Add an "about" link to registrars in RDAP

[gbrodman]

From the response profile:
2.4.6. Registrar URL - The entity with the registrar role in the RDAP response MUST contain a links member [RFC9083]. The links object MUST contain the elements: value, identical to the the RDAP Base URL for the Registrar as provided in the IANA “Registrar IDs” registry (i.e., https://www.iana.org/assignments/registrar-ids); rel:about, and href containing the Registrar URL. Note: in cases where the Registry Operator acts as sponsoring Registrar (e.g., IANA Registrar ID 9999), the href shall contain a URL from the Registry.

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This change is 

[gbrodman]

@CydeWeys friendly ping

[weiminyu]

Reviewable status: 0 of 37 files reviewed, 2 unresolved discussions (waiting on @CydeWeys)

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core/src/main/java/google/registry/rdap/UpdateRegistrarRdapBaseUrlsAction.java line 83 at r1 (raw file):

  private static void processAllRegistrars(ImmutableMap<String, String> ianaIdsToUrls) {
    int nonUpdatedRegistrars = 0;
    // Split into multiple transactions to avoid load-save-reload conflicts. Re-building a registrar

Not clear what this means. I don't see reloads in the code flow.

Code quote:

load-save-reload

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core/src/main/java/google/registry/rdap/UpdateRegistrarRdapBaseUrlsAction.java line 85 at r1 (raw file):

    // Split into multiple transactions to avoid load-save-reload conflicts. Re-building a registrar
    // requires a full (cached) load of all registrars to avoid IANA ID conflicts.
    Iterable<Registrar> registrars = tm().transact(Registrar::loadAll);

Use transact(REPEATABLE_READ, callable) can reduce race.

Code quote:

tm().transact(

[gbrodman]

Reviewable status: 0 of 37 files reviewed, 2 unresolved discussions (waiting on @CydeWeys and @weiminyu)

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core/src/main/java/google/registry/rdap/UpdateRegistrarRdapBaseUrlsAction.java line 83 at r1 (raw file):

Previously, weiminyu (Weimin Yu) wrote…

Not clear what this means. I don't see reloads in the code flow.

not directly, but as the comment notes, the Registrar.Builder::build method requires reloading all registrars to avoid IANA ID conflicts.

So, in the previous all-in-one-transaction code path, it throws an error if more than one registrar is modified -- because the firstly-changed registrar is reloaded in the "build" method of the secondly-changed registrar.

We never saw this error in practice because we never encountered the case where more than one registrar URL changed at a time.

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core/src/main/java/google/registry/rdap/UpdateRegistrarRdapBaseUrlsAction.java line 85 at r1 (raw file):

Previously, weiminyu (Weimin Yu) wrote…

Use transact(REPEATABLE_READ, callable) can reduce race.

sure

[weiminyu]

Reviewable status: 0 of 37 files reviewed, 1 unresolved discussion (waiting on @CydeWeys)

[weiminyu]

Reviewed 35 of 37 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @CydeWeys)