hbase-common/src/main/java/org/apache/hadoop/hbase/io/ByteBufferWriterOutputStream.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.io;
  19
  20 import java.io.IOException;
  21 import java.io.OutputStream;
  22 import java.nio.ByteBuffer;
  23 import java.util.Objects;
  24
  25 import org.apache.hadoop.hbase.io.util.StreamUtils;
  26 import org.apache.hadoop.hbase.util.ByteBufferUtils;
  27 import org.apache.yetus.audience.InterfaceAudience;
  28
  29 /**
  30  * When deal with OutputStream which is not ByteBufferWriter type, wrap it with this class. We will
  31  * have to write offheap ByteBuffer (DBB) data into the OS. This class is having a temp byte array
  32  * to which we can copy the DBB data for writing to the OS.
  33  * <br>
  34  * This is used while writing Cell data to WAL. In case of AsyncWAL, the OS created there is
  35  * ByteBufferWriter. But in case of FSHLog, the OS passed by DFS client, is not of type
  36  * ByteBufferWriter. We will need this temp solution until DFS client supports writing ByteBuffer
  37  * directly to the OS it creates.
  38  * <br>
  39  * Note: This class is not thread safe.
  40  */
  41 @InterfaceAudience.Private
  42 public class ByteBufferWriterOutputStream extends OutputStream
  43     implements ByteBufferWriter {
  44
  45   private static final int DEFAULT_BUFFER_SIZE = 4096;
  46
  47   private final OutputStream os;
  48   private final int bufSize;
  49   private byte[] buf;
  50
  51   public ByteBufferWriterOutputStream(OutputStream os) {
  52     this(os, DEFAULT_BUFFER_SIZE);
  53   }
  54
  55   public ByteBufferWriterOutputStream(OutputStream os, int size) {
  56     this.os = os;
  57     this.bufSize = size;
  58     this.buf = null;
  59   }
  60
  61   /**
  62    * Writes len bytes from the specified ByteBuffer starting at offset off to this OutputStream. If
  63    * off is negative or larger than the ByteBuffer then an ArrayIndexOutOfBoundsException is thrown.
  64    * If len is greater than the length of the ByteBuffer, then an ArrayIndexOutOfBoundsException is
  65    * thrown. This method does not change the position of the ByteBuffer.
  66    * @param b the ByteBuffer
  67    * @param off the start offset in the data
  68    * @param len the number of bytes to write
  69    * @throws IOException if an I/O error occurs. In particular, an IOException is thrown if the
  70    *           output stream is closed.
  71    * @throws NullPointerException if {@code b} is {@code null}
  72    */
  73   @Override
  74   public void write(ByteBuffer b, int off, int len) throws IOException {
  75     Objects.requireNonNull(b);
  76
  77     // Lazily load in the event that this version of 'write' is not invoked
  78     if (this.buf == null) {
  79       this.buf = new byte[this.bufSize];
  80     }
  81     int totalCopied = 0;
  82     while (totalCopied < len) {
  83       int bytesToCopy = Math.min((len - totalCopied), this.bufSize);
  84       ByteBufferUtils.copyFromBufferToArray(this.buf, b, off + totalCopied, 0,
  85           bytesToCopy);
  86       this.os.write(this.buf, 0, bytesToCopy);
  87       totalCopied += bytesToCopy;
  88     }
  89   }
  90
  91   @Override
  92   public void writeInt(int i) throws IOException {
  93     StreamUtils.writeInt(this.os, i);
  94   }
  95
  96   @Override
  97   public void write(int b) throws IOException {
  98     this.os.write(b);
  99   }
 100
 101   @Override
 102   public void write(byte[] b, int off, int len) throws IOException {
 103     this.os.write(b, off, len);
 104   }
 105
 106   @Override
 107   public void flush() throws IOException {
 108     this.os.flush();
 109   }
 110
 111   @Override
 112   public void close() throws IOException {
 113     this.os.close();
 114   }
 115 }