429 lines
16 KiB
Python
429 lines
16 KiB
Python
"""Session orchestration for direct-USB LibreVNA protocol communication."""
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from __future__ import annotations
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from collections import defaultdict, deque
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import logging
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import threading
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import time
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from typing import Callable, Protocol, TypeVar
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from .enums import HardwareFamily, PacketType
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from .exceptions import (
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DeviceDisconnectedError,
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NackError,
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ParseError,
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ProtocolVersionMismatch,
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TimeoutError,
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)
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from .models import DeviceInfo, DeviceStatus, Packet, StreamHandle, USBDeviceDescriptor
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from .protocol import (
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FrameScanner,
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decode_packet_payload,
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encode_frame,
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encode_packet_payload,
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ensure_no_payload_types,
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parse_device_status,
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)
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from .transport import USBTransport
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logger = logging.getLogger(__name__)
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_PACKET_QUEUE_MAX = 32768
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class _IndexedPayload(Protocol):
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"""Protocol for payload types carrying an integer `point_number` field."""
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point_number: int
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TPacketPayload = TypeVar("TPacketPayload", bound=_IndexedPayload)
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class LibreVNASession:
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"""Owns USB transport, packet queues, and request/response synchronization."""
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def __init__(self) -> None:
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"""Initialize transport, queues, synchronization primitives, and defaults."""
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self._scanner = FrameScanner()
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self._transport = USBTransport(
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on_data=self._on_transport_data,
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on_disconnect=self._on_transport_disconnect,
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)
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# The sweep free-runs between acquisitions, and subscriptions do not
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# consume request queues. Retain a bounded tail of stale datapoints.
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self._incoming: dict[PacketType, deque[Packet]] = defaultdict(lambda: deque(maxlen=_PACKET_QUEUE_MAX))
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self._subscribers: dict[PacketType, set[Callable[[Packet], None]]] = defaultdict(set)
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self._incoming_cv = threading.Condition()
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self._ack_cv = threading.Condition()
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self._send_lock = threading.Lock()
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self._awaiting_ack = False
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self._ack_result: PacketType | None = None
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self._fatal_error: Exception | None = None
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self._device_info: DeviceInfo | None = None
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self._device_status: DeviceStatus | None = None
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self._hardware_family: HardwareFamily = HardwareFamily.UNKNOWN
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@property
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def is_connected(self) -> bool:
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"""Return `True` when USB connection is active."""
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return self._transport.is_connected
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@property
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def connected_serial(self) -> str | None:
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"""Serial number of currently connected device, when available."""
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return self._transport.connected_serial
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@property
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def hardware_family(self) -> HardwareFamily:
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"""Hardware family inferred from `DeviceInfo` packet."""
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return self._hardware_family
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@staticmethod
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def list_devices() -> list[USBDeviceDescriptor]:
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"""Enumerate available direct-USB LibreVNA devices."""
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return USBTransport.list_devices()
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def connect(
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self,
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serial: str | None = None,
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*,
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strict_protocol_version: int = 14,
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timeout_s: float = 1.0,
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) -> None:
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"""Connect transport and perform startup handshake."""
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logger.info(
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"Opening USB transport (serial=%s, strict_protocol=%d, timeout=%.2fs)",
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serial,
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strict_protocol_version,
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timeout_s,
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)
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self._fatal_error = None
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self._scanner.clear()
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self._incoming.clear()
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self._transport.connect(serial=serial, timeout_s=timeout_s)
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try:
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info_packet = self.request(
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PacketType.REQUEST_DEVICE_INFO,
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PacketType.DEVICE_INFO,
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timeout_s=timeout_s,
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)
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if not isinstance(info_packet.payload, DeviceInfo):
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raise ParseError("Decoded DeviceInfo payload has unexpected type")
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self._device_info = info_packet.payload
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self._hardware_family = self._device_info.hardware_family
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logger.info(
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"Handshake OK: fw=%s protocol=%d family=%s ports=%d",
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self._device_info.firmware_version,
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self._device_info.protocol_version,
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self._device_info.hardware_family.name,
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self._device_info.num_ports,
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)
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if self._device_info.protocol_version != strict_protocol_version:
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raise ProtocolVersionMismatch(
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"Protocol version mismatch: "
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f"device={self._device_info.protocol_version}, "
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f"required={strict_protocol_version}"
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)
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self.get_device_status(timeout_s=timeout_s)
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logger.debug("Initial device status request completed")
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except Exception:
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logger.exception("Connect handshake failed, closing session")
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self.disconnect()
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raise
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def disconnect(self) -> None:
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"""Disconnect USB transport and clear session state."""
