promx

Documentation

Overview

Package promx implements obsx.MetricsProvider on top of prometheus/client_golang, preserving labels (the expvar default discards them) with a per-metric series-cardinality cap, and exposes the scrape handler mounted by generated servers at the authenticated /metrics endpoint. Values recorded through ObserveHistogram are milliseconds (matching pkg/obsx's latency buckets).

Concurrency: the steady-state IncCounter/ObserveHistogram hot path is lock-free, mirroring the sibling ExpvarMetrics in pkg/obsx/metrics.go. Each metric name's *vecState is cached in a sync.Map, so a call for an already-registered name does a lock-free Load rather than taking a provider-wide lock; unrelated metric names never contend. A mutex is reserved only for the cold path (first-ever registration of a name). Per-vec cardinality-cap bookkeeping is likewise lock-free once a series is admitted (or once the cap is reached); a tiny per-vec lock guards only the check-and-admit window so the cap holds EXACTLY under concurrent first-time-series admission. Leaf-metric writes delegate to client_golang's own internal RWMutex (MetricVec/Registry), which is already concurrency-safe, so promx does not layer its own lock on top. Code generated by apic; DO NOT EDIT.

Index

• type Config
• type Provider
  • func New(cfg Config) (*Provider, error)
  • func (p *Provider) Handler() http.Handler
  • func (p *Provider) IncCounter(name string, labels map[string]string)
  • func (p *Provider) ObserveHistogram(name string, value float64, labels map[string]string)
  • func (p *Provider) Registry() *prometheus.Registry
  • func (p *Provider) WantsLabels() bool

Types

type Config

type Config struct {
	// Namespace optionally prefixes every metric (prom "namespace_" form).
	Namespace string
	// Registry lets callers supply their own; nil creates a fresh one.
	Registry *prometheus.Registry
	// MaxSeriesPerMetric caps label cardinality per metric (default 500).
	MaxSeriesPerMetric int
	// Buckets overrides histogram buckets (default: obsx ms buckets).
	Buckets []float64
	// DisableGoCollector skips the go/process runtime collectors (tests).
	DisableGoCollector bool
}

Config configures the provider. The zero value is production-ready.

type Provider

type Provider struct {
	// contains filtered or unexported fields
}

Provider is a label-preserving Prometheus MetricsProvider.

func New

func New(cfg Config) (*Provider, error)

New builds a Provider and registers the runtime collectors.

func (*Provider) Handler

func (p *Provider) Handler() http.Handler

Handler returns the Prometheus scrape handler for this provider's registry. Mount it ONLY behind authentication.

func (*Provider) IncCounter

func (p *Provider) IncCounter(name string, labels map[string]string)

IncCounter implements obsx.MetricsProvider.

func (*Provider) ObserveHistogram

func (p *Provider) ObserveHistogram(name string, value float64, labels map[string]string)

ObserveHistogram implements obsx.MetricsProvider.

func (*Provider) Registry

func (p *Provider) Registry() *prometheus.Registry

Registry exposes the underlying registry (custom collectors).

func (*Provider) WantsLabels

func (p *Provider) WantsLabels() bool

WantsLabels reports that this provider consumes label maps (unlike the default expvar provider, which discards them). obsx's Emit* helpers use this capability check to skip building a per-call label map when the active provider would only throw it away.