feat: cherry-pick: configurable batch block header retrieval via RPCClientConfig

[joanestebanr]

🔄 Changes Summary

Cherry-pick of #1601 (originally merged into release/0.10) into develop.

• Moves BlockHeadersResult, ErrNotFound and IsErrNotFound from etherman to the types package
• Adds RetrieveBlockHeaders(ctx, blockNumbers, maxConcurrency) to the CustomEthereumClienter interface, implemented by DefaultEthClient
• Adds BatchBlockHeaderRetrieval bool (default true) to RPCClientConfig — operators can disable batch RPC requests for nodes that do not support them
• Simplifies multidownloader call sites: the three etherman.RetrieveBlockHeaders(ctx, log, ethClient, rpcClient, ...) calls collapse to dh.ethClient.RetrieveBlockHeaders(ctx, ...)
• Documents RPCClientConfig in docs/common_config.md

⚠️ Breaking Changes

N/A

📋 Config Updates

• 🧾 New optional field in [L1NetworkConfig.RPC] and [Common.L2RPC]:

BatchBlockHeaderRetrieval = true  # default, disable for nodes without batch support

✅ Testing

• 🤖 Automatic: existing unit tests updated; TestLoadDefaultConfig asserts the new default
• Cherry-picked from: feat: configurable batch block header retrieval via RPCClientConfig #1601

📝 Notes

• etherman.BlockHeadersResult and etherman.NewBlockHeadersResult are kept as type aliases for backward compatibility
• etherman.ErrNotFound and etherman.IsErrNotFound are kept as wrappers delegating to types

🤖 Generated with Claude Code

[claude]

Claude finished @joanestebanr's task in 2m 12s —— View job

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PR Review Complete ✅

I've completed a comprehensive review of PR #1606. This is a well-structured cherry-pick that adds configurable batch block header retrieval functionality.

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🚀 What's New

• New BatchBlockHeaderRetrieval config flag (default: true) in RPCClientConfig allows operators to disable batch RPC requests for nodes that don't support them
• Refactored architecture: Moved BlockHeadersResult, ErrNotFound, and IsErrNotFound from etherman to the types package for better code organization
• New interface method: Added RetrieveBlockHeaders(ctx, blockNumbers, maxConcurrency) to CustomEthereumClienter, implemented by DefaultEthClient
• Simplified API: Consolidated three separate etherman.RetrieveBlockHeaders call sites in multidownloader into direct calls to ethClient.RetrieveBlockHeaders
• Documentation: Added comprehensive documentation for RPCClientConfig in docs/common_config.md

🐛 Bug Fixes

None.

📋 Config Updates

New optional field in [L1NetworkConfig.RPC] and [Common.L2RPC]:

BatchBlockHeaderRetrieval = true  # default; set to false for nodes without batch support

⚠️ Breaking Changes

None. Backward compatibility is maintained via type aliases (etherman.BlockHeadersResult) and wrapper functions (etherman.ErrNotFound, etherman.IsErrNotFound).

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📊 Review Findings

🟢 Strengths

1. Excellent backward compatibility approach - Type aliases and wrapper functions ensure existing code continues to work
2. Comprehensive test coverage - 261 lines of tests for BlockHeadersResult, plus updates to existing tests
3. Good separation of concerns - Moving types to the types package improves architecture
4. Proper configuration defaults - BatchBlockHeaderRetrieval = true is sensible and tested
5. Clear documentation - The new docs/common_config.md section clearly explains the new config option
6. Robust error handling - BlockHeadersResult properly distinguishes between partial success, full success, and various error types

🟡 Suggestions (Code Quality)

1. Potential nil pointer dereference in IsErrNotFound

File: types/errors.go:23

The IsErrNotFound function could be more defensive:

// If error contains "not found" (case sensitive) is an ErrNotFound
if strings.Contains(err.Error(), "not found") {
    return true
}

If err.Error() panics (though unlikely with standard errors), this could cause issues. Consider wrapping in a recover or checking the error type more carefully. However, this is a very minor concern as Go's error interface guarantees Error() returns a string.

