This finally makes the (presumably) common simple case as simple as it
gets.
The still quite common (but less common) case of using a Gauge is
slightly more verbose now, but not needing to provide a separate
constructor is totally worth it.
Finally, the advanced use case is not really more verbose as in my
original suggestion. However, the logic to decide which Observer to
use is now all in the ObserverFunc handed in at construction
time. This is deliberate and desired. It makes sure the selection
mechanism is all spelled out there. No surprises buried deep in the
function code somewhere.
- Deprecate Untyped for direct instrumentation.
- Add a SetToCurrentTime method to Gauge
Note that adding the SetToCurrentTime method is not really following
Go's principle of lean interfaces. However, the Gauge interface is
already quite fat. (The only methods really required are Set and
Add. Everything else could be expressed in terms of those two.) So we
have already quite a few "convenience" methods traditionally, so I
think we should stay consistent here.
The alternatives would be:
- Not support SetToCurrentTime at all (it's only a SHOULD in the
guidelines).
- A top level function `SetToCurrentTime(Gauge)`.
- Just a helper `CurrentTime()` that returns the curent unix time in
seconds as a float (which is pretty verbose using the standard
library, see code in this commit). This would allow
`myGauge.Set(CurrentTime)`.
Weighing all circumstances, I believe the way in this commit is the
least evil. Issue #223 could be used to rework interfaces more
fundamentally in a breaking change if feasible.
All was a mess, we had duplicates of the REs for label name and metric
names here, and we sometimes used them, sometimes we used those from
common/model.
Now we are consistently using the fast checking functions from common/model.
(Tests for leading colons are included there, see
https://github.com/prometheus/common/pull/66 .)
That's the "soft" part of the deprecation: Everything that has been
marked deprecated in v0.8 or earlier and is straight-forward to
replace by a non-deprecated way, is removed here.
Sadly, this does not include the HTTP part. We first need to provide a
replacement for HTTP instrumentation (as planned for v0.8) to then
remove the deprecated parts in v0.9.
After increasing unit test coverage, it was found that the split
function call nature of metric matching wasn't working well in many
cases. By increasing test coverage, we've ensured that both the fast
path and fallback collision path are working appropriately.
With these changes, there is a further performance hit, but now the
results are ensured to be correct.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
While hash collisions are quite rare, the current state of the client
library carries a risk of merging two separate label values into a
single metric bucket. The effects are near impossible to detect and the
result will be missing or incorrect counters.
This changeset handles hash collisions by falling back to collision
resolution if multiple label values hash to the same value. This works
similar to separate chaining using a slice. Extra storage is minimized
to only the value key slice to that metrics can be differentiated
within a bucket.
In general, the cost of handling collisions is completely minimized
under normal operation. Performance does show slight increases in
certain areas, but these are more likely statistically anomalies. More
importantly, zero allocation behavior for metrics is preserved on the
fast path. Minimal allocations may be made during collision handling but
this has minimal effect.
Benchmark comparisons with and without collision resolution follow.
```
benchmark old ns/op new ns/op delta
BenchmarkCounterWithLabelValues-4 99.0 107 +8.08%
BenchmarkCounterWithLabelValuesConcurrent-4 79.6 91.0 +14.32%
BenchmarkCounterWithMappedLabels-4 518 542 +4.63%
BenchmarkCounterWithPreparedMappedLabels-4 127 137 +7.87%
BenchmarkCounterNoLabels-4 19.5 19.1 -2.05%
BenchmarkGaugeWithLabelValues-4 97.4 110 +12.94%
BenchmarkGaugeNoLabels-4 12.4 10.3 -16.94%
BenchmarkSummaryWithLabelValues-4 1204 915 -24.00%
BenchmarkSummaryNoLabels-4 936 847 -9.51%
BenchmarkHistogramWithLabelValues-4 147 147 +0.00%
BenchmarkHistogramNoLabels-4 50.6 49.3 -2.57%
BenchmarkHistogramObserve1-4 37.9 37.5 -1.06%
BenchmarkHistogramObserve2-4 122 137 +12.30%
BenchmarkHistogramObserve4-4 310 352 +13.55%
BenchmarkHistogramObserve8-4 691 729 +5.50%
BenchmarkHistogramWrite1-4 3374 3097 -8.21%
BenchmarkHistogramWrite2-4 5310 5051 -4.88%
BenchmarkHistogramWrite4-4 12094 10690 -11.61%
BenchmarkHistogramWrite8-4 19416 17755 -8.55%
BenchmarkHandler-4 11934304 13765894 +15.35%
BenchmarkSummaryObserve1-4 1119 1105 -1.25%
BenchmarkSummaryObserve2-4 3679 3430 -6.77%
BenchmarkSummaryObserve4-4 10678 7982 -25.25%
BenchmarkSummaryObserve8-4 22974 16689 -27.36%
BenchmarkSummaryWrite1-4 25962 14680 -43.46%
BenchmarkSummaryWrite2-4 38019 35073 -7.75%
BenchmarkSummaryWrite4-4 78027 56816 -27.18%
BenchmarkSummaryWrite8-4 117220 132248 +12.82%
BenchmarkMetricVecWithLabelValuesBasic-4 138 133 -3.62%
BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 150 144 -4.00%
BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 263 256 -2.66%
BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 145 155 +6.90%
BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 606 634 +4.62%
BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 746 641 -14.08%
benchmark old allocs new allocs delta
BenchmarkCounterWithLabelValues-4 0 0 +0.00%
BenchmarkCounterWithLabelValuesConcurrent-4 0 0 +0.00%
BenchmarkCounterWithMappedLabels-4 2 2 +0.00%
BenchmarkCounterWithPreparedMappedLabels-4 0 0 +0.00%
BenchmarkCounterNoLabels-4 0 0 +0.00%
BenchmarkGaugeWithLabelValues-4 0 0 +0.00%
BenchmarkGaugeNoLabels-4 0 0 +0.00%
BenchmarkSummaryWithLabelValues-4 0 0 +0.00%
BenchmarkSummaryNoLabels-4 0 0 +0.00%
BenchmarkHistogramWithLabelValues-4 0 0 +0.00%
BenchmarkHistogramNoLabels-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValuesBasic-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 0 0 +0.00%
benchmark old bytes new bytes delta
BenchmarkCounterWithLabelValues-4 0 0 +0.00%
BenchmarkCounterWithLabelValuesConcurrent-4 0 0 +0.00%
BenchmarkCounterWithMappedLabels-4 336 336 +0.00%
BenchmarkCounterWithPreparedMappedLabels-4 0 0 +0.00%
BenchmarkCounterNoLabels-4 0 0 +0.00%
BenchmarkGaugeWithLabelValues-4 0 0 +0.00%
BenchmarkGaugeNoLabels-4 0 0 +0.00%
BenchmarkSummaryWithLabelValues-4 0 0 +0.00%
BenchmarkSummaryNoLabels-4 0 0 +0.00%
BenchmarkHistogramWithLabelValues-4 0 0 +0.00%
BenchmarkHistogramNoLabels-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValuesBasic-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 0 0 +0.00%
BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 0 0 +0.00%
```
Signed-off-by: Stephen J Day <stephen.day@docker.com>
beorn7