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logger.debug("Closing USB transport and clearing session queues")
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with self._incoming_cv:
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self._fatal_error = DeviceDisconnectedError("LibreVNA session is disconnected")
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self._incoming.clear()
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self._subscribers.clear()
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self._incoming_cv.notify_all()
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with self._ack_cv:
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self._awaiting_ack = False
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self._ack_result = None
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self._ack_cv.notify_all()
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self._transport.disconnect()
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def send(self, packet: Packet, *, require_ack: bool = True, timeout_s: float = 0.5) -> None:
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"""Send one protocol packet and optionally wait for ACK/NACK."""
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payload = encode_packet_payload(packet.type, packet.payload)
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ensure_no_payload_types(packet.type, payload)
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frame = encode_frame(Packet(type=packet.type, payload=payload))
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logger.debug(
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"TX packet=%s payload=%dB require_ack=%s timeout=%.2fs",
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packet.type.name,
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len(payload),
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require_ack,
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timeout_s,
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)
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with self._send_lock:
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if require_ack:
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with self._ack_cv:
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self._awaiting_ack = True
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self._ack_result = None
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try:
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self._transport.write(frame, timeout_s=timeout_s)
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if require_ack:
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deadline = time.monotonic() + timeout_s
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with self._ack_cv:
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while self._ack_result is None:
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self._raise_if_fatal_locked()
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remaining = deadline - time.monotonic()
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if remaining <= 0:
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raise TimeoutError(f"Timeout waiting for ACK for packet {packet.type.name}")
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self._ack_cv.wait(timeout=remaining)
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result = self._ack_result
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if result == PacketType.NACK:
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raise NackError(f"Received NACK for packet {packet.type.name}")
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logger.debug("ACK received for packet %s", packet.type.name)
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finally:
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if require_ack:
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with self._ack_cv:
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self._awaiting_ack = False
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self._ack_result = None
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def request(
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self,
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packet_type: PacketType,
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response_type: PacketType,
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*,
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timeout_s: float = 1.0,
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) -> Packet:
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"""Send no-payload request packet and wait for one response packet type."""
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logger.debug(
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"Request start: packet=%s expect=%s timeout=%.2fs",
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packet_type.name,
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response_type.name,
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timeout_s,
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)
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self.clear_queue(response_type)
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self.send(Packet(type=packet_type), require_ack=True, timeout_s=timeout_s)
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packet = self.wait_for_packet(response_type, timeout_s=timeout_s)
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logger.debug("Request complete: received %s", response_type.name)
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return packet
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def collect_indexed_payloads(
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self,
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*,
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packet_type: PacketType,
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expected_points: int,
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timeout_s: float,
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payload_type: type[TPacketPayload],
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payload_error: str,
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progress_timeout_s: float | None = None,
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) -> list[TPacketPayload]:
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"""Collect one sweep from point zero, returning points in ascending order.
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Ignore the tail before the first point zero. A new point zero discards
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an incomplete earlier cycle instead of filling its gaps from a later one.
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"""
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if expected_points <= 0:
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raise ValueError("expected_points must be > 0")
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deadline = time.monotonic() + timeout_s
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progress_timeout_s = timeout_s if progress_timeout_s is None else progress_timeout_s
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progress_deadline = time.monotonic() + progress_timeout_s
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previous_point: int | None = None
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collected: list[TPacketPayload | None] = [None] * expected_points
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received = 0
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while received < expected_points:
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remaining = min(deadline, progress_deadline) - time.monotonic()
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if remaining <= 0:
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break
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packet = self.wait_for_packet(packet_type, timeout_s=remaining)
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payload = packet.payload
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if not isinstance(payload, payload_type):
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raise ParseError(payload_error)
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point_number = payload.point_number
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if point_number < 0 or point_number >= expected_points:
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raise ParseError(
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f"Received out-of-range point index {point_number}, expected 0..{expected_points - 1}"
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)
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if point_number != previous_point:
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progress_deadline = time.monotonic() + progress_timeout_s
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previous_point = point_number
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if point_number == 0:
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collected = [None] * expected_points
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received = 0
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elif collected[0] is None:
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continue
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if collected[point_number] is None:
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received += 1
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collected[point_number] = payload
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return [item for item in collected if item is not None]
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def wait_for_packet(self, packet_type: PacketType, *, timeout_s: float = 1.0) -> Packet:
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"""Wait for the next packet of requested type."""
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deadline = time.monotonic() + timeout_s
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with self._incoming_cv:
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while True:
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self._raise_if_fatal_locked()
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queue = self._incoming[packet_type]
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if queue:
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logger.debug(
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"Dequeued packet %s (remaining=%d)",
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packet_type.name,
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len(queue) - 1,
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)
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return queue.popleft()
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remaining = deadline - time.monotonic()
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if remaining <= 0:
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raise TimeoutError(f"Timeout waiting for packet {packet_type.name}")
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self._incoming_cv.wait(timeout=remaining)
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def clear_queue(self, packet_type: PacketType) -> None:
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"""Drop queued packets of a given type."""
