perf(sqlite-native): gate kv operation labels

[NathanFlurry]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[NathanFlurry]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• chore(engine): publish engine bases in ci #4649 : 3 dependent PRs (#4650 , #4652 , #4654 )
• chore: lockfile lefthook #4647
• fix(rivetkit): surface native sqlite kv errors to callers #4645
• fix(rivetkit): prevent sleep races during disconnect and db work #4644
• fix(rivetkit): isolate engine envoys and propagate startup failures #4643
• test(rivetkit): remove wasm sqlite-only fixtures and coverage #4642
• chore(sqlite-vfs): remove wasm sqlite packages and workspace wiring #4641
• chore(rivetkit): remove wasm sqlite runtime #4614
• fix(sqlite-native): restore native startup kv preload #4639
• fix(sqlite-native): delete metadata before chunk range #4638
• fix(sqlite-native): keep truncate cache coherent #4637
• fix(sqlite-vfs): use delete range for truncate cleanup #4636
• fix(sqlite-native): restore kv error hook #4635
• perf(sqlite-native): avoid cloning cached read chunks #4634
• perf(sqlite-native): gate kv operation labels #4633 👈 (View in Graphite)
• perf(sqlite-native): reuse read cache for partial writes #4632
• perf(sqlite-native): remove delete file existence probe #4631
• fix(sqlite-native): gate native read cache behind env var #4630
• fix(pegboard): isolate runner config dc lookup failures #4625 : 1 other dependent PR (#4626 )
• docs(pegboard): note runner config upsert split write risk #4624
• fix(pegboard): unpack global runner config keys correctly #4623
• fix(pegboard-gateway): enforce tunnel message state #4622
• fix(pegboard-runner): clear terminal tunnel routes #4621
• fix(pegboard): skip protocol version keys in runner pool backfill #4620
• fix(pegboard): create missing normal runner configs #4619
• fix(epoxy): reuse cached optimistic value #4618
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[claude]

PR Review: perf(sqlite-native): gate kv operation labels

Overview

This PR removes hot-path overhead in the native SQLite VFS by:

1. Eliminating per-KV-operation std::env::var("RIVET_TRACE_SQL") checks
2. Replacing eager format!() allocations with lazy format_args!() in tracing calls
3. Minor code style reformatting

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Code Quality

Positives:

• Removing eprintln! in favor of tracing::debug! is the correct approach and aligns with the CLAUDE.md convention: "Never use eprintln! or println! for logging in Rust code."
• The format_args!() swap is the idiomatic Rust pattern for lazy formatting inside tracing macros. When debug level is disabled (as in production), no heap allocation occurs.
• key_count is correctly extracted before moving keys into the async call, ensuring borrow safety.

Minor style note:

• The op label format (e.g. get(3keys)) lacks a space — get(3 keys) would be more readable. This was present in the original code too so it is consistent, but worth considering as optional polish.

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Performance Analysis

std::env::var removal (main win): std::env::var acquires a lock on the environment and is non-trivial, especially under thread contention. It was being called on every kv_get, kv_put, kv_delete, and kv_delete_range — all of which sit on the hot VFS path. Removing these checks is a meaningful improvement.

format! → format_args!: format!() always allocates a String on the heap. Since tracing::debug! is gated by the active log level, those allocations were pure waste in production. The lazy format_args! approach defers formatting until the event is actually consumed.

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Potential Issues

• Loss of RIVET_TRACE_SQL facility: Developers who relied on RIVET_TRACE_SQL=1 as a lightweight local debug knob (without a full tracing subscriber) will need to switch to a RUST_LOG=sqlite_native=debug filter instead. The env var does not appear to be documented publicly, so the impact should be minimal. A brief note in a dev doc or commit message would help if anyone relied on it.
• No behavioral changes are introduced; all KV operation semantics remain identical.

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Verdict

Clean, focused performance optimization. The changes are correct, align with project conventions, and address real overhead in the hot VFS path. Approved.