Merge pull request #36 from hnez/startup-errors

tacd: show message on screen if hardware setup failed

Author: hnez

src/main.rs

@@ -16,7 +16,9 @@
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 use anyhow::Result;
+use async_std::future::pending;
 use futures::{select, FutureExt};
+use log::{error, info};
 
 mod adc;
 mod backlight;
@@ -50,17 +52,11 @@ use regulators::Regulators;
 use setup_mode::SetupMode;
 use system::System;
 use temperatures::Temperatures;
-use ui::{setup_display, Ui, UiResources};
+use ui::{message, setup_display, Display, Ui, UiResources};
 use usb_hub::UsbHub;
 use watchdog::Watchdog;
 
-#[async_std::main]
-async fn main() -> Result<()> {
-    env_logger::init();
-
-    // Show a splash screen very early on
-    let display = setup_display();
-
+async fn init() -> Result<(Ui, HttpServer, Option<Watchdog>)> {
     // The BrokerBuilder collects topics that should be exported via the
     // MQTT/REST APIs.
     // The topics are also used to pass around data inside the tacd.
@@ -122,9 +118,6 @@ async fn main() -> Result<()> {
     // in the web interface.
     journal::serve(&mut http_server.server);
 
-    // Expose the display as a .png on the web server
-    ui::serve_display(&mut http_server.server, display.screenshooter());
-
     // Set up the user interface for the hardware display on the TAC.
     // The different screens receive updates via the topics provided in
     // the UiResources struct.
@@ -153,7 +146,19 @@ async fn main() -> Result<()> {
     // and expose the topics via HTTP and MQTT-over-websocket.
     bb.build(&mut http_server.server);
 
-    log::info!("Setup complete. Handling requests");
+    Ok((ui, http_server, watchdog))
+}
+
+async fn run(
+    ui: Ui,
+    mut http_server: HttpServer,
+    watchdog: Option<Watchdog>,
+    display: Display,
+) -> Result<()> {
+    // Expose the display as a .png on the web server
+    ui::serve_display(&mut http_server.server, display.screenshooter());
+
+    info!("Setup complete. Handling requests");
 
     // Run until the user interface, http server or (if selected) the watchdog
     // exits (with an error).
@@ -172,3 +177,32 @@ async fn main() -> Result<()> {
 
     Ok(())
 }
+
+#[async_std::main]
+async fn main() -> Result<()> {
+    env_logger::init();
+
+    // Show a splash screen very early on
+    let display = setup_display();
+
+    match init().await {
+        Ok((ui, http_server, watchdog)) => run(ui, http_server, watchdog, display).await,
+        Err(e) => {
+            // Display a detailed error message on stderr (and thus in the journal) ...
+            error!("Failed to initialize tacd: {e}");
+
+            // ... and a generic message on the LCD, as it can not fit a lot of detail.
+            display.clear();
+            display.with_lock(|target| {
+                message(
+                    target,
+                    "tacd failed to start!\n\nCheck log for info.\nWaiting for watchdog\nto restart tacd.",
+                );
+            });
+
+            // Wait forever (or more likely until the systemd watchdog timer hits)
+            // to give the user a chance to actually see the error message.
+            pending().await
+        }
+    }
+}

src/ui.rs

@@ -35,6 +35,7 @@ mod widgets;
 use alerts::{AlertList, Alerter};
 use buttons::{handle_buttons, Button, ButtonEvent, Direction, PressDuration, Source};
 pub use display::{Display, ScreenShooter};
+pub use screens::message;
 use screens::{splash, ActivatableScreen, AlertScreen, NormalScreen, Screen};
 
 pub struct UiResources {

src/ui/screens.rs

@@ -166,22 +166,24 @@ const fn row_anchor(row_num: u8) -> Point {
     Point::new(8, 52 + (row_num as i32) * 20)
 }
 
-pub(super) fn splash(target: &mut DisplayExclusive) -> Rectangle {
+pub fn message(target: &mut DisplayExclusive, text: &str) -> Rectangle {
     let ui_text_style: MonoTextStyle<BinaryColor> =
         MonoTextStyle::new(&UI_TEXT_FONT, BinaryColor::On);
 
-    let text = Text::with_alignment(
-        "Welcome",
-        Point::new(120, 120),
-        ui_text_style,
-        Alignment::Center,
-    );
+    let mut text = Text::with_alignment(text, Point::zero(), ui_text_style, Alignment::Center);
+
+    let offset = Point::new(120, 120) - text.bounding_box().center();
+    text.translate_mut(offset);
 
     text.draw(target).unwrap();
 
     text.bounding_box()
 }
 
+pub fn splash(target: &mut DisplayExclusive) -> Rectangle {
+    message(target, "Welcome")
+}
+
 pub(super) fn init(
     res: &UiResources,
     alerts: &Arc<Topic<AlertList>>,