Set internal version once on init, to avoid data race (#114)

Author: RebeccaMahany

traces/traces.go

@@ -14,38 +14,34 @@ import (
 
 const instrumentationPkg = "github.com/osquery/osquery-go"
 
-var internalVersion string
+var (
+	internalVersion string // provides the instrumentation version for attribute `otel.scope.version`
+	tracerProvider  trace.TracerProvider
+)
 
-// osqueryGoVersion returns the version of osquery-go, to be used to set the instrumentation
-// version `otel.scope.version`. It looks through build info to determine the current version
-// of the osquery-go package. Once determined, it saves the version to avoid performing this
-// work again. If the version cannot be determined, the version defaults to the current version,
-// which is hardcoded.
-func osqueryGoVersion() string {
-	if internalVersion != "" {
-		return internalVersion
-	}
+// init sets `internalVersion` and a default tracer provider.
+func init() {
+	// By default, use the global tracer provider, which is a no-op provider.
+	tracerProvider = otel.GetTracerProvider()
+
+	// Look through build info to determine the current version of the osquery-go package.
 	if info, ok := debug.ReadBuildInfo(); ok {
 		for _, dep := range info.Deps {
 			if dep == nil {
 				continue
 			}
 			if dep.Path == instrumentationPkg {
 				internalVersion = dep.Version
-				return internalVersion
+				return
 			}
 		}
 	}
 
-	// Couldn't get the version from runtime build info -- save and return 0.0.0,
+	// Couldn't get the version from runtime build info -- save 0.0.0,
 	// which is the current osquery-go version.
 	internalVersion = "0.0.0"
-	return internalVersion
 }
 
-// By default, use the global tracer provider, which is a no-op provider.
-var tracerProvider = otel.GetTracerProvider()
-
 // SetTracerProvider allows consuming libraries to set a custom/non-global tracer provider.
 func SetTracerProvider(tp trace.TracerProvider) {
 	tracerProvider = tp
@@ -56,7 +52,7 @@ func SetTracerProvider(tp trace.TracerProvider) {
 // not supported by `StartSpan` below -- i.e., any `SpanStartOption` besides
 // `WithAttributes`.
 func OsqueryGoTracer() trace.Tracer {
-	return tracerProvider.Tracer(instrumentationPkg, trace.WithInstrumentationVersion(osqueryGoVersion()))
+	return tracerProvider.Tracer(instrumentationPkg, trace.WithInstrumentationVersion(internalVersion))
 }
 
 // StartSpan is a wrapper around trace.Tracer.Start that simplifies passing in span attributes.

traces/traces_test.go

@@ -0,0 +1,27 @@
+package traces
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTraceInit(t *testing.T) {
+	t.Parallel()
+
+	// Start several spans in quick succession to confirm there's no data race on setting `internalVersion`
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i += 1 {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_, span := StartSpan(context.TODO(), "TestSpan")
+			span.End()
+		}()
+	}
+
+	wg.Wait()
+	assert.NotEmpty(t, internalVersion, "internal version should have been set")
+}