Merge pull request #358 from bobrik/ivan/propagation-args

Add a helper to extract tracing propagation args

Author: bobrik

tracing/demos/args.go

@@ -0,0 +1,19 @@
+package demos
+
+import (
+	"github.com/cloudflare/ebpf_exporter/v2/util"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// PropagationArgs returns traceID split into two big-endian u64 and a big-endian u64 spanID,
+// which is the expected format to pass tracing information into the kernel for later decoding
+// as hex decoder on the output side.
+func PropagationArgs(span trace.Span) (uint64, uint64, uint64) {
+	byteOrder := util.GetHostByteOrder()
+
+	spanContext := span.SpanContext()
+	traceID := spanContext.TraceID()
+	spanID := spanContext.SpanID()
+
+	return byteOrder.Uint64(traceID[0:8]), byteOrder.Uint64(traceID[8:16]), byteOrder.Uint64(spanID[0:8])
+}

tracing/demos/cfs-throttling/stitch.go

@@ -16,20 +16,17 @@ void cfs_clear_parent_span()
 */
 import "C"
 import (
-	"github.com/cloudflare/ebpf_exporter/v2/util"
+	"github.com/cloudflare/ebpf_exporter/v2/tracing/demos"
 	"go.opentelemetry.io/otel/trace"
 )
 
 func cfsSetParentSpan(span trace.Span) {
-	byteOrder := util.GetHostByteOrder()
-
-	traceID := span.SpanContext().TraceID()
-	spanID := span.SpanContext().SpanID()
+	traceIDHi, traceIDLo, spanID := demos.PropagationArgs(span)
 
 	C.cfs_set_parent_span(
-		C.uint64_t(byteOrder.Uint64(traceID[0:8])),
-		C.uint64_t(byteOrder.Uint64(traceID[8:16])),
-		C.uint64_t(byteOrder.Uint64(spanID[0:8])),
+		C.uint64_t(traceIDHi),
+		C.uint64_t(traceIDLo),
+		C.uint64_t(spanID),
 	)
 }
 

tracing/demos/sched/stitch.go

@@ -16,20 +16,17 @@ void sched_clear_parent_span()
 */
 import "C"
 import (
-	"github.com/cloudflare/ebpf_exporter/v2/util"
+	"github.com/cloudflare/ebpf_exporter/v2/tracing/demos"
 	"go.opentelemetry.io/otel/trace"
 )
 
 func schedSetParentSpan(span trace.Span) {
-	byteOrder := util.GetHostByteOrder()
-
-	traceID := span.SpanContext().TraceID()
-	spanID := span.SpanContext().SpanID()
+	traceIDHi, traceIDLo, spanID := demos.PropagationArgs(span)
 
 	C.sched_set_parent_span(
-		C.uint64_t(byteOrder.Uint64(traceID[0:8])),
-		C.uint64_t(byteOrder.Uint64(traceID[8:16])),
-		C.uint64_t(byteOrder.Uint64(spanID[0:8])),
+		C.uint64_t(traceIDHi),
+		C.uint64_t(traceIDLo),
+		C.uint64_t(spanID),
 	)
 }
 

tracing/demos/sock/stitch.go

@@ -16,7 +16,7 @@ void sock_set_parent_span(int sock_fd, uint64_t trace_id_hi, uint64_t trace_id_l
 */
 import "C"
 import (
-	"github.com/cloudflare/ebpf_exporter/v2/util"
+	"github.com/cloudflare/ebpf_exporter/v2/tracing/demos"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -25,15 +25,12 @@ func enableKernelTracing() {
 }
 
 func sockSentParentSpan(fd uintptr, span trace.Span) {
-	byteOrder := util.GetHostByteOrder()
-
-	traceID := span.SpanContext().TraceID()
-	spanID := span.SpanContext().SpanID()
+	traceIDHi, traceIDLo, spanID := demos.PropagationArgs(span)
 
 	C.sock_set_parent_span(
 		C.int(fd),
-		C.uint64_t(byteOrder.Uint64(traceID[0:8])),
-		C.uint64_t(byteOrder.Uint64(traceID[8:16])),
-		C.uint64_t(byteOrder.Uint64(spanID[0:8])),
+		C.uint64_t(traceIDHi),
+		C.uint64_t(traceIDLo),
+		C.uint64_t(spanID),
 	)
 }