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use crate::{
RafxCommandBuffer, RafxDeviceContext, RafxError, RafxFence, RafxFormat,
RafxPresentSuccessResult, RafxQueue, RafxResult, RafxSemaphore, RafxSwapchain,
RafxSwapchainColorSpace, RafxSwapchainDef, RafxSwapchainImage, RafxTexture,
};
use crossbeam_channel::{Receiver, Sender};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, Mutex};
/// May be implemented to get callbacks related to the swapchain being created/destroyed. This is
/// optional.
pub trait RafxSwapchainEventListener {
/// Called whenever the swapchain needs to be created (the first time, and in cases where the
/// swapchain needs to be recreated)
fn swapchain_created(
&mut self,
device_context: &RafxDeviceContext,
swapchain: &RafxSwapchain,
) -> RafxResult<()>;
/// Called whenever the swapchain will be destroyed (when VkSurface is dropped, and also in cases
/// where the swapchain needs to be recreated)
fn swapchain_destroyed(
&mut self,
device_context: &RafxDeviceContext,
swapchain: &RafxSwapchain,
) -> RafxResult<()>;
}
// This is shared state held within an Arc between the SwapchainHelper and the PresentableFrame.
// It contains the swapchain, sync primitives required to wait for the GPU to complete work, and
// sync primitives to allow the helper/presentable frame to communicate.
struct RafxSwapchainHelperSharedState {
global_frame_index: AtomicUsize,
sync_frame_index: AtomicUsize,
image_available_semaphores: Vec<RafxSemaphore>,
render_finished_semaphores: Vec<RafxSemaphore>,
in_flight_fences: Vec<RafxFence>,
result_tx: Sender<RafxResult<RafxPresentSuccessResult>>,
result_rx: Receiver<RafxResult<RafxPresentSuccessResult>>,
// Arc so that we can move the swapchain to a new RafxSwapchainHelperSharedState
swapchain: Arc<Mutex<RafxSwapchain>>,
}
impl RafxSwapchainHelperSharedState {
fn new(
device_context: &RafxDeviceContext,
swapchain: Arc<Mutex<RafxSwapchain>>,
) -> RafxResult<Self> {
let image_count = swapchain.lock().unwrap().image_count();
let mut image_available_semaphores = Vec::with_capacity(image_count);
let mut render_finished_semaphores = Vec::with_capacity(image_count);
let mut in_flight_fences = Vec::with_capacity(image_count);
for _ in 0..image_count {
image_available_semaphores.push(device_context.create_semaphore()?);
render_finished_semaphores.push(device_context.create_semaphore()?);
in_flight_fences.push(device_context.create_fence()?);
}
let (result_tx, result_rx) = crossbeam_channel::unbounded();
Ok(RafxSwapchainHelperSharedState {
global_frame_index: AtomicUsize::new(0),
sync_frame_index: AtomicUsize::new(0),
image_available_semaphores,
render_finished_semaphores,
in_flight_fences,
result_tx,
result_rx,
swapchain,
})
}
}
/// Represents an acquired image from a swapchain. It can move between threads and be sumitted by
/// any thread. The swapchain helper will not provide another image until this one is presented.
///
/// To ease error handling, the swapchain may be submitted with an error. This error will be
/// returned on the next attempt to acquire a swapchain image (i.e. the main thread).
pub struct RafxPresentableFrame {
// State that's shared among the swapchain helper and the presentable frame. Mostly immutable,
// but the swapchain itself is stored in it, wrapped by a mutex
shared_state: Option<Arc<RafxSwapchainHelperSharedState>>,
swapchain_image: RafxSwapchainImage,
global_frame_index: usize,
sync_frame_index: usize,
}
impl RafxPresentableFrame {
/// An index that starts at 0 on the first present and increments every frame, wrapping back to
/// 0 after each swapchain image has been presented once. (See image_count on
/// RafxSwapchainHelper). WARNING: This is not always the returned swapchain image. Swapchain
/// images may be acquired in any order.
