dashboard/app: add memcache to admin interface

Add memcache statistics and flush action to the admin page
in preparation for actually using memcache in future commits.

2 files changed, 48 insertions, 8 deletions

diff --git a/dashboard/app/admin.html b/dashboard/app/admin.html
index 172070821..bce5d2cda 100644
--- a/dashboard/app/admin.html
+++ b/dashboard/app/admin.html
@@ -22,6 +22,30 @@ Main page.
 	</script>
 	<br><br>
 
+	{{with $.MemcacheStats}}
+	<table class="list_table">
+		<caption><a href="https://pkg.go.dev/google.golang.org/appengine/memcache?tab=doc#Item" target="_blank">Memcache stats:</a></caption>
+		<tr>
+			<th>Hits</th>
+			<th>Misses</th>
+			<th>ByteHits</th>
+			<th>Items</th>
+			<th>Bytes</th>
+			<th>Oldest</th>
+			<th></th>
+		</tr>
+		<tr>
+			<td class="stat">{{.Hits}}</td>
+			<td class="stat">{{.Misses}}</td>
+			<td class="stat">{{.ByteHits}}</td>
+			<td class="stat">{{.Items}}</td>
+			<td class="stat">{{.Bytes}}</td>
+			<td class="stat">{{.Oldest}}</td>
+			<td><a href="?action=memcache_flush">flush</input></td>
+		</tr>
+	</table>
+	{{end}}
+
 	{{template "manager_list" $.Managers}}
 	{{template "job_list" $.Jobs}}
 </body>
diff --git a/dashboard/app/main.go b/dashboard/app/main.go
index 1039d230b..270a1750b 100644
--- a/dashboard/app/main.go
+++ b/dashboard/app/main.go
@@ -19,6 +19,7 @@ import (
 	"golang.org/x/net/context"
 	db "google.golang.org/appengine/datastore"
 	"google.golang.org/appengine/log"
+	"google.golang.org/appengine/memcache"
 )
 
 // This file contains web UI http handlers.
@@ -58,10 +59,11 @@ type uiTerminalPage struct {
 }
 
 type uiAdminPage struct {
-	Header   *uiHeader
-	Log      []byte
-	Managers []*uiManager
-	Jobs     *uiJobList
+	Header        *uiHeader
+	Log           []byte
+	Managers      []*uiManager
+	Jobs          *uiJobList
+	MemcacheStats *memcache.Statistics
 }
 
 type uiManager struct {
@@ -284,10 +286,23 @@ func handleAdmin(c context.Context, w http.ResponseWriter, r *http.Request) erro
 	if accessLevel != AccessAdmin {
 		return ErrAccess
 	}
+	switch action := r.FormValue("action"); action {
+	case "":
+	case "memcache_flush":
+		if err := memcache.Flush(c); err != nil {
+			return fmt.Errorf("failed to flush memcache: %v", err)
+		}
+	default:
+		return fmt.Errorf("unknown action %q", action)
+	}
 	hdr, err := commonHeader(c, r, w, "")
 	if err != nil {
 		return err
 	}
+	memcacheStats, err := memcache.Stats(c)
+	if err != nil {
+		return err
+	}
 	managers, err := loadManagers(c, accessLevel, "")
 	if err != nil {
 		return err
@@ -301,10 +316,11 @@ func handleAdmin(c context.Context, w http.ResponseWriter, r *http.Request) erro
 		return err
 	}
 	data := &uiAdminPage{
-		Header:   hdr,
-		Log:      errorLog,
-		Managers: managers,
-		Jobs:     &uiJobList{Jobs: jobs},
+		Header:        hdr,
+		Log:           errorLog,
+		Managers:      managers,
+		Jobs:          &uiJobList{Jobs: jobs},
+		MemcacheStats: memcacheStats,
 	}
 	return serveTemplate(w, "admin.html", data)
 }