Cache process const strings

[LesnyRumcajs]

Summary of changes

On top of #6951
This marginally improves the performance (~0.02ms for eth_chainId). Not a huge win from latency perspective, but should save some CPU cycles.

Changes introduced in this pull request:

• cache process-immutable strings

Reference issue to close (if applicable)

Closes

Other information and links

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.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• Performance

  • RPC responses (client/version, chain ID, network name, net version) now return cached shared string values to reduce allocations and improve latency.

• Refactor

  • Added dedicated handling for shared-string JSON values; conversions are now identity-like and test snapshot behavior adjusted (test override left unimplemented).

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 57521d19-55df-4d47-86ed-a3cf183f7939

📥 Commits

Reviewing files that changed from the base of the PR and between c0793f0 and 599616a.

📒 Files selected for processing (1)

• src/rpc/methods/eth.rs

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Walkthrough

Adds a specialized HasLotusJson impl for Arc<str> (identity conversions and unimplemented snapshots) and changes multiple RPC response types from String to Arc<str>, introducing process-wide OnceLock<Arc<str>> caches returned by handlers instead of per-request string allocations.

Changes

Cohort / File(s)	Summary
Lotus JSON Trait Implementation src/lotus_json/arc.rs	Add impl HasLotusJson for Arc<str> with type LotusJson = Self; into_lotus_json/from_lotus_json are identity conversions; test-only snapshots() is unimplemented!.
RPC: eth methods src/rpc/methods/eth.rs	Web3ClientVersion and EthChainId: change type Ok from String → Arc<str>; use static OnceLock<Arc<str>> to cache computed values and clone per call; added OnceLock import.
RPC: f3 methods src/rpc/methods/f3.rs	GetRawNetworkName: change type Ok from String → Arc<str> and return a cloned Arc<str> from a static OnceLock<Arc<str>> initialized once.
RPC: net methods src/rpc/methods/net.rs	NetVersion: change type Ok from String → Arc<str>; use a static OnceLock<Arc<str>> to cache the decimal representation and return clones thereafter.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant RPC_Handler as "RPC Method"
    participant ChainConfig
    participant Cache as "OnceLock<Arc<str>>"

    Client->>RPC_Handler: invoke method (e.g., NetVersion)
    RPC_Handler->>Cache: check initialized?
    alt cached
        Cache-->>RPC_Handler: clone Arc<str>
    else not cached
        RPC_Handler->>ChainConfig: read value (e.g., eth_chain_id / genesis_name)
        ChainConfig-->>RPC_Handler: value
        RPC_Handler->>Cache: initialize with Arc<str>
        Cache-->>RPC_Handler: clone Arc<str>
    end
    RPC_Handler-->>Client: return Arc<str>

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix(rpc): avoid unecessarily cloning Tipset #6227: Related — previously added a generic Arc<T> HasLotusJson impl that this PR overrides for Arc<str>.

Suggested labels

RPC

Suggested reviewers

• sudo-shashank
• hanabi1224

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 12.50% 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 'Cache process const strings' directly and clearly describes the main objective of the pull request, which implements caching of process-immutable constant strings across multiple RPC methods.
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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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch cache-process-const-strings

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch cache-process-const-strings

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[codecov]

Codecov Report

❌ Patch coverage is 24.00000% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.06%. Comparing base (b4dd6a2) to head (599616a).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/rpc/methods/eth.rs	33.33%	6 Missing ⚠️
src/lotus_json/arc.rs	37.50%	5 Missing ⚠️
src/rpc/methods/f3.rs	0.00%	5 Missing ⚠️
src/rpc/methods/net.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/rpc/methods/net.rs	0.00% <0.00%> (ø)
src/lotus_json/arc.rs	15.00% <37.50%> (+15.00%)	⬆️
src/rpc/methods/f3.rs	0.00% <0.00%> (ø)
src/rpc/methods/eth.rs	65.24% <33.33%> (-0.03%)	⬇️

... and 7 files with indirect coverage changes

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