feat: add customize tracer in extract func and add gomodule

amqptracer/tracer.go

@@ -1,6 +1,7 @@
 package amqptracer
 
 import (
+	"errors"
 	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/streadway/amqp"
 )
@@ -55,3 +56,30 @@ func Extract(hdrs amqp.Table) (opentracing.SpanContext, error) {
 	c := amqpHeadersCarrier(hdrs)
 	return opentracing.GlobalTracer().Extract(opentracing.TextMap, c)
 }
+
+// Extract extracts the span context out of the AMQP header.
+//
+// Example:
+//
+//	func ConsumeMessage(ctx context.Context, msg *amqp.Delivery) error {
+//		// Extract the span context out of the AMQP header.
+//		spCtx, _ := amqptracer.ExtractWithTracer(msg.Headers, tracer)
+//		sp := opentracing.StartSpan(
+//			"ConsumeMessage",
+//			opentracing.FollowsFrom(spCtx),
+//		)
+//		defer sp.Finish()
+//
+//		// Update the context with the span for the subsequent reference.
+//		ctx = opentracing.ContextWithSpan(ctx, sp)
+//
+//		// Actual message processing.
+//		return ProcessMessage(ctx, msg)
+//	}
+func ExtractWithTracer(hdrs amqp.Table, tracer opentracing.Tracer) (opentracing.SpanContext, error) {
+	if tracer == nil {
+		return nil, errors.New("tracer is nil")
+	}
+	c := amqpHeadersCarrier(hdrs)
+	return tracer.Extract(opentracing.TextMap, c)
+}

amqptracer/tracer_test.go

@@ -48,3 +48,19 @@ func TestExtract(t *testing.T) {
 		t.Errorf("Failed to read testprefix-fakeid correctly")
 	}
 }
+
+func TestExtractWithTracer(t *testing.T) {
+	h := map[string]interface{}{}
+	h["NotOT"] = "blah"
+	h["opname"] = "AlsoNotOT"
+	h["testprefix-fakeid"] = "42"
+
+	// Extract the tracing span out from the AMQP header
+	ctx, err := ExtractWithTracer(h, testTracer{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ctx.(testSpanContext).FakeID != 42 {
+		t.Errorf("Failed to read testprefix-fakeid correctly")
+	}
+}

go.mod

@@ -0,0 +1,9 @@
+module github.com/opentracing-contrib/go-amqp
+
+go 1.13
+
+require (
+	github.com/opentracing/opentracing-go v1.1.0
+	github.com/streadway/amqp v0.0.0-20200108173154-1c71cc93ed71
+	github.com/stretchr/testify v1.5.1 // indirect
+)