git-annex/Annex/Concurrent/Utility.hs

24 lines
566 B
Haskell
Raw Normal View History

{- git-annex concurrency utilities
-
- Copyright 2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Annex.Concurrent.Utility where
import Types.Concurrency
import GHC.Conc
{- Honor the requested level of concurrency, but only up to the number of
- CPU cores. Useful for things that are known to be CPU bound. -}
concurrencyUpToCpus :: Concurrency -> IO Int
concurrencyUpToCpus c = do
let cn = case c of
Concurrent n -> n
NonConcurrent -> 1
ConcurrentPerCpu -> 1
pn <- getNumProcessors
return (min cn pn)