Duration.hs

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
-- FIX de-dupe with apiengine-server
module Apiengine.Trace.Duration (
  Duration
, durationToMicro
, microToDuration
, durationToDiffTime
, diffTimeToDuration
) where

import           Apiengine.Trace.Prelude

import           Data.Aeson
import           Data.Time


-- | Duration with microsecond accuracy, any additional precision is ignored,
newtype Duration =
  Duration {
      getDuration :: DiffTime
    } deriving (Eq, Show)

durationToMicro :: Duration -> Integer
durationToMicro =
  truncate . (fromIntegral (1000000 :: Integer) *) . toRational . getDuration

microToDuration :: Integer -> Duration
microToDuration =
  Duration . picosecondsToDiffTime . (1000000 *) . abs

durationToDiffTime :: Duration -> DiffTime
durationToDiffTime =
  getDuration

diffTimeToDuration :: DiffTime -> Duration
diffTimeToDuration =
  microToDuration . durationToMicro . Duration

instance FromJSON Duration where
  parseJSON = withNumber "Duration" $ return . microToDuration . floor

instance ToJSON Duration where
  toJSON = Number . fromIntegral . durationToMicro