def connection_cb(pvname, conn, **kw):
logger.debug("PV '%s' connected: %s", pvname, conn)
datastore.save_conn_status(pvname, conn)
if not conn:
# save PV data with PV value as None/null
update_id = uuid.uuid1()
datastore.save_update(update_id, timestamp=time.time(),
pvname=pvname, value=None)
def epics_periodic(state, pvname, period):
""" Invoked every time a period for a scanned PV is due """
logger.debug("Periodic scan for PV '%s' with period %f secs", pvname, period)
# get the pv's value
pv = state.get('pv')
if pv:
if pv.connected:
#generate the id for the update
update_id = uuid.uuid1()
data = _gather_pv_data(pv)
datastore.save_update(update_id, **data)
else: # not connected
logger.warn("Non-connected PV '%s'. Saving with 'null' value", pvname)
# save PV data with PV value as None/null
update_id = uuid.uuid1()
datastore.save_update(update_id, timestamp=time.time(), pvname=pvname, value=None)
else:
logger.error("Missing data in 'state' for '%s'", pvname)
def subscription_cb(**kw):
""" Internally called when a new value arrives for a subscribed PV. """
logger.debug("PV callback invoked: %(pvname)s changed to value %(value)s at %(timestamp)s" % kw)
pv = kw['cb_info'][1]
pvname = kw['pvname']
value = kw['value']
max_f = pv.mode.max_freq
last_arch_time = getattr(pv, 'last_arch_time', None)
now = pv.timestamp
# archive iff
# 1) we are below max frequency
# AND
# 2) the change in value is >= delta
if last_arch_time:
freq = 1/(now - last_arch_time)
if max_f and freq > max_f: # if max_f is false, it always passes
#logger.warn("Values for '%s' arriving faster than %f Hz: %f Hz", pvname, max_f, freq)
return
# here, we've passed the frequency test
last_value = getattr(pv, 'last_value', None)
if last_value:
d = abs( last_value - value )
if d < pv.mode.delta:
logger.debug("Value '%r' below delta (%r) for '%s'", value, pv.mode.delta, pvname)
return
# if there's no previous recorded "frequency", archive
# likewise for value
# if we've made it this far, archive
setattr(pv, 'last_arch_time', now)
setattr(pv, 'last_value', value)
#generate the id for the update
update_id = uuid.uuid1()
data = _gather_pv_data(pv)
datastore.save_update(update_id, **data)