Dead simple profiler in Lua

simple_profiler.lua

local profiler = {
	call_stack = {},        -- Stack to keep track of active function calls
	timings = {},           -- Stores the total time spent in each function
	call_counts = {}        -- Stores how many times each function was called
}

local function get_time()
	return os.clock()
end

local function profiler_hook(event)
	local info = debug.getinfo(2, "nS")

	if event == "call" then
		local func_name = info.name or "[unnamed]"
		local start_time = get_time()
		-- Push the start time and function name onto the call stack
		table.insert(profiler.call_stack, {func_name, start_time})
	elseif event == "return" then
		local end_time = get_time()
		local call_info = table.remove(profiler.call_stack)  -- Pop the call from the stack
		if not call_info then return end

		local func_name = call_info[1]
		local start_time = call_info[2]
		local time_spent = end_time - start_time

		profiler.timings[func_name] = (profiler.timings[func_name] or 0) + time_spent
		profiler.call_counts[func_name] = (profiler.call_counts[func_name] or 0) + 1
	end
end

function profiler.start()
	debug.sethook(profiler_hook, "cr")  -- Hook on 'call' and 'return' events
end

function profiler.stop()
	debug.sethook()
end

function profiler.report()
	local report = {}
	for func_name, time_spent in pairs(profiler.timings) do
		table.insert(report, { func_name = func_name, time_spent = time_spent, call_count = profiler.call_counts[func_name] or 0  })
	end

	table.sort(report, function(a, b) return a.time_spent > b.time_spent end)

	-- Reset
	profiler = {
		call_stack = {},
		timings = {},
		call_counts = {}
	}

	print("Function Profiling Report:")
	print("-----------------------------------")
	for _, report_data in ipairs(report) do
		print(string.format("Function: %s | Time: %.6f s | Calls: %d", report_data.func_name, report_data.time_spent, report_data.call_count))
	end
	print("-----------------------------------")
end

profiler.start()

timer.Simple(10, function()
	profiler.stop()
	profiler.report()
end)