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use crate::{
device::{
queue::{EncoderInFlight, SubmittedWorkDoneClosure, TempResource},
DeviceError, DeviceLostClosure,
},
resource::{self, Buffer, Texture, Trackable},
snatch::SnatchGuard,
SubmissionIndex,
};
use smallvec::SmallVec;
use std::sync::Arc;
use thiserror::Error;
/// A command submitted to the GPU for execution.
///
/// ## Keeping resources alive while the GPU is using them
///
/// [`wgpu_hal`] requires that, when a command is submitted to a queue, all the
/// resources it uses must remain alive until it has finished executing.
///
/// [`wgpu_hal`]: hal
/// [`ResourceInfo::submission_index`]: crate::resource::ResourceInfo
struct ActiveSubmission {
/// The index of the submission we track.
///
/// When `Device::fence`'s value is greater than or equal to this, our queue
/// submission has completed.
index: SubmissionIndex,
/// Temporary resources to be freed once this queue submission has completed.
temp_resources: Vec<TempResource>,
/// Buffers to be mapped once this submission has completed.
mapped: Vec<Arc<Buffer>>,
/// Command buffers used by this submission, and the encoder that owns them.
///
/// [`wgpu_hal::Queue::submit`] requires the submitted command buffers to
/// remain alive until the submission has completed execution. Command
/// encoders double as allocation pools for command buffers, so holding them
/// here and cleaning them up in [`LifetimeTracker::triage_submissions`]
/// satisfies that requirement.
///
/// Once this submission has completed, the command buffers are reset and
/// the command encoder is recycled.
///
/// [`wgpu_hal::Queue::submit`]: hal::Queue::submit
encoders: Vec<EncoderInFlight>,
/// List of queue "on_submitted_work_done" closures to be called once this
/// submission has completed.
work_done_closures: SmallVec<[SubmittedWorkDoneClosure; 1]>,
}
impl ActiveSubmission {
/// Returns true if this submission contains the given buffer.
///
/// This only uses constant-time operations.
pub fn contains_buffer(&self, buffer: &Buffer) -> bool {
for encoder in &self.encoders {
// The ownership location of buffers depends on where the command encoder
// came from. If it is the staging command encoder on the queue, it is
// in the pending buffer list. If it came from a user command encoder,
// it is in the tracker.
if encoder.trackers.buffers.contains(buffer) {
return true;
}
if encoder
.pending_buffers
.contains_key(&buffer.tracker_index())
{
return true;
}
}
false
}
/// Returns true if this submission contains the given texture.
///
/// This only uses constant-time operations.
pub fn contains_texture(&self, texture: &Texture) -> bool {
for encoder in &self.encoders {
// The ownership location of textures depends on where the command encoder
// came from. If it is the staging command encoder on the queue, it is
// in the pending buffer list. If it came from a user command encoder,
// it is in the tracker.
if encoder.trackers.textures.contains(texture) {
return true;
}
if encoder
.pending_textures
.contains_key(&texture.tracker_index())
{
return true;
}
}
false
}
}
#[derive(Clone, Debug, Error)]
#[non_exhaustive]
pub enum WaitIdleError {
#[error(transparent)]
Device(#[from] DeviceError),
#[error("Tried to wait using a submission index ({0}) that has not been returned by a successful submission (last successful submission: {1})")]
WrongSubmissionIndex(SubmissionIndex, SubmissionIndex),
#[error("GPU got stuck :(")]
StuckGpu,
}
/// Resource tracking for a device.
///
/// ## Host mapping buffers
///
/// A buffer cannot be mapped until all active queue submissions that use it
/// have completed. To that end:
///
/// - Each buffer's `ResourceInfo::submission_index` records the index of the
/// most recent queue submission that uses that buffer.
///
/// - Calling `Global::buffer_map_async` adds the buffer to
/// `self.mapped`, and changes `Buffer::map_state` to prevent it
/// from being used in any new submissions.
///
/// - When the device is polled, the following `LifetimeTracker` methods decide
/// what should happen next:
///
/// 1) `triage_mapped` drains `self.mapped`, checking the submission index
/// of each buffer against the queue submissions that have finished
/// execution. Buffers used by submissions still in flight go in
/// `self.active[index].mapped`, and the rest go into
/// `self.ready_to_map`.
