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fix(utxo/sql): detect double-spend when competing txs share a batch slot#824

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sugh01 merged 1 commit into
bsv-blockchain:test/adversarial-double-spend-coveragefrom
sugh01:test/adversarial-double-spend-coverage-fix-ds-logic
May 7, 2026
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fix(utxo/sql): detect double-spend when competing txs share a batch slot#824
sugh01 merged 1 commit into
bsv-blockchain:test/adversarial-double-spend-coveragefrom
sugh01:test/adversarial-double-spend-coverage-fix-ds-logic

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@sugh01

@sugh01 sugh01 commented May 7, 2026

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github-actions Bot commented May 7, 2026 •
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🤖 Claude Code Review

Status: Complete

Summary:
The logic correctly detects double-spends when two competing transactions attempt to spend the same UTXO within a single batch. The implementation properly distinguishes between idempotent re-spends (same spending data) and actual double-spends (different spending data).

Key Changes:

  • Enhanced deduplication logic to check spending data, not just UTXO keys
  • Double-spend attempts are immediately rejected with UtxoSpentError
  • Idempotent duplicates continue to succeed as expected
  • First-arrival-wins policy is correctly enforced

Analysis:
The fix addresses a scenario where the old code would silently allow a double-spend if both competing transactions were processed in the same batch. The new code at sql.go:2041-2050 compares spending data and raises an error for the second transaction when data differs.

Observations:

  1. Logic correctness: Verified through multiple scenarios including edge cases with 3+ competing entries
  2. Error handling: Proper fallback to ProcessingError if spending data parse fails
  3. Success propagation: Line 2295 correctly uses bytes.Equal check to avoid marking double-spends as successful
  4. No tests added: The PR modifies critical double-spend detection logic but does not include new tests

Per AGENTS.md guidelines, tests should accompany changes to core validation logic, especially for security-critical paths like double-spend detection.

@sonarqubecloud

sonarqubecloud Bot commented May 7, 2026

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Quality Gate Failed Quality Gate failed

Failed conditions
61.1% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

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Benchmark Comparison Report

Baseline: main (unknown)

Current: PR-824 (595e0b2)

