GroupingAdd

gistfile1.fs

type Grouping<'T> = { IndexRef : int ref; ArrayRef : 'T [] ref }

let rec groupingAdd (value : 'T) (grouping : Grouping<'T>) = 
    let indexRef = grouping.IndexRef
    let arrayRef = grouping.ArrayRef
    let array = !arrayRef
    if Object.ReferenceEquals(array, null) then
        groupingAdd value grouping
    else 
        let index = Interlocked.Increment(indexRef)
        if index < array.Length then
            array.[index] <- value
            let mutable array' = array
            while not <| Object.ReferenceEquals(array', !arrayRef) || Object.ReferenceEquals(array', null) do
                array' <- !arrayRef
                if not <| Object.ReferenceEquals(array', null) then
                    array'.[index] <- value
        else
            lock grouping (fun () ->
                if Object.ReferenceEquals(array, !arrayRef) then
                    arrayRef := null
                    let index = array.Length
                    let newArray = Array.zeroCreate<'T> (array.Length * 2)
                    Array.Copy(array, newArray, index)
                    indexRef := index - 1
                    arrayRef := newArray
            )
            groupingAdd value grouping