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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2010 Andrew Hutchings
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef DRIZZLED_GLOBAL_BUFFER_H
#define DRIZZLED_GLOBAL_BUFFER_H
#include <drizzled/atomics.h>
namespace drizzled
{
template <class T>
class global_buffer_constraint
{
public:
global_buffer_constraint(T max)
{
setMaxSize(max);
}
T getMaxSize() const { return max_size; }
void setMaxSize(T new_size)
{
if (new_size == 0) new_size = std::numeric_limits<T>::max();
max_size= new_size;
}
bool add(T addition)
{
if (current_size.add_and_fetch(addition) > max_size)
{
current_size.add_and_fetch(T(0) - addition);
return false;
}
return true;
}
bool sub(T subtract)
{
if (current_size < subtract)
return false;
else
current_size.add_and_fetch(T(0) - subtract);
return true;
}
private:
atomic<T> current_size;
T max_size;
};
}
#endif /* DRIZZLED_GLOBAL_BUFFER_H */
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