Improved startup sequence (#20)

* Improved startup sequence

* updated comments/order

tactility/src/tactility.c

@@ -7,18 +7,36 @@
 
 #define TAG "tactility"
 
-// System services
+// region System services
+
 extern const ServiceManifest gui_service;
 extern const ServiceManifest loader_service;
 
-// System apps
+static const ServiceManifest* const system_services[] = {
+    &gui_service,
+    &loader_service // depends on gui service
+};
+
+// endregion
+
+// region System apps
+
 extern const AppManifest desktop_app;
 extern const AppManifest system_info_app;
 
+static const AppManifest* const system_apps[] = {
+    &desktop_app,
+    &system_info_app
+};
+
+// endregion
+
 static void register_system_apps() {
     TT_LOG_I(TAG, "Registering default apps");
-    tt_app_manifest_registry_add(&desktop_app);
-    tt_app_manifest_registry_add(&system_info_app);
+    int app_count = sizeof(system_apps) / sizeof(AppManifest*);
+    for (int i = 0; i < app_count; ++i) {
+        tt_app_manifest_registry_add(system_apps[i]);
+    }
 }
 
 static void register_user_apps(const AppManifest* const apps[TT_CONFIG_APPS_LIMIT]) {
@@ -34,16 +52,13 @@ static void register_user_apps(const AppManifest* const apps[TT_CONFIG_APPS_LIMI
     }
 }
 
-static void register_system_services() {
-    TT_LOG_I(TAG, "Registering system services");
-    tt_service_registry_add(&gui_service);
-    tt_service_registry_add(&loader_service);
-}
-
-static void start_system_services() {
-    TT_LOG_I(TAG, "Starting system services");
-    tt_service_registry_start(gui_service.id);
-    tt_service_registry_start(loader_service.id);
+static void register_and_start_system_services() {
+    TT_LOG_I(TAG, "Registering and starting system services");
+    int app_count = sizeof(system_services) / sizeof(ServiceManifest *);
+    for (int i = 0; i < app_count; ++i) {
+        tt_service_registry_add(system_services[i]);
+        tt_check(tt_service_registry_start(system_services[i]->id));
+    }
 }
 
 static void register_and_start_user_services(const ServiceManifest* const services[TT_CONFIG_SERVICES_LIMIT]) {
@@ -52,7 +67,7 @@ static void register_and_start_user_services(const ServiceManifest* const servic
         const ServiceManifest* manifest = services[i];
         if (manifest != NULL) {
             tt_service_registry_add(manifest);
-            tt_service_registry_start(manifest->id);
+            tt_check(tt_service_registry_start(manifest->id));
         } else {
             // reached end of list
             break;
@@ -68,21 +83,22 @@ TT_UNUSED void tt_init(const Config* config) {
 
     tt_hardware_init(config->hardware);
 
-    // Register all apps
-    register_system_services();
+    // Note: the order of starting apps and services is critical!
+    // System services are registered first so they can be used by the apps
+    register_and_start_system_services();
+    // Then we register system apps. They are not used/started yet.
     register_system_apps();
-    // TODO: move this after start_system_services, but desktop must subscribe to app registry events first.
-    register_user_apps(config->apps);
-
-    // Start all services
-    start_system_services();
+    // Then we register and start user services. They are started after system app
+    // registration just in case they want to figure out which system apps are installed.
     register_and_start_user_services(config->services);
+    // Now we register the user apps, as they might rely on the user services.
+    register_user_apps(config->apps);
 
     TT_LOG_I(TAG, "tt_init starting desktop app");
     loader_start_app(desktop_app.id, true, NULL);
 
     if (config->auto_start_app_id) {
-        TT_LOG_I(TAG, "tt_init aut-starting %s", config->auto_start_app_id);
+        TT_LOG_I(TAG, "tt_init auto-starting %s", config->auto_start_app_id);
         loader_start_app(config->auto_start_app_id, true, NULL);
     }