platypush/platypush/backend/sensor/__init__.py

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import time
from platypush.backend import Backend
from platypush.context import get_plugin
from platypush.message.event.sensor import SensorDataChangeEvent, \
SensorDataAboveThresholdEvent, SensorDataBelowThresholdEvent
class SensorBackend(Backend):
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"""
Abstract backend for polling sensors.
Triggers:
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* :class:`platypush.message.event.sensor.SensorDataChangeEvent` if the measurements of a sensor have changed
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* :class:`platypush.message.event.sensor.SensorDataAboveThresholdEvent` if the measurements of a sensor have
gone above a configured threshold
* :class:`platypush.message.event.sensor.SensorDataBelowThresholdEvent` if the measurements of a sensor have
gone below a configured threshold
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"""
default_tolerance = 1e-7
def __init__(self, plugin=None, plugin_args=None, thresholds=None, tolerance=default_tolerance, poll_seconds=None,
enabled_sensors=None, **kwargs):
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"""
:param plugin: If set, then this plugin instance, referenced by plugin id, will be polled
through ``get_plugin()``. Example: ``'gpio.sensor.bme280'`` or ``'gpio.sensor.envirophat'``.
:type plugin: str
:param plugin_args: If plugin is set and its ``get_measurement()`` method accepts optional arguments, then you
can pass those arguments through ``plugin_args``.
:type plugin_args: dict
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:param thresholds: Thresholds can be either a scalar value or a dictionary (e.g. ``{"temperature": 20.0}``).
Sensor threshold events will be fired when measurements get above or below these values.
Set it as a scalar if your get_measurement() code returns a scalar, as a dictionary if it returns a
dictionary of values. For instance, if your sensor code returns both humidity and temperature in a format
like ``{'humidity':60.0, 'temperature': 25.0}``, you'll want to set up a threshold on temperature with a
syntax like ``{'temperature':20.0}`` to trigger events when the temperature goes above/below 20 degrees.
:param tolerance: If set, then the sensor change events will be triggered only if the difference between
the new value and the previous value is higher than the specified tolerance. Example::
{
"temperature": 0.01, # Tolerance on the 2nd decimal digit
"humidity": 0.1 # Tolerance on the 1st decimal digit
}
:type tolerance: dict or float
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:param poll_seconds: If set, the thread will wait for the specified number of seconds between a read and the
next one.
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:type poll_seconds: float
:param enabled_sensors: If ``get_measurement()`` returns data in dict form, then ``enabled_sensors`` selects
which keys should be taken into account when monitoring for new events (e.g. "temperature" or "humidity").
:type enabled_sensors: dict (in the form ``name -> [True/False]``), set or list
"""
super().__init__(**kwargs)
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self.data = None
self.plugin = plugin
self.plugin_args = plugin_args or {}
self.thresholds = thresholds
self.tolerance = tolerance
self.poll_seconds = poll_seconds
if isinstance(enabled_sensors, list):
enabled_sensors = set(enabled_sensors)
if isinstance(enabled_sensors, set):
enabled_sensors = {k: True for k in enabled_sensors}
self.enabled_sensors = enabled_sensors or {}
def get_measurement(self):
"""
Wrapper around ``plugin.get_measurement()`` that can filter events on specified enabled sensors data or on
specified tolerance values. It can be overridden by derived classes.
"""
if not self.plugin:
raise NotImplementedError('No plugin specified')
plugin = get_plugin(self.plugin)
data = plugin.get_data(**self.plugin_args).output
if self.enabled_sensors:
data = {
sensor: data[sensor]
for sensor, enabled in self.enabled_sensors.items()
if enabled and sensor in data
}
return data
def get_new_data(self, new_data):
if self.data is None or new_data is None:
return new_data
# noinspection PyBroadException
try:
# Scalar data case
new_data = float(new_data)
return new_data if abs(new_data - self.data) >= self.tolerance else None
except:
# If it's not a scalar then it should be a dict
assert isinstance(new_data, dict)
ret = {}
for k, v in new_data.items():
if (v is None and self.data.get(k) is not None) \
or k not in self.data \
or self.tolerance is None:
ret[k] = v
continue
if v is None:
continue
tolerance = None
is_nan = False
old_v = None
try:
v = float(v)
old_v = float(self.data.get(k))
except (TypeError, ValueError):
is_nan = True
if not is_nan:
if isinstance(self.tolerance, dict):
tolerance = float(self.tolerance.get(k, self.default_tolerance))
else:
try:
tolerance = float(self.tolerance)
except (TypeError, ValueError):
pass
if tolerance is None or is_nan or abs(v - old_v) >= tolerance:
ret[k] = v
return ret
def on_stop(self):
if not self.plugin:
return
plugin = get_plugin(self.plugin)
if plugin and hasattr(plugin, 'close'):
plugin.close()
def run(self):
super().run()
self.logger.info('Initialized {} sensor backend'.format(self.__class__.__name__))
while not self.should_stop():
data = self.get_measurement()
new_data = self.get_new_data(data)
if new_data:
self.bus.post(SensorDataChangeEvent(data=new_data))
data_below_threshold = {}
data_above_threshold = {}
if self.thresholds:
if isinstance(self.thresholds, dict) and isinstance(data, dict):
for (measure, thresholds) in self.thresholds.items():
if measure not in data:
continue
if not isinstance(thresholds, list):
thresholds = [thresholds]
for threshold in thresholds:
if data[measure] > threshold and (self.data is None or (
measure in self.data and self.data[measure] <= threshold)):
data_above_threshold[measure] = data[measure]
elif data[measure] < threshold and (self.data is None or (
measure in self.data and self.data[measure] >= threshold)):
data_below_threshold[measure] = data[measure]
if data_below_threshold:
self.bus.post(SensorDataBelowThresholdEvent(data=data_below_threshold))
if data_above_threshold:
self.bus.post(SensorDataAboveThresholdEvent(data=data_above_threshold))
self.data = data
if new_data:
if isinstance(new_data, dict):
for k, v in new_data.items():
self.data[k] = v
else:
self.data = new_data
if self.poll_seconds:
time.sleep(self.poll_seconds)
# vim:sw=4:ts=4:et: