This project is a POC to demonstrate a method of creating typed wrappers for functions and injecting them automatically into an IServiceCollection using reflection and marker attributes without incurring a performance penalty or using any interfaces.
This works because functions wrapped in single-case struct unions are optimized to into raw function pointers by the compiler- this offers practically equivalent performance as simply calling a function directly! A breakdown of benchmarks supporting this claim are included, below.
Using this strategy, developers can achieve things like obtaining function definitions directly from the HttpContext within an HttpHandler when using Giraffe; these injected functions can be composed before injection, meaning it's completely compatible with functional dependency injection both before injection and after retrieval!
Define the wrapper type and implementation in your library code:
open FSharp.Extensions.DependencyInjection
/// Define a wrapper struct DU with one case containing a function type
[<Struct>]
type AddOne = AddOne of (int -> int)
module Wrappers =
/// Create an instance of the wrapper containing an implementation of the function
[<InjectedFunction>]
let addOne = (+) 1 |> AddOne
Automatically inject the functions from your startup code:
open FSharp.Extensions.DependencyInjection
type Startup() =
member _.ConfigureServices(services: IServiceCollection) =
services.AddAllInjectedFunctions() // or services.AddAllInjectedFunctionsParallel()
// ... etc.Retrieve and reference the function in your HttpHandler code:
let addOne (i: int) : HttpHandler =
fun next ctx ->
let (AddOne addOne) = ctx.GetService()
let result = addOne i
text $"{i} + 1 = {result}" next ctx| Method | Mean | Error | StdDev | Code Size | Gen0 | Allocated |
|---|---|---|---|---|---|---|
| RawFunctionPointer | 4.046 ns | 0.0163 ns | 0.0136 ns | 1,094 B | - | - |
| StructDUWrappedFunctionPointer | 4.050 ns | 0.0310 ns | 0.0275 ns | 1,094 B | - | - |
| ClassDUWrappedFunctionPointer | 6.488 ns | 0.0669 ns | 0.0522 ns | 1,126 B | 0.0019 | 24 B |
; Benchmarks.FunctionPointerBenchmarks+FunctionPointerBenchmarks.RawFunctionPointer()
7FF9CFDF4120 push rsi
7FF9CFDF4121 sub rsp,20
7FF9CFDF4125 mov rcx,7FF9D01EDE50
7FF9CFDF412F mov edx,5
7FF9CFDF4134 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDF4139 mov rcx,1D3B0406BA8
7FF9CFDF4143 mov rsi,[rcx]
7FF9CFDF4146 mov rcx,7FF9D00648B0
7FF9CFDF4150 mov edx,5
7FF9CFDF4155 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDF415A mov edx,[7FF9D00648EC]
7FF9CFDF4160 mov r8d,[7FF9D00648E8]
7FF9CFDF4167 mov rcx,rsi
7FF9CFDF416A add rsp,20
7FF9CFDF416E pop rsi
7FF9CFDF416F jmp qword ptr [7FF9D0201678]; Microsoft.FSharp.Core.FSharpFunc`2[[System.Int32, System.Private.CoreLib],[System.Int32, System.Private.CoreLib]].InvokeFast[[System.Int32, System.Private.CoreLib]](Microsoft.FSharp.Core.FSharpFunc`2<Int32,Microsoft.FSharp.Core.FSharpFunc`2<Int32,Int32>>, Int32, Int32)
; Total bytes of code 85; Benchmarks.FunctionPointerBenchmarks+FunctionPointerBenchmarks.StructDUWrappedFunctionPointer()
7FF9CFDF4120 push rsi
7FF9CFDF4121 sub rsp,20
; Add.instance |> fun (Add add) -> add a b
; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
7FF9CFDF4125 mov rcx,7FF9D01EDE50
7FF9CFDF412F mov edx,5
7FF9CFDF4134 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDF4139 mov rcx,276C3C06BA8
7FF9CFDF4143 mov rsi,[rcx]
7FF9CFDF4146 mov rcx,7FF9D00648B0
7FF9CFDF4150 mov edx,5
7FF9CFDF4155 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDF415A mov edx,[7FF9D00648EC]
7FF9CFDF4160 mov r8d,[7FF9D00648E8]
7FF9CFDF4167 mov rcx,rsi
7FF9CFDF416A add rsp,20
7FF9CFDF416E pop rsi
7FF9CFDF416F jmp qword ptr [7FF9D0201738]; Microsoft.FSharp.Core.FSharpFunc`2[[System.Int32, System.Private.CoreLib],[System.Int32, System.Private.CoreLib]].InvokeFast[[System.Int32, System.Private.CoreLib]](Microsoft.FSharp.Core.FSharpFunc`2<Int32,Microsoft.FSharp.Core.FSharpFunc`2<Int32,Int32>>, Int32, Int32)
; Total bytes of code 85; Benchmarks.FunctionPointerBenchmarks+FunctionPointerBenchmarks.ClassDUWrappedFunctionPointer()
7FF9CFDE4120 push rdi
7FF9CFDE4121 push rsi
7FF9CFDE4122 sub rsp,28
; Add2.instance |> fun (Add2 add) -> add a b
; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
7FF9CFDE4126 mov rcx,7FF9D01DDE50
7FF9CFDE4130 mov edx,5
7FF9CFDE4135 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDE413A mov rcx,23DD6406BA8
7FF9CFDE4144 mov rsi,[rcx]
7FF9CFDE4147 mov rdi,rsi
7FF9CFDE414A mov rcx,offset MT_Library.StructFunctions+Add2
7FF9CFDE4154 call CORINFO_HELP_NEWSFAST
7FF9CFDE4159 lea rcx,[rax+8]
7FF9CFDE415D mov rdx,rdi
7FF9CFDE4160 call CORINFO_HELP_ASSIGN_REF
7FF9CFDE4165 mov rcx,7FF9D00548B0
7FF9CFDE416F mov edx,5
7FF9CFDE4174 call CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE
7FF9CFDE4179 mov edx,[7FF9D00548EC]
7FF9CFDE417F mov r8d,[7FF9D00548E8]
7FF9CFDE4186 mov rcx,rsi
7FF9CFDE4189 add rsp,28
7FF9CFDE418D pop rsi
7FF9CFDE418E pop rdi
7FF9CFDE418F jmp qword ptr [7FF9D01F1720]; Microsoft.FSharp.Core.FSharpFunc`2[[System.Int32, System.Private.CoreLib],[System.Int32, System.Private.CoreLib]].InvokeFast[[System.Int32, System.Private.CoreLib]](Microsoft.FSharp.Core.FSharpFunc`2<Int32,Microsoft.FSharp.Core.FSharpFunc`2<Int32,Int32>>, Int32, Int32)
; Total bytes of code 117