Efremenko Arhip
dcabfcd0c3
A scrape-time collector reports scimesh_tasks/jobs/workers gauges keyed by status, sourced from cheap GROUP BY queries (StatsRepo), zero-filled across all known statuses so the dashboard shows flat zeros instead of gaps. A failed query yields no samples for that scrape rather than crashing it. Metrics is now built in main so the DB-backed collector can be registered (NewServer takes *metrics.Metrics; nil self-provisions for tests). Grafana dashboard gains a Domain state row: tasks/jobs/workers by status and a queue- depth stat.
67 lines
2.2 KiB
Go
67 lines
2.2 KiB
Go
package metrics
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import (
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"context"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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)
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// Stats is a point-in-time snapshot of the coordinator's domain state: counts of
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// tasks, jobs, and workers keyed by their status. Maps are expected to be
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// zero-filled by the provider so every known status is always present, giving
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// the dashboard flat zero lines instead of gaps.
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type Stats struct {
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Tasks map[string]int
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Jobs map[string]int
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Workers map[string]int
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}
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// StatsFunc returns the current snapshot. It is called on every scrape, so it
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// must be a cheap aggregate query.
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type StatsFunc func(context.Context) (Stats, error)
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// RegisterBusiness registers a collector that reports domain-state gauges
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// (scimesh_tasks/jobs/workers by status) sourced from collect on each scrape.
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// Deriving the gauges at scrape time keeps them fresh without a background
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// goroutine, and a failed query simply yields no samples for that scrape.
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func (m *Metrics) RegisterBusiness(collect StatsFunc) {
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m.reg.MustRegister(&businessCollector{
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collect: collect,
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tasks: prometheus.NewDesc("scimesh_tasks", "Tasks by status.", []string{"status"}, nil),
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jobs: prometheus.NewDesc("scimesh_jobs", "Jobs by status.", []string{"status"}, nil),
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workers: prometheus.NewDesc("scimesh_workers", "Workers by status.", []string{"status"}, nil),
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})
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}
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type businessCollector struct {
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collect StatsFunc
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tasks, jobs, workers *prometheus.Desc
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}
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func (c *businessCollector) Describe(ch chan<- *prometheus.Desc) {
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ch <- c.tasks
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ch <- c.jobs
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ch <- c.workers
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}
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func (c *businessCollector) Collect(ch chan<- prometheus.Metric) {
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// A bounded query so one slow scrape cannot stall Prometheus.
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ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
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defer cancel()
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s, err := c.collect(ctx)
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if err != nil {
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return // no samples this scrape; Prometheus keeps the last value
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}
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emit(ch, c.tasks, s.Tasks)
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emit(ch, c.jobs, s.Jobs)
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emit(ch, c.workers, s.Workers)
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}
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func emit(ch chan<- prometheus.Metric, desc *prometheus.Desc, counts map[string]int) {
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for status, n := range counts {
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ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(n), status)
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}
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}
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