Class MemoryStats

src/common/classes/alloc.h:86–158

class MemPool;

class MemoryStats
{
public:
	explicit MemoryStats(MemoryStats* parent = NULL)
		: mst_parent(parent), mst_usage(0), mst_mapped(0), mst_max_usage(0), mst_max_mapped(0)
	{}

	~MemoryStats()
	{}

	size_t getCurrentUsage() const noexcept { return mst_usage.value(); }
	size_t getMaximumUsage() const noexcept { return mst_max_usage; }
	size_t getCurrentMapping() const noexcept { return mst_mapped.value(); }
	size_t getMaximumMapping() const noexcept { return mst_max_mapped; }

private:
	// Forbid copying/assignment
	MemoryStats(const MemoryStats&);
	MemoryStats& operator=(const MemoryStats&);

	MemoryStats* mst_parent;

	// Currently allocated memory (without allocator overhead)
	// Useful for monitoring engine memory leaks
	AtomicCounter mst_usage;
	// Amount of memory mapped (including all overheads)
	// Useful for monitoring OS memory consumption
	AtomicCounter mst_mapped;

	// We don't particularily care about extreme precision of these max values,
	// this is why we don't synchronize them
	size_t mst_max_usage;
	size_t mst_max_mapped;

	// These methods are thread-safe due to usage of atomic counters only
	void increment_usage(size_t size) noexcept
	{
		for (MemoryStats* statistics = this; statistics; statistics = statistics->mst_parent)
		{
			const size_t temp = statistics->mst_usage.exchangeAdd(size) + size;
			if (temp > statistics->mst_max_usage)
				statistics->mst_max_usage = temp;
		}
	}

	void decrement_usage(size_t size) noexcept
	{
		for (MemoryStats* statistics = this; statistics; statistics = statistics->mst_parent)
		{
			statistics->mst_usage -= size;
		}
	}

	void increment_mapping(size_t size) noexcept
	{
		for (MemoryStats* statistics = this; statistics; statistics = statistics->mst_parent)
		{
			const size_t temp = statistics->mst_mapped.exchangeAdd(size) + size;