124 lines
4.2 KiB
Python
124 lines
4.2 KiB
Python
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"""
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Bleak connection backend.
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This creates a new event loop that is used to integrate bleak's
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asyncio functions to synchronous architecture of python-eq3bt.
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"""
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import asyncio
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import codecs
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import contextlib
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import logging
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from typing import Optional
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from bleak import BleakClient, BleakError
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from . import BackendException
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DEFAULT_TIMEOUT = 1
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# bleak backends are very loud on debug, this reduces the log spam when using --debug
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logging.getLogger("bleak.backends").setLevel(logging.WARNING)
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_LOGGER = logging.getLogger(__name__)
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class BleakConnection:
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"""Representation of a BTLE Connection."""
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def __init__(self, mac, iface):
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"""Initialize the connection."""
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self._conn: Optional[BleakClient] = None
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self._mac = mac
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self._iface = iface
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self._callbacks = {}
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self._notifyevent = asyncio.Event()
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self._notification_handle = None
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self._loop = asyncio.new_event_loop()
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def __enter__(self):
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"""
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Context manager __enter__ for connecting the device
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:rtype: BTLEConnection
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:return:
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"""
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_LOGGER.debug("Trying to connect to %s", self._mac)
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kwargs = {}
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if self._iface is not None:
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kwargs["adapter"] = self._iface
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self._conn = BleakClient(self._mac, **kwargs)
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try:
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self._loop.run_until_complete(self._conn.connect())
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except BleakError as ex:
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_LOGGER.debug(
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"Unable to connect to the device %s, retrying: %s", self._mac, ex
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)
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try:
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self._loop.run_until_complete(self._conn.connect())
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except Exception as ex2:
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_LOGGER.debug("Second connection try to %s failed: %s", self._mac, ex2)
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raise BackendException(
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"unable to connect to device using bleak"
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) from ex2
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# The notification handles are off-by-one compared to gattlib and bluepy
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self._loop.run_until_complete(
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self._conn.start_notify(self._notification_handle - 1, self.on_notification)
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)
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_LOGGER.debug("Connected to %s", self._mac)
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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if self._conn:
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self._loop.run_until_complete(self._conn.disconnect())
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self._conn = None
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async def on_notification(self, handle, data):
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"""Handle Callback from a Bluetooth (GATT) request."""
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# The notification handles are off-by-one compared to gattlib and bluepy
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handle = handle + 1
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_LOGGER.debug(
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"Got notification from %s: %s", handle, codecs.encode(data, "hex")
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)
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self._notifyevent.set()
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if handle in self._callbacks:
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self._callbacks[handle](data)
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@property
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def mac(self):
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"""Return the MAC address of the connected device."""
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return self._mac
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def set_callback(self, handle, function):
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"""Set the callback for a Notification handle. It will be called with the parameter data, which is binary."""
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self._notification_handle = handle
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self._callbacks[handle] = function
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async def wait_for_response(self, timeout):
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with contextlib.suppress(asyncio.TimeoutError):
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await asyncio.wait_for(self._notifyevent.wait(), timeout)
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def make_request(self, handle, value, timeout=DEFAULT_TIMEOUT, with_response=True):
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"""Write a GATT Command without callback - not utf-8."""
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try:
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with self:
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_LOGGER.debug(
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"Writing %s to %s",
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codecs.encode(value, "hex"),
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handle,
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)
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self._notifyevent.clear()
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self._loop.run_until_complete(
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self._conn.write_gatt_char(handle - 1, value)
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)
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if timeout:
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_LOGGER.debug("Waiting for notifications for %s", timeout)
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self._loop.run_until_complete(self.wait_for_response(timeout))
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except BleakError as ex:
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_LOGGER.debug("Got exception from bleak while making a request: %s", ex)
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raise BackendException("Exception on write using bleak") from ex
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