Policy-Based Memory Allocation
By Andrei Alexandrescu and Emery Berger, December 01, 2005
The way your application allocates memory can have a dramatic effect on its performance. Modern general-purpose memory allocators are pretty efficient, but there's always room for improvement.
December, 2005: Policy-Based Memory Allocation
Listing 2
template <class Super>
struct UseSizeHeap : public Super {
static size_t getSize(const void * ptr) {
return ((freeObject *) ptr - 1)->sz;
}
protected:
union freeObject {
size_t sz;
double _dummy; // for alignment.
};
};
template <class SuperHeap>
class SizeHeap
: public UseSizeHeap<SuperHeap> {
typedef typename
UseSizeHeap<SuperHeap>::freeObject
freeObject;
public:
void * malloc(const size_t sz) {
// Add room for a size field.
freeObject * ptr = (freeObject *)
SuperHeap::malloc(sz +
sizeof(freeObject));
// Store the requested size.
ptr->sz = sz;
return (void *) (ptr + 1);
}
void free(void * ptr) {
SuperHeap::free((freeObject *)ptr - 1);
}
};
