1 files changed, 63 insertions, 0 deletions
diff --git a/modules/caddyhttp/tracing/tracerprovider.go b/modules/caddyhttp/tracing/tracerprovider.go
new file mode 100644
index 0000000..035425e
--- /dev/null
+++ b/modules/caddyhttp/tracing/tracerprovider.go
@@ -0,0 +1,63 @@
+package tracing
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.uber.org/zap"
+)
+
+// globalTracerProvider stores global tracer provider and is responsible for graceful shutdown when nobody is using it.
+var globalTracerProvider = &tracerProvider{}
+
+type tracerProvider struct {
+	mu                     sync.Mutex
+	tracerProvider         *sdktrace.TracerProvider
+	tracerProvidersCounter int
+}
+
+// getTracerProvider create or return an existing global TracerProvider
+func (t *tracerProvider) getTracerProvider(opts ...sdktrace.TracerProviderOption) *sdktrace.TracerProvider {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	t.tracerProvidersCounter++
+
+	if t.tracerProvider == nil {
+		t.tracerProvider = sdktrace.NewTracerProvider(
+			opts...,
+		)
+	}
+
+	return t.tracerProvider
+}
+
+// cleanupTracerProvider gracefully shutdown a TracerProvider
+func (t *tracerProvider) cleanupTracerProvider(logger *zap.Logger) error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if t.tracerProvidersCounter > 0 {
+		t.tracerProvidersCounter--
+	}
+
+	if t.tracerProvidersCounter == 0 {
+		if t.tracerProvider != nil {
+			// tracerProvider.ForceFlush SHOULD be invoked according to https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#forceflush
+			if err := t.tracerProvider.ForceFlush(context.Background()); err != nil {
+				logger.Error("forcing flush", zap.Error(err))
+			}
+
+			// tracerProvider.Shutdown MUST be invoked according to https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#shutdown
+			if err := t.tracerProvider.Shutdown(context.Background()); err != nil {
+				return fmt.Errorf("tracerProvider shutdown error: %w", err)
+			}
+		}
+
+		t.tracerProvider = nil
+	}
+
+	return nil
+}