add Trace() and always log to stderr

mirko.go

@@ -1,6 +1,7 @@
 package mirko
 
 import (
+	"context"
 	"flag"
 	"fmt"
 	"net"
@@ -23,6 +24,7 @@ var (
 func init() {
 	flag.StringVar(&flagListenAddress, "listen_address", "127.0.0.1:42000", "gRPC listen address")
 	flag.StringVar(&flagDebugAddress, "debug_address", "127.0.0.1:42001", "HTTP debug/status listen address")
+	flag.Set("logtostderr", "true")
 }
 
 type Mirko struct {
@@ -82,6 +84,16 @@ func (m *Mirko) Listen() error {
 	return nil
 }
 
+func (m *Mirko) Trace(ctx context.Context, f string, args ...interface{}) {
+	tr, ok := trace.FromContext(ctx)
+	if !ok {
+		fmtd := fmt.Sprintf(f, args...)
+		glog.Warningf("No trace in %v: %s", ctx, fmtd)
+		return
+	}
+	tr.LazyPrintf(f, args...)
+}
+
 func (m *Mirko) GRPC() *grpc.Server {
 	if m.grpcServer == nil {
 		panic("GRPC() called before Listen()")