Introduce a trace wrapper

This patch introduces a wrapper to golang.org/x/net/trace with a new method
that will be useful later on, making logging and tracing less verbose.

chasquid.go

@@ -19,11 +19,11 @@ import (
 	"blitiri.com.ar/go/chasquid/internal/config"
 	"blitiri.com.ar/go/chasquid/internal/queue"
 	"blitiri.com.ar/go/chasquid/internal/systemd"
+	"blitiri.com.ar/go/chasquid/internal/trace"
 
 	_ "net/http/pprof"
 
 	"github.com/golang/glog"
-	"golang.org/x/net/trace"
 )
 
 var (
@@ -443,7 +443,7 @@ func (c *Conn) RCPT(params string) (code int, msg string) {
 	return 250, "You have an eerie feeling..."
 }
 
-func (c *Conn) DATA(params string, tr trace.Trace) (code int, msg string) {
+func (c *Conn) DATA(params string, tr *trace.Trace) (code int, msg string) {
 	if c.mail_from == "" {
 		return 503, "sender not yet given"
 	}
@@ -500,7 +500,7 @@ func (c *Conn) DATA(params string, tr trace.Trace) (code int, msg string) {
 	return 250, msgs[rand.Int()%len(msgs)]
 }
 
-func (c *Conn) STARTTLS(params string, tr trace.Trace) (code int, msg string) {
+func (c *Conn) STARTTLS(params string, tr *trace.Trace) (code int, msg string) {
 	if c.onTLS {
 		return 503, "You are already wearing that!"
 	}

internal/queue/queue.go

@@ -142,7 +142,6 @@ func (item *Item) SendLoop(q *Queue) {
 			}
 
 			tr.LazyPrintf("%s sending", to)
-			glog.Infof("%s %q -> %q", item.ID, item.From, to)
 
 			// TODO: deliver, serially or in parallel with a waitgroup.
 			// Fake a successful send for now.

internal/trace/trace.go

@@ -0,0 +1,44 @@
+// Package trace extends golang.org/x/net/trace.
+package trace
+
+import (
+	"fmt"
+
+	"github.com/golang/glog"
+	nettrace "golang.org/x/net/trace"
+)
+
+type Trace struct {
+	family string
+	title  string
+	t      nettrace.Trace
+}
+
+func New(family, title string) *Trace {
+	return &Trace{family, title, nettrace.New(family, title)}
+}
+
+func (t *Trace) LazyPrintf(format string, a ...interface{}) {
+	t.t.LazyPrintf(format, a...)
+
+	if glog.V(2) {
+		msg := fmt.Sprintf("%p %s %s: %+q", t, t.family, t.title,
+			fmt.Sprintf(format, a...))
+		glog.InfoDepth(1, msg)
+	}
+}
+
+func (t *Trace) SetError() {
+	t.t.SetError()
+}
+
+func (t *Trace) Errorf(format string, a ...interface{}) error {
+	err := fmt.Errorf(format, a...)
+	t.t.SetError()
+	t.LazyPrintf("Error: %v", err)
+	return err
+}
+
+func (t *Trace) Finish() {
+	t.t.Finish()
+}