Repository: bevyengine/bevy
File: crates/bevy_render/src/error_handler.rs (Rust)

Code before:

impl RenderErrorHandler {
    /// Creates and registers error handlers on the given device and stores them to later be polled.
    pub(crate) fn new(device: &RenderDevice) -> Self {
        let device_lost = Arc::new(Mutex::new(None));
        let uncaptured = Arc::new(Mutex::new(None));
        {
            // scoped clone to move into closures
            let device_lost = device_lost.clone();
            let uncaptured = uncaptured.clone();
            let device = device.wgpu_device();
            // we log errors as soon as they are captured so they stay chronological in logs
            // and only keep the first error, as it often causes other errors downstream
            device.set_device_lost_callback(move |reason, str| {
                bevy_log::error!("Caught DeviceLost error: {reason:?} {str}");
                assert!(device_lost.lock().unwrap().replace((reason, str)).is_none());
            });
            device.on_uncaptured_error(Arc::new(move |e| {
                bevy_log::error!("Caught rendering error: {e}");
                uncaptured
                    .lock()
                    .unwrap()
                    .get_or_insert(WgpuWrapper::new(e));
            }));
        }
        Self {
            device_lost,
            uncaptured,
        }
    }

    /// Checks to see if any errors have been caught, and returns an appropriate `RenderState`
    pub(crate) fn poll(&self) -> RenderState {
        if let Some(error) = self.uncaptured.lock().unwrap().take() {
            let (ty, str, source) = match error.into_inner() {
                wgpu::Error::OutOfMemory { source } => {
                    (ErrorType::OutOfMemory, "".to_string(), source)
                }
                wgpu::Error::Validation {
                    source,
                    description,
                } => (ErrorType::Validation, description, source),
                wgpu::Error::Internal {
                    source,
                    description,
                } => (ErrorType::Internal, description, source),
            };
            return RenderState::Errored(ty, str, Some(WgpuWrapper::new(source)));
        }
        // Device lost is more important so we let it take precedence; every error gets logged anyways.
        if let Some((_, str)) = self.device_lost.lock().unwrap().take() {

Review comment (bug):
This should document a fallback. (Ideally allow setting any of the remaining 3 variants.)
```suggestion
pub enum RenderErrorPolicy {
    /// Aborts the renderer with the given policy, see [`RenderAbortPolicy`]
    /// By default signals app exit.
    #[default]
    Abort(RenderAbortPolicy),
    /// Attempt renderer recovery the given number of times. If that fails, aborts the renderer.
    Recover(usize, WgpuSettings, RenderAbortPolicy),
}

#[derive(Default)]
pub enum RenderAbortPolicy {
    /// Panics on error.
    Panic,
    #[default]
    /// Signals app exit on error.
    Shutdown,
    /// Keeps the app alive, but stops rendering further.
    StopRendering,
}
```

You could also in theory merge both remaining variants of `RenderErrorPolicy` if you just specified the semantics of 0 retry recovery leading directly to the given shutdown.

Code after:
            RenderErrorPolicy::StopRendering => {
                // do nothing
            }
            RenderErrorPolicy::Recover(render_creation) => {
                assert!(insert_future_resources(&render_creation, main_world));
                render_world.insert_resource(RenderState::Reinitializing);
            }
        }
    }
}

impl Default for RenderErrorHandler {
    fn default() -> Self {
        // This is what we've always done historically,
        // but we could choose a new default once recovery works better.
        Self(|_, _, _| RenderErrorPolicy::Ignore)
    }
}

/// An error encountered during rendering.
#[derive(Debug)]
pub struct RenderError {
    pub ty: ErrorType,
    pub description: String,
    pub source: Option<WgpuWrapper<ErrorSource>>,
}

/// The current state of the renderer.
#[derive(Resource, Debug)]
pub(crate) enum RenderState {
    /// Just started, [`crate::RenderStartup`] will run in this state.
    Initializing,
    /// Everything is okay and we are rendering stuff every frame.
    Ready,
    /// An error was encountered, and we may decide how to handle it.
    Errored(RenderError),
    /// We are recreating the render context after an error to recover.
    Reinitializing,
}

/// Resource to allow polling wgpu error handlers.
#[derive(Resource)]
pub(crate) struct DeviceErrorHandler {
    device_lost: Arc<Mutex<Option<(wgpu::DeviceLostReason, String)>>>,
    uncaptured: Arc<Mutex<Option<WgpuWrapper<wgpu::Error>>>>,
}

impl DeviceErrorHandler {
    /// Creates and registers error handlers on the given device and stores them to later be polled.
    pub(crate) fn new(device: &RenderDevice) -> Self {
        let device_lost = Arc::new(Mutex::new(None));