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go/internal/telemetry/tag.go
Ian Cottrell a1c56757aa internal/telemetry: remove the concept of a Tagger
The Tagger interface allowed for specifying a key in a tag list and having the
value be aquired from the context automatically. It was almost never used, and
the alternative (using the key to get the value) is not that much more long
winded, so it was not holding it's own weight from a complexity persective alone
but the performance cost of having to use a list of interface rather than a list
of tags was very large. See the benchstat improvements below for the difference
it makes to both speed and memory usage, especially in the no exporter case.

name                 old time/op    new time/op    delta
Baseline-8              341ns ± 2%     342ns ± 1%     ~     (p=0.139 n=19+18)
LoggingNoExporter-8    2.46µs ± 5%    1.97µs ± 3%  -19.88%  (p=0.000 n=19+20)
Logging-8              13.3µs ± 2%    12.8µs ± 2%   -3.42%  (p=0.000 n=17+20)
LoggingStdlib-8        5.39µs ± 6%    5.34µs ± 3%     ~     (p=0.692 n=20+19)

name                 old alloc/op   new alloc/op   delta
Baseline-8              80.0B ± 0%     80.0B ± 0%     ~     (all equal)
LoggingNoExporter-8      728B ± 0%      440B ± 0%  -39.56%  (p=0.000 n=20+20)
Logging-8              2.75kB ± 0%    2.46kB ± 0%  -10.53%  (p=0.000 n=17+20)
LoggingStdlib-8          568B ± 0%      568B ± 0%     ~     (all equal)

name                 old allocs/op  new allocs/op  delta
Baseline-8               5.00 ± 0%      5.00 ± 0%     ~     (all equal)
LoggingNoExporter-8      32.0 ± 0%      23.0 ± 0%  -28.12%  (p=0.000 n=20+20)
Logging-8                88.0 ± 0%      79.0 ± 0%  -10.23%  (p=0.000 n=20+20)
LoggingStdlib-8          28.0 ± 0%      28.0 ± 0%     ~     (all equal)

Change-Id: Ic203ad0c5de7451348976b999a0d038ac532dc39
Reviewed-on: https://go-review.googlesource.com/c/tools/+/221737
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
2020-03-03 22:56:24 +00:00

65 lines
1.4 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package telemetry
import (
"fmt"
)
// Tag holds a key and value pair.
// It is normally used when passing around lists of tags.
type Tag struct {
Key interface{}
Value interface{}
}
// TagList is a way of passing around a collection of key value pairs.
// It is an alternative to the less efficient and unordered method of using
// maps.
type TagList []Tag
// Format is used for debug printing of tags.
func (t Tag) Format(f fmt.State, r rune) {
fmt.Fprintf(f, `%v="%v"`, t.Key, t.Value)
}
// Get will get a single key's value from the list.
func (l TagList) Get(k interface{}) interface{} {
for _, t := range l {
if t.Key == k {
return t.Value
}
}
return nil
}
// Format pretty prints a list.
// It is intended only for debugging.
func (l TagList) Format(f fmt.State, r rune) {
printed := false
for _, t := range l {
if t.Value == nil {
continue
}
if printed {
fmt.Fprint(f, ",")
}
fmt.Fprint(f, t)
printed = true
}
}
// Equal returns true if two lists are identical.
func (l TagList) Equal(other TagList) bool {
//TODO: make this more efficient
return fmt.Sprint(l) == fmt.Sprint(other)
}
// Less is intended only for using tag lists as a sorting key.
func (l TagList) Less(other TagList) bool {
//TODO: make this more efficient
return fmt.Sprint(l) < fmt.Sprint(other)
}