Summary

  • Regressions: 0
  • Improvements: 0
  • Unchanged: 142
  • Significance level: p < 0.05
All benchmark results (sec/op)
Benchmark Baseline Current Change p-value
_NewBlockFromBytes-4 1.695µ 1.959µ ~ 0.200
SplitSyncedParentMap_SetIfNotExists/256_buckets-4 61.87n 61.67n ~ 0.400
SplitSyncedParentMap_SetIfNotExists/16_buckets-4 61.68n 61.75n ~ 1.000
SplitSyncedParentMap_SetIfNotExists/1_bucket-4 61.73n 61.78n ~ 0.100
SplitSyncedParentMap_ConcurrentSetIfNotExists/256_buckets... 30.78n 30.70n ~ 1.000
SplitSyncedParentMap_ConcurrentSetIfNotExists/16_buckets_... 52.80n 50.82n ~ 0.100
SplitSyncedParentMap_ConcurrentSetIfNotExists/1_bucket_pa... 107.3n 107.1n ~ 0.700
MiningCandidate_Stringify_Short-4 263.6n 264.6n ~ 0.200
MiningCandidate_Stringify_Long-4 1.921µ 1.909µ ~ 0.100
MiningSolution_Stringify-4 981.4n 1003.0n ~ 0.100
BlockInfo_MarshalJSON-4 1.770µ 1.774µ ~ 0.400
NewFromBytes-4 127.7n 127.3n ~ 0.400
Mine_EasyDifficulty-4 61.28µ 61.19µ ~ 0.400
Mine_WithAddress-4 7.152µ 7.118µ ~ 0.700
BlockAssembler_AddTx-4 0.02714n 0.02913n ~ 0.700
AddNode-4 10.81 10.91 ~ 0.700
AddNodeWithMap-4 11.34 11.20 ~ 1.000
DiskTxMap_SetIfNotExists-4 3.410µ 3.432µ ~ 1.000
DiskTxMap_SetIfNotExists_Parallel-4 3.235µ 3.323µ ~ 1.000
DiskTxMap_ExistenceOnly-4 296.2n 284.8n ~ 0.100
Queue-4 192.1n 190.9n ~ 0.100
AtomicPointer-4 4.502n 4.909n ~ 0.700
ReorgOptimizations/DedupFilterPipeline/Old/10K-4 858.6µ 839.2µ ~ 0.100
ReorgOptimizations/DedupFilterPipeline/New/10K-4 845.7µ 799.8µ ~ 0.100
ReorgOptimizations/AllMarkFalse/Old/10K-4 109.0µ 102.9µ ~ 0.100
ReorgOptimizations/AllMarkFalse/New/10K-4 61.64µ 61.73µ ~ 0.700
ReorgOptimizations/HashSlicePool/Old/10K-4 61.20µ 68.43µ ~ 0.200
ReorgOptimizations/HashSlicePool/New/10K-4 11.31µ 11.42µ ~ 0.700
ReorgOptimizations/NodeFlags/Old/10K-4 5.114µ 5.520µ ~ 0.200
ReorgOptimizations/NodeFlags/New/10K-4 1.830µ 1.773µ ~ 1.000
ReorgOptimizations/DedupFilterPipeline/Old/100K-4 9.347m 9.186m ~ 1.000
ReorgOptimizations/DedupFilterPipeline/New/100K-4 9.232m 9.030m ~ 0.100
ReorgOptimizations/AllMarkFalse/Old/100K-4 1.071m 1.137m ~ 0.200
ReorgOptimizations/AllMarkFalse/New/100K-4 673.8µ 675.9µ ~ 0.700
ReorgOptimizations/HashSlicePool/Old/100K-4 596.5µ 624.5µ ~ 0.100
ReorgOptimizations/HashSlicePool/New/100K-4 313.1µ 313.7µ ~ 0.700
ReorgOptimizations/NodeFlags/Old/100K-4 51.40µ 54.49µ ~ 0.200
ReorgOptimizations/NodeFlags/New/100K-4 18.95µ 19.24µ ~ 0.400
TxMapSetIfNotExists-4 50.70n 51.15n ~ 0.200
TxMapSetIfNotExistsDuplicate-4 38.03n 37.94n ~ 0.700
ChannelSendReceive-4 583.3n 615.1n ~ 0.100
DirectSubtreeAdd/4_per_subtree-4 78.50n 78.27n ~ 1.000
DirectSubtreeAdd/64_per_subtree-4 43.18n 42.78n ~ 0.100
DirectSubtreeAdd/256_per_subtree-4 41.65n 41.53n ~ 0.700
DirectSubtreeAdd/1024_per_subtree-4 40.75n 40.02n ~ 0.100
DirectSubtreeAdd/2048_per_subtree-4 39.87n 40.11n ~ 0.400
SubtreeProcessorAdd/4_per_subtree-4 350.2n 351.3n ~ 1.000
SubtreeProcessorAdd/64_per_subtree-4 327.7n 342.5n ~ 0.100
SubtreeProcessorAdd/256_per_subtree-4 328.7n 332.5n ~ 0.700
