feat: add granular tracing

[chatton]

Description

Utilizing the #[instrument] macro to get more granular tracing. Added tests which verify the spans are being collected.

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)
• Documentation update
• Performance improvement
• Refactoring

Related Issues

Fixes #137

Checklist

• 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
• Any dependent changes have been merged and published

Testing

Additional Notes

Here's a sample of the spans putting it into one of our docker tests

  ┌──────────────────────┬───────┬───────┐
  │         Span         │ Count │  Avg  │
  ├──────────────────────┼───────┼───────┤
  │ storage worker       │ 2,448 │ 5.1ms │
  ├──────────────────────┼───────┼───────┤
  │ account worker       │ 2,448 │ 4.6ms │
  ├──────────────────────┼───────┼───────┤
  │ try_build            │ 354   │ 3.9ms │
  ├──────────────────────┼───────┼───────┤
  │ build_payload        │ 354   │ 3.8ms │
  ├──────────────────────┼───────┼───────┤
  │ execute_tx           │ 1,053 │ 925µs │
  ├──────────────────────┼───────┼───────┤
  │ validate_transaction │ 1,318 │ 41µs  │
  ├──────────────────────┼───────┼───────┤
  │ on_new_payload       │ 271   │ 4.4ms │
  ├──────────────────────┼───────┼───────┤
  │ execute_block        │ 272   │ 3.2ms │
  └──────────────────────┴───────┴───────┘

[claude]

Claude finished @chatton's task —— View job

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Code Review: Granular Tracing Implementation ✅

I've completed a comprehensive review of this PR that adds granular tracing to the ev-reth codebase. Overall, this is a well-implemented feature that adds valuable observability without compromising performance or security.

Todo List:

• Read and analyze all changed files
• Review code quality and Rust best practices
• Check for potential bugs or issues
• Evaluate performance considerations
• Assess security concerns
• Review test coverage and effectiveness
• Provide comprehensive feedback and recommendations

---

✅ Code Quality & Best Practices

Excellent implementation with proper Rust patterns:

• Appropriate use of #[instrument] macro from the tracing crate
• Consistent field naming (duration_ms, tx_count, payload_id, etc.)
• Good use of tracing::field::Empty for delayed field recording
• Proper span lifecycle management with tracing::Span::current().record()

Well-structured tracing architecture:

• Strategic placement of instrumentation on critical paths
• Clean separation between span creation and field recording
• Consistent instrumentation patterns across all modules

✅ Performance Considerations

Minimal overhead implementation:

• Uses std::time::Instant::now() only when necessary
• Lazy field evaluation prevents performance impact when tracing is disabled
• Strategic field selection (hash, transaction count, gas metrics)
• No blocking operations introduced

Efficient span management:

• Proper use of span enter/exit patterns in builder.rs:152-158
• Duration recording at span completion prevents timing inaccuracies

✅ Security Assessment

No security concerns identified:

• No exposure of sensitive data in trace fields
• Appropriate use of display formatters (% vs ?) for different field types
• No credential or private key exposure risks

✅ Test Coverage

Comprehensive test strategy:

• New test utility: test_utils.rs provides SpanCollector for validation
• Field verification tests: All instrumented functions have corresponding tests
• Integration coverage: Tests verify both span creation and field population
• Specific test cases:
  • crates/node/src/builder.rs:247-317 - Tests build_payload span fields
  • crates/node/src/builder.rs:320-401 - Tests execute_tx span fields
  • crates/node/src/payload_service.rs:302-388 - Tests try_build span fields
  • crates/node/src/txpool.rs:769-798 - Tests validate_transaction span fields
  • crates/node/src/validator.rs:293-367 - Tests ensure_well_formed_payload span fields

🔍 Minor Issues & Suggestions

1. Bug in Balance Validation (crates/node/src/txpool.rs:436-444)

// Current code has logical issue:
let EvTxEnvelope::EvNode(tx) = consensus else {
    if sender_balance < *pooled.cost() {
        return Err(InvalidPoolTransactionError::Overdraft { cost: *pooled.cost(), balance: sender_balance });
    }
    return Ok(()); // Early return for non-EvNode transactions
};

Issue: The balance check for non-EvNode transactions occurs in the wrong branch. The failing test non_sponsored_evnode_rejects_insufficient_balance at line 708 indicates non-sponsored EvNode transactions don't get proper balance validation.

Recommendation: Move the balance validation logic after the pattern match to ensure all transaction types are properly validated.

2. Error Message Fragility (crates/node/src/validator.rs:248-257)

const UNKNOWN_TX_TYPE_ERROR_MSG: &str = "unexpected tx type";

fn is_unknown_tx_type_error(err: &alloy_rpc_types::engine::PayloadError) -> bool {
    matches!(err, alloy_rpc_types::engine::PayloadError::Decode(_))
        && err.to_string().contains(UNKNOWN_TX_TYPE_ERROR_MSG)
}

Issue: String matching for error detection is fragile and could break with upstream changes.

Recommendation: Consider adding more robust error pattern matching or upstream contribution to add proper error variants.

3. Test Organization

The test utilities are well-designed, but consider extracting the SpanCollector to a shared test crate if tracing tests expand across more modules.

📊 Key Metrics Tracked

The implementation captures essential observability metrics:

• Performance: duration_ms for all critical operations
• Transaction Processing: tx_count, tx_hash, nonce, gas_limit
• Block Operations: block_number, block_hash, parent_hash
• Validation: payload_id, transaction origin tracking

🎯 Overall Assessment

This is a high-quality implementation that:

• ✅ Adds valuable observability without performance impact
• ✅ Follows Rust and tracing best practices
• ✅ Includes comprehensive test coverage
• ✅ Maintains code clarity and consistency
• ✅ Properly handles async contexts with instrumentation

The PR successfully addresses issue #137 and significantly improves the observability of the ev-reth execution flow.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch cian/add-granular-tracing

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