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/*
* 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.translog;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TwoPhaseCommit;
import org.apache.lucene.store.AlreadyClosedException;
import org.apache.lucene.util.Accountable;
import org.apache.lucene.util.IOUtils;
import org.apache.lucene.util.RamUsageEstimator;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.common.UUIDs;
import org.elasticsearch.common.bytes.BytesArray;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.bytes.ReleasablePagedBytesReference;
import org.elasticsearch.common.io.stream.ReleasableBytesStreamOutput;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.common.lease.Releasables;
import org.elasticsearch.common.lucene.uid.Versions;
import org.elasticsearch.common.util.BigArrays;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import org.elasticsearch.common.util.concurrent.FutureUtils;
import org.elasticsearch.common.util.concurrent.ReleasableLock;
import org.elasticsearch.index.VersionType;
import org.elasticsearch.index.engine.Engine;
import org.elasticsearch.index.shard.AbstractIndexShardComponent;
import org.elasticsearch.index.shard.IndexShardComponent;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* A Translog is a per index shard component that records all non-committed index operations in a durable manner.
* In Elasticsearch there is one Translog instance per {@link org.elasticsearch.index.engine.InternalEngine}. The engine
* records the current translog generation {@link Translog#getGeneration()} in it's commit metadata using {@link #TRANSLOG_GENERATION_KEY}
* to reference the generation that contains all operations that have not yet successfully been committed to the engines lucene index.
* Additionally, since Elasticsearch 2.0 the engine also records a {@link #TRANSLOG_UUID_KEY} with each commit to ensure a strong association
* between the lucene index an the transaction log file. This UUID is used to prevent accidential recovery from a transaction log that belongs to a
* different engine.
*
* Each Translog has only one translog file open at any time referenced by a translog generation ID. This ID is written to a translog.ckp file that is designed
* to fit in a single disk block such that a write of the file is atomic. The checkpoint file is written on each fsync operation of the translog and records the number of operations
* written, the current tranlogs file generation and it's fsynced offset in bytes.
*
*
* When a translog is opened the checkpoint is use to retrieve the latest translog file generation and subsequently to open the last written file to recovery operations.
* The {@link org.elasticsearch.index.translog.Translog.TranslogGeneration}, given when the translog is opened / constructed is compared against
* the latest generation and all consecutive translog files singe the given generation and the last generation in the checkpoint will be recovered and preserved until the next
* generation is committed using {@link Translog#commit()}. In the common case the translog file generation in the checkpoint and the generation passed to the translog on creation are
* the same. The only situation when they can be different is when an actual translog commit fails in between {@link Translog#prepareCommit()} and {@link Translog#commit()}. In such a case
* the currently being committed translog file will not be deleted since it's commit was not successful. Yet, a new/current translog file is already opened at that point such that there is more than
* one translog file present. Such an uncommitted translog file always has a translog-${gen}.ckp associated with it which is an fsynced copy of the it's last translog.ckp such that in
* disaster recovery last fsynced offsets, number of operation etc. are still preserved.
*
*/
public class Translog extends AbstractIndexShardComponent implements IndexShardComponent, Closeable, TwoPhaseCommit {
/*
* TODO
* - we might need something like a deletion policy to hold on to more than one translog eventually (I think sequence IDs needs this) but we can refactor as we go
* - use a simple BufferedOutputStream to write stuff and fold BufferedTranslogWriter into it's super class... the tricky bit is we need to be able to do random access reads even from the buffer
* - we need random exception on the FileSystem API tests for all this.
* - we need to page align the last write before we sync, we can take advantage of ensureSynced for this since we might have already fsynced far enough
*/
public static final String TRANSLOG_GENERATION_KEY = "translog_generation";
public static final String TRANSLOG_UUID_KEY = "translog_uuid";
public static final String TRANSLOG_FILE_PREFIX = "translog-";
public static final String TRANSLOG_FILE_SUFFIX = ".tlog";
public static final String CHECKPOINT_SUFFIX = ".ckp";
public static final String CHECKPOINT_FILE_NAME = "translog" + CHECKPOINT_SUFFIX;
static final Pattern PARSE_STRICT_ID_PATTERN = Pattern.compile("^" + TRANSLOG_FILE_PREFIX + "(\\d+)(\\.tlog)$");
// the list of translog readers is guaranteed to be in order of translog generation
private final List readers = new ArrayList<>();
private volatile ScheduledFuture syncScheduler;
// this is a concurrent set and is not protected by any of the locks. The main reason
// is that is being accessed by two separate classes (additions & reading are done by Translog, remove by View when closed)
private final Set outstandingViews = ConcurrentCollections.newConcurrentSet();
private BigArrays bigArrays;
protected final ReleasableLock readLock;
protected final ReleasableLock writeLock;
private final Path location;
private TranslogWriter current;
private final static long NOT_SET_GENERATION = -1; // -1 is safe as it will not cause a translog deletion.
private volatile long currentCommittingGeneration = NOT_SET_GENERATION;
private volatile long lastCommittedTranslogFileGeneration = NOT_SET_GENERATION;
private final AtomicBoolean closed = new AtomicBoolean();
private final TranslogConfig config;
private final String translogUUID;
/**
* Creates a new Translog instance. This method will create a new transaction log unless the given {@link TranslogConfig} has
* a non-null {@link org.elasticsearch.index.translog.Translog.TranslogGeneration}. If the generation is null this method
* us destructive and will delete all files in the translog path given.
