test.fs

type CircularBuffer<'b>(bufferSize) = 
    let buffer : 'b option array = Array.init bufferSize (fun _ -> None)
    let mutable currentIndex = bufferSize - 1
    let lockObj = System.Object()

    member x.Add item = 
        lock (lockObj) 
            (fun () -> 
                let newIndex = 
                    if currentIndex = bufferSize - 1 then
                        0
                    else currentIndex + 1 
                buffer.[newIndex] <- Some item
                currentIndex <- newIndex
            )

    member x.GetBuffer () = 
        let rec getItem n i items = 
            let i = if i < 0 then bufferSize - 1 else i
            match n >= bufferSize, buffer.[i] with
            |false, None
            |true,_ -> items
            |_, Some s -> getItem (n+1) (i-1) (s::items)
        lock (lockObj) 
            (fun () -> 
                getItem 0 currentIndex []
            )
    member x.GetCurrent () = buffer.[currentIndex]