Data.Atomics.Counter.IORef

This version uses a boxed IORef representation, but it can be somewhat cheaper because it uses raw CAS rather than full atomicModifyIORef.

Documentation

newtype AtomicCounter

Constructors

AtomicCounter (IORef Int)

type CTicket = Ticket Int

newCounter :: IO AtomicCounter

Create a new counter initialized to zero.

readCounterForCAS :: AtomicCounter -> IO CTicket

Try repeatedly until we successfully increment the counter. incrCounter =

peekCTicket :: CTicket -> Int

readCounter :: AtomicCounter -> IO Int

writeCounter :: AtomicCounter -> Int -> IO ()

Make a non-atomic write to the counter. No memory-barrier.

casCounter :: AtomicCounter -> CTicket -> Int -> IO (Bool, CTicket)