*
* @param config the configuration of this translog
* @param translogGeneration the translog generation to open. If this is null a new translog is created. If non-null
* the translog tries to open the given translog generation. The generation is treated as the last generation referenced
* form already committed data. This means all operations that have not yet been committed should be in the translog
* file referenced by this generation. The translog creation will fail if this generation can't be opened.
*
* @see TranslogConfig#getTranslogPath()
*
*/
public Translog(TranslogConfig config, TranslogGeneration translogGeneration) throws IOException {
super(config.getShardId(), config.getIndexSettings());
this.config = config;
if (translogGeneration == null || translogGeneration.translogUUID == null) { // legacy case
translogUUID = UUIDs.randomBase64UUID();
} else {
translogUUID = translogGeneration.translogUUID;
}
bigArrays = config.getBigArrays();
ReadWriteLock rwl = new ReentrantReadWriteLock();
readLock = new ReleasableLock(rwl.readLock());
writeLock = new ReleasableLock(rwl.writeLock());
this.location = config.getTranslogPath();
Files.createDirectories(this.location);
try {
if (translogGeneration != null) {
final Checkpoint checkpoint = readCheckpoint();
final Path nextTranslogFile = location.resolve(getFilename(checkpoint.generation + 1));
final Path currentCheckpointFile = location.resolve(getCommitCheckpointFileName(checkpoint.generation));
// this is special handling for error condition when we create a new writer but we fail to bake
// the newly written file (generation+1) into the checkpoint. This is still a valid state
// we just need to cleanup before we continue
// we hit this before and then blindly deleted the new generation even though we managed to bake it in and then hit this:
// https://discuss.elastic.co/t/cannot-recover-index-because-of-missing-tanslog-files/38336 as an example
//
// For this to happen we must have already copied the translog.ckp file into translog-gen.ckp so we first check if that file exists
// if not we don't even try to clean it up and wait until we fail creating it
assert Files.exists(nextTranslogFile) == false || Files.size(nextTranslogFile) <= TranslogWriter.getHeaderLength(translogUUID) : "unexpected translog file: [" + nextTranslogFile + "]";
if (Files.exists(currentCheckpointFile) // current checkpoint is already copied
&& Files.deleteIfExists(nextTranslogFile)) { // delete it and log a warning
logger.warn("deleted previously created, but not yet committed, next generation [{}]. This can happen due to a tragic exception when creating a new generation", nextTranslogFile.getFileName());
}
this.readers.addAll(recoverFromFiles(translogGeneration, checkpoint));
if (readers.isEmpty()) {
throw new IllegalStateException("at least one reader must be recovered");
}
boolean success = false;
try {
current = createWriter(checkpoint.generation + 1);
this.lastCommittedTranslogFileGeneration = translogGeneration.translogFileGeneration;
success = true;
} finally {
// we have to close all the recovered ones otherwise we leak file handles here
// for instance if we have a lot of tlog and we can't create the writer we keep on holding
// on to all the uncommitted tlog files if we don't close
if (success == false) {
IOUtils.closeWhileHandlingException(readers);
}
}
} else {
IOUtils.rm(location);
logger.debug("wipe translog location - creating new translog");
Files.createDirectories(location);
final long generation = 1;
Checkpoint checkpoint = new Checkpoint(0, 0, generation);
Checkpoint.write(location.resolve(CHECKPOINT_FILE_NAME), checkpoint, StandardOpenOption.WRITE, StandardOpenOption.CREATE_NEW);
current = createWriter(generation);
this.lastCommittedTranslogFileGeneration = NOT_SET_GENERATION;
}
// now that we know which files are there, create a new current one.
} catch (Throwable t) {
// close the opened translog files if we fail to create a new translog...
