def test_a_reservoir_of_100_out_of_1000_elements():
reservoir = ExponentiallyDecayingReservoir(100, 0.99)
for i in xrange(1000):
reservoir.update(i)
assert len(reservoir) == 100
snapshot = reservoir.snapshot()
assert len(snapshot) == 100
assert_all_values_between(reservoir, 0, 1000)
def test_spot_fall():
clock = ManualClock()
reservoir = ExponentiallyDecayingReservoir(1000, 0.015, clock)
rate_per_minute = 10
interval_millis = 60 * 1000 / rate_per_minute
# mode 1: steady regime for 120 minutes
for i in xrange(120 * rate_per_minute):
reservoir.update(9998)
clock.add_millis(interval_millis)
# switching to mode 2: 10 more minutes with the same rate, but smaller value
for i in xrange(10 * rate_per_minute):
reservoir.update(178)
clock.add_millis(interval_millis)
# expect that quantiles should be more about mode 2 after 10 minutes
print reservoir.snapshot().p95
assert reservoir.snapshot().p95 == 178
def test_quantiles_should_be_based_on_weights():
clock = ManualClock()
reservoir = ExponentiallyDecayingReservoir(1000, 0.015, clock)
for i in xrange(40):
reservoir.update(177)
clock.add_seconds(120)
for i in xrange(10):
reservoir.update(9999)
assert len(reservoir.snapshot()) == 50
# the first added 40 items (177) have weights 1
# the next added 10 items (9999) have weights ~6
# so, it's 40 vs 60 distribution, not 40 vs 10
assert reservoir.snapshot().median == 9999
assert reservoir.snapshot().p75 == 9999
def test_long_period_of_inactivity_should_not_corrupt_sampling_state():
clock = ManualClock()
reservoir = ExponentiallyDecayingReservoir(10, 0.015, clock)
# add 1000 values at a rate of 10 values / second
for i in xrange(1000):
reservoir.update(1000 + i)
clock.add_millis(100)
assert len(reservoir.snapshot()) == 10
assert_all_values_between(reservoir, 1000, 2000)
# wait for 15 hours and add another value.
# this should trigger a rescale. Note that the number of samples will be reduced to 2
# because of the very small scaling factor that will make all existing priorities equal to zero after rescale.
clock.add_hours(15)
reservoir.update(2000)
assert len(reservoir.snapshot()) == 2
assert_all_values_between(reservoir, 1000, 3000)
# add 1000 values at a rate of 10 values / second
for i in xrange(1000):
reservoir.update(3000 + i)
clock.add_millis(100)
assert len(reservoir.snapshot()) == 10
assert_all_values_between(reservoir, 3000, 4000)
def __init__(self, reservoir=None, clock=time):
self.reservoir = reservoir if reservoir is not None else ExponentiallyDecayingReservoir(
)
self.histogram = Histogram(self.reservoir)
self.clock = clock
self.meter = Meter(clock)