gistfile1.hs

{-# LANGUAGE OverloadedStrings #-}
import qualified Network.HTTP.Conduit as H
import Control.Exception
import Web.Scotty
import System.Environment
import System.IO
import System.Directory
import Control.Monad
import Control.Monad.IO.Class
import qualified  Data.ByteString.Lazy.Char8 as BS

main :: IO ()
main = do
  port <- getEnv "PORT"
  cachedir <- getEnv "cachedir"
  scotty (read port) $ do
    get "/:domain/favicon.ico" $ do
      domain <- param "domain"
      let filename = cachedir ++ "/" ++ domain
      liftIO (proxy domain filename)
      header "Content-Disposition" "binary/data"
      file filename

proxy :: String -> String -> IO ()
proxy domain filename = do
  exists <- doesFileExist filename
  when (not exists) fetch

  where fetch = handle handler $ H.simpleHttp url >>= BS.writeFile filename
        url = "http://" ++ domain ++ "/favicon.ico"

        handler :: SomeException -> IO ()
        handler e = hPutStrLn stderr (show e)

This requires GHC HEAD.

weighttp -n 1000000 -c 100 -t 4 -k localhost:3001/google.com/favicon.ico

to warm it up, then

weighttp -n 10000000 -c 100 -t 4 -k localhost:3001/google.com/favicon.ico

for the actual test (4 threads simulating 25 concurrent connections apiece)

node: 44019 req/s
haskell: 112398 req/s