SubtreeProcessorAdd/1024_per_subtree-4 323.9n 337.5n ~ 0.100
SubtreeProcessorAdd/2048_per_subtree-4 327.5n 332.9n ~ 0.400
SubtreeProcessorRotate/4_per_subtree-4 328.8n 344.0n ~ 0.200
SubtreeProcessorRotate/64_per_subtree-4 326.6n 340.1n ~ 0.100
SubtreeProcessorRotate/256_per_subtree-4 323.9n 338.8n ~ 0.100
SubtreeProcessorRotate/1024_per_subtree-4 329.8n 340.7n ~ 0.100
SubtreeNodeAddOnly/4_per_subtree-4 90.92n 92.63n ~ 0.400
SubtreeNodeAddOnly/64_per_subtree-4 66.56n 67.26n ~ 0.400
SubtreeNodeAddOnly/256_per_subtree-4 65.92n 66.36n ~ 0.100
SubtreeNodeAddOnly/1024_per_subtree-4 65.46n 65.36n ~ 0.500
SubtreeCreationOnly/4_per_subtree-4 174.0n 161.7n ~ 0.100
SubtreeCreationOnly/64_per_subtree-4 790.5n 627.0n ~ 0.100
SubtreeCreationOnly/256_per_subtree-4 2.854µ 2.246µ ~ 0.100
SubtreeCreationOnly/1024_per_subtree-4 8.583µ 6.735µ ~ 0.100
SubtreeCreationOnly/2048_per_subtree-4 14.91µ 12.86µ ~ 0.100
SubtreeProcessorOverheadBreakdown/64_per_subtree-4 348.0n 330.2n ~ 0.400
SubtreeProcessorOverheadBreakdown/1024_per_subtree-4 327.3n 330.5n ~ 1.000
ParallelGetAndSetIfNotExists/1k_nodes-4 701.8µ 685.3µ ~ 0.100
ParallelGetAndSetIfNotExists/10k_nodes-4 1.900m 1.855m ~ 0.700
ParallelGetAndSetIfNotExists/50k_nodes-4 10.003m 9.437m ~ 0.100
ParallelGetAndSetIfNotExists/100k_nodes-4 19.26m 18.79m ~ 0.400
SequentialGetAndSetIfNotExists/1k_nodes-4 725.1µ 722.7µ ~ 1.000
SequentialGetAndSetIfNotExists/10k_nodes-4 3.731m 3.590m ~ 0.400
SequentialGetAndSetIfNotExists/50k_nodes-4 12.81m 13.00m ~ 1.000
SequentialGetAndSetIfNotExists/100k_nodes-4 24.55m 24.90m ~ 0.400
ProcessOwnBlockSubtreeNodesParallel/1k_nodes-4 764.4µ 782.9µ ~ 0.700
ProcessOwnBlockSubtreeNodesParallel/10k_nodes-4 4.842m 5.021m ~ 0.200
ProcessOwnBlockSubtreeNodesParallel/100k_nodes-4 22.18m 22.52m ~ 0.700
ProcessOwnBlockSubtreeNodesSequential/1k_nodes-4 894.7µ 786.5µ ~ 0.100
ProcessOwnBlockSubtreeNodesSequential/10k_nodes-4 6.827m 7.423m ~ 0.100
ProcessOwnBlockSubtreeNodesSequential/100k_nodes-4 48.31m 51.21m ~ 0.200
CalcBlockWork-4 566.2n 526.8n ~ 0.700
CalculateWork-4 702.0n 709.2n ~ 0.700
BuildBlockLocatorString_Helpers/Size_10-4 1.318µ 1.303µ ~ 0.200
BuildBlockLocatorString_Helpers/Size_100-4 12.59µ 12.60µ ~ 0.700
BuildBlockLocatorString_Helpers/Size_1000-4 132.6µ 126.3µ ~ 1.000
CatchupWithHeaderCache-4 104.3m 104.3m ~ 1.000
_prepareTxsPerLevel-4 414.9m 414.4m ~ 1.000
_prepareTxsPerLevelOrdered-4 3.687m 3.806m ~ 0.700
_prepareTxsPerLevel_Comparison/Original-4 418.8m 419.5m ~ 0.400
_prepareTxsPerLevel_Comparison/Optimized-4 3.616m 3.770m ~ 0.100
SubtreeSizes/10k_tx_4_per_subtree-4 1.363m 1.413m ~ 0.200
SubtreeSizes/10k_tx_16_per_subtree-4 326.9µ 330.7µ ~ 1.000
SubtreeSizes/10k_tx_64_per_subtree-4 77.27µ 78.46µ ~ 0.100
SubtreeSizes/10k_tx_256_per_subtree-4 19.33µ 19.65µ ~ 0.100
SubtreeSizes/10k_tx_512_per_subtree-4 9.564µ 9.717µ ~ 0.100
SubtreeSizes/10k_tx_1024_per_subtree-4 4.781µ 4.807µ ~ 0.400
SubtreeSizes/10k_tx_2k_per_subtree-4 2.378µ 2.396µ ~ 0.100
BlockSizeScaling/10k_tx_64_per_subtree-4 76.23µ 76.35µ ~ 0.400
BlockSizeScaling/10k_tx_256_per_subtree-4 19.12µ 19.01µ ~ 0.100
