feat(crontab/middleware): add support for otel protocol tracing (#346)

* feat(crontab/middleware): add support for otel protocol tracing

* feat(crontab/middleware): add support for otel protocol tracing

* feat(crontab/middleware): add support for otel protocol tracing

crontab/middleware/tracing/tracing.go

@@ -0,0 +1,101 @@
+package tracing
+
+import (
+	"context"
+	"time"
+
+	"github.com/flc1125/go-cron/v4"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+)
+
+var scopeName = "github.com/go-kratos-ecosystem/components/v2/crontab/middleware/otel"
+
+var (
+	attrJobName     = attribute.Key("cron.job.name")
+	attrJobID       = attribute.Key("cron.job.id")
+	attrJobPrevTime = attribute.Key("cron.job.prev.time")
+	attrJobNextTime = attribute.Key("cron.job.next.time")
+	attrJobDuration = attribute.Key("cron.job.duration")
+)
+
+type JobWithName interface {
+	cron.Job
+	Name() string
+}
+
+type options struct {
+	tp trace.TracerProvider
+}
+
+type Option func(*options)
+
+func newOptions(opts ...Option) *options {
+	opt := &options{
+		tp: otel.GetTracerProvider(),
+	}
+	for _, o := range opts {
+		o(opt)
+	}
+	return opt
+}
+
+func New(opts ...Option) cron.Middleware {
+	o := newOptions(opts...)
+
+	tracer := o.tp.Tracer(scopeName)
+	return func(original cron.Job) cron.Job {
+		return cron.JobFunc(func(ctx context.Context) (err error) {
+			job, ok := any(original).(JobWithName)
+			if !ok {
+				return original.Run(ctx)
+			}
+
+			// The span is created here, and it will be ended when the job is done.
+			var span trace.Span
+			ctx, span = tracer.Start(ctx, job.Name(),
+				trace.WithSpanKind(trace.SpanKindInternal),
+			)
+			defer span.End()
+			defer func(starting time.Time) {
+				span.SetAttributes(
+					attrJobDuration.String(time.Since(starting).String()),
+				)
+
+				if err != nil {
+					span.RecordError(err)
+					span.SetStatus(codes.Error, err.Error())
+				} else {
+					span.SetStatus(codes.Ok, "")
+				}
+			}(time.Now())
+
+			// Set attributes.
+			span.SetAttributes(append(
+				[]attribute.KeyValue{
+					attrJobName.String(job.Name()),
+				},
+				entryAttributes(ctx)...,
+			)...)
+
+			// The job is run here.
+			err = job.Run(ctx)
+			return
+		})
+	}
+}
+
+func entryAttributes(ctx context.Context) []attribute.KeyValue {
+	entry, ok := cron.EntryFromContext(ctx)
+	if !ok {
+		return []attribute.KeyValue{}
+	}
+
+	return []attribute.KeyValue{
+		attrJobID.Int(int(entry.ID())),
+		attrJobPrevTime.String(entry.Prev().String()),
+		attrJobNextTime.String(entry.Next().String()),
+	}
+}