IOUtils.closeWhileHandlingException(current);
IOUtils.closeWhileHandlingException(readers);
throw t;
}
}
/** recover all translog files found on disk */
private final ArrayList recoverFromFiles(TranslogGeneration translogGeneration, Checkpoint checkpoint) throws IOException {
boolean success = false;
ArrayList foundTranslogs = new ArrayList<>();
final Path tempFile = Files.createTempFile(location, TRANSLOG_FILE_PREFIX, TRANSLOG_FILE_SUFFIX); // a temp file to copy checkpoint to - note it must be in on the same FS otherwise atomic move won't work
boolean tempFileRenamed = false;
try (ReleasableLock lock = writeLock.acquire()) {
logger.debug("open uncommitted translog checkpoint {}", checkpoint);
final String checkpointTranslogFile = getFilename(checkpoint.generation);
for (long i = translogGeneration.translogFileGeneration; i < checkpoint.generation; i++) {
Path committedTranslogFile = location.resolve(getFilename(i));
if (Files.exists(committedTranslogFile) == false) {
throw new IllegalStateException("translog file doesn't exist with generation: " + i + " lastCommitted: " + lastCommittedTranslogFileGeneration + " checkpoint: " + checkpoint.generation + " - translog ids must be consecutive");
}
final TranslogReader reader = openReader(committedTranslogFile, Checkpoint.read(location.resolve(getCommitCheckpointFileName(i))));
foundTranslogs.add(reader);
logger.debug("recovered local translog from checkpoint {}", checkpoint);
}
foundTranslogs.add(openReader(location.resolve(checkpointTranslogFile), checkpoint));
Path commitCheckpoint = location.resolve(getCommitCheckpointFileName(checkpoint.generation));
if (Files.exists(commitCheckpoint)) {
Checkpoint checkpointFromDisk = Checkpoint.read(commitCheckpoint);
if (checkpoint.equals(checkpointFromDisk) == false) {
throw new IllegalStateException("Checkpoint file " + commitCheckpoint.getFileName() + " already exists but has corrupted content expected: " + checkpoint + " but got: " + checkpointFromDisk);
}
} else {
// we first copy this into the temp-file and then fsync it followed by an atomic move into the target file
// that way if we hit a disk-full here we are still in an consistent state.
Files.copy(location.resolve(CHECKPOINT_FILE_NAME), tempFile, StandardCopyOption.REPLACE_EXISTING);
IOUtils.fsync(tempFile, false);
Files.move(tempFile, commitCheckpoint, StandardCopyOption.ATOMIC_MOVE);
tempFileRenamed = true;
// we only fsync the directory the tempFile was already fsynced
IOUtils.fsync(commitCheckpoint.getParent(), true);
}
success = true;
} finally {
if (success == false) {
IOUtils.closeWhileHandlingException(foundTranslogs);
}
if (tempFileRenamed == false) {
try {
Files.delete(tempFile);
} catch (IOException ex) {
logger.warn("failed to delete temp file {}", ex, tempFile);
}
}
}
return foundTranslogs;
}
TranslogReader openReader(Path path, Checkpoint checkpoint) throws IOException {
FileChannel channel = FileChannel.open(path, StandardOpenOption.READ);
try {
assert Translog.parseIdFromFileName(path) == checkpoint.generation : "expected generation: " + Translog.parseIdFromFileName(path) + " but got: " + checkpoint.generation;
TranslogReader reader = TranslogReader.open(channel, path, checkpoint, translogUUID);
channel = null;
return reader;
} finally {
IOUtils.close(channel);
}
}
/**
* Extracts the translog generation from a file name.
*
* @throws IllegalArgumentException if the path doesn't match the expected pattern.
*/
public static long parseIdFromFileName(Path translogFile) {
final String fileName = translogFile.getFileName().toString();
final Matcher matcher = PARSE_STRICT_ID_PATTERN.matcher(fileName);
if (matcher.matches()) {
try {
return Long.parseLong(matcher.group(1));
} catch (NumberFormatException e) {
throw new IllegalStateException("number formatting issue in a file that passed PARSE_STRICT_ID_PATTERN: " + fileName + "]", e);
}
}
throw new IllegalArgumentException("can't parse id from file: " + fileName);
}
/** Returns {@code true} if this {@code Translog} is still open. */
public boolean isOpen() {
return closed.get() == false;
}
@Override
public void close() throws IOException {
if (closed.compareAndSet(false, true)) {
try (ReleasableLock lock = writeLock.acquire()) {
try {
current.sync();
} finally {
closeFilesIfNoPendingViews();
}
} finally {
FutureUtils.cancel(syncScheduler);
logger.debug("translog closed");
}
}
}
/**
* Returns all translog locations as absolute paths.
* These paths don't contain actual translog files they are
* directories holding the transaction logs.
*/
public Path location() {
return location;
}
/**
* Returns the generation of the current transaction log.
*/
public long currentFileGeneration() {
try (ReleasableLock lock = readLock.acquire()) {
return current.getGeneration();
}
}
/**
* Returns the number of operations in the transaction files that aren't committed to lucene..
*/
public int totalOperations() {
return totalOperations(lastCommittedTranslogFileGeneration);
}
/**
* Returns the size in bytes of the translog files that aren't committed to lucene.
*/
public long sizeInBytes() {
return sizeInBytes(lastCommittedTranslogFileGeneration);
}
/**
* Returns the number of operations in the transaction files that aren't committed to lucene..
*/
private int totalOperations(long minGeneration) {
try (ReleasableLock ignored = readLock.acquire()) {
ensureOpen();
return Stream.concat(readers.stream(), Stream.of(current))
.filter(r -> r.getGeneration() >= minGeneration)
.mapToInt(BaseTranslogReader::totalOperations)
.sum();
}
}
/**
* Returns the size in bytes of the translog files that aren't committed to lucene.
