Primes

open System.Threading
open System.Numerics

let waitFor o= ignore(Monitor.Wait o)
let wakeWaiters = Monitor.PulseAll

/// Make a named thread that runs f
let mkThread name f = Thread (ThreadStart f, Name=name)
/// Make a named thread and start it immediately
let startThread name f = (mkThread name f).Start()


let primes :ref<Set<bigint>>= ref (Set.singleton 2I) //start with just the prime 2, listed //TODO: this is kinda a messy way to say 2

type bigOddIntGen (min:bigint) =
    let next=ref min
    member this.Next = lock this <| fun () ->
        let v = !next
        next:= v + 2I
        v

let unchecked = bigOddIntGen(3I)

///a lockable object for printign to the screen
let stdout = ref ()

let rec primeMaker maxVal :unit=
    let isPrime n =
        ///returns possible prime divisors of the nukmber n (won't return til it has all of them)
        let possibleDivisors = lock primes <| fun () ->
            while (!primes |> Set.maxElement) * (2I) < n  do //(Set.exists (fun p -> (bigint 2)*p>=n) (!primes)) do
                printfn "**********************";
                waitFor primes
            Set.filter (fun p -> p<=n/(2I)) (!primes)

        not <| Set.exists (fun p -> n % p = bigint.Zero) possibleDivisors


    let printer name n=
        let pf () = lock stdout <| fun () ->
            ignore <| printfn "%s found prime: %s" name (n.ToString())
            //HACK: BigInt>ToSting is broken: only preserves 50 digits. there is a work around but not using it
        pf ()
        //startThread "printer" pf;


    ///Adds a p to out set of primes
    let addPrime p = lock primes <| fun () ->
        primes:= (!primes).Add p;
        wakeWaiters primes

    let x = unchecked.Next
    if maxVal<>None && x>maxVal.Value then ();
    elif isPrime x then
        printer Thread.CurrentThread.Name x;
        addPrime x;
    primeMaker maxVal;


//primeMaker "t1" (BigInteger(System.Int32.MaxValue))

let pm=fun () -> primeMaker <| Some (BigInteger(System.Int32.MaxValue))

for i in [1..54] do
    let name = sprintf "t%d" i
    startThread name pm;