mirror of
https://github.com/prometheus/statsd_exporter.git
synced 2025-01-26 22:28:08 +00:00
Break out event handling into its own function
It's idiomatic in go to keep code indentation due to nested loops to a minimum. Decoupling the events handling function into its own function makes it easier to read the code and test the behavior in isolation of the channel handling. It's now also easily possible to process events in parallel without having to touch actual business code. Signed-off-by: Tobias Schmidt <tobidt@gmail.com>
This commit is contained in:
Tobias Schmidt
parent
3b846b33a8
commit
ab844a3f63
1 changed files with 125 additions and 120 deletions
245
exporter.go
245
exporter.go
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@ -253,6 +253,8 @@ func escapeMetricName(metricName string) string {
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return metricName
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}
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// Listen handles all events sent to the given channel sequentially. It
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// terminates when the channel is closed.
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func (b *Exporter) Listen(e <-chan Events) {
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for {
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events, ok := <-e
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@ -261,130 +263,133 @@ func (b *Exporter) Listen(e <-chan Events) {
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return
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}
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for _, event := range events {
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var help string
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metricName := ""
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prometheusLabels := event.Labels()
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mapping, labels, present := b.mapper.GetMapping(event.MetricName(), event.MetricType())
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if mapping == nil {
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mapping = &mapper.MetricMapping{}
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}
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if mapping.Action == mapper.ActionTypeDrop {
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continue
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}
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if mapping.HelpText == "" {
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help = defaultHelp
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} else {
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help = mapping.HelpText
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}
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if present {
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metricName = escapeMetricName(mapping.Name)
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for label, value := range labels {
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prometheusLabels[label] = value
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}
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} else {
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eventsUnmapped.Inc()
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metricName = escapeMetricName(event.MetricName())
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}
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switch ev := event.(type) {
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case *CounterEvent:
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// We don't accept negative values for counters. Incrementing the counter with a negative number
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// will cause the exporter to panic. Instead we will warn and continue to the next event.
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if event.Value() < 0.0 {
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log.Debugf("Counter %q is: '%f' (counter must be non-negative value)", metricName, event.Value())
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eventStats.WithLabelValues("illegal_negative_counter").Inc()
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continue
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}
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counter, err := b.Counters.Get(
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metricName,
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prometheusLabels,
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help,
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)
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if err == nil {
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counter.Add(event.Value())
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eventStats.WithLabelValues("counter").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("counter").Inc()
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}
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case *GaugeEvent:
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gauge, err := b.Gauges.Get(
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metricName,
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prometheusLabels,
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help,
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)
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if err == nil {
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if ev.relative {
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gauge.Add(event.Value())
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} else {
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gauge.Set(event.Value())
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}
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eventStats.WithLabelValues("gauge").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("gauge").Inc()
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}
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case *TimerEvent:
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t := mapper.TimerTypeDefault
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if mapping != nil {
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t = mapping.TimerType
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}
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if t == mapper.TimerTypeDefault {
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t = b.mapper.Defaults.TimerType
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}
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switch t {
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case mapper.TimerTypeHistogram:
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histogram, err := b.Histograms.Get(
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metricName,
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prometheusLabels,
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help,
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mapping,
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)
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if err == nil {
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histogram.Observe(event.Value() / 1000) // prometheus presumes seconds, statsd millisecond
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eventStats.WithLabelValues("timer").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("timer").Inc()
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}
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case mapper.TimerTypeDefault, mapper.TimerTypeSummary:
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summary, err := b.Summaries.Get(
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metricName,
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prometheusLabels,
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help,
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mapping,
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)
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if err == nil {
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summary.Observe(event.Value())
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eventStats.WithLabelValues("timer").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("timer").Inc()
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}
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default:
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panic(fmt.Sprintf("unknown timer type '%s'", t))
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}
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default:
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log.Debugln("Unsupported event type")
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eventStats.WithLabelValues("illegal").Inc()
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}
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b.handleEvent(event)
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}
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}
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}
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// handleEvent processes a single Event according to the configured mapping.
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func (b *Exporter) handleEvent(event Event) {
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mapping, labels, present := b.mapper.GetMapping(event.MetricName(), event.MetricType())
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if mapping == nil {
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mapping = &mapper.MetricMapping{}
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}
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if mapping.Action == mapper.ActionTypeDrop {
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return
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}
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help := defaultHelp
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if mapping.HelpText != "" {
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help = mapping.HelpText
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}
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metricName := ""
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prometheusLabels := event.Labels()
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if present {
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metricName = escapeMetricName(mapping.Name)
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for label, value := range labels {
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prometheusLabels[label] = value
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}
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} else {
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eventsUnmapped.Inc()
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metricName = escapeMetricName(event.MetricName())
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}
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switch ev := event.(type) {
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case *CounterEvent:
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// We don't accept negative values for counters. Incrementing the counter with a negative number
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// will cause the exporter to panic. Instead we will warn and continue to the next event.
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if event.Value() < 0.0 {
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log.Debugf("Counter %q is: '%f' (counter must be non-negative value)", metricName, event.Value())
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eventStats.WithLabelValues("illegal_negative_counter").Inc()
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return
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}
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counter, err := b.Counters.Get(
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metricName,
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prometheusLabels,
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help,
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)
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if err == nil {
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counter.Add(event.Value())
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eventStats.WithLabelValues("counter").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("counter").Inc()
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}
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case *GaugeEvent:
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gauge, err := b.Gauges.Get(
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metricName,
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prometheusLabels,
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help,
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)
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if err == nil {
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if ev.relative {
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gauge.Add(event.Value())
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} else {
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gauge.Set(event.Value())
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}
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eventStats.WithLabelValues("gauge").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("gauge").Inc()
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}
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case *TimerEvent:
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t := mapper.TimerTypeDefault
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if mapping != nil {
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t = mapping.TimerType
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}
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if t == mapper.TimerTypeDefault {
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t = b.mapper.Defaults.TimerType
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}
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switch t {
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case mapper.TimerTypeHistogram:
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histogram, err := b.Histograms.Get(
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metricName,
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prometheusLabels,
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help,
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mapping,
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)
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if err == nil {
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histogram.Observe(event.Value() / 1000) // prometheus presumes seconds, statsd millisecond
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eventStats.WithLabelValues("timer").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("timer").Inc()
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}
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case mapper.TimerTypeDefault, mapper.TimerTypeSummary:
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summary, err := b.Summaries.Get(
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metricName,
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prometheusLabels,
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help,
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mapping,
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)
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if err == nil {
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summary.Observe(event.Value())
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eventStats.WithLabelValues("timer").Inc()
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} else {
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log.Debugf(regErrF, metricName, err)
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conflictingEventStats.WithLabelValues("timer").Inc()
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}
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default:
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panic(fmt.Sprintf("unknown timer type '%s'", t))
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}
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default:
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log.Debugln("Unsupported event type")
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eventStats.WithLabelValues("illegal").Inc()
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}
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}
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func NewExporter(mapper *mapper.MetricMapper) *Exporter {
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return &Exporter{
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Counters: NewCounterContainer(),
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