From 17b0dac481c01425651326e8814b45058cd40f06 Mon Sep 17 00:00:00 2001 From: Tomas Janousek Date: Thu, 12 Nov 2020 10:02:44 +0000 Subject: Optimize Date plugin again (refresh timezone only once a minute) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This makes the Date plugin approximately twice as fast, and makes xmobar up to about 5–10 % faster if Date is the only active plugin. (If more expensive plugins like Network or MultiCpu are used, it doesn't make any measurable difference.) Micro-benchmark results on my HW: Date Benchmarks/Date mean 2.833 μs ( +- 16.08 ns ) Date Benchmarks/DateZonedTime mean 5.020 μs ( +- 32.91 ns ) Date Benchmarks/DateWithTimeZone mean 2.827 μs ( +- 20.52 ns ) (DateZonedTime is the original implementation and DateWithTimeZone is the implementation we had since 0.34 which never refreshes timezone.) Real-life measurements (done overnight on an idle laptop, with all measured xmobars running in parallel to ensure comparable conditions; xmobars configured to only display date and with rate 10 — once per second): $ time timeout 6h xmobar .xmobarrc-DateZonedTime real 360m0,010s user 0m9,867s sys 0m4,644s (9.867 + 4.644) / (360 * 60) = 0.000672 $ time timeout 6h xmobar .xmobarrc-Date real 360m0,008s user 0m9,535s sys 0m4,327s (9.535 + 4.327) / (360 * 60) = 0.000642 $ time timeout 6h xmobar .xmobarrc-Date-10m real 360m0,010s user 0m9,780s sys 0m4,215s (9.780 + 4.215) / (360 * 60) = 0.000648 $ time timeout 6h xmobar .xmobarrc-DateWithTimeZone real 360m0,006s user 0m9,658s sys 0m4,166s (9.658 + 4.166) / (360 * 60) = 0.000640 (.xmobarrc-Date-10m is the proposed implementation, but with timezone refresh every 10 minutes instead of every 1 minute) Interpretation of these results: * refreshing xmobar with just date takes around 650 μs * that is xmobar with just date uses around 0.065 % of CPU time * refreshing timezone takes additional cca 30 μs When we only refresh timezone once a minute, these 30 μs become 0.5 μs amortized, and that should be acceptable to even the most dedicated perfectionist :-) Fixes: a58e32f7c8af ("Revert "Optimize date plugin"") Fixes: 878db3908060 ("Optimize date plugin") Co-authored-by: Sibi Prabakaran --- src/Xmobar/Plugins/Date.hs | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'src') diff --git a/src/Xmobar/Plugins/Date.hs b/src/Xmobar/Plugins/Date.hs index 1cb0596..d7de2e9 100644 --- a/src/Xmobar/Plugins/Date.hs +++ b/src/Xmobar/Plugins/Date.hs @@ -17,22 +17,35 @@ -- ----------------------------------------------------------------------------- -module Xmobar.Plugins.Date (Date(..)) where +module Xmobar.Plugins.Date (Date(..), date) where import Xmobar.Run.Exec #if ! MIN_VERSION_time(1,5,0) import System.Locale #endif +import Data.IORef import Data.Time +import Control.Concurrent.Async (concurrently_) data Date = Date String String Int deriving (Read, Show) instance Exec Date where alias (Date _ a _) = a - run (Date f _ _) = date f rate (Date _ _ r) = r + start (Date f _ r) cb = + -- refresh time zone once a minute to avoid wasting CPU cycles + withRefreshingZone 600 $ \zone -> + doEveryTenthSeconds r $ date zone f >>= cb -date :: String -> IO String -date format = fmap (formatTime defaultTimeLocale format) getZonedTime +date :: IORef TimeZone -> String -> IO String +date zoneRef format = do + zone <- readIORef zoneRef + fmap (formatTime defaultTimeLocale format . utcToZonedTime zone) getCurrentTime + +withRefreshingZone :: Int -> (IORef TimeZone -> IO ()) -> IO () +withRefreshingZone r action = do + zone <- newIORef =<< getCurrentTimeZone + let refresh = atomicWriteIORef zone =<< getCurrentTimeZone + concurrently_ (doEveryTenthSeconds r refresh) (action zone) -- cgit v1.2.3