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from __future__ import absolute_import
from kafka.metrics import AnonMeasurable, NamedMeasurable
from kafka.metrics.compound_stat import AbstractCompoundStat
from kafka.metrics.stats import Histogram
from kafka.metrics.stats.sampled_stat import AbstractSampledStat
class BucketSizing(object):
CONSTANT = 0
LINEAR = 1
class Percentiles(AbstractSampledStat, AbstractCompoundStat):
"""A compound stat that reports one or more percentiles"""
def __init__(self, size_in_bytes, bucketing, max_val, min_val=0.0,
percentiles=None):
super(Percentiles, self).__init__(0.0)
self._percentiles = percentiles or []
self._buckets = int(size_in_bytes / 4)
if bucketing == BucketSizing.CONSTANT:
self._bin_scheme = Histogram.ConstantBinScheme(self._buckets,
min_val, max_val)
elif bucketing == BucketSizing.LINEAR:
if min_val != 0.0:
raise ValueError('Linear bucket sizing requires min_val'
' to be 0.0.')
self.bin_scheme = Histogram.LinearBinScheme(self._buckets, max_val)
else:
ValueError('Unknown bucket type: %s' % (bucketing,))
def stats(self):
measurables = []
def make_measure_fn(pct):
return lambda config, now: self.value(config, now,
pct / 100.0)
for percentile in self._percentiles:
measure_fn = make_measure_fn(percentile.percentile)
stat = NamedMeasurable(percentile.name, AnonMeasurable(measure_fn))
measurables.append(stat)
return measurables
def value(self, config, now, quantile):
self.purge_obsolete_samples(config, now)
count = sum(sample.event_count for sample in self._samples)
if count == 0.0:
return float('NaN')
sum_val = 0.0
quant = float(quantile)
for b in range(self._buckets):
for sample in self._samples:
assert type(sample) is self.HistogramSample
hist = sample.histogram.counts
sum_val += hist[b]
if sum_val / count > quant:
return self._bin_scheme.from_bin(b)
return float('inf')
def combine(self, samples, config, now):
return self.value(config, now, 0.5)
def new_sample(self, time_ms):
return Percentiles.HistogramSample(self._bin_scheme, time_ms)
def update(self, sample, config, value, time_ms):
assert type(sample) is self.HistogramSample
sample.histogram.record(value)
class HistogramSample(AbstractSampledStat.Sample):
def __init__(self, scheme, now):
super(Percentiles.HistogramSample, self).__init__(0.0, now)
self.histogram = Histogram(scheme)
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