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eulerfx/Async.Race.fs

Created June 21, 2018 20:58
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  1. eulerfx created this gist Jun 21, 2018.
    18 changes: 18 additions & 0 deletions Async.Race.fs
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,18 @@
    let race (a:Async<'a>) (b:Async<'a>) : Async<'a * Async<'a>> = async {
    return!
    Async.FromContinuations <| fun (ok,err,cnc) ->
    let state = ref 0
    let iv = new TaskCompletionSource<_>()
    let ok a =
    if (Interlocked.CompareExchange(state, 1, 0) = 0) then
    ok (a, iv.Task |> Async.AwaitTask)
    else
    iv.SetResult a
    let err (ex:exn) =
    if (Interlocked.CompareExchange(state, 1, 0) = 0) then err ex
    else iv.SetException ex
    let cnc ex =
    if (Interlocked.CompareExchange(state, 1, 0) = 0) then cnc ex
    else iv.SetCanceled ()
    Async.StartThreadPoolWithContinuations (a, ok, err, cnc)
    Async.StartThreadPoolWithContinuations (b, ok, err, cnc) }