source: XmlTools2/trunk/libs/pool_allocator.h@ 908

/*
 * 42TinyJS
 *
 * A fork of TinyJS with the goal to makes a more JavaScript/ECMA compliant engine
 *
 * Authored By Armin Diedering <armin@diedering.de>
 *
 * Copyright (C) 2010-2013 ardisoft
 *
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:

 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */


#ifndef pool_allocator_h__
#define pool_allocator_h__

#include <typeinfo>
#include <stdint.h>
#include <string>
#include "config.h"
#include "TinyJS_Threading.h"

/************************************************************************
 * TinyJS must many many times allocates and frees objects
 * To prevent memory fragmentation and speed ups allocates & frees, i have
 * added to 42TinyJS a pool_allocator. This allocator allocates every 64 objects
 * as a pool of objects. Is an object needed it can faster allocated from this pool as 
 * from the heap.
 ************************************************************************/ 

#if !defined(DEBUG_POOL_ALLOCATOR) && (defined(_DEBUG) || defined(LOG_POOL_ALLOCATOR_MEMORY_USAGE))
#       define DEBUG_POOL_ALLOCATOR
#endif

struct block_head;
class fixed_size_allocator {
public:
        ~fixed_size_allocator();
        static void *alloc(size_t,const char* for_class=0);
        static void free(void *, size_t);
        size_t objectSize() { return object_size; }
#ifndef NO_THREADING
        static CScriptMutex locker;
#endif
private:
        fixed_size_allocator(size_t num_objects, size_t object_size, const char* for_class); 
        fixed_size_allocator(const fixed_size_allocator&);
        fixed_size_allocator& operator=(const fixed_size_allocator&);
        void *_alloc(size_t);
        bool _free(void* p, size_t);
        size_t num_objects;
        size_t object_size;
        void *head_of_free_list;
        block_head *head;
        int refs;
#ifdef DEBUG_POOL_ALLOCATOR
        // Debug
        std::string name;
        int allocs;
        int frees;
        int current;
        int max;
        int blocks;
#endif
};
//**************************************************************************************
template<typename T, int num_objects=64>
class fixed_size_object {
public:
        static void* operator new(size_t size) {
#ifdef DEBUG_POOL_ALLOCATOR
                return fixed_size_allocator::alloc(size, typeid(T).name());
#else
                return fixed_size_allocator::alloc(size);
#endif
        }
        static void* operator new(size_t size, void* p) {
                return p;
        }
        static void operator delete(void* p, size_t size) {
                fixed_size_allocator::free(p, size);
        }
private:
};
#if 0 // under construction
template<typename T>
class block_allocator_stl {
public : 
        //    typedefs

        typedef T value_type;
        typedef value_type* pointer;
        typedef const value_type* const_pointer;
        typedef value_type& reference;
        typedef const value_type& const_reference;
        typedef std::size_t size_type;
        typedef std::ptrdiff_t difference_type;
public : 
        //    convert an allocator<T> to allocator<U>

        template<typename U>
        struct rebind {
                typedef block_allocator_stl<U> other;
        };

        inline explicit block_allocator_stl() {}
        inline ~block_allocator_stl() {}
        inline block_allocator_stl(block_allocator_stl const&) {}
        template<typename U>
        inline block_allocator_stl(block_allocator_stl<U> const&) {}
        inline block_allocator_stl<T> &operator=(block_allocator_stl<T> const&) {}
        template<typename U>
        inline block_allocator_stl<T> &operator=(block_allocator_stl<U> const&) {}

        //    address

        inline pointer address(reference r) { return &r; }
        inline const_pointer address(const_reference r) { return &r; }

        //    memory allocation
        inline pointer allocate(size_type cnt, const void*) { 
                        return reinterpret_cast<pointer>(fixed_size_allocator::get(cnt * sizeof (T), true, typeid(T).name())->alloc(cnt * sizeof (T)));
                        //                      return reinterpret_cast<pointer>(::operator new(cnt * sizeof (T))); 
        }
        inline void deallocate(pointer p, size_type cnt) { 
                fixed_size_allocator::get(cnt * sizeof (T), false)->free(p, cnt * sizeof (T));
                //              ::operator delete(p); 
        }

        //    size

        inline size_type max_size() const { 
                return SIZE_MAX / sizeof(T);
        }

        inline void construct(pointer _Ptr, value_type& _Val) {
                ::new ((void*)_Ptr) value_type(_Val);
        }
        inline void destroy(pointer _Ptr) {
                _Ptr->~value_type();
        }
};
#endif

#endif // pool_allocator_h__