*/
private long sizeInBytes(long minGeneration) {
try (ReleasableLock ignored = readLock.acquire()) {
ensureOpen();
return Stream.concat(readers.stream(), Stream.of(current))
.filter(r -> r.getGeneration() >= minGeneration)
.mapToLong(BaseTranslogReader::sizeInBytes)
.sum();
}
}
TranslogWriter createWriter(long fileGeneration) throws IOException {
TranslogWriter newFile;
try {
newFile = TranslogWriter.create(shardId, translogUUID, fileGeneration, location.resolve(getFilename(fileGeneration)), getChannelFactory(), config.getBufferSize());
} catch (IOException e) {
throw new TranslogException(shardId, "failed to create new translog file", e);
}
return newFile;
}
/**
* Read the Operation object from the given location. This method will try to read the given location from
* the current or from the currently committing translog file. If the location is in a file that has already
* been closed or even removed the method will return null instead.
*/
public Translog.Operation read(Location location) {
try (ReleasableLock lock = readLock.acquire()) {
final BaseTranslogReader reader;
final long currentGeneration = current.getGeneration();
if (currentGeneration == location.generation) {
reader = current;
} else if (readers.isEmpty() == false && readers.get(readers.size() - 1).getGeneration() == location.generation) {
reader = readers.get(readers.size() - 1);
} else if (currentGeneration < location.generation) {
throw new IllegalStateException("location generation [" + location.generation + "] is greater than the current generation [" + currentGeneration + "]");
} else {
return null;
}
return reader.read(location);
} catch (IOException e) {
throw new ElasticsearchException("failed to read source from translog location " + location, e);
}
}
/**
* Adds a delete / index operations to the transaction log.
*
* @see org.elasticsearch.index.translog.Translog.Operation
* @see Index
* @see org.elasticsearch.index.translog.Translog.Delete
*/
public Location add(Operation operation) throws IOException {
final ReleasableBytesStreamOutput out = new ReleasableBytesStreamOutput(bigArrays);
try {
final BufferedChecksumStreamOutput checksumStreamOutput = new BufferedChecksumStreamOutput(out);
final long start = out.position();
out.skip(Integer.BYTES);
writeOperationNoSize(checksumStreamOutput, operation);
final long end = out.position();
final int operationSize = (int) (end - Integer.BYTES - start);
out.seek(start);
out.writeInt(operationSize);
out.seek(end);
final ReleasablePagedBytesReference bytes = out.bytes();
try (ReleasableLock lock = readLock.acquire()) {
ensureOpen();
Location location = current.add(bytes);
assert assertBytesAtLocation(location, bytes);
return location;
}
} catch (AlreadyClosedException | IOException ex) {
closeOnTragicEvent(ex);
throw ex;
} catch (Throwable e) {
closeOnTragicEvent(e);
throw new TranslogException(shardId, "Failed to write operation [" + operation + "]", e);
} finally {
Releasables.close(out.bytes());
}
}
boolean assertBytesAtLocation(Translog.Location location, BytesReference expectedBytes) throws IOException {
// tests can override this
ByteBuffer buffer = ByteBuffer.allocate(location.size);
current.readBytes(buffer, location.translogLocation);
return new BytesArray(buffer.array()).equals(expectedBytes);
}
/**
* Snapshots the current transaction log allowing to safely iterate over the snapshot.
* Snapshots are fixed in time and will not be updated with future operations.
*/
public Snapshot newSnapshot() {
return createSnapshot(Long.MIN_VALUE);
}
private Snapshot createSnapshot(long minGeneration) {
try (ReleasableLock ignored = readLock.acquire()) {
ensureOpen();
Snapshot[] snapshots = Stream.concat(readers.stream(), Stream.of(current))
.filter(reader -> reader.getGeneration() >= minGeneration)
.map(BaseTranslogReader::newSnapshot).toArray(Snapshot[]::new);
return new MultiSnapshot(snapshots);
}
}
/**
* Returns a view into the current translog that is guaranteed to retain all current operations
* while receiving future ones as well
*/
public Translog.View newView() {
try (ReleasableLock lock = readLock.acquire()) {
ensureOpen();
View view = new View(lastCommittedTranslogFileGeneration);
outstandingViews.add(view);
return view;
}
}
/**
* Sync's the translog.
*/
public void sync() throws IOException {
try (ReleasableLock lock = readLock.acquire()) {
if (closed.get() == false) {
current.sync();
}
} catch (Throwable ex) {
closeOnTragicEvent(ex);
throw ex;
}
}
public boolean syncNeeded() {
try (ReleasableLock lock = readLock.acquire()) {
return current.syncNeeded();
}
}
/** package private for testing */
public static String getFilename(long generation) {
return TRANSLOG_FILE_PREFIX + generation + TRANSLOG_FILE_SUFFIX;
}
static String getCommitCheckpointFileName(long generation) {
return TRANSLOG_FILE_PREFIX + generation + CHECKPOINT_SUFFIX;
}
/**
* Ensures that the given location has be synced / written to the underlying storage.
