sfw/sfwl/core/paged_allocator.h

115 lines
3.0 KiB
C++

//--STRIP
#ifndef PAGED_ALLOCATOR_H
#define PAGED_ALLOCATOR_H
//--STRIP
/*************************************************************************/
/* paged_allocator.h */
/* From https://github.com/Relintai/pandemonium_engine (MIT) */
/*************************************************************************/
//--STRIP
#include "core/memory.h"
#include "spin_lock.h"
#include "core/typedefs.h"
//--STRIP
template <class T, bool thread_safe = false>
class PagedAllocator {
T **page_pool = nullptr;
T ***available_pool = nullptr;
uint32_t pages_allocated = 0;
uint32_t allocs_available = 0;
uint32_t page_shift = 0;
uint32_t page_mask = 0;
uint32_t page_size = 0;
SpinLock spin_lock;
public:
T *alloc() {
if (thread_safe) {
spin_lock.lock();
}
if (unlikely(allocs_available == 0)) {
uint32_t pages_used = pages_allocated;
pages_allocated++;
page_pool = (T **)memrealloc(page_pool, sizeof(T *) * pages_allocated);
available_pool = (T ***)memrealloc(available_pool, sizeof(T **) * pages_allocated);
page_pool[pages_used] = (T *)memalloc(sizeof(T) * page_size);
available_pool[pages_used] = (T **)memalloc(sizeof(T *) * page_size);
for (uint32_t i = 0; i < page_size; i++) {
available_pool[0][i] = &page_pool[pages_used][i];
}
allocs_available += page_size;
}
allocs_available--;
T *alloc = available_pool[allocs_available >> page_shift][allocs_available & page_mask];
if (thread_safe) {
spin_lock.unlock();
}
memnew_placement(alloc, T);
return alloc;
}
void free(T *p_mem) {
if (thread_safe) {
spin_lock.lock();
}
p_mem->~T();
available_pool[allocs_available >> page_shift][allocs_available & page_mask] = p_mem;
if (thread_safe) {
spin_lock.unlock();
}
allocs_available++;
}
void reset(bool p_allow_unfreed = false) {
if (!p_allow_unfreed || !HAS_TRIVIAL_DESTRUCTOR(T)) {
ERR_FAIL_COND(allocs_available < pages_allocated * page_size);
}
if (pages_allocated) {
for (uint32_t i = 0; i < pages_allocated; i++) {
memfree(page_pool[i]);
memfree(available_pool[i]);
}
memfree(page_pool);
memfree(available_pool);
page_pool = nullptr;
available_pool = nullptr;
pages_allocated = 0;
allocs_available = 0;
}
}
bool is_configured() const {
return page_size > 0;
}
void configure(uint32_t p_page_size) {
ERR_FAIL_COND(page_pool != nullptr); //sanity check
ERR_FAIL_COND(p_page_size == 0);
page_size = nearest_power_of_2_templated(p_page_size);
page_mask = page_size - 1;
page_shift = get_shift_from_power_of_2(page_size);
}
// Power of 2 recommended because of alignment with OS page sizes.
// Even if element is bigger, its still a multiple and get rounded amount of pages
PagedAllocator(uint32_t p_page_size = 4096) {
configure(p_page_size);
}
~PagedAllocator() {
ERR_FAIL_COND_MSG(allocs_available < pages_allocated * page_size, "Pages in use exist at exit in PagedAllocator");
reset();
}
};
//--STRIP
#endif // PAGED_ALLOCATOR_H
//--STRIP