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