97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
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package telemetry
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import (
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"fmt"
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"io"
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"sort"
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"sync"
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"sync/atomic"
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)
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// Gauge 可增可减的瞬时值。
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type Gauge struct {
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metricName string
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help string
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labelNames []string
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mu sync.RWMutex
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values map[string]*gaugeChild
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}
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type gaugeChild struct {
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labels Labels
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bits atomic.Uint64
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}
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func newGauge(name, help string, labelNames []string) *Gauge {
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return &Gauge{
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metricName: name,
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help: help,
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labelNames: append([]string(nil), labelNames...),
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values: make(map[string]*gaugeChild),
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}
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}
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// Set 直接设置当前值。
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func (g *Gauge) Set(v float64, labels Labels) {
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child := g.getOrCreate(labels)
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child.bits.Store(float64bits(v))
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}
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// Inc +1。
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func (g *Gauge) Inc(labels Labels) { g.Add(1, labels) }
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// Dec -1。
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func (g *Gauge) Dec(labels Labels) { g.Add(-1, labels) }
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// Add 累加 v(可负)。
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func (g *Gauge) Add(v float64, labels Labels) {
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child := g.getOrCreate(labels)
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for {
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bits := child.bits.Load()
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cur := float64frombits(bits)
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next := float64bits(cur + v)
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if child.bits.CompareAndSwap(bits, next) {
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return
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}
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}
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}
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func (g *Gauge) getOrCreate(labels Labels) *gaugeChild {
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key := labelKey(g.labelNames, labels)
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g.mu.RLock()
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if c, ok := g.values[key]; ok {
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g.mu.RUnlock()
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return c
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}
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g.mu.RUnlock()
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g.mu.Lock()
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defer g.mu.Unlock()
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if c, ok := g.values[key]; ok {
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return c
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}
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c := &gaugeChild{labels: copyLabels(labels, g.labelNames)}
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g.values[key] = c
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return c
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}
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func (g *Gauge) collect(w io.Writer) {
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fmt.Fprintf(w, "# HELP %s %s\n", g.metricName, g.help)
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fmt.Fprintf(w, "# TYPE %s gauge\n", g.metricName)
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g.mu.RLock()
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keys := make([]string, 0, len(g.values))
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for k := range g.values {
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keys = append(keys, k)
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}
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sort.Strings(keys)
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defer g.mu.RUnlock()
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for _, k := range keys {
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child := g.values[k]
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val := float64frombits(child.bits.Load())
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writeMetricLine(w, g.metricName, child.labels, val)
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}
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}
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