89 lines
1.9 KiB
Go
89 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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"math"
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"strconv"
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"strings"
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)
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// copyLabels 返回只包含 labelNames 中声明的 key 的副本,缺失补空串。
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// 这样序列化时输出顺序和数量固定。
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func copyLabels(labels Labels, names []string) Labels {
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if len(names) == 0 {
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return Labels{}
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}
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out := make(Labels, len(names))
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for _, n := range names {
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out[n] = labels[n]
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}
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return out
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}
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func mergeLabels(a, b Labels) Labels {
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out := make(Labels, len(a)+len(b))
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for k, v := range a {
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out[k] = v
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}
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for k, v := range b {
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out[k] = v
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}
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return out
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}
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// formatLabels 序列化为 `{k1="v1",k2="v2"}`;空集合返回空字符串。
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// value 内的 `\`, `"`, 换行会按 Prometheus 规范转义。
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func formatLabels(labels Labels) string {
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if len(labels) == 0 {
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return ""
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}
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keys := sortedKeys(labels)
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var sb strings.Builder
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sb.WriteByte('{')
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for i, k := range keys {
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if i > 0 {
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sb.WriteByte(',')
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}
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sb.WriteString(k)
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sb.WriteString(`="`)
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sb.WriteString(escapeLabelValue(labels[k]))
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sb.WriteByte('"')
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}
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sb.WriteByte('}')
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return sb.String()
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}
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func escapeLabelValue(v string) string {
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if !strings.ContainsAny(v, "\\\"\n") {
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return v
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}
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var sb strings.Builder
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sb.Grow(len(v) + 2)
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for i := 0; i < len(v); i++ {
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switch v[i] {
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case '\\':
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sb.WriteString(`\\`)
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case '"':
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sb.WriteString(`\"`)
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case '\n':
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sb.WriteString(`\n`)
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default:
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sb.WriteByte(v[i])
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}
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}
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return sb.String()
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}
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func writeMetricLine(w io.Writer, name string, labels Labels, value float64) {
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fmt.Fprintf(w, "%s%s %s\n", name, formatLabels(labels), formatFloat(value))
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}
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func formatFloat(f float64) string {
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return strconv.FormatFloat(f, 'g', -1, 64)
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}
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// float64 bits 互转,封装到独立文件避免重复。
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func float64bits(f float64) uint64 { return math.Float64bits(f) }
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func float64frombits(b uint64) float64 { return math.Float64frombits(b) }
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