/*
* Licensed to Elastic Search and Shay Banon under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Elastic Search 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.fs;
import org.elasticsearch.ElasticSearchException;
import org.elasticsearch.common.io.FileChannelInputStream;
import org.elasticsearch.common.io.stream.BytesStreamInput;
import org.elasticsearch.index.translog.Translog;
import org.elasticsearch.index.translog.TranslogStreams;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/**
* @author kimchy (shay.banon)
*/
public class FsChannelSnapshot implements Translog.Snapshot {
private final long id;
private final int totalOperations;
private final RafReference raf;
private final FileChannel channel;
private final long length;
private Translog.Operation lastOperationRead = null;
private int position = 0;
private ByteBuffer cacheBuffer;
public FsChannelSnapshot(long id, RafReference raf, long length, int totalOperations) throws FileNotFoundException {
this.id = id;
this.raf = raf;
this.channel = raf.raf().getChannel();
this.length = length;
this.totalOperations = totalOperations;
}
@Override public long translogId() {
return this.id;
}
@Override public long position() {
return this.position;
}
@Override public long length() {
return this.length;
}
@Override public int estimatedTotalOperations() {
return this.totalOperations;
}
@Override public InputStream stream() throws IOException {
return new FileChannelInputStream(channel, position, lengthInBytes());
}
@Override public long lengthInBytes() {
return length - position;
}
@Override public boolean hasNext() {
try {
if (position > length) {
return false;
}
if (cacheBuffer == null) {
cacheBuffer = ByteBuffer.allocate(1024);
}
cacheBuffer.limit(4);
int bytesRead = channel.read(cacheBuffer, position);
if (bytesRead < 4) {
return false;
}
cacheBuffer.flip();
int opSize = cacheBuffer.getInt();
position += 4;
if ((position + opSize) > length) {
// restore the position to before we read the opSize
position -= 4;
return false;
}
if (cacheBuffer.capacity() < opSize) {
cacheBuffer = ByteBuffer.allocate(opSize);
}
cacheBuffer.clear();
cacheBuffer.limit(opSize);
channel.read(cacheBuffer, position);
cacheBuffer.flip();
position += opSize;
lastOperationRead = TranslogStreams.readTranslogOperation(new BytesStreamInput(cacheBuffer.array(), 0, opSize));
return true;
} catch (Exception e) {
return false;
}
}
@Override public Translog.Operation next() {
return this.lastOperationRead;
}
@Override public void seekForward(long length) {
this.position += length;
}
@Override public boolean release() throws ElasticSearchException {
raf.decreaseRefCount(true);
return true;
}
}