*
* @return Returns true iff this call caused an actual sync operation otherwise false
*/
public boolean ensureSynced(Location location) throws IOException {
try (ReleasableLock lock = readLock.acquire()) {
if (location.generation == current.getGeneration()) { // if we have a new one it's already synced
ensureOpen();
return current.syncUpTo(location.translogLocation + location.size);
}
} catch (Throwable ex) {
closeOnTragicEvent(ex);
throw ex;
}
return false;
}
private void closeOnTragicEvent(Throwable ex) {
if (current.getTragicException() != null) {
try {
close();
} catch (AlreadyClosedException inner) {
// don't do anything in this case. The AlreadyClosedException comes from TranslogWriter and we should not add it as suppressed because
// will contain the Exception ex as cause. See also https://github.com/elastic/elasticsearch/issues/15941
} catch (Exception inner) {
assert (ex != inner.getCause());
ex.addSuppressed(inner);
}
}
}
/**
* return stats
*/
public TranslogStats stats() {
// acquire lock to make the two numbers roughly consistent (no file change half way)
try (ReleasableLock lock = readLock.acquire()) {
return new TranslogStats(totalOperations(), sizeInBytes());
}
}
private boolean isReferencedGeneration(long generation) { // used to make decisions if a file can be deleted
return generation >= lastCommittedTranslogFileGeneration;
}
public TranslogConfig getConfig() {
return config;
}
/**
* a view into the translog, capturing all translog file at the moment of creation
* and updated with any future translog.
*/
/**
* a view into the translog, capturing all translog file at the moment of creation
* and updated with any future translog.
*/
public class View implements Closeable {
AtomicBoolean closed = new AtomicBoolean();
final long minGeneration;
View(long minGeneration) {
this.minGeneration = minGeneration;
}
/** this smallest translog generation in this view */
public long minTranslogGeneration() {
return minGeneration;
}
/**
* The total number of operations in the view.
*/
public int totalOperations() {
return Translog.this.totalOperations(minGeneration);
}
/**
* Returns the size in bytes of the files behind the view.
*/
public long sizeInBytes() {
return Translog.this.sizeInBytes(minGeneration);
}
/** create a snapshot from this view */
public Snapshot snapshot() {
ensureOpen();
return Translog.this.createSnapshot(minGeneration);
}
void ensureOpen() {
if (closed.get()) {
throw new AlreadyClosedException("View is already closed");
}
}
@Override
public void close() throws IOException {
if (closed.getAndSet(true) == false) {
logger.trace("closing view starting at translog [{}]", minTranslogGeneration());
boolean removed = outstandingViews.remove(this);
assert removed : "View was never set but was supposed to be removed";
trimUnreferencedReaders();
closeFilesIfNoPendingViews();
}
}
}
public static class Location implements Accountable, Comparable {
public final long generation;
public final long translogLocation;
public final int size;
Location(long generation, long translogLocation, int size) {
this.generation = generation;
this.translogLocation = translogLocation;
this.size = size;
}
@Override
public long ramBytesUsed() {
return RamUsageEstimator.NUM_BYTES_OBJECT_HEADER + 2 * Long.BYTES + Integer.BYTES;
}
@Override
public Collection getChildResources() {
return Collections.emptyList();
}
@Override
public String toString() {
return "[generation: " + generation + ", location: " + translogLocation + ", size: " + size + "]";
}
@Override
public int compareTo(Location o) {
if (generation == o.generation) {
return Long.compare(translogLocation, o.translogLocation);
}
return Long.compare(generation, o.generation);
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Location location = (Location) o;
if (generation != location.generation) {
return false;
}
if (translogLocation != location.translogLocation) {
return false;
}
return size == location.size;
}
@Override
public int hashCode() {
int result = Long.hashCode(generation);
result = 31 * result + Long.hashCode(translogLocation);
result = 31 * result + size;
return result;
}
}
/**
* A snapshot of the transaction log, allows to iterate over all the transaction log operations.
*/
public interface Snapshot {
/**
* The total number of operations in the translog.
*/
int totalOperations();
/**
* Returns the next operation in the snapshot or null if we reached the end.
*/
Translog.Operation next() throws IOException;
}
/**
* A generic interface representing an operation performed on the transaction log.
* Each is associated with a type.