BlockSizeScaling/10k_tx_1024_per_subtree-4 4.723µ 4.765µ ~ 1.000
BlockSizeScaling/50k_tx_64_per_subtree-4 393.6µ 400.1µ ~ 0.700
BlockSizeScaling/50k_tx_256_per_subtree-4 93.99µ 95.11µ ~ 0.200
BlockSizeScaling/50k_tx_1024_per_subtree-4 23.50µ 23.69µ ~ 0.100
SubtreeAllocations/small_subtrees_exists_check-4 167.6µ 160.9µ ~ 0.200
SubtreeAllocations/small_subtrees_data_fetch-4 167.1µ 170.4µ ~ 0.700
SubtreeAllocations/small_subtrees_full_validation-4 333.4µ 329.1µ ~ 0.200
SubtreeAllocations/medium_subtrees_exists_check-4 9.491µ 9.399µ ~ 0.200
SubtreeAllocations/medium_subtrees_data_fetch-4 9.906µ 9.965µ ~ 1.000
SubtreeAllocations/medium_subtrees_full_validation-4 19.17µ 19.46µ ~ 0.100
SubtreeAllocations/large_subtrees_exists_check-4 2.270µ 2.259µ ~ 0.500
SubtreeAllocations/large_subtrees_data_fetch-4 2.399µ 2.400µ ~ 0.700
SubtreeAllocations/large_subtrees_full_validation-4 4.820µ 4.854µ ~ 0.100
_BufferPoolAllocation/16KB-4 2.496µ 2.346µ ~ 0.100
_BufferPoolAllocation/32KB-4 4.956µ 5.905µ ~ 0.100
_BufferPoolAllocation/64KB-4 12.15µ 11.90µ ~ 0.700
_BufferPoolAllocation/128KB-4 21.77µ 23.32µ ~ 0.100
_BufferPoolAllocation/512KB-4 90.26µ 81.59µ ~ 0.100
_BufferPoolConcurrent/32KB-4 13.97µ 12.13µ ~ 0.100
_BufferPoolConcurrent/64KB-4 21.40µ 19.50µ ~ 0.100
_BufferPoolConcurrent/512KB-4 109.6µ 106.4µ ~ 0.200
_SubtreeDeserializationWithBufferSizes/16KB-4 506.4µ 491.6µ ~ 0.700
_SubtreeDeserializationWithBufferSizes/32KB-4 507.1µ 479.4µ ~ 0.200
_SubtreeDeserializationWithBufferSizes/64KB-4 518.5µ 490.0µ ~ 0.100
_SubtreeDeserializationWithBufferSizes/128KB-4 514.1µ 484.3µ ~ 0.100
_SubtreeDeserializationWithBufferSizes/512KB-4 510.0µ 483.6µ ~ 0.100
_SubtreeDataDeserializationWithBufferSizes/16KB-4 28.31m 28.71m ~ 0.700
_SubtreeDataDeserializationWithBufferSizes/32KB-4 28.25m 27.50m ~ 0.100
_SubtreeDataDeserializationWithBufferSizes/64KB-4 27.89m 27.47m ~ 0.700
_SubtreeDataDeserializationWithBufferSizes/128KB-4 28.20m 27.59m ~ 0.100
_SubtreeDataDeserializationWithBufferSizes/512KB-4 28.27m 27.61m ~ 0.700
_PooledVsNonPooled/Pooled-4 645.2n 647.8n ~ 0.600
_PooledVsNonPooled/NonPooled-4 4.707µ 4.900µ ~ 1.000
_MemoryFootprint/Current_512KB_32concurrent-4 5.769µ 5.623µ ~ 0.200
_MemoryFootprint/Proposed_32KB_32concurrent-4 7.809µ 7.219µ ~ 0.200
_MemoryFootprint/Alternative_64KB_32concurrent-4 7.419µ 7.187µ ~ 0.200
StoreBlock_Sequential/BelowCSVHeight-4 333.3µ 337.0µ ~ 0.400
StoreBlock_Sequential/AboveCSVHeight-4 343.0µ 334.4µ ~ 0.700
GetUtxoHashes-4 255.9n 255.4n ~ 0.400
GetUtxoHashes_ManyOutputs-4 43.58µ 44.97µ ~ 0.400
_NewMetaDataFromBytes-4 240.3n 240.2n ~ 0.600
_Bytes-4 619.5n 625.6n ~ 0.200
_MetaBytes-4 561.7n 567.6n ~ 0.700

Threshold: >10% with p < 0.05 | Generated: 2026-05-07 09:11 UTC

@sugh01 sugh01 merged commit a06974a into bsv-blockchain:test/adversarial-double-spend-coverage May 7, 2026
25 checks passed
@sugh01 sugh01 deleted the test/adversarial-double-spend-coverage-fix-ds-logic branch May 7, 2026 11:01
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