some higher volume mods for the vps

cmd/server/main.go

@@ -88,6 +88,12 @@ func openDB(dsn, logLevel string) (*gorm.DB, error) {
 			if err := db.Exec("PRAGMA busy_timeout=5000;").Error; err != nil {
 				slog.Warn("Failed to set busy timeout for SQLite", "error", err)
 			}
+			if err := db.Exec("PRAGMA synchronous=NORMAL;").Error; err != nil {
+				slog.Warn("Failed to set synchronous for SQLite", "error", err)
+			}
+			if err := db.Exec("PRAGMA cache_size=-64000;").Error; err != nil { // 64MB cache
+				slog.Warn("Failed to set cache size for SQLite", "error", err)
+			}
 		}
 	}
 

docker-compose.dev.yaml

@@ -22,6 +22,7 @@ services:
       - LOG_LEVEL
       - ENABLE_USER_REGISTRATION
       - GITHUB_TOKEN
+      - MAX_CONCURRENT_RENDERS=${MAX_CONCURRENT_RENDERS:-5}
 
 volumes:
   go_modules:

docker-compose.https.yaml

@@ -13,6 +13,7 @@ services:
       - PRODUCTION
       - ENABLE_USER_REGISTRATION
       - GITHUB_TOKEN
+      - MAX_CONCURRENT_RENDERS=${MAX_CONCURRENT_RENDERS:-5}
 
     healthcheck:
       test: ["CMD", "/app/tronbyt-server", "health"]

docker-compose.postgres.yaml

@@ -16,6 +16,7 @@ services:
       - ENABLE_USER_REGISTRATION
       - SINGLE_USER_AUTO_LOGIN
       - GITHUB_TOKEN
+      - MAX_CONCURRENT_RENDERS=${MAX_CONCURRENT_RENDERS:-5}
       - DB_DSN=host=db user=tronbyt password=tronbyt dbname=tronbyt port=5432 sslmode=disable TimeZone=UTC
     depends_on:
       - db

docker-compose.redis.yaml

@@ -17,6 +17,7 @@ services:
       - ENABLE_USER_REGISTRATION
       - SINGLE_USER_AUTO_LOGIN
       - GITHUB_TOKEN
+      - MAX_CONCURRENT_RENDERS=${MAX_CONCURRENT_RENDERS:-5}
 
     healthcheck:
       test: ["CMD", "/app/tronbyt-server", "health"]

docker-compose.yaml

@@ -16,6 +16,7 @@ services:
       - ENABLE_USER_REGISTRATION
       - SINGLE_USER_AUTO_LOGIN
       - GITHUB_TOKEN
+      - MAX_CONCURRENT_RENDERS=${MAX_CONCURRENT_RENDERS:-5}
 
     healthcheck:
       test: ["CMD", "/app/tronbyt-server", "health"]

internal/config/config.go

@@ -28,6 +28,7 @@ type Settings struct {
 	TrustedProxies         string `env:"TRONBYT_TRUSTED_PROXIES"  envDefault:"*"`
 	LogLevel               string `env:"LOG_LEVEL"                envDefault:"INFO"`
 	EnableUpdateChecks     bool   `env:"ENABLE_UPDATE_CHECKS"     envDefault:"true"`
+	MaxConcurrentRenders   int    `env:"MAX_CONCURRENT_RENDERS"   envDefault:"10"`
 }
 
 // TemplateConfig holds configuration values needed in templates.

internal/server/handlers_device_api.go

@@ -8,13 +8,24 @@ import (
 	"tronbyt-server/internal/data"
 
 	"gorm.io/gorm"
-	"gorm.io/gorm/clause"
 )
 
 // handleNextApp is the handler for GET /{id}/next.
 func (s *Server) handleNextApp(w http.ResponseWriter, r *http.Request) {
 	id := r.PathValue("id")
 
