module Criterion.Measurement
(
getTime
, runForAtLeast
, secs
, time
, time_
) where
import Control.Monad (when)
import Data.Time.Clock.POSIX (getPOSIXTime)
import Text.Printf (printf)
time :: IO a -> IO (Double, a)
time act = do
start <- getTime
result <- act
end <- getTime
let !delta = end start
return (delta, result)
time_ :: IO a -> IO Double
time_ act = do
start <- getTime
_ <- act
end <- getTime
return $! end start
getTime :: IO Double
getTime = realToFrac `fmap` getPOSIXTime
runForAtLeast :: Double -> Int -> (Int -> IO a) -> IO (Double, Int, a)
runForAtLeast howLong initSeed act = loop initSeed (0::Int) =<< getTime
where
loop !seed !iters initTime = do
now <- getTime
when (now initTime > howLong * 10) $
fail (printf "took too long to run: seed %d, iters %d" seed iters)
(elapsed,result) <- time (act seed)
if elapsed < howLong
then loop (seed * 2) (iters+1) initTime
else return (elapsed, seed, result)
secs :: Double -> String
secs k
| k < 0 = '-' : secs (k)
| k >= 1 = k `with` "s"
| k >= 1e-3 = (k*1e3) `with` "ms"
| k >= 1e-6 = (k*1e6) `with` "us"
| k >= 1e-9 = (k*1e9) `with` "ns"
| k >= 1e-12 = (k*1e12) `with` "ps"
| otherwise = printf "%g s" k
where with (t :: Double) (u :: String)
| t >= 1e9 = printf "%.4g %s" t u
| t >= 1e6 = printf "%.0f %s" t u
| t >= 1e5 = printf "%.1f %s" t u
| t >= 1e4 = printf "%.2f %s" t u
| t >= 1e3 = printf "%.3f %s" t u
| t >= 1e2 = printf "%.4f %s" t u
| t >= 1e1 = printf "%.5f %s" t u
| otherwise = printf "%.6f %s" t u