metrics: Add simple template metrics feature

tpl/template.go

@@ -15,6 +15,7 @@ package tpl
 
 import (
 	"io"
+	"time"
 
 	"text/template/parse"
 
@@ -22,6 +23,7 @@ import (
 	texttemplate "text/template"
 
 	bp "github.com/gohugoio/hugo/bufferpool"
+	"github.com/gohugoio/hugo/metrics"
 )
 
 var (
@@ -66,13 +68,16 @@ type TemplateDebugger interface {
 // TemplateAdapter implements the TemplateExecutor interface.
 type TemplateAdapter struct {
 	Template
+	Metrics metrics.Provider
 }
 
 // Execute executes the current template. The actual execution is performed
 // by the embedded text or html template, but we add an implementation here so
 // we can add a timer for some metrics.
 func (t *TemplateAdapter) Execute(w io.Writer, data interface{}) error {
-	// TODO(moorereason) metrics fmt.Println("Execute:", t.Name())
+	if t.Metrics != nil {
+		defer t.Metrics.MeasureSince(t.Name(), time.Now())
+	}
 	return t.Template.Execute(w, data)
 }