Single app.UseWhen vs multiple app.UseWhen

Question

In ASP .NET Core app want to make one of my controllers sessionless. So I do the following:

app.UseWhen(
context => context.GetRouteValue("controller") is not "SomeValue",
app => app.UseMiddleware<SessionMiddleware>());

Then I decided to disable some other middleware for this controller. And I wonder if there is a difference between this

app.UseWhen(
context => context.GetRouteValue("controller") is not "SomeValue",
app =>
{
    app.UseMiddleware<SessionMiddleware>();
    app.UseMiddleware<SomeOtherMiddleware>();
});

and this

app.UseWhen(
context => context.GetRouteValue("controller") is not "SomeValue",
app => app.UseMiddleware<SessionMiddleware>());

app.UseWhen(
context => context.GetRouteValue("controller") is not "SomeValue",
app => app.UseMiddleware<SomeOtherMiddleware>());

It should behave the same, but is there any overhead in registering two middlewares separately? Or both calls will end up being the same (optimized by compiler)?

Answer 1

The source code for UseWhen is here: https://github.com/dotnet/aspnetcore/blob/3f8edf130a14d34024a42ebd678fa3f699ef5916/src/Http/Http.Abstractions/src/Extensions/UseWhenExtensions.cs#L22.

There would be some small overhead for calling it twice but since this is only done once on startup and not per request, I'd say it doesn't matter.

I would personally prefer having just one as you don't need to duplicate conditions.