pub fn rotating_frame_index(&self) -> usize {
// The sync_frame_index can be used as-is for this purpose
self.sync_frame_index
}
pub fn incrementing_frame_index(&self) -> usize {
self.global_frame_index
}
/// Returns the acquired swapchain image
pub fn swapchain_texture(&self) -> &RafxTexture {
&self.swapchain_image.texture
}
/// Returns the swapchain. The swapchain helper code generally assumes ownership/management of
/// the swapchain. Messing with it may invalidate assumptions in the swapchain helper code, so
/// mutating operations on it are not recommended
pub fn swapchain(&self) -> &Arc<Mutex<RafxSwapchain>> {
&self.shared_state.as_ref().unwrap().swapchain
}
/// Submits the given command buffers and schedules the swapchain image to be presented after
/// their completion
pub fn present(
mut self,
queue: &RafxQueue,
command_buffers: &[&RafxCommandBuffer],
) -> RafxResult<RafxPresentSuccessResult> {
log::trace!(
"Calling RafxPresentableFrame::present with {} command buffers",
command_buffers.len()
);
let result = self.do_present(queue, command_buffers);
// Let the shared state arc drop, this will unblock the next frame
let shared_state = self.shared_state.take().unwrap();
shared_state.result_tx.send(result.clone()).unwrap();
result
}
/// Presents the current swapchain image and returns the given error during the next image
/// acquisition attempt
pub fn present_with_error(
mut self,
queue: &RafxQueue,
error: RafxError,
) {
log::warn!(
"Calling RafxPresentableFrame::present_with_error {:?}",
error
);
//TODO: AFAIK there is no way to simply trigger the semaphore and skip calling do_present
// with no command buffers. The downside of doing this is that we end up with both the
// end user's result and a result from do_present and have no sensible way of merging them
//TODO: Might be able to do this without presenting by having command buffers that can be
// submitted that trigger the semaphore.
let _ = self.do_present(queue, &mut []);
// Let the shared state arc drop, this will unblock the next frame
let shared_state = self.shared_state.take().unwrap();
shared_state.result_tx.send(Err(error)).unwrap();
}
pub fn do_present(
&mut self,
queue: &RafxQueue,
command_buffers: &[&RafxCommandBuffer],
) -> RafxResult<RafxPresentSuccessResult> {
// A present can only occur using the result from the previous acquire_next_image call
let shared_state = self.shared_state.as_ref().unwrap();
let sync_frame_index = shared_state.sync_frame_index.load(Ordering::Relaxed);
assert!(self.sync_frame_index == sync_frame_index);
let frame_fence = &shared_state.in_flight_fences[sync_frame_index];
let wait_semaphores = [&shared_state.image_available_semaphores[sync_frame_index]];
let signal_semaphores = [&shared_state.render_finished_semaphores[sync_frame_index]];
queue.submit(
command_buffers,
&wait_semaphores,
&signal_semaphores,
Some(frame_fence),
)?;
let swapchain = shared_state.swapchain.lock().unwrap();
//NOTE: Don't bail for error until we update the frame indices
let result = queue.present(
&*swapchain,
&signal_semaphores,
self.swapchain_image.swapchain_image_index,
);
shared_state.sync_frame_index.store(
(sync_frame_index + 1) % shared_state.in_flight_fences.len(),
Ordering::Relaxed,
);
shared_state
.global_frame_index
.fetch_add(1, Ordering::Relaxed);
result
}
}
impl Drop for RafxPresentableFrame {
fn drop(&mut self) {
if self.shared_state.is_some() {
self.shared_state.take().unwrap().result_tx.send(Err(RafxError::StringError("SwapchainHelperPresentableFrame was dropped without calling present or present_with_error".to_string()))).unwrap();
}
}
}
pub enum TryAcquireNextImageResult {
Success(RafxPresentableFrame),
// While this is an "error" being returned as success, it is expected and recoverable while
// other errors usually aren't. This way the ? operator can still be used to bail out the
// unrecoverable errors and the different flavors of "success" should be explicitly handled
// in a match
DeviceReset,
}
pub struct RafxSwapchainHelper {
device_context: RafxDeviceContext,
shared_state: Option<Arc<RafxSwapchainHelperSharedState>>,
format: RafxFormat,
color_space: RafxSwapchainColorSpace,
swapchain_def: RafxSwapchainDef,
image_count: usize,
// False initially, set to true when we produce the first presentable frame to indicate that
// future frames need to wait for its result to be sent via the result_tx/result_rx channel
expect_result_from_previous_frame: bool,
}
impl RafxSwapchainHelper {
pub fn new(
device_context: &RafxDeviceContext,
swapchain: RafxSwapchain,
mut event_listener: Option<&mut dyn RafxSwapchainEventListener>,
) -> RafxResult<Self> {
let format = swapchain.format();
let color_space = swapchain.color_space();
let image_count = swapchain.image_count();
let swapchain_def = swapchain.swapchain_def().clone();
let shared_state = Arc::new(RafxSwapchainHelperSharedState::new(
device_context,
Arc::new(Mutex::new(swapchain)),
)?);
if let Some(event_listener) = event_listener.as_mut() {
let swapchain = shared_state.swapchain.lock().unwrap();
event_listener.swapchain_created(device_context, &*swapchain)?;
}
Ok(RafxSwapchainHelper {
device_context: device_context.clone(),
shared_state: Some(shared_state),
format,
color_space,
image_count,
swapchain_def,
expect_result_from_previous_frame: false,
})
}
pub fn destroy(
&mut self,
mut event_listener: Option<&mut dyn RafxSwapchainEventListener>,
) -> RafxResult<()> {
log::debug!("Destroying swapchain helper");
// If there is a frame in flight, wait until it is submitted. This hopefully means we are
// the only holder of this arc and we can unwrap it
self.wait_until_previous_frame_submitted()?;
if let Some(shared_state) = self.shared_state.take() {
let begin_wait_time = rafx_base::Instant::now();
while Arc::strong_count(&shared_state) > 1 {
// It's possible the previous frame has not finished dropping. Wait until this
// occurs.
