perfermance test for kong old and new dns client library

perf.lua

--[[
run it by this command:

$ resty --shdict "kong_dns_cache 10m"  ./perf.lua

]]

setmetatable(_G, nil) -- disable the _G write guard alert log introduced in OpenResty 1.15.8.1

pcall(require, "luarocks.loader")
require("kong.globalpatches")()
local json = require("cjson").encode

local not_found_answers = { errcode = 3, errstr = "not found" }

local a_answers = {{ address = "127.0.0.1", class = 1, ttl = 300, type = 1 }}

-- inject r.query
local resolver = require("resty.dns.resolver")

local query_func = function(self, original_query_func, name, options)
  return original_query_func(self, name, options)
end

local old_new = resolver.new
resolver.new = function(...)
  local r, err = old_new(...)
  if not r then
    return nil, err
  end
  local original_query_func = r.query
  r.query = function(self, ...)
    return query_func(self, original_query_func, ...)
  end
  return r
end

resolver.tag = "modified"
--- end of inject r.query

-- restore its API overlapped by the compatible layer
package.loaded["kong.resty.dns_client"] = nil
local client = require("kong.dns.client")
client.resolve = client._resolve

_G.busted_legacy_dns_client = true
package.loaded["kong.resty.dns.client"] = nil
local dns_client = require("kong.resty.dns.client")

--- TEST APIs
local n

local t
local function measure_function_time(f)
  t = os.clock()
  f()
  local delta = os.clock() - t
  print(string.format("  run resolve() %d times: %.4f s; avg: %.6f ms per calls",
    n, delta, delta/n *1000))
  return delta
end


local function test(name, f)
  local new_delta, old_delta
  print(name)

  -- new
  local cli = assert(client.new({ family = { "SRV", "A" }, }))

  print("+ NEW DNS client")
  local new_delta = measure_function_time(function ()
    f(function (host) return cli:resolve(host, nil, nil, {}) end)
  end)
  -- print("+ stats: ", json(cli.stats))

  -- old
  assert(dns_client.init({ order = { "LAST", "SRV", "A", "CNAME" }, }))

  print("+ OLD DNS client")
  local old_delta = measure_function_time(function ()
    f(function (host) return dns_client.resolve(host, nil, nil, {}, nil) end)
  end)

  -- last
  local improved = (1/(new_delta/n))/(1/(old_delta/n)) - 1
  print(("+ Improved: %.2f%%\n"):format(improved * 100))
end

--- run test
print("\n--- runing perf test ---\n")

--- 100% Hit
n = 10000000
local title = "+ 100% hit (miss the first time)"

test(title, function (cli_resolve)
  local answers, err, tries

  -- skip first miss --
  answers, err, tries = cli_resolve("www.konghq.com")
  assert(not err, "err:".. tostring(err) .. " tries:" .. json(tries))
  t = os.clock()

  -- run HIT query
  for i = 1, n do
    answers, err, tries = cli_resolve("www.konghq.com")
  end
  assert(not err)
  assert(answers[1].name == "www.konghq.com")
end)

--- 0% Hit
n = 100000
local title = "+ 0% Hit (Every query to the nameserver succeeds.)"
local count = 0

query_func = function(self, original_query_func, name, options)
  count = count + 1
  if options.qtype == 33 then -- SRV
    return not_found_answers
  end
  a_answers[1].name = name
  return a_answers
end

test(title, function (cli_resolve)
  local answers, err, tries
  count = 0
  for i = 1, n do
    answers, err, tries = cli_resolve(i .. ".konghq.com")
  end
  assert(answers[1].name == n .. ".konghq.com")
  assert(count == n or count == n*2)
end)

how to test: link