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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.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.io.Channels;
import org.elasticsearch.common.util.concurrent.ReleasableLock;
import org.elasticsearch.index.shard.ShardId;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
/**
*/
public final class BufferingTranslogWriter extends TranslogWriter {
private byte[] buffer;
private int bufferCount;
private WrapperOutputStream bufferOs = new WrapperOutputStream();
/* the total offset of this file including the bytes written to the file as well as into the buffer */
private volatile long totalOffset;
public BufferingTranslogWriter(ShardId shardId, long generation, ChannelReference channelReference, int bufferSize) throws IOException {
super(shardId, generation, channelReference);
this.buffer = new byte[bufferSize];
this.totalOffset = writtenOffset;
}
@Override
public Translog.Location add(BytesReference data) throws IOException {
try (ReleasableLock lock = writeLock.acquire()) {
ensureOpen();
final long offset = totalOffset;
if (data.length() >= buffer.length) {
flush();
// we use the channel to write, since on windows, writing to the RAF might not be reflected
// when reading through the channel
try {
data.writeTo(channel);
} catch (Throwable ex) {
closeWithTragicEvent(ex);
throw ex;
}
writtenOffset += data.length();
totalOffset += data.length();
} else {
if (data.length() > buffer.length - bufferCount) {
flush();
}
data.writeTo(bufferOs);
totalOffset += data.length();
}
operationCounter++;
return new Translog.Location(generation, offset, data.length());
}
}
protected final void flush() throws IOException {
assert writeLock.isHeldByCurrentThread();
if (bufferCount > 0) {
ensureOpen();
// we use the channel to write, since on windows, writing to the RAF might not be reflected
// when reading through the channel
final int bufferSize = bufferCount;
try {
Channels.writeToChannel(buffer, 0, bufferSize, channel);
} catch (Throwable ex) {
closeWithTragicEvent(ex);
throw ex;
}
writtenOffset += bufferSize;
bufferCount = 0;
}
}
@Override
protected void readBytes(ByteBuffer targetBuffer, long position) throws IOException {
try (ReleasableLock lock = readLock.acquire()) {
if (position >= writtenOffset) {
assert targetBuffer.hasArray() : "buffer must have array";
final int sourcePosition = (int) (position - writtenOffset);
System.arraycopy(buffer, sourcePosition,
targetBuffer.array(), targetBuffer.position(), targetBuffer.limit());
targetBuffer.position(targetBuffer.limit());
return;
}
}
// we don't have to have a read lock here because we only write ahead to the file, so all writes has been complete
// for the requested location.
Channels.readFromFileChannelWithEofException(channel, position, targetBuffer);
}
@Override
public boolean syncNeeded() {
return totalOffset != lastSyncedOffset;
}
@Override
public synchronized void sync() throws IOException {
if (syncNeeded()) {
ensureOpen(); // this call gives a better exception that the incRef if we are closed by a tragic event
channelReference.incRef();
try {
final long offsetToSync;
final int opsCounter;
try (ReleasableLock lock = writeLock.acquire()) {
flush();
offsetToSync = totalOffset;
opsCounter = operationCounter;
}
// we can do this outside of the write lock but we have to protect from
// concurrent syncs
ensureOpen(); // just for kicks - the checkpoint happens or not either way
checkpoint(offsetToSync, opsCounter, channelReference);
lastSyncedOffset = offsetToSync;
} finally {
channelReference.decRef();
}
}
}
public void updateBufferSize(int bufferSize) {
try (ReleasableLock lock = writeLock.acquire()) {
ensureOpen();
if (this.buffer.length != bufferSize) {
flush();
this.buffer = new byte[bufferSize];
}
} catch (IOException e) {
throw new TranslogException(shardId, "failed to flush", e);
}
}
class WrapperOutputStream extends OutputStream {
@Override
public void write(int b) throws IOException {
buffer[bufferCount++] = (byte) b;
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
// we do safety checked when we decide to use this stream...
System.arraycopy(b, off, buffer, bufferCount, len);
bufferCount += len;
}
}
@Override
public long sizeInBytes() {
return totalOffset;
}
}