if (rafx_base::Instant::now() - begin_wait_time).as_secs_f32() > 1.0 {
// Bail early, we won't properly clean up
log::error!("A presentable frame was submitted but still isn't dropped. Can't clean up the swapchain");
break;
}
}
match Arc::try_unwrap(shared_state) {
Ok(shared_state) => {
log::debug!("wait for all fences to complete");
let fences: Vec<_> = shared_state.in_flight_fences.iter().map(|x| x).collect();
self.device_context.wait_for_fences(&fences)?;
if let Some(event_listener) = event_listener.as_mut() {
let old_swapchain = shared_state.swapchain.lock().unwrap();
log::debug!("destroy the swapchain");
event_listener
.swapchain_destroyed(&self.device_context, &*old_swapchain)?;
}
}
Err(_arc) => {
let error = "The swapchain could not be destroyed, a PresentableFrame exists that is using it";
log::error!("{}", error);
return Err(error)?;
}
}
}
Ok(())
}
pub fn format(&self) -> RafxFormat {
self.format
}
pub fn color_space(&self) -> RafxSwapchainColorSpace {
self.color_space
}
pub fn image_count(&self) -> usize {
self.image_count
}
pub fn swapchain_def(&self) -> &RafxSwapchainDef {
&self.swapchain_def
}
pub fn wait_until_previous_frame_submitted(
&mut self
) -> RafxResult<Option<RafxPresentSuccessResult>> {
if self.expect_result_from_previous_frame {
self.expect_result_from_previous_frame = false;
Ok(Some(
self.shared_state
.as_ref()
.unwrap()
.result_rx
.recv()
.unwrap()?,
))
} else {
Ok(None)
}
}
pub fn wait_until_sync_frame_idle(
&mut self,
sync_frame_index: usize,
) -> RafxResult<()> {
self.shared_state.as_ref().unwrap().in_flight_fences[sync_frame_index].wait()
}
pub fn acquire_next_image(
&mut self,
window_width: u32,
window_height: u32,
event_listener: Option<&mut dyn RafxSwapchainEventListener>,
) -> RafxResult<RafxPresentableFrame> {
//
// Block until the previous frame completes being submitted to GPU
//
let previous_frame_result = self.wait_until_previous_frame_submitted();
//
// Block until the next sync frame index finishes submitting. It's not safe to modify
// resources associated with it until the last execution of it fully completes.
//
let next_sync_frame = self
.shared_state
.as_ref()
.unwrap()
.sync_frame_index
.load(Ordering::Relaxed);
self.wait_until_sync_frame_idle(next_sync_frame)?;
//
// Check the result of the previous frame. Possible outcomes:
// - Previous frame was successful: immediately try rendering again with the same swapchain
// - We've never tried rendering before: try rendering with the initial swapchain
// - Previous frame failed but resolvable by rebuilding the swapchain - skip trying to
// render again with the same swapchain
// - Previous frame failed with unrecoverable error: bail
//
let rebuild_swapchain = match &previous_frame_result {
Ok(result) => {
match result {
// We tried to render, check the previous render result
Some(result) => match result {
RafxPresentSuccessResult::Success => false,
RafxPresentSuccessResult::SuccessSuboptimal => {
log::debug!("Swapchain is sub-optimal, rebuilding");
//TODO: This can occur persistently when the app is minimized, so ignore
// if the size has not changed. However, we could also consider adding
// a counter to limit the frequency. (A sensible case for this is
// resizing a window - to avoid rebuilding swapchain every frame during
// the resize.
