KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > caucho > vfs > TempBuffer


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  *
23  * Free Software Foundation, Inc.
24  * 59 Temple Place, Suite 330
25  * Boston, MA 02111-1307 USA
26  *
27  * @author Scott Ferguson
28  */
29
30 package com.caucho.vfs;
31
32 import com.caucho.util.FreeList;
33
34 import java.io.IOException JavaDoc;
35
36 /**
37  * Pooled temporary byte buffer.
38  */
39 public class TempBuffer {
40   private static FreeList<TempBuffer> _freeList = new FreeList<TempBuffer>(32);
41   public static final int SIZE = 16 * 1024;
42
43   TempBuffer _next;
44   final byte []_buf;
45   int _offset;
46   int _length;
47   int _bufferCount;
48
49   /**
50    * Create a new TempBuffer.
51    */
52   public TempBuffer(int size)
53   {
54     _buf = new byte[size];
55   }
56
57   /**
58    * Allocate a TempBuffer, reusing one if available.
59    */
60   public static TempBuffer allocate()
61   {
62     TempBuffer next = _freeList.allocate();
63
64     if (next == null)
65       return new TempBuffer(SIZE);
66
67     next._next = null;
68
69     next._offset = 0;
70     next._length = 0;
71     next._bufferCount = 0;
72
73     return next;
74   }
75
76   /**
77    * Clears the buffer.
78    */
79   public void clear()
80   {
81     _next = null;
82
83     _offset = 0;
84     _length = 0;
85     _bufferCount = 0;
86   }
87
88   /**
89    * Returns the buffer's underlying byte array.
90    */
91   public final byte []getBuffer()
92   {
93     return _buf;
94   }
95
96   /**
97    * Returns the number of bytes in the buffer.
98    */
99   public final int getLength()
100   {
101     return _length;
102   }
103
104   /**
105    * Sets the number of bytes used in the buffer.
106    */
107   public final void setLength(int length)
108   {
109     _length = length;
110   }
111
112   public final int getCapacity()
113   {
114     return _buf.length;
115   }
116
117   public int getAvailable()
118   {
119     return _buf.length - _length;
120   }
121
122   public final TempBuffer getNext()
123   {
124     return _next;
125   }
126
127   public final void setNext(TempBuffer next)
128   {
129     _next = next;
130   }
131
132   public int write(byte []buf, int offset, int length)
133   {
134     byte []thisBuf = _buf;
135     int thisLength = _length;
136
137     if (thisBuf.length - thisLength < length)
138       length = thisBuf.length - thisLength;
139
140     System.arraycopy(buf, offset, thisBuf, thisLength, length);
141
142     _length = thisLength + length;
143
144     return length;
145   }
146
147   public static TempBuffer copyFromStream(ReadStream is)
148     throws IOException JavaDoc
149   {
150     TempBuffer head = TempBuffer.allocate();
151     TempBuffer tail = head;
152     int len;
153
154     while ((len = is.readAll(tail._buf, 0, tail._buf.length)) == tail._buf.length) {
155       TempBuffer buf = TempBuffer.allocate();
156       tail._length = len;
157       tail._next = buf;
158       tail = buf;
159     }
160
161     if (len == 0 && head == tail)
162       return null; // XXX: TempBuffer leak of _head?
163 else if (len == 0) {
164       for (TempBuffer ptr = head; ptr.getNext() != null; ptr = ptr.getNext()) {
165         TempBuffer next = ptr.getNext();
166
167     if (next.getNext() == null) {
168       TempBuffer.free(next);
169       ptr._next = null;
170     }
171       }
172     }
173     else
174       tail._length = len;
175
176     return head;
177   }
178
179   /**
180    * Frees a single buffer.
181    */
182   public static void free(TempBuffer buf)
183   {
184     buf._next = null;
185
186     if (buf._buf.length == SIZE)
187       _freeList.free(buf);
188   }
189
190   public static void freeAll(TempBuffer buf)
191   {
192     while (buf != null) {
193       TempBuffer next = buf._next;
194       buf._next = null;
195       if (buf._buf.length == SIZE)
196         _freeList.free(buf);
197       buf = next;
198     }
199   }
200 }
201
Popular Tags