Waste less memory when model binding

[dougbu]

Loops through ModelMetadata.Properties in ComplexTypeModelBinder eat 1.3% of the total memory used in the BigModelBinding scenario. Boxing the List<ModelMetadata> Enumerators could be completely avoided by switching from foreach to for (twice) in this class.

Similarly, enumerating children of the DefaultComplexObjectValidationStrategy eats about 0.8% of the total used in the same scenario. The fix here is a bit more complicated because that Enumerator class is not currently exposed. Still, it could be exposed and made into a struct because everything's in an Internal namespace.

BigModelBinding

Exercises HomeController.Index() view using ./loadtest.ps1. Binds an instance of the Model using form data from ./postdata.txt.

Excess Enumerators

[rynowak]

I don't believe you that the fix with DefaultComplexObjectValidationStrategy is so straightforward. There's an interface involved.

[dougbu]

I don't believe you that the fix with DefaultComplexObjectValidationStrategy is so straightforward. There's an interface involved.

@rynowak agreed. I said that one was (at least) "a bit more complicated". Would likely require special-casing that strategy class or (somehow) reducing the size of its Enumerator class.

[Eilon]

Let's do the simple change for avoiding enumerator allocations. Let's not do the rest of the change, as it is unlikely to simple, and the benefits are small.

[dougbu]

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