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with self._incoming_cv:
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dropped = len(self._incoming[packet_type])
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self._incoming[packet_type].clear()
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if dropped:
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logger.debug("Cleared %d queued packet(s) of type %s", dropped, packet_type.name)
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def get_device_info(self) -> DeviceInfo:
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"""Return cached `DeviceInfo` from successful `connect()` handshake."""
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if self._device_info is None:
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raise DeviceDisconnectedError("Device info is not available before connect()")
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return self._device_info
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def get_device_status(self, *, timeout_s: float = 1.0) -> DeviceStatus:
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"""Request and return current `DeviceStatus`."""
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packet = self.request(
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PacketType.REQUEST_DEVICE_STATUS,
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PacketType.DEVICE_STATUS,
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timeout_s=timeout_s,
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)
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if not isinstance(packet.payload, (bytes, bytearray, memoryview)):
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raise ParseError("DeviceStatus packet payload has unexpected type")
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status = parse_device_status(bytes(packet.payload), self._hardware_family)
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self._device_status = status
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logger.debug(
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"Device status: source_locked=%s lo_locked=%s adc_overload=%s unlevel=%s",
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status.source_locked,
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status.lo_locked,
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status.adc_overload,
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status.unlevel,
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)
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return status
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def subscribe(self, packet_type: PacketType, callback: Callable[[Packet], None]) -> StreamHandle:
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"""Register packet callback and return handle for unsubscription."""
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stop_event = threading.Event()
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with self._incoming_cv:
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self._subscribers[packet_type].add(callback)
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logger.debug(
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"Subscriber added for %s (count=%d)",
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packet_type.name,
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len(self._subscribers[packet_type]),
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)
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def _close() -> None:
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"""Unsubscribe callback from session packet subscribers."""
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with self._incoming_cv:
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callbacks = self._subscribers.get(packet_type)
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if callbacks is not None:
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callbacks.discard(callback)
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logger.debug(
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"Subscriber removed for %s (count=%d)",
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packet_type.name,
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len(callbacks),
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)
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return StreamHandle(stop_event=stop_event, close_callback=_close)
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def _on_transport_data(self, chunk: bytes) -> None:
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"""Decode incoming USB chunk and route packets to queues/subscribers."""
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try:
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packets = self._scanner.feed(chunk)
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if logger.isEnabledFor(logging.DEBUG) and packets:
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logger.debug("RX chunk=%dB decoded_packets=%d", len(chunk), len(packets))
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except Exception as exc:
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self._set_fatal_error(exc)
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return
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for packet in packets:
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try:
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decoded_payload = decode_packet_payload(packet)
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except Exception as exc:
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self._set_fatal_error(exc)
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return
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decoded_packet = Packet(type=packet.type, payload=decoded_payload)
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self._dispatch_packet(decoded_packet)
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def _on_transport_disconnect(self, exc: Exception) -> None:
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"""Receive asynchronous transport disconnect event."""
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self._set_fatal_error(exc)
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def _dispatch_packet(self, packet: Packet) -> None:
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"""Route packet into ack waiter, queue, and subscriber callbacks."""
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if logger.isEnabledFor(logging.DEBUG) and packet.type not in {
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PacketType.VNA_DATAPOINT,
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}:
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logger.debug("Dispatch packet %s", packet.type.name)
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if packet.type in {PacketType.ACK, PacketType.NACK}:
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with self._ack_cv:
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if self._awaiting_ack and self._ack_result is None:
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self._ack_result = packet.type
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self._ack_cv.notify_all()
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return
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callbacks: list[Callable[[Packet], None]] = []
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with self._incoming_cv:
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callbacks = list(self._subscribers.get(packet.type, set()))
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queue = self._incoming[packet.type]
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if len(queue) == queue.maxlen and not callbacks and packet.type != PacketType.VNA_DATAPOINT:
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self._set_fatal_error(ParseError(f"Packet queue overflow for {packet.type.name}"))
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return
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queue.append(packet)
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self._incoming_cv.notify_all()
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for callback in callbacks:
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try:
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callback(packet)
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except Exception as exc:
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logger.exception("Subscriber callback failed for packet %s", packet.type.name)
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self._set_fatal_error(exc)
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return
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def _set_fatal_error(self, exc: Exception) -> None:
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"""Mark session as failed and wake all waiting operations."""
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with self._incoming_cv:
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with self._ack_cv:
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if self._fatal_error is None:
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self._fatal_error = exc
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logger.error("Session fatal error: %s", exc, exc_info=exc)
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self._incoming_cv.notify_all()
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self._ack_cv.notify_all()
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def _raise_if_fatal_locked(self) -> None:
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"""Raise stored fatal error (called while condition lock is held)."""
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if self._fatal_error is None:
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return
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exc = self._fatal_error
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if isinstance(exc, DeviceDisconnectedError):
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raise exc
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raise DeviceDisconnectedError(f"Session stopped due to transport/protocol error: {exc}") from exc
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