116 lines
4 KiB
C++
116 lines
4 KiB
C++
/* file ArenaAlloc.hpp
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*
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* author: Roland Conybeare, Jul 2025
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*/
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#pragma once
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#include "IAlloc.hpp"
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#include "ObjectStatistics.hpp"
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namespace xo {
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namespace gc {
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/** @class ArenaAlloc
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* @brief Bump allocator with fixed capacity
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*
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* @text
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*
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* before @ref release_redline_memory
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*
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* <-----allocated----> <-free-> <-reserved->
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* XXXXXXXXXXXXXXXXXXXX______________________
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* ^ ^ ^ ^
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* lo free redline hi
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* limit
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*
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* after @ref release_redline_memory
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*
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* <-----allocated----> <--------free------->
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* XXXXXXXXXXXXXXXXXXXX______________________
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* ^ ^ ^
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* lo free hi
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* limit
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* @endtext
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*
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* TODO: rename to ArenaAlloc
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**/
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class ArenaAlloc : public IAlloc {
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public:
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~ArenaAlloc();
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/** create allocator with capacity @p z,
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* with reserved capacity @p redline_z.
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**/
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static up<ArenaAlloc> make(const std::string & name,
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#ifdef REDLINE_MEMORY
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std::size_t redline_z,
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#endif
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std::size_t z,
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bool debug_flag);
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std::byte * free_ptr() const { return free_ptr_; }
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void set_free_ptr(std::byte * x);
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void capture_object_statistics(capture_phase phase,
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ObjectStatistics * p_dest) const;
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// inherited from IAlloc...
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virtual const std::string & name() const final override { return name_; }
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virtual std::size_t size() const final override;
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virtual std::size_t available() const final override;
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virtual std::size_t allocated() const final override;
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virtual bool contains(const void * x) const final override;
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virtual bool is_before_checkpoint(const void * x) const final override;
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virtual std::size_t before_checkpoint() const final override;
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virtual std::size_t after_checkpoint() const final override;
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virtual void clear() final override;
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virtual void checkpoint() final override;
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virtual std::byte * alloc(std::size_t z) final override;
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#ifdef REDLINE_MEMORY
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virtual void release_redline_memory() final override;
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#endif
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private:
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ArenaAlloc(const std::string & name,
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#ifdef REDLINE_MEMORY
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std::size_t rz,
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#endif
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std::size_t z, bool debug_flag);
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private:
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/**
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* Invariants:
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* - @ref free_ always a multiple of word size (assumed to be sizeof(void*))
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**/
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/** optional instance name, for diagnostics **/
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std::string name_;
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/** allocator owns memory in range [@ref lo_, @ref hi_) **/
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std::byte * lo_ = nullptr;
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/** checkpoint (for GC support); divides objects into
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* older (addresses below checkpoint)
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* and younger (addresses above checkpoint)
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**/
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std::byte * checkpoint_;
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/** free pointer. memory in range [@ref free_, @ref limit_) available **/
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std::byte * free_ptr_ = nullptr;
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/** soft limit: end of released memory **/
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std::byte * limit_ = nullptr;
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#ifdef REDLINE_MEMORY
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/** amount of last-resort memory to reserve **/
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std::size_t redline_z_ = 0;
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#endif
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/** hard limit: end of allocated memory **/
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std::byte * hi_ = nullptr;
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/** true to enable detailed debug logging **/
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bool debug_flag_ = false;
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};
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} /*namespace gc*/
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} /*namespace xo*/
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/* end ArenaAlloc.hpp */
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