*/
public interface Operation extends Writeable {
enum Type {
@Deprecated
CREATE((byte) 1),
INDEX((byte) 2),
DELETE((byte) 3);
private final byte id;
Type(byte id) {
this.id = id;
}
public byte id() {
return this.id;
}
public static Type fromId(byte id) {
switch (id) {
case 1:
return CREATE;
case 2:
return INDEX;
case 3:
return DELETE;
default:
throw new IllegalArgumentException("No type mapped for [" + id + "]");
}
}
}
Type opType();
long estimateSize();
Source getSource();
/**
* Reads the type and the operation from the given stream. The operatino must be written with
* {@link #writeType(Operation, StreamOutput)}
*/
static Operation readType(StreamInput input) throws IOException {
Translog.Operation.Type type = Translog.Operation.Type.fromId(input.readByte());
switch (type) {
case CREATE:
// the deserialization logic in Index was identical to that of Create when create was deprecated
return new Index(input);
case DELETE:
return new Translog.Delete(input);
case INDEX:
return new Index(input);
default:
throw new IOException("No type for [" + type + "]");
}
}
/**
* Writes the type and translog operation to the given stream
*/
static void writeType(Translog.Operation operation, StreamOutput output) throws IOException {
output.writeByte(operation.opType().id());
operation.writeTo(output);
}
}
public static class Source {
public final BytesReference source;
public final String routing;
public final String parent;
public final long timestamp;
public final long ttl;
public Source(BytesReference source, String routing, String parent, long timestamp, long ttl) {
this.source = source;
this.routing = routing;
this.parent = parent;
this.timestamp = timestamp;
this.ttl = ttl;
}
}
public static class Index implements Operation {
public static final int SERIALIZATION_FORMAT = 6; // since 2.0-beta1 and 1.1
private final String id;
private final String type;
private final long version;
private final VersionType versionType;
private final BytesReference source;
private final String routing;
private final String parent;
private final long timestamp;
private final long ttl;
public Index(StreamInput in) throws IOException {
final int format = in.readVInt(); // SERIALIZATION_FORMAT
assert format == SERIALIZATION_FORMAT : "format was: " + format;
id = in.readString();
type = in.readString();
source = in.readBytesReference();
routing = in.readOptionalString();
parent = in.readOptionalString();
this.version = in.readLong();
this.timestamp = in.readLong();
this.ttl = in.readLong();
this.versionType = VersionType.fromValue(in.readByte());
assert versionType.validateVersionForWrites(this.version);
}
public Index(Engine.Index index) {
this.id = index.id();
this.type = index.type();
this.source = index.source();
this.routing = index.routing();
this.parent = index.parent();
this.version = index.version();
this.timestamp = index.timestamp();
this.ttl = index.ttl();
this.versionType = index.versionType();
}
public Index(String type, String id, byte[] source) {
this.type = type;
this.id = id;
this.source = new BytesArray(source);
version = Versions.MATCH_ANY;
versionType = VersionType.INTERNAL;
routing = null;
parent = null;
timestamp = 0;
ttl = 0;
}
@Override
public Type opType() {
return Type.INDEX;
}
@Override
public long estimateSize() {
return ((id.length() + type.length()) * 2) + source.length() + 12;
}
public String type() {
return this.type;
}
public String id() {
return this.id;
}
public String routing() {
return this.routing;
}
public String parent() {
return this.parent;
}
public long timestamp() {
return this.timestamp;
}
public long ttl() {
return this.ttl;
}
public BytesReference source() {
return this.source;
}
public long version() {
return this.version;
}
public VersionType versionType() {
return versionType;
}
@Override
public Source getSource() {
return new Source(source, routing, parent, timestamp, ttl);
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeVInt(SERIALIZATION_FORMAT);
out.writeString(id);
out.writeString(type);
out.writeBytesReference(source);
out.writeOptionalString(routing);
out.writeOptionalString(parent);
out.writeLong(version);
out.writeLong(timestamp);
out.writeLong(ttl);
out.writeByte(versionType.getValue());
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Index index = (Index) o;
if (version != index.version ||
timestamp != index.timestamp ||
ttl != index.ttl ||
id.equals(index.id) == false ||
type.equals(index.type) == false ||
versionType != index.versionType ||
source.equals(index.source) == false) {
return false;
}
if (routing != null ? !routing.equals(index.routing) : index.routing != null) {
return false;
}
return !(parent != null ? !parent.equals(index.parent) : index.parent != null);
}
@Override
public int hashCode() {
int result = id.hashCode();
result = 31 * result + type.hashCode();
result = 31 * result + Long.hashCode(version);
result = 31 * result + versionType.hashCode();
result = 31 * result + source.hashCode();
result = 31 * result + (routing != null ? routing.hashCode() : 0);
result = 31 * result + (parent != null ? parent.hashCode() : 0);
result = 31 * result + Long.hashCode(timestamp);
result = 31 * result + Long.hashCode(ttl);
return result;
}
@Override
public String toString() {
return "Index{" +
"id='" + id + '\'' +
", type='" + type + '\'' +
'}';
}
}
public static class Delete implements Operation {
public static final int SERIALIZATION_FORMAT = 2; // since 2.0-beta1 and 1.1
private final Term uid;
private final long version;
private final VersionType versionType;
public Delete(StreamInput in) throws IOException {
final int format = in.readVInt();// SERIALIZATION_FORMAT
assert format == SERIALIZATION_FORMAT : "format was: " + format;
uid = new Term(in.readString(), in.readString());
this.version = in.readLong();
this.versionType = VersionType.fromValue(in.readByte());
assert versionType.validateVersionForWrites(this.version);
}
public Delete(Engine.Delete delete) {
this.uid = delete.uid();
this.version = delete.version();
this.versionType = delete.versionType();
}
public Delete(Term uid) {
this(uid, Versions.MATCH_ANY, VersionType.INTERNAL);
}
public Delete(Term uid, long version, VersionType versionType) {
this.uid = uid;
this.version = version;
this.versionType = versionType;
}
@Override
public Type opType() {
return Type.DELETE;
}
@Override
public long estimateSize() {
return ((uid.field().length() + uid.text().length()) * 2) + 20;
}
public Term uid() {
return this.uid;
}
public long version() {
return this.version;
}
public VersionType versionType() {
return this.versionType;
}
@Override
public Source getSource() {
throw new IllegalStateException("trying to read doc source from delete operation");
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeVInt(SERIALIZATION_FORMAT);
out.writeString(uid.field());
out.writeString(uid.text());
out.writeLong(version);
out.writeByte(versionType.getValue());
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Delete delete = (Delete) o;
return version == delete.version &&
uid.equals(delete.uid) &&
versionType == delete.versionType;
}
@Override
public int hashCode() {
int result = uid.hashCode();
result = 31 * result + Long.hashCode(version);
result = 31 * result + versionType.hashCode();
return result;
}
@Override
public String toString() {
return "Delete{" +
"uid=" + uid +
'}';
}
}
public enum Durability {
/**
* Async durability - translogs are synced based on a time interval.
