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 --- bench/main.hs | 22 +++++++++++++++++++++- changelog.md | 4 ++-- readme.md | 1 + src/Xmobar/Plugins/Date.hs | 21 +++++++++++++++++---- xmobar.cabal | 2 +- 5 files changed, 42 insertions(+), 8 deletions(-) diff --git a/bench/main.hs b/bench/main.hs index f8db78c..10639eb 100644 --- a/bench/main.hs +++ b/bench/main.hs @@ -1,12 +1,14 @@ module Main (main) where +import Data.IORef (newIORef) +import Data.Time import Gauge import Xmobar import Xmobar.Plugins.Monitors.Cpu main :: IO () main = do - defaultMain =<< sequence [cpuBench] + defaultMain =<< sequence [cpuBench, dateBench] mkCpuArgs :: IO CpuArguments mkCpuArgs = getArguments ["-L", "3", "-H", "50", "--normal", "green", "--high", "red", "-t", "Cpu: %"] @@ -17,3 +19,21 @@ cpuBench = do return $ bgroup "Cpu Benchmarks" [ bench "CPU normal args" $ nfIO (runCpu cpuArgs) ] + +dateBench :: IO Benchmark +dateBench = do + let format = "D: %B %d %A W%V" + zone <- getCurrentTimeZone + zone' <- newIORef =<< getCurrentTimeZone + return $ bgroup "Date Benchmarks" + [ bench "Date" $ nfIO (date zone' format) + , bench "DateZonedTime" $ nfIO (dateZonedTime format) + , bench "DateWithTimeZone" $ nfIO (dateWithTimeZone zone format) + ] + +dateZonedTime :: String -> IO String +dateZonedTime format = fmap (formatTime defaultTimeLocale format) getZonedTime + +dateWithTimeZone :: TimeZone -> String -> IO String +dateWithTimeZone zone format = + fmap (formatTime defaultTimeLocale format . utcToZonedTime zone) getCurrentTime diff --git a/changelog.md b/changelog.md index 859d475..28ae950 100644 --- a/changelog.md +++ b/changelog.md @@ -6,8 +6,8 @@ _New features_ _Bug fixes_ - - Fix date plugin not picking up DST and timezone changes - (Fixed by reverting the optimization merged in 0.34). + - Fix date plugin not picking up DST and timezone changes (refresh + timezone once a minute to preserve the optimized performace of 0.34). ## Version 0.36 (August, 2020) diff --git a/readme.md b/readme.md index 5b8e747..f9b209e 100644 --- a/readme.md +++ b/readme.md @@ -1540,6 +1540,7 @@ will display "N/A" if for some reason the `date` invocation fails. - Format is a time format string, as accepted by the standard ISO C `strftime` function (or Haskell's `formatCalendarTime`). +- Timezone changes are picked up automatically every minute. - Sample usage: `Run Date "%a %b %_d %Y %H:%M:%S" "date" 10` ## `DateZone Format Locale Zone Alias RefreshRate` 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) diff --git a/xmobar.cabal b/xmobar.cabal index 57dfcb9..c03db46 100644 --- a/xmobar.cabal +++ b/xmobar.cabal @@ -357,5 +357,5 @@ benchmark xmobarbench hs-source-dirs: bench ghc-options: -funbox-strict-fields -Wall -fno-warn-unused-do-bind -O2 - build-depends: base, gauge, xmobar, mtl + build-depends: base, gauge, xmobar, mtl, time default-language: Haskell2010 -- cgit v1.2.3