Remove unnecessary GetTypeInfo from Microsoft.Extensions.

[eerhardt]

I also made a slight optimization to CallSiteFactory to use ToArray instead of ToList.

These were showing up as 5% of ServiceCollection.BuildServiceProvider() in a simple benchmark:

    public class DIBench
    {
        private readonly ServiceCollection services = new ServiceCollection();

        public DIBench()
        {
            services.AddTransient<Service1>();
            services.AddTransient<Service2a>();
            services.AddTransient<Service2b>();
            services.AddTransient<Service3a>();
            services.AddTransient<Service4>();
            services.AddTransient<Service4>();
            services.AddTransient<Service5>();
            services.AddTransient<Service6>();
            services.AddTransient<Service7>();
            services.AddTransient<Service8>();
            services.AddTransient<Service9>();
            services.AddTransient<Service10>();
            services.AddTransient<Service11>();
            services.AddTransient<Service12>();
            services.AddTransient<Service13>();
            services.AddTransient<Service14>();
            services.AddTransient<Service15>();
            services.AddTransient<Service16>();
            services.AddTransient<Service17>();
            services.AddTransient<Service18>();
            services.AddTransient<Service19>();
            services.AddTransient<Service20>();
            services.AddTransient<Service21>();
            services.AddTransient<Service22>();
            services.AddTransient<Service23>();
            services.AddTransient<Service24>();
            services.AddTransient<Service25>();
            services.AddTransient<Service26>();
            services.AddTransient<Service27>();
            services.AddTransient<Service28>();
            services.AddTransient<Service29>();
        }

        [Benchmark]
        public object BuildServiceProvider()
        {
            var sp = services.BuildServiceProvider();

            return sp;
        }
    }

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Issue Details

Description:	I also made a slight optimization to CallSiteFactory to use ToArray instead of ToList.
Author:	eerhardt
Assignees:	-
Labels:	area-Extensions-DependencyInjection
Milestone:	-

[davidfowl]

Nice clean up. We should do this in ASP.NET too...

[eerhardt]

We should do this in ASP.NET too...

Will log an issue (and maybe make a PR if it looks quick).

[stephentoub]

(Some of this LINQ usage pains me to look at :), but that's not related to your PR.)

[stephentoub]

What was the benefit of this change? Is _descriptors accessed a lot such that the overhead of going through _descriptors as a list vs an array mattered?

[eerhardt]

The benefit was very minimal, probably not even observable. I started this change by looking at CallSiteFactory.Populate (which is 75% of the above benchmark). And this ToList() jumped out at me and looking at the code I noticed we don't need a List, but can just use an Array instead. I just figured while I was in here, it was one less object to create.

[stephentoub]

I just figured while I was in here, it was one less object to create.

But unless the array is the exact right size, ToArray needs to allocate one at the end and copy all the elements to it. ToList doesn't. So you still generally end up with another object, but typically a bigger one.

[eerhardt]

In this case, the Type that is passed in to descriptors is always an IServiceCollection, which implements ICollection<T>. So the size will be known up-front and only a single Array needs to be allocated. It won't need to be resized in the end.

[stephentoub]

Cool