The previous implementation of SeriesGrouper required breaking a metric object apart into its constituents, converting tags and keys into unoptimized maps, only to have it put them back together into another metric object. This resulted in a significant performance overhead. This overhead was further compounded when the number of fields was large.
This change adds a new AddMetric method to SeriesGrouper which preserves the metric object and removes the back-and-forth conversion.
Additionlly the method used for calculating the metric's hash was switched to use maphash, which is optimized for this case.
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Benchmarks
Before:
BenchmarkMergeOne-16 106012 11790 ns/op
BenchmarkMergeTwo-16 48529 24819 ns/op
BenchmarkGroupID-16 780018 1608 ns/op
After:
BenchmarkMergeOne-16 907093 1173 ns/op
BenchmarkMergeTwo-16 508321 2168 ns/op
BenchmarkGroupID-16 11217788 99.4 ns/op
David Bennett
Patrick Hemmer
Daniel Nelson