if window_height != self.swapchain_def.height
|| window_width != self.swapchain_def.width
{
true
} else {
false
}
}
RafxPresentSuccessResult::DeviceReset => {
log::debug!("Swapchain sent DeviceReset, rebuilding");
true
}
},
// We have not rendered yet, so assume the swapchain we have is fine
None => false,
}
}
// An unrecoverable failure occurred, bail
Err(e) => return Err(e.clone()),
};
//
// If we don't have any reason yet to rebuild the swapchain, try to render
//
if !rebuild_swapchain {
// This case is taken if we have never rendered a frame or if the previous render was successful
let result = self.try_acquire_next_image(window_width, window_height)?;
if let TryAcquireNextImageResult::Success(presentable_frame) = result {
return Ok(presentable_frame);
}
// if not successful (TryAcquireNextImageResult::DeviceReset), fall through to
// try to recreate the swapchain
};
//
// Rebuild the swapchain and try again. Any failure after a rebuild will be fatal
//
self.rebuild_swapchain(window_width, window_height, event_listener)?;
let result = self.try_acquire_next_image(window_width, window_height)?;
if let TryAcquireNextImageResult::Success(presentable_frame) = result {
Ok(presentable_frame)
} else {
Err(RafxError::StringError(
"Failed to recreate swapchain".to_string(),
))
}
}
pub fn try_acquire_next_image(
&mut self,
window_width: u32,
window_height: u32,
) -> RafxResult<TryAcquireNextImageResult> {
match self.do_try_acquire_next_image(window_width, window_height) {
#[cfg(feature = "rafx-vulkan")]
Err(RafxError::VkError(ash::vk::Result::ERROR_OUT_OF_DATE_KHR)) => {
Ok(TryAcquireNextImageResult::DeviceReset)
}
result @ _ => result,
}
}
fn do_try_acquire_next_image(
&mut self,
window_width: u32,
window_height: u32,
) -> RafxResult<TryAcquireNextImageResult> {
// If a frame is still outstanding from a previous acquire_next_swapchain_image call, wait
// to receive the result of that frame. If the result was an error, return that error now.
// This allows us to handle errors from the render thread in the main thread. This wait is
// only blocking on getting the previous frame submitted. It's possible the GPU is still
// processing it, and even the frame before it.
self.wait_until_previous_frame_submitted()?;
// check if window size changed and we are out of date
let shared_state = self.shared_state.as_ref().unwrap();
let mut swapchain = shared_state.swapchain.lock().unwrap();
let swapchain_def = swapchain.swapchain_def();
if swapchain_def.width != window_width || swapchain_def.height != window_height {
log::debug!("Force swapchain rebuild due to changed window size");
return Ok(TryAcquireNextImageResult::DeviceReset);
}
// This index iterates from 0..max_num_frames, wrapping around to 0. This ensures we use a
// different set of sync primitives per frame in flight
let sync_frame_index = shared_state.sync_frame_index.load(Ordering::Relaxed);
let global_frame_index = shared_state.global_frame_index.load(Ordering::Relaxed);
// If this swapchain image is still being process on the GPU, block until it is flushed
let frame_fence = &shared_state.in_flight_fences[sync_frame_index];
self.device_context.wait_for_fences(&[frame_fence]).unwrap();
// Acquire the next image and signal the image available semaphore when it's ready to use
let image_available_semaphore = &shared_state.image_available_semaphores[sync_frame_index];
let swapchain_image = swapchain.acquire_next_image_semaphore(image_available_semaphore)?;
self.expect_result_from_previous_frame = true;
Ok(TryAcquireNextImageResult::Success(RafxPresentableFrame {
shared_state: Some(shared_state.clone()),
swapchain_image,
sync_frame_index,
global_frame_index,
}))
}
fn rebuild_swapchain(
&mut self,
window_width: u32,
window_height: u32,
mut event_listener: Option<&mut dyn RafxSwapchainEventListener>,
) -> RafxResult<()> {
log::info!("Rebuild Swapchain");
let shared_state = self.shared_state.take().unwrap();
{
let mut swapchain = shared_state.swapchain.lock().unwrap();
if let Some(event_listener) = event_listener.as_mut() {
event_listener.swapchain_destroyed(&self.device_context, &*swapchain)?;
}
let mut swapchain_def = swapchain.swapchain_def().clone();
swapchain_def.width = window_width;
swapchain_def.height = window_height;
swapchain.rebuild(&swapchain_def)?;
if let Some(event_listener) = event_listener.as_mut() {
event_listener.swapchain_created(&self.device_context, &swapchain)?;
}
self.format = swapchain.format();
self.image_count = swapchain.image_count();
self.swapchain_def = swapchain_def;
}
self.shared_state = Some(Arc::new(RafxSwapchainHelperSharedState::new(
&self.device_context,
shared_state.swapchain.clone(),
)?));
Ok(())
}
}
impl Drop for RafxSwapchainHelper {
fn drop(&mut self) {
// This will be a no-op if destroy() was already called
self.destroy(None).unwrap();
}
}