package org.apache.lucene.store;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.
*/
import java.io.IOException;
import java.util.zip.CRC32;
import java.util.zip.Checksum;
/** Writes bytes through to a primary IndexOutput, computing
* checksum. Note that you cannot use seek().
*
* @lucene.internal
*/
public class ChecksumIndexOutput extends IndexOutput {
IndexOutput main;
Checksum digest;
Directory directory;
String filename;
public ChecksumIndexOutput(IndexOutput main,Directory directory,String filename) {
this.main = main;
digest = new CRC32();
this.directory=directory;
this.filename=filename;
}
@Override
public void writeByte(byte b) throws IOException {
digest.update(b);
main.writeByte(b);
}
@Override
public void writeBytes(byte[] b, int offset, int length) throws IOException {
digest.update(b, offset, length);
main.writeBytes(b, offset, length);
}
public long getChecksum() {
return digest.getValue();
}
@Override
public void flush() throws IOException {
main.flush();
}
@Override
public void close() throws IOException {
main.close();
}
@Override
public long getFilePointer() {
return main.getFilePointer();
}
@Override
public void seek(long pos) {
throw new RuntimeException("not allowed");
}
/**
* Starts but does not complete the commit of this file (=
* writing of the final checksum at the end). After this
* is called must call {@link #finishCommit} and the
* {@link #close} to complete the commit.
*/
public void prepareCommit() throws IOException {
final long checksum = getChecksum();
// // Intentionally write a mismatched checksum. This is
// // because we want to 1) test, as best we can, that we
// // are able to write a long to the file, but 2) not
// // actually "commit" the file yet. This (prepare
// // commit) is phase 1 of a two-phase commit.
// final long pos = main.getFilePointer();
// main.writeLong(checksum-1);
// main.flush();
// main.seek(pos);
if(this.directory.fileExists(this.filename))
{
this.directory.deleteFile(this.filename);
}
IndexOutput check=directory.createOutput(this.filename);
check.writeLong(checksum-1);
check.close();
}
/** See {@link #prepareCommit} */
public void finishCommit() throws IOException {
if (this.directory.fileExists(this.filename)) {
this.directory.deleteFile(this.filename);
}
IndexOutput check = directory.createOutput(this.filename);
check.writeLong(getChecksum());
check.close();
}
@Override
public long length() throws IOException {
return main.length();
}
}