001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.io;
019
020import java.io.IOException;
021import java.io.OutputStream;
022import java.nio.ByteBuffer;
023
024import org.apache.hadoop.hbase.io.util.StreamUtils;
025import org.apache.hadoop.hbase.util.ByteBufferUtils;
026import org.apache.yetus.audience.InterfaceAudience;
027
028/**
029 * When deal with OutputStream which is not ByteBufferWriter type, wrap it with this class. We will
030 * have to write offheap ByteBuffer (DBB) data into the OS. This class is having a temp byte array
031 * to which we can copy the DBB data for writing to the OS.
032 * <br>
033 * This is used while writing Cell data to WAL. In case of AsyncWAL, the OS created there is
034 * ByteBufferWriter. But in case of FSHLog, the OS passed by DFS client, is not of type
035 * ByteBufferWriter. We will need this temp solution until DFS client supports writing ByteBuffer
036 * directly to the OS it creates.
037 * <br>
038 * Note: This class is not thread safe.
039 */
040@InterfaceAudience.Private
041public class ByteBufferWriterOutputStream extends OutputStream
042    implements ByteBufferWriter {
043
044  private static final int TEMP_BUF_LENGTH = 4 * 1024;
045  private final OutputStream os;
046  private byte[] tempBuf = null;
047
048  public ByteBufferWriterOutputStream(OutputStream os) {
049    this.os = os;
050  }
051
052  @Override
053  public void write(ByteBuffer b, int off, int len) throws IOException {
054    byte[] buf = null;
055    if (len > TEMP_BUF_LENGTH) {
056      buf = new byte[len];
057    } else {
058      if (this.tempBuf == null) {
059        this.tempBuf = new byte[TEMP_BUF_LENGTH];
060      }
061      buf = this.tempBuf;
062    }
063    ByteBufferUtils.copyFromBufferToArray(buf, b, off, 0, len);
064    this.os.write(buf, 0, len);
065  }
066
067  @Override
068  public void writeInt(int i) throws IOException {
069    StreamUtils.writeInt(this.os, i);
070  }
071
072  @Override
073  public void write(int b) throws IOException {
074    this.os.write(b);
075  }
076
077  @Override
078  public void write(byte b[], int off, int len) throws IOException {
079    this.os.write(b, off, len);
080  }
081
082  @Override
083  public void flush() throws IOException {
084    this.os.flush();
085  }
086
087  @Override
088  public void close() throws IOException {
089    this.os.close();
090  }
091}