverySource.INSTANCE), NoOpEngine::new);
recoverShardFromStore(primary);
assertEquals(primary.seqNoStats().getMaxSeqNo(), primary.getMaxSeqNoOfUpdatesOrDeletes());
assertEquals(nbDocs, primary.docStats().getCount());

IndexShard replica = newShard(false, Settings.EMPTY, NoOpEngine::new);
recoverReplica(replica, primary, true);
assertEquals(replica.seqNoStats().getMaxSeqNo(), replica.getMaxSeqNoOfUpdatesOrDeletes());
assertEquals(nbDocs, replica.docStats().getCount());
closeShards(primary, replica);
}
}
63 changes: 0 additions & 63 deletions server/src/test/java/org/elasticsearch/index/engine/NoOpEngineTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,14 +21,12 @@

import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.MergePolicy;
import org.apache.lucene.index.NoMergePolicy;
import org.apache.lucene.store.LockObtainFailedException;
import org.elasticsearch.cluster.routing.IndexShardRoutingTable;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.ShardRoutingState;
import org.elasticsearch.cluster.routing.TestShardRouting;
import org.elasticsearch.common.bytes.BytesArray;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.core.internal.io.IOUtils;
import org.elasticsearch.index.IndexSettings;
Expand All @@ -37,8 +35,6 @@
import org.elasticsearch.index.seqno.SequenceNumbers;
import org.elasticsearch.index.shard.DocsStats;
import org.elasticsearch.index.store.Store;
import org.elasticsearch.index.translog.Translog;
import org.elasticsearch.index.translog.TranslogCorruptedException;
import org.elasticsearch.index.translog.TranslogDeletionPolicy;
import org.elasticsearch.test.IndexSettingsModule;

Expand All @@ -50,7 +46,6 @@

import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.instanceOf;
import static org.hamcrest.Matchers.is;

public class NoOpEngineTests extends EngineTestCase {
private static final IndexSettings INDEX_SETTINGS = IndexSettingsModule.newIndexSettings("index", Settings.EMPTY);
Expand All @@ -59,7 +54,6 @@ public void testNoopEngine() throws IOException {
engine.close();
final NoOpEngine engine = new NoOpEngine(noOpConfig(INDEX_SETTINGS, store, primaryTranslogDir));
expectThrows(UnsupportedOperationException.class, () -> engine.syncFlush(null, null));
expectThrows(UnsupportedOperationException.class, () -> engine.ensureTranslogSynced(null));
assertThat(engine.refreshNeeded(), equalTo(false));
assertThat(engine.shouldPeriodicallyFlush(), equalTo(false));
engine.close();
Expand Down Expand Up @@ -106,63 +100,6 @@ public void testNoopAfterRegularEngine() throws IOException {
noOpEngine.close();
}

public void testNoopEngineWithInvalidTranslogUUID() throws IOException {
IOUtils.close(engine, store);
final AtomicLong globalCheckpoint = new AtomicLong(SequenceNumbers.NO_OPS_PERFORMED);
try (Store store = createStore()) {
EngineConfig config = config(defaultSettings, store, createTempDir(), newMergePolicy(), null, null, globalCheckpoint::get);
int numDocs = scaledRandomIntBetween(10, 100);
try (InternalEngine engine = createEngine(config)) {
for (int i = 0; i < numDocs; i++) {
ParsedDocument doc = testParsedDocument(Integer.toString(i), null, testDocument(), new BytesArray("{}"), null);
engine.index(new Engine.Index(newUid(doc), doc, i, primaryTerm.get(), 1, null, Engine.Operation.Origin.REPLICA,
System.nanoTime(), -1, false, SequenceNumbers.UNASSIGNED_SEQ_NO, 0));
if (rarely()) {
engine.flush();
}
globalCheckpoint.set(engine.getLocalCheckpoint());
}
flushAndTrimTranslog(engine);
}

final Path newTranslogDir = createTempDir();
// A new translog will have a different UUID than the existing store/noOp engine does
Translog newTranslog = createTranslog(newTranslogDir, () -> 1L);
newTranslog.close();

EngineCreationFailureException e = expectThrows(EngineCreationFailureException.class,
() -> new NoOpEngine(noOpConfig(INDEX_SETTINGS, store, newTranslogDir)));
assertThat(e.getCause(), instanceOf(TranslogCorruptedException.class));
}
}

public void testNoopEngineWithNonZeroTranslogOperations() throws IOException {
IOUtils.close(engine, store);
final AtomicLong globalCheckpoint = new AtomicLong(SequenceNumbers.NO_OPS_PERFORMED);
try (Store store = createStore()) {
final MergePolicy mergePolicy = NoMergePolicy.INSTANCE;
EngineConfig config = config(defaultSettings, store, createTempDir(), mergePolicy, null, null, globalCheckpoint::get);
int numDocs = scaledRandomIntBetween(10, 100);
try (InternalEngine engine = createEngine(config)) {
for (int i = 0; i < numDocs; i++) {
ParsedDocument doc = testParsedDocument(Integer.toString(i), null, testDocument(), new BytesArray("{}"), null);
engine.index(new Engine.Index(newUid(doc), doc, i, primaryTerm.get(), 1, null, Engine.Operation.Origin.REPLICA,
System.nanoTime(), -1, false, SequenceNumbers.UNASSIGNED_SEQ_NO, 0));
if (rarely()) {
engine.flush();
}
globalCheckpoint.set(engine.getLocalCheckpoint());
}
engine.syncTranslog();
engine.flushAndClose();
engine.close();

IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> new NoOpEngine(engine.engineConfig));
assertThat(e.getMessage(), is("Expected 0 translog operations but there were " + numDocs));
}
}
}

public void testNoOpEngineDocStats() throws Exception {
IOUtils.close(engine, store);
final AtomicLong globalCheckpoint = new AtomicLong(SequenceNumbers.NO_OPS_PERFORMED);
Expand Down