Level sets dependency graph to consume etcd 3.1.5

vendor/golang.org/x/net/trace/trace.go

@@ -91,7 +91,7 @@ var DebugUseAfterFinish = false
 // It returns two bools; the first indicates whether the page may be viewed at all,
 // and the second indicates whether sensitive events will be shown.
 //
-// AuthRequest may be replaced by a program to customise its authorisation requirements.
+// AuthRequest may be replaced by a program to customize its authorization requirements.
 //
 // The default AuthRequest function returns (true, true) if and only if the request
 // comes from localhost/127.0.0.1/[::1].
@@ -238,7 +238,7 @@ func Render(w io.Writer, req *http.Request, sensitive bool) {
 
 	completedMu.RLock()
 	defer completedMu.RUnlock()
-	if err := pageTmpl.ExecuteTemplate(w, "Page", data); err != nil {
+	if err := pageTmpl().ExecuteTemplate(w, "Page", data); err != nil {
 		log.Printf("net/trace: Failed executing template: %v", err)
 	}
 }
@@ -333,7 +333,8 @@ func New(family, title string) Trace {
 	tr.ref()
 	tr.Family, tr.Title = family, title
 	tr.Start = time.Now()
-	tr.events = make([]event, 0, maxEventsPerTrace)
+	tr.maxEvents = maxEventsPerTrace
+	tr.events = tr.eventsBuf[:0]
 
 	activeMu.RLock()
 	s := activeTraces[tr.Family]
@@ -650,8 +651,8 @@ type event struct {
 	Elapsed    time.Duration // since previous event in trace
 	NewDay     bool          // whether this event is on a different day to the previous event
 	Recyclable bool          // whether this event was passed via LazyLog
-	What       interface{}   // string or fmt.Stringer
 	Sensitive  bool          // whether this event contains sensitive information
+	What       interface{}   // string or fmt.Stringer
 }
 
 // WhenString returns a string representation of the elapsed time of the event.
@@ -692,14 +693,17 @@ type trace struct {
 	IsError bool
 
 	// Append-only sequence of events (modulo discards).
-	mu     sync.RWMutex
-	events []event
+	mu        sync.RWMutex
+	events    []event
+	maxEvents int
 
 	refs     int32 // how many buckets this is in
 	recycler func(interface{})
 	disc     discarded // scratch space to avoid allocation
 
 	finishStack []byte // where finish was called, if DebugUseAfterFinish is set
+
+	eventsBuf [4]event // preallocated buffer in case we only log a few events
 }
 
 func (tr *trace) reset() {
@@ -711,11 +715,15 @@ func (tr *trace) reset() {
 	tr.traceID = 0
 	tr.spanID = 0
 	tr.IsError = false
+	tr.maxEvents = 0
 	tr.events = nil
 	tr.refs = 0
 	tr.recycler = nil
 	tr.disc = 0
 	tr.finishStack = nil
+	for i := range tr.eventsBuf {
+		tr.eventsBuf[i] = event{}
+	}
 }
 
 // delta returns the elapsed time since the last event or the trace start,
@@ -744,7 +752,7 @@ func (tr *trace) addEvent(x interface{}, recyclable, sensitive bool) {
 		and very unlikely to be the fault of this code.
 
 		The most likely scenario is that some code elsewhere is using
-		a requestz.Trace after its Finish method is called.
+		a trace.Trace after its Finish method is called.
 		You can temporarily set the DebugUseAfterFinish var
 		to help discover where that is; do not leave that var set,
 		since it makes this package much less efficient.
@@ -753,11 +761,11 @@ func (tr *trace) addEvent(x interface{}, recyclable, sensitive bool) {
 	e := event{When: time.Now(), What: x, Recyclable: recyclable, Sensitive: sensitive}
 	tr.mu.Lock()
 	e.Elapsed, e.NewDay = tr.delta(e.When)
-	if len(tr.events) < cap(tr.events) {
+	if len(tr.events) < tr.maxEvents {
 		tr.events = append(tr.events, e)
 	} else {
 		// Discard the middle events.
-		di := int((cap(tr.events) - 1) / 2)
+		di := int((tr.maxEvents - 1) / 2)
 		if d, ok := tr.events[di].What.(*discarded); ok {
 			(*d)++
 		} else {
@@ -777,7 +785,7 @@ func (tr *trace) addEvent(x interface{}, recyclable, sensitive bool) {
 			go tr.recycler(tr.events[di+1].What)
 		}
 		copy(tr.events[di+1:], tr.events[di+2:])
-		tr.events[cap(tr.events)-1] = e
+		tr.events[tr.maxEvents-1] = e
 	}
 	tr.mu.Unlock()
 }
@@ -803,7 +811,7 @@ func (tr *trace) SetTraceInfo(traceID, spanID uint64) {
 func (tr *trace) SetMaxEvents(m int) {
 	// Always keep at least three events: first, discarded count, last.
 	if len(tr.events) == 0 && m > 3 {
-		tr.events = make([]event, 0, m)
+		tr.maxEvents = m
 	}
 }
 
@@ -894,10 +902,18 @@ func elapsed(d time.Duration) string {
 	return string(b)
 }
 
-var pageTmpl = template.Must(template.New("Page").Funcs(template.FuncMap{
-	"elapsed": elapsed,
-	"add":     func(a, b int) int { return a + b },
-}).Parse(pageHTML))
+var pageTmplCache *template.Template
+var pageTmplOnce sync.Once
+
+func pageTmpl() *template.Template {
+	pageTmplOnce.Do(func() {
+		pageTmplCache = template.Must(template.New("Page").Funcs(template.FuncMap{
+			"elapsed": elapsed,
+			"add":     func(a, b int) int { return a + b },
+		}).Parse(pageHTML))
+	})
+	return pageTmplCache
+}
 
 const pageHTML = `
 {{template "Prolog" .}}