97 lines
4 KiB
C++
97 lines
4 KiB
C++
/*************************************************************************/
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/* pooled_list.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) 2007-2022 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2022 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 POOLED_LIST_H
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#define POOLED_LIST_H
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#include "core/templates/local_vector.h"
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// Simple template to provide a pool with O(1) allocate and free.
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// The freelist could alternatively be a linked list placed within the unused elements
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// to use less memory, however a separate freelist is probably more cache friendly.
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//
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// NOTE: Take great care when using this with non POD types. The construction and destruction
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// is done in the LocalVector, NOT as part of the pool. So requesting a new item does not guarantee
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// a constructor is run, and free does not guarantee a destructor.
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// You should generally handle clearing
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// an item explicitly after a request, as it may contain 'leftovers'.
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// This is by design for fastest use in the BVH. If you want a more general pool
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// that does call constructors / destructors on request / free, this should probably be
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// a separate template.
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template <class T, bool force_trivial = false>
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class PooledList {
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LocalVector<T, uint32_t, force_trivial> list;
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LocalVector<uint32_t, uint32_t, true> freelist;
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// not all list members are necessarily used
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int _used_size;
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public:
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PooledList() {
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_used_size = 0;
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}
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int estimate_memory_use() const {
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return (list.size() * sizeof(T)) + (freelist.size() * sizeof(uint32_t));
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}
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const T &operator[](uint32_t p_index) const {
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return list[p_index];
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}
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T &operator[](uint32_t p_index) {
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return list[p_index];
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}
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int size() const { return _used_size; }
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T *request(uint32_t &r_id) {
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_used_size++;
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if (freelist.size()) {
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// pop from freelist
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int new_size = freelist.size() - 1;
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r_id = freelist[new_size];
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freelist.resize(new_size);
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return &list[r_id];
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}
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r_id = list.size();
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list.resize(r_id + 1);
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return &list[r_id];
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}
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void free(const uint32_t &p_id) {
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// should not be on free list already
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CRASH_COND(p_id >= list.size());
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freelist.push_back(p_id);
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_used_size--;
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}
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};
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#endif // POOLED_LIST_H
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