c81cb64416
It uses the (`const T &&... p_args`) forward reference, to avoid copying the memory in case it's an rvalue, or pass a reference in case it's an lvalue. This is an example: ```c++ PagedAllocator<btShapeBox> box_allocator; btShapeBox* box = box_allocator.alloc( btVector3(1.0, 1.0, 1.0) ); ```
135 lines
4.9 KiB
C++
135 lines
4.9 KiB
C++
/*************************************************************************/
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/* paged_allocator.h */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#ifndef PAGED_ALLOCATOR_H
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#define PAGED_ALLOCATOR_H
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#include "core/os/memory.h"
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#include "core/os/spin_lock.h"
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#include "core/typedefs.h"
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#include <type_traits>
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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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template <class... Args>
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T *alloc(const Args &&...p_args) {
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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(p_args...));
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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 || !std::is_trivially_destructible<T>::value) {
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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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PagedAllocator(uint32_t p_page_size = 4096) { // 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
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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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