*/
ASYNC,
/**
* Request durability - translogs are synced for each high levle request (bulk, index, delete)
*/
REQUEST;
}
private static void verifyChecksum(BufferedChecksumStreamInput in) throws IOException {
// This absolutely must come first, or else reading the checksum becomes part of the checksum
long expectedChecksum = in.getChecksum();
long readChecksum = in.readInt() & 0xFFFF_FFFFL;
if (readChecksum != expectedChecksum) {
throw new TranslogCorruptedException("translog stream is corrupted, expected: 0x" +
Long.toHexString(expectedChecksum) + ", got: 0x" + Long.toHexString(readChecksum));
}
}
/**
* Reads a list of operations written with {@link #writeOperations(StreamOutput, List)}
*/
public static List readOperations(StreamInput input) throws IOException {
ArrayList operations = new ArrayList<>();
int numOps = input.readInt();
final BufferedChecksumStreamInput checksumStreamInput = new BufferedChecksumStreamInput(input);
for (int i = 0; i < numOps; i++) {
operations.add(readOperation(checksumStreamInput));
}
return operations;
}
static Translog.Operation readOperation(BufferedChecksumStreamInput in) throws IOException {
final Translog.Operation operation;
try {
final int opSize = in.readInt();
if (opSize < 4) { // 4byte for the checksum
throw new AssertionError("operation size must be at least 4 but was: " + opSize);
}
in.resetDigest(); // size is not part of the checksum!
if (in.markSupported()) { // if we can we validate the checksum first
// we are sometimes called when mark is not supported this is the case when
// we are sending translogs across the network with LZ4 compression enabled - currently there is no way s
// to prevent this unfortunately.
in.mark(opSize);
in.skip(opSize - 4);
verifyChecksum(in);
in.reset();
}
operation = Translog.Operation.readType(in);
verifyChecksum(in);
} catch (EOFException e) {
throw new TruncatedTranslogException("reached premature end of file, translog is truncated", e);
} catch (AssertionError | Exception e) {
throw new TranslogCorruptedException("translog corruption while reading from stream", e);
}
return operation;
}
/**
* Writes all operations in the given iterable to the given output stream including the size of the array
* use {@link #readOperations(StreamInput)} to read it back.
*/
public static void writeOperations(StreamOutput outStream, List toWrite) throws IOException {
final ReleasableBytesStreamOutput out = new ReleasableBytesStreamOutput(BigArrays.NON_RECYCLING_INSTANCE);
try {
outStream.writeInt(toWrite.size());
final BufferedChecksumStreamOutput checksumStreamOutput = new BufferedChecksumStreamOutput(out);
for (Operation op : toWrite) {
out.reset();
final long start = out.position();
out.skip(Integer.BYTES);
writeOperationNoSize(checksumStreamOutput, op);
long end = out.position();
int operationSize = (int) (out.position() - Integer.BYTES - start);
out.seek(start);
out.writeInt(operationSize);
out.seek(end);
ReleasablePagedBytesReference bytes = out.bytes();
bytes.writeTo(outStream);
}
} finally {
Releasables.close(out.bytes());
}
}
public static void writeOperationNoSize(BufferedChecksumStreamOutput out, Translog.Operation op) throws IOException {
// This BufferedChecksumStreamOutput remains unclosed on purpose,
// because closing it closes the underlying stream, which we don't
// want to do here.
