perf(cors) cache normalized configured origins

A refactor on top of the previous commit. We now distinguish the
requests origins' LRU cache from the plugin's configured normalized
origins.

kong/plugins/cors/handler.lua

@@ -1,8 +1,9 @@
 local BasePlugin = require "kong.plugins.base_plugin"
 local responses  = require "kong.tools.responses"
 local lrucache   = require "resty.lrucache"
+local url        = require "socket.url"
+
 
-local url             = require "socket.url"
 local req_get_method  = ngx.req.get_method
 local re_find         = ngx.re.find
 local concat          = table.concat
@@ -17,28 +18,33 @@ CorsHandler.PRIORITY = 2000
 CorsHandler.VERSION = "0.1.0"
 
 
--- per-worker cache of parsed origins
-local CACHE_SIZE = 10 ^ 4
-local parsed_domains
+-- per-plugin cache of normalized origins for runtime comparison
+local mt_cache = { __mode = "k" }
+local config_cache = setmetatable({}, mt_cache)
 
 
-local function parse_origin_domain(domain)
-  local parsed_obj = url.parse(domain)
-  if parsed_obj and parsed_obj.host then
-    local port = parsed_obj.port
-    if not port and parsed_obj.scheme then
-      if parsed_obj.scheme == "http" then
-        port = 80
-      elseif parsed_obj.scheme == "https" then
-        port = 443
-      end
-    end
-    return (parsed_obj.scheme and parsed_obj.scheme .. "://" or "") .. 
-            parsed_obj.host .. 
-            (port and ":" .. port or "")
-  else
+-- per-worker cache of parsed requests origins with 1000 slots
+local normalized_req_domains = lrucache.new(10e3)
+
+
+local function normalize_origin(domain)
+  local parsed_obj = assert(url.parse(domain))
+  if not parsed_obj.host then
     return domain
   end
+
+  local port = parsed_obj.port
+  if not port and parsed_obj.scheme then
+    if parsed_obj.scheme == "http" then
+      port = 80
+
+    elseif parsed_obj.scheme == "https" then
+      port = 443
+    end
+  end
+
+  return (parsed_obj.scheme and parsed_obj.scheme .. "://" or "") ..
+          parsed_obj.host .. (port and ":" .. port or "")
 end
 
 
@@ -76,21 +82,26 @@ local function configure_origin(ngx, conf)
 
   local req_origin = ngx.var.http_origin
   if req_origin then
+    local normalized_domains = config_cache[conf]
+    if not normalized_domains then
+      normalized_domains = {}
 
-    local parsed_req_origin = parse_origin_domain(req_origin)
-
-    for _, domain in ipairs(conf.origins) do
-      if not parsed_domains then
-        parsed_domains = lrucache.new(CACHE_SIZE)
+      for _, domain in ipairs(conf.origins) do
+        table.insert(normalized_domains, normalize_origin(domain))
       end
 
-      local parsed_domain = parsed_domains:get(domain)
-      if not parsed_domain then
-        parsed_domain = parse_origin_domain(domain)
-        parsed_domains:set(domain, parsed_domain)
-      end
+      config_cache[conf] = normalized_domains
+    end
+
+    local normalized_req_origin = normalized_req_domains:get(req_origin)
+    if not normalized_req_origin then
+      normalized_req_origin = normalize_origin(req_origin)
+      normalized_req_domains:set(req_origin, normalized_req_origin)
+    end
 
-      local from, _, err = re_find(parsed_req_origin, "^" .. parsed_domain .. "$", "jo")
+    for _, normalized_domain in ipairs(normalized_domains) do
+      local from, _, err = re_find(normalized_req_origin,
+                                   normalized_domain .. "$", "ajo")
       if err then
         ngx.log(ngx.ERR, "[cors] could not search for domain: ", err)
       end