Drizzled Public API Documentation

global_buffer.h
1 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
2  * vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
3  *
4  * Copyright (C) 2010 Andrew Hutchings
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; version 2 of the License.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18  */
19 
20 #pragma once
21 
22 #include <drizzled/atomics.h>
23 
24 namespace drizzled
25 {
26 template <class T>
28 {
29 public:
31  {
32  setMaxSize(max);
33  }
34 
35  T getMaxSize() const { return max_size; }
36  void setMaxSize(T new_size)
37  {
38  if (new_size == 0) new_size = std::numeric_limits<T>::max();
39  max_size= new_size;
40  }
41 
42  bool add(T addition)
43  {
44  if (current_size.add_and_fetch(addition) > max_size)
45  {
46  current_size.add_and_fetch(T(0) - addition);
47  return false;
48  }
49  return true;
50  }
51 
52  bool sub(T subtract)
53  {
54  if (current_size < subtract)
55  return false;
56  else
57  current_size.add_and_fetch(T(0) - subtract);
58 
59  return true;
60  }
61 
62 private:
63  atomic<T> current_size;
64  T max_size;
65 };
66 
67 }