67 lines
1.5 KiB
Go
67 lines
1.5 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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"net/http"
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"sort"
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"sync"
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)
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// collector 是 Counter / Gauge / Histogram 共同实现的内部接口。
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type collector interface {
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collect(w io.Writer)
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}
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// Registry 持有已注册的全部指标,提供 Prometheus 文本格式导出。
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type Registry struct {
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mu sync.RWMutex
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entries map[string]collector
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order []string // 保留注册顺序,使输出可预测
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}
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func newRegistry() *Registry {
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return &Registry{
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entries: make(map[string]collector),
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}
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}
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func (r *Registry) register(name string, c collector) error {
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r.mu.Lock()
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defer r.mu.Unlock()
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if _, exists := r.entries[name]; exists {
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return fmt.Errorf("metric %q already registered", name)
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}
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r.entries[name] = c
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r.order = append(r.order, name)
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return nil
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}
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// Gather 把所有指标按注册顺序写入 w,文本格式遵循 Prometheus 0.0.4。
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func (r *Registry) Gather(w io.Writer) error {
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r.mu.RLock()
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order := append([]string(nil), r.order...)
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defer r.mu.RUnlock()
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for _, name := range order {
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r.entries[name].collect(w)
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}
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return nil
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}
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// Handler 返回标准 Prometheus 抓取端点。
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func (r *Registry) Handler() http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
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w.Header().Set("Content-Type", "text/plain; version=0.0.4; charset=utf-8")
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_ = r.Gather(w)
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})
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}
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// 注册顺序的辅助,用于测试断言。
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func (r *Registry) names() []string {
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r.mu.RLock()
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defer r.mu.RUnlock()
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out := append([]string(nil), r.order...)
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sort.Strings(out)
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return out
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}
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