fix: use ArcSwap for SyncStatus

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

Reference issue to close (if applicable)

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Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

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Summary by CodeRabbit

• Refactor
  • Updated how sync status is shared and read across sync components, daemon warmup behavior, garbage collection scheduling, RPC handlers, health probes, and offline/snapshot tooling to reduce locking and better reflect the latest state.
• Tests
  • Updated healthcheck and RPC test scaffolding/fixtures to use the new sync-status access pattern, keeping readiness/liveness checks and syncing assertions consistent.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 923a9bd4-61a2-40a4-8850-16ffe909cdb1

📥 Commits

Reviewing files that changed from the base of the PR and between b07705e and 828f0f7.

📒 Files selected for processing (1)

• src/health/mod.rs

🔗 Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

• filecoin-project/lotus (manual)

🚧 Files skipped from review as they are similar to previous changes (1)

• src/health/mod.rs

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Walkthrough

Replaces parking_lot::RwLock with arc_swap::ArcSwap as the synchronization mechanism for SyncStatus throughout the codebase. The SyncStatus type alias changes from Arc<RwLock<SyncStatusReport>> to Arc<ArcSwap<SyncStatusReport>>, and all read/write callsites are updated to use load()/store() accordingly.

Changes

ArcSwap SyncStatus Migration

Layer / File(s)	Summary
SyncStatus type alias and test helpers src/chain_sync/sync_status.rs	Imports arc_swap::ArcSwap, drops parking_lot::RwLock, and changes the exported SyncStatus type alias from Arc<RwLock<SyncStatusReport>> to Arc<ArcSwap<SyncStatusReport>>. Adds test-only builder methods with_status() and with_current_head_epoch() on SyncStatusReport.
ChainFollower initialization and periodic update src/chain_sync/chain_follower.rs	Replaces RwLock import with ArcSwap; initializes sync_status via ArcSwap::from_pointee(SyncStatusReport::init()); updates the periodic refresh loop to use load()/shallow_clone()/store() instead of read()/write()/clone_from().
Consumer read callsites across services src/daemon/mod.rs, src/db/gc/snapshot.rs, src/health/endpoints.rs, src/rpc/methods/sync.rs, src/rpc/methods/eth.rs, src/tool/offline_server/server.rs, src/tool/subcommands/api_cmd/*	Replaces all .read() accesses on sync_status with .load() across the daemon cache warmup guard, GC scheduler, health endpoint checks (check_sync_status_synced, check_sync_status_not_error, check_epoch_up_to_date, check_f3_running), RPC sync/eth handlers, and offline server and snapshot tool initializations. Forest.SyncStatus RPC response type changes from SyncStatusReport to Arc<SyncStatusReport>.
Health endpoint test scaffolding updated for ArcSwap src/health/mod.rs	Replaces RwLock construction with ArcSwap::from_pointee in all health tests; replaces write()-based field mutation with store() calls using reconstructed SyncStatusReport values. Covers test_check_readyz, test_check_livez, test_check_healthz, and test_check_unknown_healthcheck_endpoint.
RPC sync test scaffolding and assertions src/rpc/methods/sync.rs	Updates test RPCState.sync_status initialization from Arc<RwLock<...>> to Default::default() with ArcSwap backing; updates sync_status_test assertions to compare via load().clone() and mutate via store() with reconstructed SyncStatusReport values.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• ChainSafe/forest#6165: Modifies GC scheduling logic in src/db/gc/snapshot.rs to gate on sync_status, the same file updated in this PR to switch from read() to load().

Suggested reviewers

• akaladarshi

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 52.17% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: replacing RwLock-based SyncStatus with ArcSwap across the codebase for concurrent atomic reference swapping.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[codecov]

Codecov Report

❌ Patch coverage is 91.39785% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.41%. Comparing base (9aa6f70) to head (ddb176a).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/chain_sync/chain_follower.rs	33.33%	2 Missing ⚠️
src/daemon/mod.rs	0.00%	1 Missing ⚠️
src/db/gc/snapshot.rs	0.00%	1 Missing ⚠️
src/health/endpoints.rs	75.00%	1 Missing ⚠️
src/rpc/methods/eth.rs	0.00%	1 Missing ⚠️
src/rpc/methods/sync.rs	92.85%	1 Missing ⚠️
...tool/subcommands/api_cmd/generate_test_snapshot.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/chain_sync/sync_status.rs	24.13% <100.00%> (+12.13%)	⬆️
src/health/mod.rs	95.76% <100.00%> (+0.81%)	⬆️
src/tool/offline_server/server.rs	27.23% <100.00%> (ø)
src/tool/subcommands/api_cmd/test_snapshot.rs	82.09% <100.00%> (ø)
src/daemon/mod.rs	24.74% <0.00%> (ø)
src/db/gc/snapshot.rs	0.00% <0.00%> (ø)
src/health/endpoints.rs	89.47% <75.00%> (ø)
src/rpc/methods/eth.rs	65.11% <0.00%> (+0.02%)	⬆️
src/rpc/methods/sync.rs	73.37% <92.85%> (+1.15%)	⬆️
...tool/subcommands/api_cmd/generate_test_snapshot.rs	7.00% <0.00%> (ø)
... and 1 more

... and 10 files with indirect coverage changes

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