+	renderMetrics.RecordRequest()
+
+	// Acquire per-device semaphore to prevent queue backup from same device.
+	// If already processing a request for this device, return cached image immediately.
+	if !s.acquireDeviceSemaphore(id) {
+		slog.Debug("Device busy, serving cached image", "device", id)
+		s.serveCachedImageForDevice(w, r, id)
+		return
+	}
+	// Ensure semaphore is released when this function returns
+	defer s.releaseDeviceSemaphore(id)
+
 	var device *data.Device
 	if d, err := DeviceFromContext(r.Context()); err == nil {
 		device = d
@@ -64,10 +75,10 @@ func (s *Server) handleNextApp(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Update device info if needed
-	// We use a transaction with locking to avoid race conditions with other requests
+	// Note: Removed SELECT FOR UPDATE row locking as it was causing lock contention
+	// and "locking protocol" errors when requests timed out mid-transaction
 	err := s.DB.Transaction(func(tx *gorm.DB) error {
-		// Lock the row to ensure we read the latest state and no one else updates it
-		freshDevice, err := gorm.G[data.Device](tx, clause.Locking{Strength: "UPDATE"}).Where("id = ?", device.ID).First(r.Context())
+		freshDevice, err := gorm.G[data.Device](tx).Where("id = ?", device.ID).First(r.Context())
 		if err != nil {
 			return err
 		}
@@ -107,9 +118,13 @@ func (s *Server) handleNextApp(w http.ResponseWriter, r *http.Request) {
 		// Send default image if error (or not found)
 		slog.Error("Failed to get next app image", "device", device.ID, "error", err)
 		s.sendDefaultImage(w, r, device)
+		webpMetrics.RecordWebPServed(0)
+		webpMetrics.RecordUniqueDevice(device.ID)
 		return
 	}
 
+	webpMetrics.RecordUniqueDevice(device.ID)
+
 	// For HTTP devices, we assume "Sent" equals "Displaying" (or roughly so).
 	// We update DisplayingApp here so the Preview uses the explicit field instead of fallback.
 	if app != nil {
@@ -142,6 +157,8 @@ func (s *Server) handleNextApp(w http.ResponseWriter, r *http.Request) {
 	dwell := device.GetEffectiveDwellTime(app)
 	w.Header().Set("Tronbyt-Dwell-Secs", fmt.Sprintf("%d", dwell))
 
+	webpMetrics.RecordWebPServed(len(imgData))
+
 	if _, err := w.Write(imgData); err != nil {
 		slog.Error("Failed to write image data to response", "error", err)
 		// Log error, but can't change HTTP status after writing headers.

internal/server/handlers_user.go

@@ -429,3 +429,24 @@ func (s *Server) handleRefreshSystemRepo(w http.ResponseWriter, r *http.Request)
 
 	http.Redirect(w, r, "/auth/edit", http.StatusSeeOther)
 }
+
+func (s *Server) handleAdminDashboard(w http.ResponseWriter, r *http.Request) {
+	user := GetUser(r)
+	if !user.IsAdmin {
+		http.Error(w, "Forbidden", http.StatusForbidden)
+		return
+	}
+
+	var totalDevices, totalUsers int64
+	s.DB.Model(&data.Device{}).Count(&totalDevices)
+	s.DB.Model(&data.User{}).Count(&totalUsers)
+
+	stats := GetStatsSnapshot()
+
+	s.renderTemplate(w, r, "admin_dashboard", TemplateData{
+		User:         user,
+		TotalDevices: totalDevices,
+		TotalUsers:   totalUsers,
+		Stats:        stats,
+	})
+}

internal/server/helpers.go

@@ -86,6 +86,11 @@ type TemplateData struct {
 	AppConfig   map[string]any
 	AppMetadata *apps.AppMetadata
 
+	// Admin Dashboard
+	TotalDevices int64
+	TotalUsers   int64
+	Stats        StatsSnapshot
+
 	// Device Update Extras
 	ColorFilterOptions       []ColorFilterOption
 	ShowFullAnimationOptions []ShowFullAnimationOption