Add certificate provider registry implementation

[yashykt]

This change is 

[markdroth]

Just one minor suggestion. Otherwise, looks great!

Reviewed 20 of 20 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @yashykt)

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src/core/ext/xds/certificate_provider_registry.cc, line 57 at r1 (raw file):

  // hurting performance (which is unlikely, since these allocations
  // only occur at gRPC initialization time).
  absl::InlinedVector<std::unique_ptr<CertificateProviderFactory>, 3>

Why not just use std::map<> here? That would make lookups more efficient at run-time.

[yashykt]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @markdroth)

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src/core/ext/xds/certificate_provider_registry.cc, line 57 at r1 (raw file):

Previously, markdroth (Mark D. Roth) wrote…

Why not just use std::map<> here? That would make lookups more efficient at run-time.

I don't have data for this, but from sounds like for a small number of elements vectors are faster than std::map.

[markdroth]

Reviewable status: complete! all files reviewed, all discussions resolved

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src/core/ext/xds/certificate_provider_registry.cc, line 57 at r1 (raw file):

Previously, yashykt (Yash Tibrewal) wrote…

I don't have data for this, but from sounds like for a small number of elements vectors are faster than std::map.

A map seems more natural to me, but I guess it doesn't really matter. This is fine for now.

[yashykt]

Issues: #24092, #24093

[yashykt]

Thanks for reviewing!