chcking perf of hash funcs

dict_keys.fs

//output
//good keys
//struct custom 1.506934 sec 0.000000 collisions
//struct auto 4.832881 sec 0.776863 collisions
//struct auto explicit 3.166931 sec 0.776863 collisions
//bad keys
//struct custom 3.631251 sec 0.061893 collisions
//struct auto 10.340693 sec 0.777034 collisions
//struct auto explicit 8.893612 sec 0.777034 collisions


open System
open System.Collections.Generic

let check keys e name =
    let dict =  new Dictionary<_,_>(Array.length keys, e)//, HashIdentity.Structural)
    let stopWatch = System.Diagnostics.Stopwatch.StartNew()
    let add k = dict.Add(k, 1.02)
    Array.iter add keys    
    stopWatch.Stop()
    let hsahes = new HashSet<int>()
    let add_hash x =  hsahes.Add(e.GetHashCode(x)) |> not
    let collisions = Array.filter add_hash keys |> Array.length
    printfn "%s %f sec %f collisions" name stopWatch.Elapsed.TotalSeconds (double(collisions) / double(keys.Length))

type StructTuple<'T,'T2> =
   struct
      val fst: 'T
      val snd : 'T2
      new(fst: 'T, snd : 'T2) = {fst = fst; snd = snd}
   end

let bad_keys = seq{
    let rnd = new Random();
    while true do
        let j = uint32(rnd.Next(0, 3346862))
        let k = uint16 (rnd.Next(0, 658))
        yield StructTuple(j,k)
}

let good_keys = seq{
    for k in 0us..658us do
        for j in 0u.. 3346862u do
            yield StructTuple(j,k)
}

module CmpHelpers = 
    let inline combine (h1:int) (h2:int) = (h1 <<< 5) + h1 ^^^ h2;

type StructTupleComparer<'T,'T2>() =
    let cmparer = EqualityComparer<Object>.Default
    interface IEqualityComparer<StructTuple<'T,'T2>> with
        member this.Equals (a,b) = cmparer.Equals(a.fst, b.fst) && cmparer.Equals(a.snd, b.snd)
        member this.GetHashCode (x) = CmpHelpers.combine (cmparer.GetHashCode(x.fst)) (cmparer.GetHashCode(x.snd)) 

type AutoGeneratedStructTupleComparer<'T,'T2>() =
    let cmparer = LanguagePrimitives.GenericEqualityComparer
    interface IEqualityComparer<StructTuple<'T,'T2>> with
        member this.Equals (a:StructTuple<'T,'T2>,b:StructTuple<'T,'T2>) = 
                LanguagePrimitives.HashCompare.GenericEqualityERIntrinsic<'T> a.fst b.fst
                    && LanguagePrimitives.HashCompare.GenericEqualityERIntrinsic<'T2> a.snd b.snd
        member this.GetHashCode (x:StructTuple<'T,'T2>) = 
                let mutable num = 0
                num <- -1640531527 + (LanguagePrimitives.HashCompare.GenericHashWithComparerIntrinsic<'T2> cmparer x.snd + ((num <<< 6) + (num >>> 2)))
                -1640531527 + (LanguagePrimitives.HashCompare.GenericHashWithComparerIntrinsic<'T> cmparer x.fst + ((num <<< 6) + (num >>> 2)));


let uniq (sq:seq<'a>) = Array.ofSeq (new HashSet<_>(sq)) 

[<EntryPoint>]
let main argv = 
    let count = 15000000
    let keys = good_keys |> Seq.take count |> uniq
    printfn "good keys"
    check keys (new StructTupleComparer<_,_>()) "struct custom"
    check keys HashIdentity.Structural "struct auto"
    check keys (new AutoGeneratedStructTupleComparer<_,_>()) "struct auto explicit"


    let keys = bad_keys |> Seq.take count |>  uniq
    printfn "bad keys"
    check keys (new StructTupleComparer<_,_>()) "struct custom"
    check keys HashIdentity.Structural "struct auto"
    check keys (new AutoGeneratedStructTupleComparer<_,_>()) "struct auto explicit"

    

    Console.ReadLine() |> ignore
    0 // return an integer exit code