From 333444b4e17ecc707fefeadaba3bd0e634d59bf0 Mon Sep 17 00:00:00 2001
From: kolaente <k@knt.li>
Date: Fri, 15 May 2020 14:42:32 +0200
Subject: [PATCH] Improve metrics performance

---
 pkg/metrics/active_users.go | 26 ++++++++++++++++++++++----
 pkg/metrics/metrics.go      |  5 +++++
 pkg/routes/metrics.go       | 25 +------------------------
 3 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/pkg/metrics/active_users.go b/pkg/metrics/active_users.go
index e0ae26e78a..2d07f5a5e2 100644
--- a/pkg/metrics/active_users.go
+++ b/pkg/metrics/active_users.go
@@ -19,6 +19,7 @@ package metrics
 import (
 	"bytes"
 	"code.vikunja.io/api/pkg/log"
+	"code.vikunja.io/web"
 	"encoding/gob"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -37,7 +38,15 @@ type ActiveUser struct {
 	LastSeen time.Time
 }
 
+// ActiveUsersMap is the type used to save active users
+type ActiveUsersMap map[int64]*ActiveUser
+
+// activeUsers holds a map with all active users
+var activeUsers ActiveUsersMap
+
 func init() {
+	activeUsers = make(ActiveUsersMap)
+
 	promauto.NewGaugeFunc(prometheus.GaugeOpts{
 		Name: "vikunja_active_users",
 		Help: "The currently active users on this node",
@@ -57,8 +66,17 @@ func init() {
 	})
 }
 
+// SetUserActive sets a user as active and pushes it to redis
+func SetUserActive(a web.Auth) (err error) {
+	activeUsers[a.GetID()] = &ActiveUser{
+		UserID:   a.GetID(),
+		LastSeen: time.Now(),
+	}
+	return PushActiveUsers()
+}
+
 // GetActiveUsers returns the active users from redis
-func GetActiveUsers() (users []*ActiveUser, err error) {
+func GetActiveUsers() (users ActiveUsersMap, err error) {
 
 	activeUsersR, err := r.Get(ActiveUsersKey).Bytes()
 	if err != nil {
@@ -80,11 +98,11 @@ func GetActiveUsers() (users []*ActiveUser, err error) {
 	return
 }
 
-// SetActiveUsers sets the active users from redis
-func SetActiveUsers(users []*ActiveUser) (err error) {
+// PushActiveUsers pushed the content of the activeUsers map to redis
+func PushActiveUsers() (err error) {
 	var b bytes.Buffer
 	e := gob.NewEncoder(&b)
-	if err := e.Encode(users); err != nil {
+	if err := e.Encode(activeUsers); err != nil {
 		return err
 	}
 
diff --git a/pkg/metrics/metrics.go b/pkg/metrics/metrics.go
index 335da531da..715543ef87 100644
--- a/pkg/metrics/metrics.go
+++ b/pkg/metrics/metrics.go
@@ -48,6 +48,11 @@ const (
 func InitMetrics() {
 	r = red.GetRedis()
 
+	// init active users, sometimes we'll have garbage from previous runs in redis instead
+	if err := PushActiveUsers(); err != nil {
+		log.Fatalf("Could not set initial count for active users, error was %s", err)
+	}
+
 	// Register total list count metric
 	promauto.NewGaugeFunc(prometheus.GaugeOpts{
 		Name: "vikunja_list_count",
diff --git a/pkg/routes/metrics.go b/pkg/routes/metrics.go
index 1f811abfbc..a0a9031c79 100644
--- a/pkg/routes/metrics.go
+++ b/pkg/routes/metrics.go
@@ -26,7 +26,6 @@ import (
 	"code.vikunja.io/api/pkg/user"
 	"github.com/labstack/echo/v4"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"time"
 )
 
 func setupMetrics(a *echo.Group) {
@@ -77,11 +76,6 @@ func setupMetrics(a *echo.Group) {
 		}
 	}
 
-	// init active users, sometimes we'll have garbage from previous runs in redis instead
-	if err := metrics.SetActiveUsers([]*metrics.ActiveUser{}); err != nil {
-		log.Fatalf("Could not set initial count for active users, error was %s", err)
-	}
-
 	a.GET("/metrics", echo.WrapHandler(promhttp.Handler()))
 }
 
@@ -110,22 +104,5 @@ func updateActiveUsersFromContext(c echo.Context) (err error) {
 		return
 	}
 
-	allActiveUsers, err := metrics.GetActiveUsers()
-	if err != nil {
-		return
-	}
-
-	var uupdated bool
-	for in, u := range allActiveUsers {
-		if u.UserID == auth.GetID() {
-			allActiveUsers[in].LastSeen = time.Now()
-			uupdated = true
-		}
-	}
-
-	if !uupdated {
-		allActiveUsers = append(allActiveUsers, &metrics.ActiveUser{UserID: auth.GetID(), LastSeen: time.Now()})
-	}
-
-	return metrics.SetActiveUsers(allActiveUsers)
+	return metrics.SetUserActive(auth)
 }