improve: AreaCombat::areas to array #1653

mehah · 2023-09-30T01:54:51Z

Accessing the array index is almost ~2x faster than using a std::map. There would only be advantages to using std::map if there were a large number of records, which is not the case.

Memory consumption may be a little higher with an array, as it will allocate memory to directions that may not be used, but it is irrelevant compared to the performance gain.

Benchmark:

struct Teste {
	bool any = false;
};

std::array<std::unique_ptr<Teste>, 8> arrayTest;
std::map<int, std::unique_ptr<Teste>> mapTest;
arrayTest[3] = std::make_unique<Teste>();
arrayTest[4] = std::make_unique<Teste>();
arrayTest[5] = std::make_unique<Teste>();
arrayTest[6] = std::make_unique<Teste>();

Benchmark bm;
for (size_t i = 0; i < 999999999; ++i) {
	const auto &v = arrayTest[3 + (rand() % 6)];
}
g_logger().info("Array: " + std::to_string(bm.duration()) + "ms");

bm.reset();
bm.start();
for (size_t i = 0; i < 999999999; ++i) {
	const auto &v = mapTest[3 + (rand() % 6)];
}
g_logger().info("Map: " + std::to_string(bm.duration()) + "ms");