///
/// 2) `triage_submissions` moves entries in `self.active[i]` for completed
/// submissions to `self.ready_to_map`. At this point, both
/// `self.active` and `self.ready_to_map` are up to date with the given
/// submission index.
///
/// 3) `handle_mapping` drains `self.ready_to_map` and actually maps the
/// buffers, collecting a list of notification closures to call.
///
/// Only calling `Global::buffer_map_async` clones a new `Arc` for the
/// buffer. This new `Arc` is only dropped by `handle_mapping`.
pub(crate) struct LifetimeTracker {
/// Buffers for which a call to [`Buffer::map_async`] has succeeded, but
/// which haven't been examined by `triage_mapped` yet to decide when they
/// can be mapped.
mapped: Vec<Arc<Buffer>>,
/// Resources used by queue submissions still in flight. One entry per
/// submission, with older submissions appearing before younger.
///
/// Entries are added by `track_submission` and drained by
/// `LifetimeTracker::triage_submissions`. Lots of methods contribute data
/// to particular entries.
active: Vec<ActiveSubmission>,
/// Buffers the user has asked us to map, and which are not used by any
/// queue submission still in flight.
ready_to_map: Vec<Arc<Buffer>>,
/// Queue "on_submitted_work_done" closures that were initiated for while there is no
/// currently pending submissions. These cannot be immediately invoked as they
/// must happen _after_ all mapped buffer callbacks are mapped, so we defer them
/// here until the next time the device is maintained.
work_done_closures: SmallVec<[SubmittedWorkDoneClosure; 1]>,
/// Closure to be called on "lose the device". This is invoked directly by
/// device.lose or by the UserCallbacks returned from maintain when the device
/// has been destroyed and its queues are empty.
pub device_lost_closure: Option<DeviceLostClosure>,
}
impl LifetimeTracker {
pub fn new() -> Self {
Self {
mapped: Vec::new(),
active: Vec::new(),
ready_to_map: Vec::new(),
work_done_closures: SmallVec::new(),
device_lost_closure: None,
}
}
/// Return true if there are no queue submissions still in flight.
pub fn queue_empty(&self) -> bool {
self.active.is_empty()
}
/// Start tracking resources associated with a new queue submission.
pub fn track_submission(
&mut self,
index: SubmissionIndex,
temp_resources: impl Iterator<Item = TempResource>,
encoders: Vec<EncoderInFlight>,
) {
self.active.push(ActiveSubmission {
index,
temp_resources: temp_resources.collect(),
mapped: Vec::new(),
encoders,
work_done_closures: SmallVec::new(),
});
}
pub(crate) fn map(&mut self, value: &Arc<Buffer>) {
self.mapped.push(value.clone());
}
/// Returns the submission index of the most recent submission that uses the
/// given buffer.
pub fn get_buffer_latest_submission_index(&self, buffer: &Buffer) -> Option<SubmissionIndex> {
// We iterate in reverse order, so that we can bail out early as soon
// as we find a hit.
self.active.iter().rev().find_map(|submission| {
if submission.contains_buffer(buffer) {
Some(submission.index)
} else {
None
}
})
}
/// Returns the submission index of the most recent submission that uses the
/// given texture.
pub fn get_texture_latest_submission_index(
&self,
texture: &Texture,
) -> Option<SubmissionIndex> {
// We iterate in reverse order, so that we can bail out early as soon
// as we find a hit.
self.active.iter().rev().find_map(|submission| {
if submission.contains_texture(texture) {
Some(submission.index)
} else {
None
}
})
}
/// Sort out the consequences of completed submissions.
///
/// Assume that all submissions up through `last_done` have completed.
///
/// - Buffers used by those submissions are now ready to map, if requested.
/// Add any buffers in the submission's [`mapped`] list to
/// [`self.ready_to_map`], where [`LifetimeTracker::handle_mapping`]
/// will find them.
///
/// Return a list of [`SubmittedWorkDoneClosure`]s to run.
