Added integration support for DataDog APM Tracing

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/internal/globaltracer.go

@@ -0,0 +1,94 @@
+package internal // import "gopkg.in/DataDog/dd-trace-go.v1/ddtrace/internal"
+
+import (
+	"sync"
+
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
+)
+
+var (
+	mu           sync.RWMutex   // guards globalTracer
+	globalTracer ddtrace.Tracer = &NoopTracer{}
+)
+
+// SetGlobalTracer sets the global tracer to t.
+func SetGlobalTracer(t ddtrace.Tracer) {
+	mu.Lock()
+	defer mu.Unlock()
+	globalTracer = t
+}
+
+// GetGlobalTracer returns the currently active tracer.
+func GetGlobalTracer() ddtrace.Tracer {
+	mu.RLock()
+	defer mu.RUnlock()
+	return globalTracer
+}
+
+// Testing is set to true when the mock tracer is active. It usually signifies that we are in a test
+// environment. This value is used by tracer.Start to prevent overriding the GlobalTracer in tests.
+var Testing = false
+
+var _ ddtrace.Tracer = (*NoopTracer)(nil)
+
+// NoopTracer is an implementation of ddtrace.Tracer that is a no-op.
+type NoopTracer struct{}
+
+// StartSpan implements ddtrace.Tracer.
+func (NoopTracer) StartSpan(operationName string, opts ...ddtrace.StartSpanOption) ddtrace.Span {
+	return NoopSpan{}
+}
+
+// SetServiceInfo implements ddtrace.Tracer.
+func (NoopTracer) SetServiceInfo(name, app, appType string) {}
+
+// Extract implements ddtrace.Tracer.
+func (NoopTracer) Extract(carrier interface{}) (ddtrace.SpanContext, error) {
+	return NoopSpanContext{}, nil
+}
+
+// Inject implements ddtrace.Tracer.
+func (NoopTracer) Inject(context ddtrace.SpanContext, carrier interface{}) error { return nil }
+
+// Stop implements ddtrace.Tracer.
+func (NoopTracer) Stop() {}
+
+var _ ddtrace.Span = (*NoopSpan)(nil)
+
+// NoopSpan is an implementation of ddtrace.Span that is a no-op.
+type NoopSpan struct{}
+
+// SetTag implements ddtrace.Span.
+func (NoopSpan) SetTag(key string, value interface{}) {}
+
+// SetOperationName implements ddtrace.Span.
+func (NoopSpan) SetOperationName(operationName string) {}
+
+// BaggageItem implements ddtrace.Span.
+func (NoopSpan) BaggageItem(key string) string { return "" }
+
+// SetBaggageItem implements ddtrace.Span.
+func (NoopSpan) SetBaggageItem(key, val string) {}
+
+// Finish implements ddtrace.Span.
+func (NoopSpan) Finish(opts ...ddtrace.FinishOption) {}
+
+// Tracer implements ddtrace.Span.
+func (NoopSpan) Tracer() ddtrace.Tracer { return NoopTracer{} }
+
+// Context implements ddtrace.Span.
+func (NoopSpan) Context() ddtrace.SpanContext { return NoopSpanContext{} }
+
+var _ ddtrace.SpanContext = (*NoopSpanContext)(nil)
+
+// NoopSpanContext is an implementation of ddtrace.SpanContext that is a no-op.
+type NoopSpanContext struct{}
+
+// SpanID implements ddtrace.SpanContext.
+func (NoopSpanContext) SpanID() uint64 { return 0 }
+
+// TraceID implements ddtrace.SpanContext.
+func (NoopSpanContext) TraceID() uint64 { return 0 }
+
+// ForeachBaggageItem implements ddtrace.SpanContext.
+func (NoopSpanContext) ForeachBaggageItem(handler func(k, v string) bool) {}