The gateway can lose connectivity to the Galaxy database, and the
database is often unreachable exactly when the gateway restarts. The
hierarchy cache was purely in-memory, so a cold start with no database
left clients with an Unavailable browse surface until SQL came back.
Add a JSON snapshot store: each successful heavy refresh writes the raw
hierarchy and attribute rowsets to disk atomically (temp file + rename),
and the first refresh after startup restores that snapshot before any
SQL runs. Restored data is served as Stale until a live query confirms
it; a live query that observes the same time_of_last_deploy promotes it
to Healthy with no heavy re-query.
Persistence is on by default (MxGateway:Galaxy:PersistSnapshot) and
writes to C:\ProgramData\MxGateway\galaxy-snapshot.json.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
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