org.elasticsearch.index.translog.Checkpoint Maven / Gradle / Ivy
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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.codecs.CodecUtil;
import org.apache.lucene.store.DataInput;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.OutputStreamIndexOutput;
import org.apache.lucene.store.SimpleFSDirectory;
import org.elasticsearch.common.io.Channels;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.nio.file.OpenOption;
import java.nio.file.Path;
/**
*/
class Checkpoint {
final long offset;
final int numOps;
final long generation;
private static final int INITIAL_VERSION = 1; // start with 1, just to recognize there was some magic serialization logic before
private static final String CHECKPOINT_CODEC = "ckp";
static final int FILE_SIZE = CodecUtil.headerLength(CHECKPOINT_CODEC)
+ Integer.BYTES // ops
+ Long.BYTES // offset
+ Long.BYTES // generation
+ CodecUtil.footerLength();
static final int LEGACY_NON_CHECKSUMMED_FILE_LENGTH = Integer.BYTES // ops
+ Long.BYTES // offset
+ Long.BYTES; // generation
Checkpoint(long offset, int numOps, long generation) {
this.offset = offset;
this.numOps = numOps;
this.generation = generation;
}
private void write(DataOutput out) throws IOException {
out.writeLong(offset);
out.writeInt(numOps);
out.writeLong(generation);
}
// reads a checksummed checkpoint introduced in ES 5.0.0
static Checkpoint readChecksummedV1(DataInput in) throws IOException {
return new Checkpoint(in.readLong(), in.readInt(), in.readLong());
}
// reads checkpoint from ES < 5.0.0
static Checkpoint readNonChecksummed(DataInput in) throws IOException {
return new Checkpoint(in.readLong(), in.readInt(), in.readLong());
}
@Override
public String toString() {
return "Checkpoint{" +
"offset=" + offset +
", numOps=" + numOps +
", translogFileGeneration= " + generation +
'}';
}
public static Checkpoint read(Path path) throws IOException {
try (Directory dir = new SimpleFSDirectory(path.getParent())) {
try (final IndexInput indexInput = dir.openInput(path.getFileName().toString(), IOContext.DEFAULT)) {
if (indexInput.length() == LEGACY_NON_CHECKSUMMED_FILE_LENGTH) {
// OLD unchecksummed file that was written < ES 5.0.0
return Checkpoint.readNonChecksummed(indexInput);
}
// We checksum the entire file before we even go and parse it. If it's corrupted we barf right here.
CodecUtil.checksumEntireFile(indexInput);
final int fileVersion = CodecUtil.checkHeader(indexInput, CHECKPOINT_CODEC, INITIAL_VERSION, INITIAL_VERSION);
return Checkpoint.readChecksummedV1(indexInput);
}
}
}
public static void write(ChannelFactory factory, Path checkpointFile, Checkpoint checkpoint, OpenOption... options) throws IOException {
final ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream(FILE_SIZE) {
@Override
public synchronized byte[] toByteArray() {
// don't clone
return buf;
}
};
final String resourceDesc = "checkpoint(path=\"" + checkpointFile + "\", gen=" + checkpoint + ")";
try (final OutputStreamIndexOutput indexOutput =
new OutputStreamIndexOutput(resourceDesc, checkpointFile.toString(), byteOutputStream, FILE_SIZE)) {
CodecUtil.writeHeader(indexOutput, CHECKPOINT_CODEC, INITIAL_VERSION);
checkpoint.write(indexOutput);
CodecUtil.writeFooter(indexOutput);
assert indexOutput.getFilePointer() == FILE_SIZE :
"get you number straights. Bytes written: " + indexOutput.getFilePointer() + " buffer size: " + FILE_SIZE;
assert indexOutput.getFilePointer() < 512 :
"checkpoint files have to be smaller 512b for atomic writes. size: " + indexOutput.getFilePointer();
}
// now go and write to the channel, in one go.
try (FileChannel channel = factory.open(checkpointFile, options)) {
Channels.writeToChannel(byteOutputStream.toByteArray(), channel);
// no need to force metadata, file size stays the same and we did the full fsync
// when we first created the file, so the directory entry doesn't change as well
channel.force(false);
}
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Checkpoint that = (Checkpoint) o;
if (offset != that.offset) {
return false;
}
if (numOps != that.numOps) {
return false;
}
return generation == that.generation;
}
@Override
public int hashCode() {
int result = Long.hashCode(offset);
result = 31 * result + numOps;
result = 31 * result + Long.hashCode(generation);
return result;
}
}