def __init__(self, read_interval=5, log_interval=600):
"""Constructs the PeriodicReader object:
'read_interval': the time interval between calls to the 'reader'
read() method in seconds.
'log_interval': the time interval between points when the readings
are summarized and logged to the logging handlers in seconds.
"""
self.read_interval = read_interval
self.log_interval = log_interval
# create a list of reader objects that read sensors.
self.readers = []
# create a list of handlers to be called with summarized readings
# at each logging event.
self.logging_handlers = []
# create a dictionary to hold all the readings collected during a
# logging interval. The keys of the dictionary will be the reading ID,
# and the values will be a two-tuple, the first value being the
# reading_type from the readers.base_reader module, and the second value
# will be a list of readings, each reading being a tuple of the form:
# (timestamp, value)
self.read_data = {}
# Create a poster object to post readings to the local MQTT broker.
# It runs in a separate thread and must be started
self.poster = mqtt_poster.MQTTposter()
self.poster.start()
# track whether a call has been make to log readings before.
self.first_log_call = True
def get_last(meter_id):
"""Returns a (ts, val) tuple for Meter ID 'meter_id'. If that
Meter ID is not present (None, None) is returned.
"""
return last_reads.get(meter_id, (None, None))
def set_last(meter_id, ts, val):
"""Sets the last meter reading for Meter ID 'meter_id'.
The attributes stored are the timestamp 'ts' and the
value 'val'.
"""
last_reads[meter_id] = (ts, val)
# Start up the object that will post the final readings to the MQTT
# broker.
mqtt = mqtt_poster.MQTTposter()
mqtt.start()
# start the rtlamr program.
rtlamr = subprocess.Popen(['/home/pi/gocode/bin/rtlamr',
'-gainbyindex=24', # index 24 was found to be the most sensitive
'-format=csv'], stdout=subprocess.PIPE, text=True)
# Get the Meter multipliers from the Settings file and put
# them into a dictionary.
meter_mult = {
'Gas': getattr(settings, 'METER_MULT_GAS', 1000.0),
'Elec': getattr(settings, 'METER_MULT_ELEC', 1.0),
'Water': getattr(settings, 'METER_MULT_WATER', 1.0),
}