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tsweb: cache prometheus metric names & types

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Signed-off-by: Anton Tolchanov <anton@tailscale.com>
This commit is contained in:
Anton Tolchanov
2022-11-17 11:33:19 -08:00
committed by Anton Tolchanov
parent 3c27632ffe
commit f40bb199f5
2 changed files with 34 additions and 11 deletions
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37
tsweb/tsweb.go
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@ -455,18 +455,30 @@ func WritePrometheusExpvar(w io.Writer, kv expvar.KeyValue) {
writePromExpVar(w, "", kv)
}
func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
key := kv.Key
type prometheusMetricDetails struct {
Name string
Type string
Label string
}
var prometheusMetricCache sync.Map // string => *prometheusMetricDetails
func prometheusMetric(prefix string, key string) (string, string, string) {
cachekey := prefix + key
if v, ok := prometheusMetricCache.Load(cachekey); ok {
d := v.(*prometheusMetricDetails)
return d.Name, d.Type, d.Label
}
var typ string
var label string
switch {
case strings.HasPrefix(kv.Key, gaugePrefix):
case strings.HasPrefix(key, gaugePrefix):
typ = "gauge"
key = strings.TrimPrefix(kv.Key, gaugePrefix)
key = strings.TrimPrefix(key, gaugePrefix)
case strings.HasPrefix(kv.Key, counterPrefix):
case strings.HasPrefix(key, counterPrefix):
typ = "counter"
key = strings.TrimPrefix(kv.Key, counterPrefix)
key = strings.TrimPrefix(key, counterPrefix)
}
if strings.HasPrefix(key, labelMapPrefix) {
key = strings.TrimPrefix(key, labelMapPrefix)
@ -474,7 +486,18 @@ func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
label, key = a, b
}
}
name := strings.ReplaceAll(prefix+key, "-", "_")
d := &prometheusMetricDetails{
Name: strings.ReplaceAll(prefix+key, "-", "_"),
Type: typ,
Label: label,
}
prometheusMetricCache.Store(cachekey, d)
return d.Name, d.Type, d.Label
}
func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
key := kv.Key
name, typ, label := prometheusMetric(prefix, key)
switch v := kv.Value.(type) {
case PrometheusVar: