a bit more simplification without an apparent performance gain
{- * Hedgewars, a free turn based strategy game * Copyright (c) 2004-2015 Andrey Korotaev <unC0Rr@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. \-}{-# LANGUAGE BangPatterns #-}module JoinsMonitor( JoinsMonitor , newJoinMonitor , cleanup , joinsSentry ) whereimport qualified Data.Map as Mapimport Data.Timeimport Data.IORefimport qualified Data.ByteString as Bimport Data.Maybeimport Control.Monadnewtype JoinsMonitor = JoinsMonitor (IORef (Map.Map B.ByteString [UTCTime]))newJoinMonitor :: IO JoinsMonitornewJoinMonitor = do ioref <- newIORef Map.empty return (JoinsMonitor ioref)cleanup :: JoinsMonitor -> UTCTime -> IO ()cleanup (JoinsMonitor ref) time = modifyIORef ref f where f = Map.mapMaybe (\v -> let v' = takeWhile (\t -> diffUTCTime time t < 60*60) v in if null v' then Nothing else Just v')joinsSentry :: JoinsMonitor -> B.ByteString -> UTCTime -> IO BooljoinsSentry (JoinsMonitor ref) host time = do m <- readIORef ref let lastJoins = map (diffUTCTime time) $ Map.findWithDefault [] host m let last30sec = length $ takeWhile (< 30) lastJoins let last2min = length $ takeWhile (< 120) lastJoins let last10min = length $ takeWhile (< 600) lastJoins let pass = last30sec < 2 && last2min < 3 && last10min < 5 when pass $ writeIORef ref $ Map.alter (Just . (:) time . fromMaybe []) host m return pass