///
/// [`mapped`]: ActiveSubmission::mapped
/// [`self.ready_to_map`]: LifetimeTracker::ready_to_map
/// [`SubmittedWorkDoneClosure`]: crate::device::queue::SubmittedWorkDoneClosure
#[must_use]
pub fn triage_submissions(
&mut self,
last_done: SubmissionIndex,
command_allocator: &crate::command::CommandAllocator,
) -> SmallVec<[SubmittedWorkDoneClosure; 1]> {
profiling::scope!("triage_submissions");
//TODO: enable when `is_sorted_by_key` is stable
//debug_assert!(self.active.is_sorted_by_key(|a| a.index));
let done_count = self
.active
.iter()
.position(|a| a.index > last_done)
.unwrap_or(self.active.len());
let mut work_done_closures: SmallVec<_> = self.work_done_closures.drain(..).collect();
for a in self.active.drain(..done_count) {
self.ready_to_map.extend(a.mapped);
for encoder in a.encoders {
let raw = unsafe { encoder.land() };
command_allocator.release_encoder(raw);
}
drop(a.temp_resources);
work_done_closures.extend(a.work_done_closures);
}
work_done_closures
}
pub fn schedule_resource_destruction(
&mut self,
temp_resource: TempResource,
last_submit_index: SubmissionIndex,
) {
let resources = self
.active
.iter_mut()
.find(|a| a.index == last_submit_index)
.map(|a| &mut a.temp_resources);
if let Some(resources) = resources {
resources.push(temp_resource);
}
}
pub fn add_work_done_closure(&mut self, closure: SubmittedWorkDoneClosure) {
match self.active.last_mut() {
Some(active) => {
active.work_done_closures.push(closure);
}
// We must defer the closure until all previously occurring map_async closures
// have fired. This is required by the spec.
None => {
self.work_done_closures.push(closure);
}
}
}
/// Determine which buffers are ready to map, and which must wait for the
/// GPU.
///
/// See the documentation for [`LifetimeTracker`] for details.
pub(crate) fn triage_mapped(&mut self) {
if self.mapped.is_empty() {
return;
}
for buffer in self.mapped.drain(..) {
let submission = self
.active
.iter_mut()
.rev()
.find(|a| a.contains_buffer(&buffer));
submission
.map_or(&mut self.ready_to_map, |a| &mut a.mapped)
.push(buffer);
}
}
/// Map the buffers in `self.ready_to_map`.
///
/// Return a list of mapping notifications to send.
///
/// See the documentation for [`LifetimeTracker`] for details.
#[must_use]
pub(crate) fn handle_mapping(
&mut self,
raw: &dyn hal::DynDevice,
snatch_guard: &SnatchGuard,
) -> Vec<super::BufferMapPendingClosure> {
if self.ready_to_map.is_empty() {
return Vec::new();
}
let mut pending_callbacks: Vec<super::BufferMapPendingClosure> =
Vec::with_capacity(self.ready_to_map.len());
for buffer in self.ready_to_map.drain(..) {
// This _cannot_ be inlined into the match. If it is, the lock will be held
// open through the whole match, resulting in a deadlock when we try to re-lock
// the buffer back to active.
let mapping = std::mem::replace(
&mut *buffer.map_state.lock(),
resource::BufferMapState::Idle,
);
let pending_mapping = match mapping {
resource::BufferMapState::Waiting(pending_mapping) => pending_mapping,
// Mapping cancelled
resource::BufferMapState::Idle => continue,
// Mapping queued at least twice by map -> unmap -> map
// and was already successfully mapped below
resource::BufferMapState::Active { .. } => {
*buffer.map_state.lock() = mapping;
continue;
}
_ => panic!("No pending mapping."),
};
let status = if pending_mapping.range.start != pending_mapping.range.end {
let host = pending_mapping.op.host;
let size = pending_mapping.range.end - pending_mapping.range.start;
match super::map_buffer(
raw,
&buffer,
pending_mapping.range.start,
size,
host,
snatch_guard,
) {
Ok(mapping) => {
*buffer.map_state.lock() = resource::BufferMapState::Active {
mapping,
range: pending_mapping.range.clone(),
host,
};
Ok(())
}
Err(e) => {
log::error!("Mapping failed: {e}");
Err(e)
}
}
} else {
*buffer.map_state.lock() = resource::BufferMapState::Active {
mapping: hal::BufferMapping {
ptr: std::ptr::NonNull::dangling(),
is_coherent: true,
},
range: pending_mapping.range,
host: pending_mapping.op.host,
};
Ok(())
};
pending_callbacks.push((pending_mapping.op, status));
}
pending_callbacks
}
}