out.resetDigest();
Translog.Operation.writeType(op, out);
long checksum = out.getChecksum();
out.writeInt((int) checksum);
}
@Override
public void prepareCommit() throws IOException {
try (ReleasableLock lock = writeLock.acquire()) {
ensureOpen();
if (currentCommittingGeneration != NOT_SET_GENERATION) {
throw new IllegalStateException("already committing a translog with generation: " + currentCommittingGeneration);
}
currentCommittingGeneration = current.getGeneration();
TranslogReader currentCommittingTranslog = current.closeIntoReader();
readers.add(currentCommittingTranslog);
Path checkpoint = location.resolve(CHECKPOINT_FILE_NAME);
assert Checkpoint.read(checkpoint).generation == currentCommittingTranslog.getGeneration();
Path commitCheckpoint = location.resolve(getCommitCheckpointFileName(currentCommittingTranslog.getGeneration()));
Files.copy(checkpoint, commitCheckpoint);
IOUtils.fsync(commitCheckpoint, false);
IOUtils.fsync(commitCheckpoint.getParent(), true);
// create a new translog file - this will sync it and update the checkpoint data;
current = createWriter(current.getGeneration() + 1);
logger.trace("current translog set to [{}]", current.getGeneration());
} catch (Throwable t) {
IOUtils.closeWhileHandlingException(this); // tragic event
throw t;
}
}
@Override
public void commit() throws IOException {
try (ReleasableLock lock = writeLock.acquire()) {
ensureOpen();
if (currentCommittingGeneration == NOT_SET_GENERATION) {
prepareCommit();
}
assert currentCommittingGeneration != NOT_SET_GENERATION;
assert readers.stream().filter(r -> r.getGeneration() == currentCommittingGeneration).findFirst().isPresent()
: "reader list doesn't contain committing generation [" + currentCommittingGeneration + "]";
lastCommittedTranslogFileGeneration = current.getGeneration(); // this is important - otherwise old files will not be cleaned up
currentCommittingGeneration = NOT_SET_GENERATION;
trimUnreferencedReaders();
}
}
void trimUnreferencedReaders() {
try (ReleasableLock ignored = writeLock.acquire()) {
if (closed.get()) {
// we're shutdown potentially on some tragic event - don't delete anything
return;
}
long minReferencedGen = outstandingViews.stream().mapToLong(View::minTranslogGeneration).min().orElse(Long.MAX_VALUE);
minReferencedGen = Math.min(lastCommittedTranslogFileGeneration, minReferencedGen);
final long finalMinReferencedGen = minReferencedGen;
List unreferenced = readers.stream().filter(r -> r.getGeneration() < finalMinReferencedGen).collect(Collectors.toList());
for (final TranslogReader unreferencedReader : unreferenced) {
Path translogPath = unreferencedReader.path();
logger.trace("delete translog file - not referenced and not current anymore {}", translogPath);
IOUtils.closeWhileHandlingException(unreferencedReader);
IOUtils.deleteFilesIgnoringExceptions(translogPath,
translogPath.resolveSibling(getCommitCheckpointFileName(unreferencedReader.getGeneration())));
}
readers.removeAll(unreferenced);
}
}
void closeFilesIfNoPendingViews() throws IOException {
try (ReleasableLock ignored = writeLock.acquire()) {
if (closed.get() && outstandingViews.isEmpty()) {
logger.trace("closing files. translog is closed and there are no pending views");
ArrayList toClose = new ArrayList<>(readers);
toClose.add(current);
IOUtils.close(toClose);
}
}
}
@Override
public void rollback() throws IOException {
ensureOpen();
close();
}
/**
* References a transaction log generation
*/
public final static class TranslogGeneration {
public final String translogUUID;
public final long translogFileGeneration;
public TranslogGeneration(String translogUUID, long translogFileGeneration) {
this.translogUUID = translogUUID;
this.translogFileGeneration = translogFileGeneration;
}
}
/**
* Returns the current generation of this translog. This corresponds to the latest uncommitted translog generation
*/
public TranslogGeneration getGeneration() {
try (ReleasableLock lock = writeLock.acquire()) {
return new TranslogGeneration(translogUUID, currentFileGeneration());
}
}
/**
* Returns true iff the given generation is the current gbeneration of this translog
*/
public boolean isCurrent(TranslogGeneration generation) {
try (ReleasableLock lock = writeLock.acquire()) {
if (generation != null) {
if (generation.translogUUID.equals(translogUUID) == false) {
throw new IllegalArgumentException("commit belongs to a different translog: " + generation.translogUUID + " vs. " + translogUUID);
}
return generation.translogFileGeneration == currentFileGeneration();
}
}
return false;
}
long getFirstOperationPosition() { // for testing
return current.getFirstOperationOffset();
}
private void ensureOpen() {
if (closed.get()) {
throw new AlreadyClosedException("translog is already closed", current.getTragicException());
}
}
/**
* The number of currently open views
*/
int getNumOpenViews() {
return outstandingViews.size();
}
TranslogWriter.ChannelFactory getChannelFactory() {
return TranslogWriter.ChannelFactory.DEFAULT;
}
/**
* If this {@code Translog} was closed as a side-effect of a tragic exception,
* e.g. disk full while flushing a new segment, this returns the root cause exception.
* Otherwise (no tragic exception has occurred) it returns null.
*/
public Throwable getTragicException() {
return current.getTragicException();
}
/** Reads and returns the current checkpoint */
final Checkpoint readCheckpoint() throws IOException {
return Checkpoint.read(location.resolve(CHECKPOINT_FILE_NAME));
}
/**
* Returns the translog uuid used to associate a lucene index with a translog.
*/
public String getTranslogUUID() {
return translogUUID;
}
}