- Replace legacy MsgClient (low-level TCP frames) with RpcClient (high-level
RPC) to match dbv2's RpcServer interface; the old MsgClient-based version
was incompatible with the current RPC routing protocol
- Apply all hardening fixes from the service copies:
- Outer try/except in _flush_loop to prevent any exception from killing
the background thread
- _safe_json() helper for unserializable extra fields (fallback to str/repr)
- Timestamp generated at push() (enqueue time) instead of _send() time
- Event-based flush() synchronization instead of unreliable sleep(0.6)
- Queue maxsize=10000 with drop-oldest policy to prevent unbounded memory
- put_nowait with Full handling ensures push() never blocks business threads
- RpcClient construction wrapped in try/except
- Add explicit service_name parameter example for all 4 services in comments
- This is the template file referenced by db/README.md and copied by new
services; keeping it in sync prevents propagating old bugs
qing