safekeeper: use arc for global timelines and config

[oldmanfleming]

Hello! I was interested in potentially making some contributions to Neon and looking through the issue backlog I found 8200 which seemed like a good first issue to attempt to tackle. I see it was assigned a while ago so apologies if I'm stepping on any toes with this PR. I also apologize for the size of this PR. I'm not sure if there is a simple way to reduce it given the footprint of the components being changed.

Problem

This PR is attempting to address part of the problem outlined in issue 8200. Namely to remove global static usage of timeline state in favour of Arc<GlobalTimelines> and to replace wasteful clones of SafeKeeperConf with Arc<SafeKeeperConf>. I did not opt to tackle RemoteStorage in this PR to minimize the amount of changes as this PR is already quite large. I also did not opt to introduce an SafekeeperApp wrapper struct to similarly minimize changes but I can tackle either or both of these omissions in this PR if folks would like.

Summary of changes

• Remove static usage of GlobalTimelines in favour of Arc<GlobalTimelines>
• Wrap SafeKeeperConf in Arc to avoid wasteful clones of the underlying struct

Some additional thoughts

• We seem to currently store SafeKeeperConf in GlobalTimelines and then expose it through a publicget_global_config function which requires locking. This seems needlessly wasteful and based on observed usage we could remove this public accessor and force consumers to acquire SafeKeeperConf through the new Arc reference.

[arpad-m]

LGTM, cc @arssher just to make sure

[github-actions]

7051 tests run: 6726 passed, 0 failed, 325 skipped (full report)

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Flaky tests (2)

Postgres 14

• test_replica_query_race: release-x86-64
• test_prefetch[None]: release-x86-64

Code coverage* (full report)

• functions: 31.4% (8332 of 26527 functions)
• lines: 47.7% (65545 of 137449 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
c0a55ee at 2024-12-09T17:14:00.178Z :recycle:}

[arpad-m]

status: blocked on #10059. @oldmanfleming after it merged, could you merge main? (better not a rebase as we merge with squash anyways)

[oldmanfleming]

@arpad-m Thanks for the review! #10059 is merged and I merged main to this branch. Let me know if I messed something up with the merging

[arpad-m]

@oldmanfleming thanks for merging latest main. I will give some time for @arssher and @petuhovskiy to give it a look as they are more familiar with the code than I am, but it looks good from my point of view. Definitely an improvement.

[petuhovskiy]

Very cool, thank you @oldmanfleming!

@arpad-m can you run the CI and merge this?

[bayandin]

arpad-m can you run the CI and merge this?

The CI has passed already 🎉

[arpad-m]

Merged, thanks again.

[oldmanfleming]

@arpad-m No problemo 😄