lib/periodic: add function to inject metrics in task (#4204)

Add StartWithMetrics function to the periodic task library to have full control over the metrics that are exposed by the library.

gateway/gateway.go

@@ -314,7 +314,7 @@ func (g *Gateway) Run(ctx context.Context) error {
 	}
 	revStore := &pathhealth.MemoryRevocationStore{}
 
-	// periodicly clean up the revocation store.
+	// periodically clean up the revocation store.
 	revCleaner := periodic.Start(periodic.Func{
 		Task: func(ctx context.Context) {
 			revStore.Cleanup(ctx)

private/periodic/BUILD.bazel

@@ -7,6 +7,7 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//pkg/log:go_default_library",
+        "//pkg/metrics:go_default_library",
         "//private/periodic/internal/metrics:go_default_library",
         "@com_github_opentracing_opentracing_go//:go_default_library",
     ],
@@ -15,8 +16,9 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = ["periodic_test.go"],
-    embed = [":go_default_library"],
     deps = [
+        ":go_default_library",
+        "//pkg/metrics:go_default_library",
         "//pkg/private/xtest:go_default_library",
         "@com_github_stretchr_testify//assert:go_default_library",
     ],

private/periodic/internal/metrics/BUILD.bazel

@@ -1,25 +1,13 @@
-load("//tools/lint:go.bzl", "go_library", "go_test")
+load("//tools/lint:go.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
     srcs = ["metrics.go"],
     importpath = "github.com/scionproto/scion/private/periodic/internal/metrics",
     visibility = ["//visibility:public"],
     deps = [
-        "//pkg/private/prom:go_default_library",
+        "//pkg/metrics:go_default_library",
         "@com_github_iancoleman_strcase//:go_default_library",
         "@com_github_prometheus_client_golang//prometheus:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    srcs = ["metrics_test.go"],
-    embed = [":go_default_library"],
-    deps = [
-        "//pkg/private/prom/promtest:go_default_library",
-        "@com_github_prometheus_client_golang//prometheus/testutil:go_default_library",
-        "@com_github_stretchr_testify//assert:go_default_library",
-        "@com_github_stretchr_testify//require:go_default_library",
-    ],
-)

private/periodic/internal/metrics/metrics.go

@@ -16,113 +16,70 @@ package metrics
 
 import (
 	"strings"
-	"time"
 
 	"github.com/iancoleman/strcase"
 	"github.com/prometheus/client_golang/prometheus"
 
-	"github.com/scionproto/scion/pkg/private/prom"
+	"github.com/scionproto/scion/pkg/metrics"
 )
 
-const (
-	// EventStop indicates a stop event took place.
-	EventStop = "stop"
-	// EventKill indicates a kill event took place.
-	EventKill = "kill"
-	// EventTrigger indicates a trigger event took place.
-	EventTrigger = "triggered"
-)
-
-// ExportMetric is the interface to export periodic metrics.
-type ExportMetric interface {
-	Runtime(time.Duration)
-	StartTimestamp(time.Time)
-	Period(time.Duration)
-	Event(string)
-}
+// Metrics is the standard metrics used in periodic.Runner
 
-// NewMetric returns the ExportMetric to be used for the exporting metrics.
-func NewMetric(prefix string) ExportMetric {
-	return newExporter(prefix)
+// Deprecated: Metrics is used only in the deprecated function periodic.Start
+// which exists only for compatibility reasons. Use periodic.StartWithMetrics
+// along with periodic.Metrics instead.
+type Metrics struct {
+	Events    func(string) metrics.Counter
+	Runtime   metrics.Gauge
+	Timestamp metrics.Gauge
+	Period    metrics.Gauge
 }
 
-type exporter struct {
-	events            *prometheus.CounterVec
-	runtime           prometheus.Counter
-	timestamp, period prometheus.Gauge
-}
-
-func newExporter(prefix string) exporter {
+func NewMetric(prefix string) Metrics {
 	namespace := strcase.ToSnake(strings.Replace(prefix, ".", "_", -1))
 	subsystem := "periodic"
 
-	events := prom.NewCounterVecWithLabels(namespace, subsystem, "event_total",
-		"Total number of events.", EventLabels{EventTrigger})
-
-	runtime := prom.SafeRegister(
-		prometheus.NewCounter(prometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: subsystem,
-			Name:      "runtime_duration_seconds_total",
-			Help:      "Total time spend on every periodic run.",
-		}),
-	).(prometheus.Counter)
-
-	timestamp := prom.SafeRegister(
-		prometheus.NewGauge(prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: subsystem,
-			Name:      "runtime_timestamp_seconds",
-			Help:      "The unix timestamp when the periodic run started.",
-		}),
-	).(prometheus.Gauge)
-
-	period := prom.SafeRegister(
-		prometheus.NewGauge(prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: subsystem,
-			Name:      "period_duration_seconds",
-			Help:      "The period of this job.",
-		}),
-	).(prometheus.Gauge)
-
-	return exporter{
-		events:    events,
-		runtime:   runtime,
-		timestamp: timestamp,
-		period:    period,
+	events := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: namespace,
+		Subsystem: subsystem,
+		Name:      "event_total",
+		Help:      "Total number of events.",
+	},
+		[]string{"event_type"},
+	)
+
+	runtime := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: namespace,
+		Subsystem: subsystem,
+		Name:      "runtime_duration_seconds_total",
+		Help:      "Total time spend on every periodic run.",
+	},
+		[]string{},
+	)
+
+	timestamp := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: namespace,
+		Subsystem: subsystem,
+		Name:      "runtime_timestamp_seconds",
+		Help:      "The unix timestamp when the periodic run started.",
+	},
+		[]string{},
+	)
+	period := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: namespace,
+		Subsystem: subsystem,
+		Name:      "period_duration_seconds",
+		Help:      "The period of this job.",
+	},
+		[]string{},
+	)
+
+	return Metrics{
+		Events: func(s string) metrics.Counter {
+			return metrics.NewPromCounter(events).With("event_type", s)
+		},
+		Runtime:   metrics.NewPromGauge(runtime),
+		Timestamp: metrics.NewPromGauge(timestamp),
+		Period:    metrics.NewPromGauge(period),
 	}
 }
-
-func (e exporter) StartTimestamp(t time.Time) {
-	e.timestamp.Set(float64(t.UnixNano() / 1e9))
-}
-
-func (e exporter) Period(d time.Duration) {
-	e.period.Set(d.Seconds())
-}
-
-func (e exporter) Runtime(d time.Duration) {
-	e.runtime.Add(float64(d) / 1e9)
-}
-
-func (e exporter) Event(s string) {
-	l := EventLabels{s}
-	e.events.WithLabelValues(l.Values()...).Inc()
-}
-
-// EventLabels is used by clients to pass in a safe way labels
-// values to prometheus metric types (e.g. counter).
-type EventLabels struct {
-	eventType string
-}
-
-// Labels returns the name of the labels in correct order.
-func (l EventLabels) Labels() []string {
-	return []string{"event_type"}
-}
-
-// Values returns the values of the label in correct order.
-func (l EventLabels) Values() []string {
-	return []string{l.eventType}
-}