prometheus-0.1.0.3: src/System/Metrics/Prometheus/Metric/Counter.hs

module System.Metrics.Prometheus.Metric.Counter
       ( Counter
       , CounterSample (..)
       , new
       , add
       , inc
       , sample
       ) where


import           Data.Atomics.Counter (AtomicCounter, incrCounter_, newCounter,
                                       readCounter)


newtype Counter = Counter { unCounter :: AtomicCounter }
newtype CounterSample = CounterSample { unCounterSample :: Int }


new :: IO Counter
new = Counter <$> newCounter 0


add :: Int -> Counter -> IO ()
add by = incrCounter_ by . unCounter


inc :: Counter -> IO ()
inc = add 1


sample :: Counter -> IO CounterSample
sample = fmap CounterSample . readCounter . unCounter