client_golang/prometheus/go_collector.go

package prometheus

import (
	"fmt"
	"runtime"
	"runtime/debug"
	"time"
)

type goCollector struct {
	goroutines Gauge
	gcDesc     *Desc

	// memstats object to reuse
	ms *runtime.MemStats
	// metrics to describe and collect
	metrics memStatsMetrics
}

// NewGoCollector returns a collector which exports metrics about the current
// go process.
func NewGoCollector() *goCollector {
	return &goCollector{
		ms: new(runtime.MemStats),
		goroutines: NewGauge(GaugeOpts{
			Namespace: "go",
			Name:      "goroutines",
			Help:      "Number of goroutines that currently exist.",
		}),
		gcDesc: NewDesc(
			"go_gc_duration_seconds",
			"A summary of the GC invocation durations.",
			nil, nil),
		metrics: memStatsMetrics{
			{
				desc: NewDesc(
					memstatNamespace("alloc_bytes"),
					"Number of bytes allocated and still in use.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Alloc) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("alloc_bytes_total"),
					"Total number of bytes allocated, even if freed.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.TotalAlloc) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("sys_bytes"),
					"Number of bytes obtained from system",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Sys) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("lookups_total"),
					"Total number of pointer lookups.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Lookups) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("mallocs_total"),
					"Total number of mallocs.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Mallocs) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("frees_total"),
					"Total number of frees.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Frees) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_alloc_bytes"),
					"Number heap bytes allocated and still in use.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapAlloc) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_sys_bytes"),
					"Total bytes in heap obtained from system.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_idle_bytes"),
					"Number bytes in heap waiting to be used.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapIdle) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_inuse_bytes"),
					"Number of bytes in heap that are in use.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapInuse) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_released_bytes"),
					"Number of bytes in heap released to OS.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapReleased) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("heap_objects"),
					"Number of allocated objects.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapObjects) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("stack_bytes_inuse"),
					"Number of bytes in use by the stack allocator.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackInuse) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("stack_sys_bytes"),
					"Number of bytes in obtained from system for stack allocator.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("mspan_inuse"),
					"Number of mspan structures in use.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanInuse) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("mspan_sys"),
					"Number of mspan structures obtained from system.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("mcache_inuse"),
					"Number of mcache structures in use.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheInuse) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("mcache_sys"),
					"Number of mcache structures obtained from system.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("buck_hash_sys"),
					"Profiling bucket hash table.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.BuckHashSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("gc_metadata"),
					"GC metadata.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.GCSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("other_sys"),
					"Other system allocations.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.OtherSys) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("next_gc"),
					"Next collection will happen when HeapAlloc ≥ this amount.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.NextGC) },
				valType: GaugeValue,
			}, {
				desc: NewDesc(
					memstatNamespace("last_gc"),
					"End time of last garbage collection (nanoseconds since 1970).",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.LastGC) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("pause_total"),
					"Total garbage collection pauses for all collections.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.PauseTotalNs) },
				valType: CounterValue,
			}, {
				desc: NewDesc(
					memstatNamespace("gc_total"),
					"Number of garbage collection.",
					nil, nil,
				),
				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.NumGC) },
				valType: CounterValue,
			},
		},
	}
}

func memstatNamespace(s string) string {
	return fmt.Sprintf("go_memstats_%s", s)
}

// Describe returns all descriptions of the collector.
func (c *goCollector) Describe(ch chan<- *Desc) {
	ch <- c.goroutines.Desc()
	ch <- c.gcDesc

	for _, i := range c.metrics {
		ch <- i.desc
	}
}

// Collect returns the current state of all metrics of the collector.
func (c *goCollector) Collect(ch chan<- Metric) {
	c.goroutines.Set(float64(runtime.NumGoroutine()))
	ch <- c.goroutines

	var stats debug.GCStats
	stats.PauseQuantiles = make([]time.Duration, 5)
	debug.ReadGCStats(&stats)

	quantiles := make(map[float64]float64)
	for idx, pq := range stats.PauseQuantiles[1:] {
		quantiles[float64(idx+1)/float64(len(stats.PauseQuantiles)-1)] = pq.Seconds()
	}
	quantiles[0.0] = stats.PauseQuantiles[0].Seconds()
	ch <- MustNewConstSummary(c.gcDesc, uint64(stats.NumGC), float64(stats.PauseTotal.Seconds()), quantiles)

	runtime.ReadMemStats(c.ms)
	for _, i := range c.metrics {
		ch <- MustNewConstMetric(i.desc, i.valType, i.eval(c.ms))
	}
}

// memStatsMetrics provide description, value, and value type for memstat metrics
type memStatsMetrics []struct {
	desc    *Desc
	eval    func(*runtime.MemStats) float64
	valType ValueType
}