hadoop IFileOutputStream 源码
haddop IFileOutputStream 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/IFileOutputStream.java
/**
* 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.
*/
package org.apache.hadoop.mapred;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FilterOutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.DataChecksum;
/**
* A Checksum output stream.
* Checksum for the contents of the file is calculated and
* appended to the end of the file on close of the stream.
* Used for IFiles
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class IFileOutputStream extends FilterOutputStream {
/**
* The output stream to be checksummed.
*/
private final DataChecksum sum;
private byte[] barray;
private boolean closed = false;
private boolean finished = false;
/**
* Create a checksum output stream that writes
* the bytes to the given stream.
* @param out
*/
public IFileOutputStream(OutputStream out) {
super(out);
sum = DataChecksum.newDataChecksum(DataChecksum.Type.CRC32,
Integer.MAX_VALUE);
barray = new byte[sum.getChecksumSize()];
}
@Override
public void close() throws IOException {
if (closed) {
return;
}
closed = true;
try {
finish();
} finally {
IOUtils.closeStream(out);
}
}
/**
* Finishes writing data to the output stream, by writing
* the checksum bytes to the end. The underlying stream is not closed.
* @throws IOException
*/
public void finish() throws IOException {
if (finished) {
return;
}
finished = true;
sum.writeValue(barray, 0, false);
out.write (barray, 0, sum.getChecksumSize());
out.flush();
}
/**
* Write bytes to the stream.
*/
@Override
public void write(byte[] b, int off, int len) throws IOException {
sum.update(b, off,len);
out.write(b,off,len);
}
@Override
public void write(int b) throws IOException {
barray[0] = (byte) (b & 0xFF);
write(barray,0,1);
}
}
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