layers/craters/generation/cell_cache.h

Line	Branch	Exec	Source
1			/// @file
2			/// @brief `CraterCellCache`, the craters of generated cells kept for reuse.
3			#pragma once
4
5			#include "terraingen/layers/craters/generation/population.h"
6			#include "terraingen/util/lru_cache.h"
7
8			#include <cstddef>
9			#include <cstdint>
10			#include <functional>
11			#include <memory>
12
13			namespace terraingen {
14
15			/// The craters drawn in each cell of each band, kept so tiles and point queries generate
16			/// each cell once.
17			///
18			/// Holds about `maxCraters` craters at most, evicting least recently used cells; thread-safe.
19			/// Cells regenerate identically, so eviction never changes results.
20			class CraterCellCache {
21			public:
22			/// @param maxCraters Most craters held across every cell; positive.
23			/// @throws std::invalid_argument if `maxCraters` is zero.
24			explicit CraterCellCache(std::size_t maxCraters = 4000000);
25
26			/// The craters of `cell` in the band of `exponent`, drawn by `generate` when not held.
27		2765204	std::shared_ptr<const CraterList> Get(int exponent, const CellIndex& cell,
28			const std::function<CraterList()>& generate) {
29	1/1 ✓ Branch 1 taken 2765204 times.	2765204	return cache_.Get({exponent, cell.i, cell.j}, generate);
30			}
31
32			/// The number of craters held across every cell.
33		4	std::size_t Size() const {
34		4	return cache_.Size();
35			}
36
37			/// The most craters held.
38		1	std::size_t MaxCraters() const {
39		1	return cache_.Capacity();
40			}
41
42			/// The number of cells evicted since construction.
43		2	std::size_t Evictions() const {
44		2	return cache_.Evictions();
45			}
46
47			private:
48			struct Key {
49		2659100	int exponent;
50		2659100	std::int32_t i;
51		2659100	std::int32_t j;
52
53	3/6 ✗ Branch 0 not taken. ✓ Branch 1 taken 2659100 times. ✗ Branch 2 not taken. ✓ Branch 3 taken 2659100 times. ✗ Branch 4 not taken. ✓ Branch 5 taken 2659100 times.	2659100	bool operator==(const Key&) const = default;
54			};
55			struct KeyHash {
56			std::size_t operator()(const Key& key) const;
57			};
58
59			LruCache<Key, CraterList, KeyHash> cache_;
60			};
61
62			/// A source for `CraterGenerationOptions::cellCraters` that draws each cell with
63			/// `GenerateCellCraters` once and keeps it in `cache`; every argument must outlive it.
64			CellCraterSource CachedCellCraters(CraterCellCache& cache, const SurfaceCells& cells,
65			const SizeFrequencyDistribution& density,
66			const CraterAgeModel& ages, std::uint32_t seed);
67
68			} // namespace terraingen
69

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