From 80cf699a732117151dca13c02e6f7fc2ee52343c Mon Sep 17 00:00:00 2001
From: Sam <sam@sam.wf>
Date: Sun, 25 Jun 2023 15:49:19 +0200
Subject: [PATCH] feat(backend): cache user/member counts

---
 backend/db/db.go            |  5 +++++
 backend/db/metrics.go       | 41 +++++++++++++++++++++++++++++++++++++
 backend/routes/meta/meta.go | 27 +-----------------------
 3 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/backend/db/db.go b/backend/db/db.go
index 5f7af5a..13e12f2 100644
--- a/backend/db/db.go
+++ b/backend/db/db.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/url"
 	"os"
+	"sync"
 
 	"codeberg.org/pronounscc/pronouns.cc/backend/log"
 	"emperror.dev/errors"
@@ -41,6 +42,10 @@ type DB struct {
 	baseURL     *url.URL
 
 	TotalRequests prometheus.Counter
+
+	activeUsersDay, activeUsersWeek, activeUsersMonth int64
+	usersTotal, membersTotal                          int64
+	countMu                                           sync.RWMutex
 }
 
 func New() (*DB, error) {
diff --git a/backend/db/metrics.go b/backend/db/metrics.go
index c2a4cf9..e9e34ef 100644
--- a/backend/db/metrics.go
+++ b/backend/db/metrics.go
@@ -21,6 +21,11 @@ func (db *DB) initMetrics() (err error) {
 		if err != nil {
 			log.Errorf("getting user count for metrics: %v", err)
 		}
+
+		db.countMu.Lock()
+		db.usersTotal = count
+		db.countMu.Unlock()
+
 		return float64(count)
 	}))
 	if err != nil {
@@ -35,6 +40,11 @@ func (db *DB) initMetrics() (err error) {
 		if err != nil {
 			log.Errorf("getting member count for metrics: %v", err)
 		}
+
+		db.countMu.Lock()
+		db.membersTotal = count
+		db.countMu.Unlock()
+
 		return float64(count)
 	}))
 	if err != nil {
@@ -49,6 +59,11 @@ func (db *DB) initMetrics() (err error) {
 		if err != nil {
 			log.Errorf("getting active user count for metrics: %v", err)
 		}
+
+		db.countMu.Lock()
+		db.activeUsersMonth = count
+		db.countMu.Unlock()
+
 		return float64(count)
 	}))
 	if err != nil {
@@ -63,6 +78,11 @@ func (db *DB) initMetrics() (err error) {
 		if err != nil {
 			log.Errorf("getting active user count for metrics: %v", err)
 		}
+
+		db.countMu.Lock()
+		db.activeUsersWeek = count
+		db.countMu.Unlock()
+
 		return float64(count)
 	}))
 	if err != nil {
@@ -77,6 +97,11 @@ func (db *DB) initMetrics() (err error) {
 		if err != nil {
 			log.Errorf("getting active user count for metrics: %v", err)
 		}
+
+		db.countMu.Lock()
+		db.activeUsersDay = count
+		db.countMu.Unlock()
+
 		return float64(count)
 	}))
 	if err != nil {
@@ -107,6 +132,22 @@ func (db *DB) initMetrics() (err error) {
 	return nil
 }
 
+func (db *DB) Counts(ctx context.Context) (numUsers, numMembers, usersDay, usersWeek, usersMonth int64) {
+	db.countMu.Lock()
+	if numUsers != 0 {
+		defer db.countMu.Unlock()
+		return db.usersTotal, db.membersTotal, db.activeUsersDay, db.activeUsersWeek, db.activeUsersMonth
+	}
+	db.countMu.Unlock()
+
+	numUsers, _ = db.TotalUserCount(ctx)
+	numMembers, _ = db.TotalMemberCount(ctx)
+	usersDay, _ = db.ActiveUsers(ctx, ActiveDay)
+	usersWeek, _ = db.ActiveUsers(ctx, ActiveWeek)
+	usersMonth, _ = db.ActiveUsers(ctx, ActiveMonth)
+	return numUsers, numMembers, usersDay, usersWeek, usersMonth
+}
+
 func (db *DB) TotalUserCount(ctx context.Context) (numUsers int64, err error) {
 	err = db.QueryRow(ctx, "SELECT COUNT(*) FROM users WHERE deleted_at IS NULL").Scan(&numUsers)
 	if err != nil {
diff --git a/backend/routes/meta/meta.go b/backend/routes/meta/meta.go
index da59f8d..ebae428 100644
--- a/backend/routes/meta/meta.go
+++ b/backend/routes/meta/meta.go
@@ -4,9 +4,7 @@ import (
 	"net/http"
 	"os"
 
-	"codeberg.org/pronounscc/pronouns.cc/backend/db"
 	"codeberg.org/pronounscc/pronouns.cc/backend/server"
-	"emperror.dev/errors"
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/render"
 )
@@ -39,30 +37,7 @@ type MetaUsers struct {
 func (s *Server) meta(w http.ResponseWriter, r *http.Request) error {
 	ctx := r.Context()
 
-	numUsers, err := s.DB.TotalUserCount(ctx)
-	if err != nil {
-		return errors.Wrap(err, "querying user count")
-	}
-
-	activeMonth, err := s.DB.ActiveUsers(ctx, db.ActiveMonth)
-	if err != nil {
-		return errors.Wrap(err, "querying user count")
-	}
-
-	activeWeek, err := s.DB.ActiveUsers(ctx, db.ActiveWeek)
-	if err != nil {
-		return errors.Wrap(err, "querying user count")
-	}
-
-	activeDay, err := s.DB.ActiveUsers(ctx, db.ActiveDay)
-	if err != nil {
-		return errors.Wrap(err, "querying user count")
-	}
-
-	numMembers, err := s.DB.TotalMemberCount(ctx)
-	if err != nil {
-		return errors.Wrap(err, "querying user count")
-	}
+	numUsers, numMembers, activeDay, activeWeek, activeMonth := s.DB.Counts(ctx)
 
 	render.JSON(w, r, MetaResponse{
 		GitRepository: server.Repository,