Replace the default asyncio executor (capped at ~32 threads) with a
dedicated ThreadPoolExecutor sized for large-topology parallelism.
When 500 nodes each call _connect_nio, up to 500 OS threads can now
send blocking ubridge commands in parallel — no longer serialised by
either the event loop or a small thread pool.
- ubridge_hypervisor: module-level _ubridge_sync_pool (max_workers=500)
- docker_vm._connect_nio: dispatches to the dedicated pool instead of
the default executor
Replace the 3-5 sequential await _ubridge_send calls in _connect_nio
with a single run_in_executor batch. The batch holds the node-level
asyncio Lock to prevent interleaving with async sends, then uses the
hypervisor's new send_batch_sync method which does blocking socket
sendall/recv inside the thread pool. Different nodes' batches now
run in true OS-thread parallelism rather than serialising through
the asyncio event loop between every command.
- ubridge_hypervisor.send_batch_sync: blocking batch send using
the underlying socket from the asyncio transport, protected by
threading.Lock.
- _connect_nio: builds command list (add_nio_udp, start_capture,
bridge start, reset_packet_filters, add_packet_filter) and
dispatches to the default executor.
Add ubridge_control_transport to [Server] config (default "tcp", fully
backward compatible). Selecting "unix" switches the uBridge hypervisor
control channel from the unauthenticated TCP listener (-H) to an AF_UNIX
socket (-U) authenticated in-kernel via SO_PEERCRED.
- UBridgeHypervisor: supports both socket_path (AF_UNIX) and host/port
(TCP); a new `endpoint` property unifies log/error strings for both
- Hypervisor: unix mode allocates a short socket path under a 0700
private runtime dir and unlinks it on stop; tcp mode restores the
original getaddrinfo ephemeral-port allocation
- base_node: reads the transport from config and passes host through
- schemas/config.py + config_samples/gns3_server.conf: new option
Default deployments are unchanged. "unix" requires a ubridge build that
understands -U.
