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Bambosa

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CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

these were added for AOT I think so I assume these are compile time

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

especially when they probably work with source generators

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

a shame the UnmanagedCallersAttribute is sealed, would have liked to just have a CdeclAttribute to default the calling convention

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

yeah I think this is the route I will go down

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

some things to think about, thanks for the info guys

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

yeah I was thinking if I went down that route I would just have some lookup to get the function pointer for the given function

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

I guess I will have to use unsafe then as the overhead for the stub is too big for the use case (interacting with an ECS)

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

yeah just checked

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

also I thought the default calling convention for unmanaged callers only was cdecl? is it not?

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

yeah but there seems to be a pretty beefy overhead to using it

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

so I should pass it as delegate* unmanaged[Cdecl]<int, void>?

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

it currently works with this rust code and executes fine:

#[no_mangle]
pub extern "C" fn callback(number: i32, callback: unsafe extern "C" fn(i32)) {
    (|n| unsafe { callback(n) })(number);
}

#[no_mangle]
pub extern "C" fn callback(number: i32, callback: unsafe extern "C" fn(i32)) {
    (|n| unsafe { callback(n) })(number);
}

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

I just wish there was an easy way to get the same benefit without the consumer having to dip into unsafe code

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

with the delegate* managed<int, void> it only works against static methods which makes it safe to execute from native code

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

is there a way to take a managed delegate and convert it to a function pointer without the huge overheads?

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

Test.Callback(1234, &Callback); is perfect other than the fact the user consuming this static method has to be an unsafe context to give me a delegate* managed<int, void>

40 replies

CC#

•Created by Bambosa on 9/16/2023 in #help

❔ How can I provide a safe zero cost abstraction over passing managed function pointers over FFI

I want to be able to pass a callback function from a safe managed context over FFI without these insane overheads, here is the benchmark I used:

[MemoryDiagnoser(false)]
public class Benchmarks
{
    [Params(10, 100, 1000, 10000)] public int Iterations { get; set; }
    
    [Benchmark]
    public void CallbackSafe()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback(1234, Callback);
    }
    
    [Benchmark]
    public void CallbackSafe2()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback2(1234, Callback);
    }
    
    [Benchmark]
    public unsafe void CallbackUnsafe()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback(1234, &Callback);
    }
    
    private static void Callback(int i){ }
}

[MemoryDiagnoser(false)]
public class Benchmarks
{
    [Params(10, 100, 1000, 10000)] public int Iterations { get; set; }
    
    [Benchmark]
    public void CallbackSafe()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback(1234, Callback);
    }
    
    [Benchmark]
    public void CallbackSafe2()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback2(1234, Callback);
    }
    
    [Benchmark]
    public unsafe void CallbackUnsafe()
    {
        for (var i = 0; i < Iterations; i++)
            Test.Callback(1234, &Callback);
    }
    
    private static void Callback(int i){ }
}

40 replies

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