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/****************************************************************************
* Core Library Version 1.7, August 2004
* Copyright (c) 1995-2004 Exact Computation Project
* All rights reserved.
*
* This file is part of CORE (http://cs.nyu.edu/exact/core/); you may
* redistribute it under the terms of the Q Public License version 1.0.
* See the file LICENSE.QPL distributed with CORE.
*
* Licensees holding a valid commercial license may use this file in
* accordance with the commercial license agreement provided with the
* software.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*
* File: MemoryPool.h
* Synopsis:
* a memory pool template class.
*
* Written by
* Zilin Du <zilin@cs.nyu.edu>
* Chee Yap <yap@cs.nyu.edu>
* Sylvain Pion <pion@cs.nyu.edu>
*
* WWW URL: http://cs.nyu.edu/exact/
* Email: exact@cs.nyu.edu
*
* $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.2-branch/Core/include/CORE/MemoryPool.h $
* $Id: MemoryPool.h 30667 2006-04-19 16:56:12Z glisse $
***************************************************************************/
#ifndef _CORE_MEMORYPOOL_H_
#define _CORE_MEMORYPOOL_H_
#include <new> // for placement new
#include <assert.h>
CORE_BEGIN_NAMESPACE
#define CORE_EXPANSION_SIZE 1024
template< class T, int nObjects = CORE_EXPANSION_SIZE >
class MemoryPool {
public:
MemoryPool() : head( 0 ) {}
void* allocate(std::size_t size);
void free(void* p);
// Access the corresponding static global allocator.
static MemoryPool<T>& global_allocator() {
return memPool;
}
private:
struct Thunk {
T object;
Thunk* next;
};
private:
Thunk* head; // next available block in the pool
private:
// Static global allocator.
static MemoryPool<T, nObjects> memPool;
};
template <class T, int nObjects >
MemoryPool<T, nObjects> MemoryPool<T, nObjects>::memPool;
template< class T, int nObjects >
void* MemoryPool< T, nObjects >::allocate(std::size_t) {
if ( head == 0 ) { // if no more memory in the pool
const int last = nObjects - 1;
// use the global operator new to allocate a block for the pool
Thunk* pool = reinterpret_cast<Thunk*>(
::operator new(nObjects * sizeof(Thunk)));
// initialize the chain (one-directional linked list)
head = pool;
for (int i = 0; i < last; ++i ) {
pool[i].next = &pool[i+1];
}
pool[last].next = 0;
}
// set head to point to the next object in the list
Thunk* currentThunk = head;
head = currentThunk->next;
return currentThunk;
}
template< class T, int nObjects >
void MemoryPool< T, nObjects >::free(void* t) {
assert(t != 0);
if (t == 0) return; // for safety
// recycle the object memory, by putting it back into the chain
reinterpret_cast<Thunk*>(t)->next = head;
head = reinterpret_cast<Thunk*>(t);
}
CORE_END_NAMESPACE
#endif // _CORE_MEMORYPOOL_H_
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