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Serialize mochad requests (#11029)

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All mochad devices are sharing a single socket interface. When multiple
threads are issuing requests to the mochad daemon at the same time the
write read cycle might get crossed between the threads. This is normally
not an issue for 1-way X10 devices because as long as the request issued
successfully and data is read over the socket then we know as much as
mochad will tell us (since there is no ACK from the request for most
X10 devices). However, where it does matter is on the device __init__()
because we're relying on the mochad daemon's internal state to take an
educated guess at the device's state to intialize things with. When
there are multiple devices being initialized at the same time the wires
can get crossed between and the wrong device state may be read.

To address this potential issue this commit adds locking using a
semaphore around all pairs of send_cmd() and read_data() (which is what
pymochad.device.Device.get_status() does internally) calls to the mochad
controller to ensure we're only ever dealing with a single request at a
time.

Fixes mtreinish/pymochad#4
This commit is contained in:
Matthew Treinish 2017-12-08 09:18:52 -08:00 • committed by Paulus Schoutsen
parent f7c2ec19ef
commit 1f1115f631
3 changed files with 19 additions and 10 deletions
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13
homeassistant/components/light/mochad.py
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@ -62,7 +62,8 @@ class MochadLight(Light):
def _get_device_status(self):
"""Get the status of the light from mochad."""
status = self.device.get_status().rstrip()
with mochad.REQ_LOCK:
status = self.device.get_status().rstrip()
return status == 'on'
@property
@ -88,12 +89,14 @@ class MochadLight(Light):
def turn_on(self, **kwargs):
"""Send the command to turn the light on."""
self._brightness = kwargs.get(ATTR_BRIGHTNESS, 255)
self.device.send_cmd("xdim {}".format(self._brightness))
self._controller.read_data()
with mochad.REQ_LOCK:
self.device.send_cmd("xdim {}".format(self._brightness))
self._controller.read_data()
self._state = True
def turn_off(self, **kwargs):
"""Send the command to turn the light on."""
self.device.send_cmd('off')
self._controller.read_data()
with mochad.REQ_LOCK:
self.device.send_cmd('off')
self._controller.read_data()
self._state = False