`Headers.fromEntries`: using `CaseInsensitiveMap.fromEntries`

[gmpassos]

• Headers:
  • Added the constructor Headers.fromEntries.
  • Added the internal constructor _fromEntries, which uses CaseInsensitiveMap.fromEntries for optimization.
  • Renamed the internal constructor _ to _from, redirecting it to this._fromEntries.

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• [✅ ] I’ve reviewed the contributor guide and applied the relevant portions to this PR.

[gmpassos]

FYI: @kevmoo

[gmpassos]

I made some tweaks.

nice

[kevmoo]

@gmpassos – and some more tweaks 😄

[kevmoo]

@gmpassos – do you have benchmarks showing this makes things notably faster?

[kevmoo]

@gmpassos – we need to roll this through our internal "stuff" before we publish. To make sure nothing breaks. I'll let you know when publish happens!

[gmpassos]

@gmpassos – we need to roll this through our internal "stuff" before we publish. To make sure nothing breaks. I'll let you know when publish happens!

Thanks for the quick response and attention. I will wait for the publication...

[kevmoo]

Looks like @devoncarew landed in the Dart SDK 50 minutes ago. We'll have to wait a few hours to make sure that rolls into our internal...things...before we publish

[gmpassos]

@gmpassos – do you have benchmarks showing this makes things notably faster?

In my benchmark, I get a 1-2% improvement, but note that you need to have real-world headers (real browsers send many more headers than simple HTTP clients). Additionally, you need a heavy load, as this also affects the GC. This is more significant for slower/smaller servers. On a medium-sized server with low traffic, this won't have much impact.

I'm also looking for a way to avoid computation of all canonicalized keys just to build the headers. This will significantly improve performance, or we could use a specialized cache of canonicalized keys, but this will be a future optimization.

[kevmoo]

shelf published w/ this! @gmpassos !