Serialize G2 GATT ops for reliable packet delivery - #5
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Serialize every GATT op — characteristic writes on both legs and the descriptor writes that enable notifications — on one op thread, issuing each only after the stack reports the previous one retired. Replaces the fixed 8 ms pacing, which never covered single-packet command bursts and still lost packets on multi-packet ones (8.65% measured; 40% during connect+auth). Zero lost writes measured after.
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Improve G2 bluetooth reliability
Android GATT client
com.android.bluetoothallows only one packet in flight per connection. On boot-up, or heavy utilization times, many important packets don't get sent.The solution is to centralise and enqueue packets, and tick when the GATT stack.
Symptom
On boot about 50% of the times, it was noticed that calendar events didn't appear. Packets never got sent. This was due to a stampede at connect time.
Logs
Logs collected on G2 smart glasses
Comparison
flow both runs: connect, auth, dashboard, calendar sync, Mentra Maps.
Notes:
failcounter is now stricter: it counts writes refused by the stack or neverretired, versus refused-only before.
Raw log lines -
grep -E "BGCAP:|G2/GATT:"Before (HEAD)
Totals: ok=264 fail=25 (8.65% lost). First three lines are the connect+auth window: 12 of 30
writes lost (40%) while CCC descriptor writes and the auth sequence raced for the GATT slot.
After (this PR)
Totals: ok=300 fail=0 (0.00% lost). Connect+auth window is a single clean
ok=23 fail=0, andsustained bursts run at 35-38 writes/s with zero loss — throughput up, loss gone.
the large elapsed on each run's first line is a logging artifact