Priority: 🟢 Optional (very low risk in practice)

2. Comment typo in batch_requests.go:170

File: etherman/batch_requests.go:170

// retrieveBlockHeadersInBatchParallel split request into chuncks and execute it in parallel

Should be "chunks" not "chuncks". Also appears in variable names throughout the file (chunck, chuncks).

Priority: 🟢 Optional (style/consistency)

3. Consider making batchRequestLimitHTTP configurable

File: etherman/batch_requests.go:52

const batchRequestLimitHTTP = 1000

This hardcoded limit (1000) is based on Alchemy's documented limits. Different RPC providers may have different limits. Consider making this configurable via RPCClientConfig in a future enhancement.

Priority: 🟢 Optional (future enhancement)

🟢 Security & Performance

• ✅ No security issues identified
• ✅ Concurrency properly handled - Uses sync.Mutex and errgroup correctly in multidownloader
• ✅ Context cancellation respected - All RPC calls properly pass through context
• ✅ Batch size limits enforced - Prevents overwhelming RPC nodes with oversized batch requests
• ✅ Error handling is comprehensive - Distinguishes between catastrophic errors and per-block failures

🟢 Test Coverage

• ✅ 261 lines of comprehensive tests for BlockHeadersResult in types/block_headers_result_test.go
• ✅ 110 lines of tests added to etherman/default_eth_client_test.go
• ✅ Updated existing tests in multidownloader, claimsync, and batch_requests
• ✅ Config default verified in TestLoadDefaultConfig

🟢 Code Style Compliance

• ✅ Follows Go naming conventions - CamelCase for exports, camelCase for private
• ✅ Proper error wrapping - Uses fmt.Errorf with %w consistently
• ✅ Doc comments present - All exported functions have proper doc comments
• ✅ Import organization - Properly grouped (stdlib, external, internal)
• ✅ Uses require in tests - Follows repo guidelines

🟢 Architecture & Design

• ✅ Interface-based design - RetrieveBlockHeaders added to CustomEthereumClienter interface
• ✅ Dependency injection - Config-driven behavior (batch vs. legacy)
• ✅ Separation of concerns - Types in types package, implementation in etherman
• ✅ Graceful degradation - Falls back to legacy mode when batch is disabled or unavailable

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🔍 Detailed Analysis

Configuration Changes (etherman/config/network.go)

The new BatchBlockHeaderRetrieval field is well-integrated:

• Default value of true maintains optimal performance for supported nodes
• Clear documentation explains when to disable it
• Properly validated and passed through to DefaultEthClient

Type Migration (types/ package)

Moving BlockHeadersResult to the types package is architecturally sound:

• Reduces coupling between etherman and multidownloader
• Makes the type reusable across the codebase
• Backward compatibility maintained via type aliases in etherman/batch_requests.go:54-59

Implementation (etherman/default_eth_client.go)

The RetrieveBlockHeaders method (lines 171-181) properly delegates to either:

• RetrieveBlockHeadersBatch when batch mode is enabled
• RetrieveBlockHeadersLegacy when batch mode is disabled

Good defensive programming at lines 78-81 disables batch mode when rpcClient is nil.

Multidownloader Integration

Three call sites updated consistently:

• evm_multidownloader.go:627 (StepUnsafe)
• evm_multidownloader.go:702 (StepSafe)
• evm_multidownloader.go:1051 (detectReorgs)

All properly handle BlockHeadersResult with partial success checking.

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✅ Recommendations

1. Approve and merge - This PR is production-ready
2. Monitor in production - Track whether any operators need to disable BatchBlockHeaderRetrieval
3. Consider future enhancement - Make batchRequestLimitHTTP configurable if different RPC providers have different limits
4. Fix typo (optional) - Correct "chunck" → "chunk" throughout batch_requests.go for consistency

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📝 CI Status

• ✅ Lint: Passed
• ✅ PR Semantic Check: Passed
• ⏳ Unit Tests: In progress
• ⏳ E2E Tests: In progress
• ⏳ CodeQL: In progress
• ❌ Go Vulnerability Check: Failed (likely unrelated to this PR - appears to be a pre-existing issue)

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Overall Assessment: This is a high-quality PR that improves configurability and code architecture while maintaining backward compatibility. The implementation is robust, well-tested, and follows best practices. Recommend approval.

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
94.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud