org.apache.hadoop.hdfs.client.HdfsDataOutputStream Maven / Gradle / Ivy
/**
* 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.hdfs.client;
import java.io.IOException;
import java.io.OutputStream;
import java.util.EnumSet;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.crypto.CryptoOutputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.hdfs.DFSOutputStream;
import org.apache.hadoop.util.Preconditions;
/**
* The Hdfs implementation of {@link FSDataOutputStream}.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class HdfsDataOutputStream extends FSDataOutputStream {
public HdfsDataOutputStream(DFSOutputStream out, FileSystem.Statistics stats,
long startPosition) throws IOException {
super(out, stats, startPosition);
}
public HdfsDataOutputStream(DFSOutputStream out, FileSystem.Statistics stats)
throws IOException {
this(out, stats, 0L);
}
public HdfsDataOutputStream(CryptoOutputStream out,
FileSystem.Statistics stats, long startPosition) throws IOException {
super(out, stats, startPosition);
Preconditions.checkArgument(
out.getWrappedStream() instanceof DFSOutputStream,
"CryptoOutputStream should wrap a DFSOutputStream");
}
public HdfsDataOutputStream(CryptoOutputStream out,
FileSystem.Statistics stats) throws IOException {
this(out, stats, 0L);
}
/**
* Get the actual number of replicas of the current block.
*
* This can be different from the designated replication factor of the file
* because the namenode does not maintain replication for the blocks which are
* currently being written to. Depending on the configuration, the client may
* continue to write to a block even if a few datanodes in the write pipeline
* have failed, or the client may add a new datanodes once a datanode has
* failed.
*
* @return the number of valid replicas of the current block
*/
public synchronized int getCurrentBlockReplication() throws IOException {
OutputStream wrappedStream = getWrappedStream();
if (wrappedStream instanceof CryptoOutputStream) {
wrappedStream = ((CryptoOutputStream) wrappedStream).getWrappedStream();
}
return ((DFSOutputStream) wrappedStream).getCurrentBlockReplication();
}
/**
* Sync buffered data to DataNodes (flush to disk devices).
*
* @param syncFlags
* Indicate the detailed semantic and actions of the hsync.
* @throws IOException
* @see FSDataOutputStream#hsync()
*/
public void hsync(EnumSet syncFlags) throws IOException {
OutputStream wrappedStream = getWrappedStream();
if (wrappedStream instanceof CryptoOutputStream) {
wrappedStream.flush();
wrappedStream = ((CryptoOutputStream) wrappedStream).getWrappedStream();
}
((DFSOutputStream) wrappedStream).hsync(syncFlags);
}
public enum SyncFlag {
/**
* When doing sync to DataNodes, also update the metadata (block length) in
* the NameNode.
*/
UPDATE_LENGTH,
/**
* Sync the data to DataNode, close the current block, and allocate a new
* block
*/
END_BLOCK
}
}