hbase-common/src/main/java/org/apache/hadoop/hbase/io/ByteArrayOutputStream.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.OutputStream;
  21 import java.nio.BufferOverflowException;
  22 import java.nio.ByteBuffer;
  23 import java.util.Arrays;
  24
  25 import org.apache.hadoop.hbase.nio.ByteBuff;
  26 import org.apache.hadoop.hbase.util.ByteBufferUtils;
  27 import org.apache.hadoop.hbase.util.Bytes;
  28 import org.apache.yetus.audience.InterfaceAudience;
  29
  30 /**
  31  * Our own implementation of ByteArrayOutputStream where all methods are NOT synchronized and
  32  * supports writing ByteBuffer directly to it.
  33  */
  34 @InterfaceAudience.Private
  35 public class ByteArrayOutputStream extends OutputStream implements ByteBufferWriter {
  36
  37   // Borrowed from openJDK:
  38   // http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8-b132/java/util/ArrayList.java#221
  39   private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
  40
  41   private byte[] buf;
  42   private int pos = 0;
  43
  44   public ByteArrayOutputStream() {
  45     this(32);
  46   }
  47
  48   public ByteArrayOutputStream(int capacity) {
  49     this.buf = new byte[capacity];
  50   }
  51
  52   @Override
  53   public void write(ByteBuffer b, int off, int len) {
  54     checkSizeAndGrow(len);
  55     ByteBufferUtils.copyFromBufferToArray(this.buf, b, off, this.pos, len);
  56     this.pos += len;
  57   }
  58
  59   @Override
  60   public void writeInt(int i) {
  61     checkSizeAndGrow(Bytes.SIZEOF_INT);
  62     Bytes.putInt(this.buf, this.pos, i);
  63     this.pos += Bytes.SIZEOF_INT;
  64   }
  65
  66   @Override
  67   public void write(int b) {
  68     checkSizeAndGrow(Bytes.SIZEOF_BYTE);
  69     buf[this.pos] = (byte) b;
  70     this.pos++;
  71   }
  72
  73   @Override
  74   public void write(byte[] b, int off, int len) {
  75     checkSizeAndGrow(len);
  76     System.arraycopy(b, off, this.buf, this.pos, len);
  77     this.pos += len;
  78   }
  79
  80   private void checkSizeAndGrow(int extra) {
  81     long capacityNeeded = this.pos + (long) extra;
  82     if (capacityNeeded > this.buf.length) {
  83       // guarantee it's possible to fit
  84       if (capacityNeeded > MAX_ARRAY_SIZE) {
  85         throw new BufferOverflowException();
  86       }
  87       // double until hit the cap
  88       long nextCapacity = Math.min(this.buf.length << 1, MAX_ARRAY_SIZE);
  89       // but make sure there is enough if twice the existing capacity is still too small
  90       nextCapacity = Math.max(nextCapacity, capacityNeeded);
  91       if (nextCapacity > MAX_ARRAY_SIZE) {
  92         throw new BufferOverflowException();
  93       }
  94       byte[] newBuf = new byte[(int) nextCapacity];
  95       System.arraycopy(buf, 0, newBuf, 0, buf.length);
  96       buf = newBuf;
  97     }
  98   }
  99
 100   /**
 101    * Resets the <code>pos</code> field of this byte array output stream to zero. The output stream
 102    * can be used again.
 103    */
 104   public void reset() {
 105     this.pos = 0;
 106   }
 107
 108   /**
 109    * Copies the content of this Stream into a new byte array.
 110    * @return  the contents of this output stream, as new byte array.
 111    */
 112   public byte[] toByteArray() {
 113     return Arrays.copyOf(buf, pos);
 114   }
 115
 116   public void toByteBuff(ByteBuff buff) {
 117     buff.put(buf, 0, pos);
 118   }
 119
 120   /**
 121    * @return the underlying array where the data gets accumulated
 122    */
 123   public byte[] getBuffer() {
 124     return this.buf;
 125   }
 126
 127   /**
 128    * @return The current size of the buffer.
 129    */
 130   public int size() {
 131     return this.pos;
 132   }
 133 }