Moved to google.golang.org/genproto/googleapis/api/annotations

Fixes #52

vendor/github.com/go-kit/kit/tracing/opentracing/grpc.go

@@ -0,0 +1,70 @@
+package opentracing
+
+import (
+	"context"
+	"encoding/base64"
+	"strings"
+
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+	"google.golang.org/grpc/metadata"
+
+	"github.com/go-kit/kit/log"
+)
+
+// ToGRPCRequest returns a grpc RequestFunc that injects an OpenTracing Span
+// found in `ctx` into the grpc Metadata. If no such Span can be found, the
+// RequestFunc is a noop.
+func ToGRPCRequest(tracer opentracing.Tracer, logger log.Logger) func(ctx context.Context, md *metadata.MD) context.Context {
+	return func(ctx context.Context, md *metadata.MD) context.Context {
+		if span := opentracing.SpanFromContext(ctx); span != nil {
+			// There's nothing we can do with an error here.
+			if err := tracer.Inject(span.Context(), opentracing.TextMap, metadataReaderWriter{md}); err != nil {
+				logger.Log("err", err)
+			}
+		}
+		return ctx
+	}
+}
+
+// FromGRPCRequest returns a grpc RequestFunc that tries to join with an
+// OpenTracing trace found in `req` and starts a new Span called
+// `operationName` accordingly. If no trace could be found in `req`, the Span
+// will be a trace root. The Span is incorporated in the returned Context and
+// can be retrieved with opentracing.SpanFromContext(ctx).
+func FromGRPCRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) func(ctx context.Context, md metadata.MD) context.Context {
+	return func(ctx context.Context, md metadata.MD) context.Context {
+		var span opentracing.Span
+		wireContext, err := tracer.Extract(opentracing.TextMap, metadataReaderWriter{&md})
+		if err != nil && err != opentracing.ErrSpanContextNotFound {
+			logger.Log("err", err)
+		}
+		span = tracer.StartSpan(operationName, ext.RPCServerOption(wireContext))
+		return opentracing.ContextWithSpan(ctx, span)
+	}
+}
+
+// A type that conforms to opentracing.TextMapReader and
+// opentracing.TextMapWriter.
+type metadataReaderWriter struct {
+	*metadata.MD
+}
+
+func (w metadataReaderWriter) Set(key, val string) {
+	key = strings.ToLower(key)
+	if strings.HasSuffix(key, "-bin") {
+		val = string(base64.StdEncoding.EncodeToString([]byte(val)))
+	}
+	(*w.MD)[key] = append((*w.MD)[key], val)
+}
+
+func (w metadataReaderWriter) ForeachKey(handler func(key, val string) error) error {
+	for k, vals := range *w.MD {
+		for _, v := range vals {
+			if err := handler(k, v); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}