Fix data race on finality checkpoint - #84
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damilolaedwards wants to merge 1 commit into
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FetchFinality wrote to n.finality without holding a lock while Finality() read it directly. The epoch cron, the finalized checkpoint event handler, and any consumer calling FetchFinality could all run this concurrently. Added finalityMu and guarded both the read compare write in FetchFinality and the read in Finality(), the same pattern already used for spec and genesis.
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Summary
FetchFinality wrote to n.finality without holding a lock, while Finality() read it directly with no synchronization. The epoch cron, the finalized_checkpoint event handler, and any consumer calling FetchFinality directly can all run this concurrently, which is a real data race, not just staleness: a reader can observe a partially published Finality struct.
Fix adds a finalityMu RWMutex and guards the read-compare-write in FetchFinality and the read in Finality(), matching the existing pattern already used for spec and genesis.
Test plan