1 /*
   2  * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.xml.internal.stream.util;
  27 
  28 import java.lang.ref.*;
  29 
  30 /**
  31  * Buffer allocator for buffers of sizes 128 B, 2 KB and 8 KB. Includes
  32  * methods for allocating and freeing buffers.
  33  *
  34  * @author Binu.John@sun.com
  35  * @author Santiago.PericasGeertsen@sun.com
  36  */
  37 public class BufferAllocator {
  38     public static int SMALL_SIZE_LIMIT = 128;
  39     public static int MEDIUM_SIZE_LIMIT = 2048;
  40     public static int LARGE_SIZE_LIMIT = 8192;
  41 
  42     char[] smallCharBuffer;
  43     char[] mediumCharBuffer;
  44     char[] largeCharBuffer;
  45 
  46     byte[] smallByteBuffer;
  47     byte[] mediumByteBuffer;
  48     byte[] largeByteBuffer;
  49 
  50     public BufferAllocator() {
  51     }
  52 
  53     public char[] getCharBuffer(int size) {
  54         if (size <= SMALL_SIZE_LIMIT) {
  55             char[] buffer = smallCharBuffer;
  56             smallCharBuffer = null;
  57             return buffer;
  58         }
  59         else if (size <= MEDIUM_SIZE_LIMIT) {
  60             char[] buffer = mediumCharBuffer;
  61             mediumCharBuffer = null;
  62             return buffer;
  63         }
  64         else if (size <= LARGE_SIZE_LIMIT) {
  65             char[] buffer = largeCharBuffer;
  66             largeCharBuffer = null;
  67             return buffer;
  68         }
  69         return null;
  70     }
  71 
  72     public void returnCharBuffer(char[] c) {
  73         if (c == null) {
  74             return;
  75         }
  76         if (c.length <= SMALL_SIZE_LIMIT) {
  77             smallCharBuffer = c;
  78         }
  79         else if (c.length <= MEDIUM_SIZE_LIMIT) {
  80             mediumCharBuffer = c;
  81         }
  82         else if (c.length <= LARGE_SIZE_LIMIT) {
  83             largeCharBuffer = c;
  84         }
  85     }
  86 
  87     public byte[] getByteBuffer(int size) {
  88         if (size <= SMALL_SIZE_LIMIT) {
  89             byte[] buffer = smallByteBuffer;
  90             smallByteBuffer = null;
  91             return buffer;
  92         }
  93         else if (size <= MEDIUM_SIZE_LIMIT) {
  94             byte[] buffer = mediumByteBuffer;
  95             mediumByteBuffer = null;
  96             return buffer;
  97         }
  98         else if (size <= LARGE_SIZE_LIMIT) {
  99             byte[] buffer = largeByteBuffer;
 100             largeByteBuffer = null;
 101             return buffer;
 102         }
 103         return null;
 104     }
 105 
 106     public void returnByteBuffer(byte[] b) {
 107         if (b == null) {
 108             return;
 109         }
 110         if (b.length <= SMALL_SIZE_LIMIT) {
 111             smallByteBuffer = b;
 112         }
 113         else if (b.length <= MEDIUM_SIZE_LIMIT) {
 114             mediumByteBuffer = b;
 115         }
 116         else if (b.length <= LARGE_SIZE_LIMIT) {
 117             largeByteBuffer = b;
 118         }
 119     }
 120 
 121 }