fix(rust_brain): preserve HLC on snapshot restore and gossip replay - #71
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v0.6.0 added HybridLogicalClock enforcement but restore_from_file(), bulk_write(), and gossip.receive() did not round-trip HLC timestamps. After disaster-recovery restore, nodes received fresh HLC values, causing TimestampRegression on valid causal successor writes and silent rejection of gossiped updates. - Add _parse_hlc() for snapshot/wire normalisation with legacy fallback - restore_from_file: restore hlc, update global clock, hold lock - bulk_write: pass hlc from row payloads - gossip.receive: apply hlc, reject stale overwrites, skip missing-hlc updates - Add regression tests for restore round-trip and gossip ordering Co-authored-by: Daniel <DJLougen@users.noreply.github.com>
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Bug and impact
v0.6.0 added Hybrid Logical Clock (HLC) enforcement on
RustBrain.remember(), but three code paths did not round-trip HLC timestamps:restore_from_file()— restored nodes got fresh HLC values instead of snapshot valuesbulk_write()— ignoredhlcin row payloadsgossip.receive()— applied gossip events without HLC, causing silent rejection or stale overwritesConcrete trigger: After disaster-recovery snapshot restore, a valid causal successor write (e.g.
hlc=(5000, 11, 'nodeA')after restored(5000, 10, 'nodeA')) raisedTimestampRegressionbecause restore assigned a fresh wall-clock HLC. Gossiped updates with correct causal ordering were similarly rejected or could overwrite newer local state.Impact: Silent data loss after backup restore and broken cross-node memory sync in distributed deployments.
Root cause
MemoryNode.to_dict()serialises HLC, but restore/gossip/bulk paths never read it back. The global_hlcclock was not advanced during restore, so monotonic enforcement compared against wrong timestamps.Fix
_parse_hlc()for snapshot/wire normalisation with legacy fallbackrestore_from_file: restorehlc, update global clock via_hlc.update(), hold lock during restorebulk_write: passhlcfrom row payloadsgossip.receive: applyhlc, reject stale overwrites, skip missing-hlc updates on existing keysValidation
pytest tests/test_hlc_snapshot_gossip.py tests/test_enterprise_backup.py— 13 passed