def save_sample(self, metric, value, timestamp=None,
dimensions=None, hostname=None, device_name=None):
"""Save a simple sample, evict old values if needed.
"""
if timestamp is None:
timestamp = time.time()
if metric not in self._sample_store:
raise exceptions.CheckException("Saving a sample for an undefined metric: %s" % metric)
try:
value = util.cast_metric_val(value)
except ValueError as ve:
raise exceptions.NaN(ve)
# Data eviction rules
key = (tuple(sorted(dimensions.items())), device_name)
if self.is_gauge(metric):
self._sample_store[metric][key] = ((timestamp, value, hostname, device_name), )
elif self.is_counter(metric):
if self._sample_store[metric].get(key) is None:
self._sample_store[metric][key] = [(timestamp, value, hostname, device_name)]
else:
self._sample_store[metric][key] = self._sample_store[metric][key][-1:] + \
[(timestamp, value, hostname, device_name)]
else:
raise exceptions.CheckException("%s must be either gauge or counter, skipping sample at %s" %
(metric, time.ctime(timestamp)))
if self.is_gauge(metric):
# store[metric][dimensions] = (ts, val) - only 1 value allowed
assert len(self._sample_store[metric][key]) == 1, self._sample_store[metric]
elif self.is_counter(metric):
assert len(self._sample_store[metric][key]) in (1, 2), self._sample_store[metric]
def _rate(cls, sample1, sample2):
"""Simple rate.
"""
try:
rate_interval = sample2[0] - sample1[0]
if rate_interval == 0:
raise exceptions.Infinity()
delta = sample2[1] - sample1[1]
if delta < 0:
raise exceptions.UnknownValue()
return (sample2[0], delta / rate_interval, sample2[2], sample2[3])
except exceptions.Infinity:
raise
except exceptions.UnknownValue:
raise
except Exception as e:
raise exceptions.NaN(e)
