libcruft-util/pool.hpp

101 lines
2.6 KiB
C++

/*
* This file is part of libgim.
*
* libgim 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, either version 3 of the License, or (at your option) any later
* version.
*
* libgim 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 libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2010 Danny Robson <danny@blubinc.net>
*/
#ifndef __UTIL_POOL_HPP
#define __UTIL_POOL_HPP
#include "nocopy.hpp"
template <typename T>
class pool : public nocopy {
protected:
union node {
char _data[sizeof (T)];
node *_chain;
};
node *m_head;
node *m_next;
unsigned int m_capacity;
public:
pool (unsigned int _capacity):
m_capacity (_capacity)
{
static_assert (sizeof (T) >= sizeof (uintptr_t),
"pool<T>'s chained block system requires that T be at least pointer sized");
m_head = (node *)operator new (sizeof (T) * m_capacity);
m_next = m_head;
for (unsigned int i = 0; i < m_capacity - 1; ++i)
m_next[i]._chain = &m_next[i + 1];
m_next[m_capacity - 1]._chain = NULL;
}
~pool () {
check (m_next != NULL);
unsigned int doomed_count = 0;
for (node *cursor = m_next; cursor != NULL; cursor = cursor->_chain)
++doomed_count;
check_eq (doomed_count, m_capacity);
operator delete (m_head);
}
unsigned int capacity (void) const
{ return m_capacity; }
template <typename ...Args>
T* acquire (Args&... args) {
if (!m_next)
throw std::bad_alloc ();
node *newnext = m_next->_chain;
T *data = (T*)&m_next->_data;
try {
new (data) T (args...);
} catch (...) {
m_next->_chain = newnext;
throw;
}
m_next = newnext;
return data;
}
void release (T *data) {
data->~T();
node *newnode = (node *)data;
newnode->_chain = m_next;
m_next = newnode;
}
};
#endif // __UTIL_POOL_HPP