convert ip from string to integer (LE) Benchmarks

bench_ip_str_to_int.lua

local ffi = require 'ffi'

local ip = "127.1.2.3"
local p = ffi.cast('const uint8_t *', ip)

local ffi_string = ffi.string
local tonumber = tonumber

local getaddr_ffi = function(ip)
	local prev = 0
	local dot = ('.'):byte()
	local addr = 0
	for i = 0, #ip do
		if i == #ip or p[i] == dot then
			local byte = tonumber(ffi_string(p+prev, i-prev))
			addr = addr * 256 + byte
			prev = i+1
		end
	end
	return addr
end

local getaddr_luafind = function(ip)
	local addr = 0
	local s = 1
	while s < #ip do
		local p = ip:find(".", s, true)
		addr = addr * 256 + tonumber(ip:sub(s, p-1))
		s = p+1
	end
	addr = addr*256+tonumber(ip:sub(s))
	return addr
end

local getaddr_inetaton = (function()
	local b = ffi.new('uint8_t[4]')

	ffi.cdef[[int inet_aton(const char *cp, struct in_addr *pin);]]

	local C = ffi.C
	local cast = ffi.cast

	if ffi.abi('le') then
		return function(ip)
			if C.inet_aton(ip, cast('void *', b)) ~= 1 then return false end
			b[0], b[1], b[2], b[3] = b[3], b[2], b[1], b[0] -- BE -> LE for poor
			return cast('uint32_t *', b)[0]
		end
	else
		return function(ip)
			if C.inet_aton(ip, cast('void *', b)) ~= 1 then return false end
			return cast('uint32_t *', b)[0]
		end
	end

end)()

local function bench(text, func, args)
	collectgarbage('collect')
	collectgarbage('collect')

	print(text, "Starting: GC:", gcinfo())

	local s = os.clock()
	local N = 1e7
	for _ = 1, N do
		func(args)
	end
	local d = os.clock()-s
	print(text, "Finished: ", d, gcinfo(), "CPS (million per second):", N/d/1e6)

	collectgarbage('collect')
	collectgarbage('collect')
end

bench("ffi", getaddr_ffi, ip)
bench("inet_aton", getaddr_inetaton, ip)
bench("luafind", getaddr_luafind, ip)

--[[
time luajit-2.1.0-beta3 binary/ip.lua
ffi     Starting: GC:   50
ffi     Finished:       0.793544        55      CPS (million per second):       12.601695684171
inet_aton       Starting: GC:   54
inet_aton       Finished:       0.246071        58      CPS (million per second):       40.638677454881
luafind Starting: GC:   56
luafind Finished:       0.002955        60      CPS (million per second):       3384.0947546531
luajit-2.1.0-beta3 binary/ip.lua  1.04s user 0.00s system 99% cpu 1.050 total

time luajit-2.1.0-beta3 -joff binary/ip.lua
ffi     Starting: GC:   50
ffi     Finished:       9.120691        108     CPS (million per second):       1.0964081559171
inet_aton       Starting: GC:   50
inet_aton       Finished:       8.13562 103     CPS (million per second):       1.229162620673
luafind Starting: GC:   50
luafind Finished:       2.727144        50      CPS (million per second):       3.6668397415025
luajit-2.1.0-beta3 -joff binary/ip.lua  19.95s user 0.04s system 99% cpu 20.045 total
]]