collector.go

package exporter

import (
	"github.com/prometheus/client_golang/prometheus"
	"go.uber.org/zap"
)

const metricsNamespace = "gearman"

type collector struct {
	exporter          *Exporter
	gearman           *gearman
	up                *prometheus.Desc
	versionInfo       *prometheus.Desc
	statusJobs        *prometheus.Desc
	statusJobsRunning *prometheus.Desc
	statusJobsWaiting *prometheus.Desc
	statusWorkers     *prometheus.Desc
}

// based on https://github.com/hnlq715/nginx-vts-exporter/
func newFuncMetric(metricName string, docString string, labels []string) *prometheus.Desc {
	return prometheus.NewDesc(
		prometheus.BuildFQName(metricsNamespace, "", metricName),
		docString, labels, nil,
	)
}

func (e *Exporter) newCollector(g *gearman) *collector {
	return &collector{
		exporter:          e,
		gearman:           g,
		up:                newFuncMetric("up", "is gearman up", []string{}),
		versionInfo:       newFuncMetric("version_info", "gearman version", []string{"version"}),
		statusJobs:        newFuncMetric("jobs", "number of jobs queued or running", []string{"function"}),
		statusJobsRunning: newFuncMetric("jobs_running", "number of running jobs", []string{"function"}),
		statusJobsWaiting: newFuncMetric("jobs_waiting", "number of jobs waiting for an available worker", []string{"function"}),
		statusWorkers:     newFuncMetric("workers", "number of capable workers", []string{"function"}),
	}
}

func (c *collector) Describe(ch chan<- *prometheus.Desc) {
	ch <- c.up
	ch <- c.versionInfo
	ch <- c.statusJobs
	ch <- c.statusJobsRunning
	ch <- c.statusJobsWaiting
	ch <- c.statusWorkers
}

func (c *collector) collectVersion(ch chan<- prometheus.Metric) {
	up := 1.0
	version, err := c.gearman.getVersion()
	if err != nil {
		c.exporter.logger.Error("failed to get gearman version", zap.Error(err))
		up = 0.0
		version = "unknown"
	}
	ch <- prometheus.MustNewConstMetric(
		c.up,
		prometheus.GaugeValue,
		up)

	ch <- prometheus.MustNewConstMetric(
		c.versionInfo,
		prometheus.GaugeValue,
		1,
		version)
}
func (c *collector) collectStatus(ch chan<- prometheus.Metric) {
	s, err := c.gearman.getStatus()
	if err != nil {
		c.exporter.logger.Error("failed to get gearman status", zap.Error(err))
		return
	}

	for k, v := range s {
		ch <- prometheus.MustNewConstMetric(
			c.statusJobs,
			prometheus.GaugeValue,
			float64(v.total),
			k)

		ch <- prometheus.MustNewConstMetric(
			c.statusJobsRunning,
			prometheus.GaugeValue,
			float64(v.running),
			k)

		ch <- prometheus.MustNewConstMetric(
			c.statusJobsWaiting,
			prometheus.GaugeValue,
			float64(v.total-v.running),
			k)

		ch <- prometheus.MustNewConstMetric(
			c.statusWorkers,
			prometheus.GaugeValue,
			float64(v.workers),
			k)
	}
}

func (c *collector) Collect(ch chan<- prometheus.Metric) {
	c.collectVersion(ch)
	c.collectStatus(ch)
}