Changed quantization to use monotonic clock readings.
Stopping panicing when monotonic clock readings go backwards because
https://github.com/kubernetes/kubernetes/issues/96459 reported it
happening.
Re-organized sampleAndWaterMarkHistograms::innerSet to `defer` the
Unlock call, because that is the preferred pattern.
Kubernetes-commit: 0809220fd04d26892f0fcfd3bf54cc4baeda22da
Introduce min, average, and standard deviation for the number of
executing mutating and readOnly requests.
Introduce min, max, average, and standard deviation for the number
waiting and number waiting per priority level.
Later:
Revised to use a series of windows
Use three individuals instead of array of powers
Later:
Add coarse queue count metrics, removed windowed avg and stddev
Add metrics for number of queued mutating and readOnly requests,
to complement metrics for number executing.
Later:
Removed windowed average and standard deviation because consumers can
derive such from integrals of consumer's chosen window.
Also replaced "requestKind" Prometheus label with "request_kind".
Later:
Revised to focus on sampling
Make the clock intrinsic to a TimedObserver
... so that the clock can be read while holding the observer's lock;
otherwise, forward progress is not guaranteed (and violations were
observed in testing).
Bug fixes and histogram buckets revision
SetX1 to 1 when queue length limit is zero, beause dividing by zero is nasty.
Remove obsolete argument in gen_test.go.
Add a bucket boundary at 0 for sample-and-water-mark histograms, to
distinguish zeroes from non-zeros.
This includes adding Integrator test.
Simplified test code.
More pervasively used "ctlr" instead of "ctl" as abbreviation for
"controller".
Kubernetes-commit: 57ecea22296797a93b0157169db0ff2e477f58d0
Mike Spreitzer