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use crate::{Epoch, Index};
use std::{
cmp::Ordering,
fmt::{self, Debug},
hash::Hash,
marker::PhantomData,
};
use wgt::{Backend, WasmNotSendSync};
type IdType = u64;
type ZippedIndex = Index;
type NonZeroId = std::num::NonZeroU64;
const INDEX_BITS: usize = std::mem::size_of::<ZippedIndex>() * 8;
const EPOCH_BITS: usize = INDEX_BITS - BACKEND_BITS;
const BACKEND_BITS: usize = 3;
const BACKEND_SHIFT: usize = INDEX_BITS * 2 - BACKEND_BITS;
pub const EPOCH_MASK: u32 = (1 << (EPOCH_BITS)) - 1;
/// The raw underlying representation of an identifier.
#[repr(transparent)]
#[cfg_attr(
any(feature = "serde", feature = "trace"),
derive(serde::Serialize),
serde(into = "SerialId")
)]
#[cfg_attr(
any(feature = "serde", feature = "replay"),
derive(serde::Deserialize),
serde(from = "SerialId")
)]
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct RawId(NonZeroId);
impl RawId {
#[doc(hidden)]
#[inline]
pub fn from_non_zero(non_zero: NonZeroId) -> Self {
Self(non_zero)
}
#[doc(hidden)]
#[inline]
pub fn into_non_zero(self) -> NonZeroId {
self.0
}
/// Zip together an identifier and return its raw underlying representation.
pub fn zip(index: Index, epoch: Epoch, backend: Backend) -> RawId {
assert_eq!(0, epoch >> EPOCH_BITS);
assert_eq!(0, (index as IdType) >> INDEX_BITS);
let v = index as IdType
| ((epoch as IdType) << INDEX_BITS)
| ((backend as IdType) << BACKEND_SHIFT);
Self(NonZeroId::new(v).unwrap())
}
/// Unzip a raw identifier into its components.
#[allow(trivial_numeric_casts)]
pub fn unzip(self) -> (Index, Epoch, Backend) {
(
(self.0.get() as ZippedIndex) as Index,
(((self.0.get() >> INDEX_BITS) as ZippedIndex) & (EPOCH_MASK as ZippedIndex)) as Index,
self.backend(),
)
}
pub fn backend(self) -> Backend {
match self.0.get() >> (BACKEND_SHIFT) as u8 {
0 => Backend::Empty,
1 => Backend::Vulkan,
2 => Backend::Metal,
3 => Backend::Dx12,
4 => Backend::Gl,
_ => unreachable!(),
}
}
}
/// Coerce a slice of identifiers into a slice of optional raw identifiers.
///
/// There's two reasons why we know this is correct:
/// * `Option<T>` is guaranteed to be niche-filled to 0's.
/// * The `T` in `Option<T>` can inhabit any representation except 0's, since
/// its underlying representation is `NonZero*`.
pub fn as_option_slice<T: Marker>(ids: &[Id<T>]) -> &[Option<Id<T>>] {
// SAFETY: Any Id<T> is repr(transparent) over `Option<RawId>`, since both
// are backed by non-zero types.
unsafe { std::slice::from_raw_parts(ids.as_ptr().cast(), ids.len()) }
}
/// An identifier for a wgpu object.
///
/// An `Id<T>` value identifies a value stored in a [`Global`]'s [`Hub`].
///
/// ## Note on `Id` typing
///
/// You might assume that an `Id<T>` can only be used to retrieve a resource of
/// type `T`, but that is not quite the case. The id types in `wgpu-core`'s
/// public API ([`TextureId`], for example) can refer to resources belonging to
/// any backend, but the corresponding resource types ([`Texture<A>`], for
/// example) are always parameterized by a specific backend `A`.
///
/// So the `T` in `Id<T>` is usually a resource type like `Texture<Empty>`,
/// where [`Empty`] is the `wgpu_hal` dummy back end. These empty types are
/// never actually used, beyond just making sure you access each `Storage` with
/// the right kind of identifier. The members of [`Hub<A>`] pair up each
/// `X<Empty>` type with the resource type `X<A>`, for some specific backend
/// `A`.
///
/// [`Global`]: crate::global::Global
/// [`Hub`]: crate::hub::Hub
/// [`Hub<A>`]: crate::hub::Hub
/// [`Texture<A>`]: crate::resource::Texture
/// [`Registry`]: crate::hub::Registry
/// [`Empty`]: hal::api::Empty
#[repr(transparent)]
#[cfg_attr(any(feature = "serde", feature = "trace"), derive(serde::Serialize))]
#[cfg_attr(any(feature = "serde", feature = "replay"), derive(serde::Deserialize))]
#[cfg_attr(
any(feature = "serde", feature = "trace", feature = "replay"),
serde(transparent)
)]
pub struct Id<T: Marker>(RawId, PhantomData<T>);
// This type represents Id in a more readable (and editable) way.
#[allow(dead_code)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
enum SerialId {
// The only variant forces RON to not ignore "Id"
Id(Index, Epoch, Backend),
}
impl From<RawId> for SerialId {
fn from(id: RawId) -> Self {
let (index, epoch, backend) = id.unzip();
Self::Id(index, epoch, backend)
}
}
impl From<SerialId> for RawId {
fn from(id: SerialId) -> Self {
match id {
SerialId::Id(index, epoch, backend) => RawId::zip(index, epoch, backend),
}
}
}
impl<T> Id<T>
where
T: Marker,
{
/// # Safety
///
/// The raw id must be valid for the type.
pub unsafe fn from_raw(raw: RawId) -> Self {
Self(raw, PhantomData)
}
/// Coerce the identifiers into its raw underlying representation.
pub fn into_raw(self) -> RawId {
self.0
}
#[allow(dead_code)]
pub(crate) fn dummy(index: u32) -> Self {
Id::zip(index, 1, Backend::Empty)
}
#[allow(dead_code)]
pub(crate) fn is_valid(&self) -> bool {
self.backend() != Backend::Empty
}
/// Get the backend this identifier corresponds to.
#[inline]
pub fn backend(self) -> Backend {
self.0.backend()
}
#[inline]
pub fn zip(index: Index, epoch: Epoch, backend: Backend) -> Self {
Id(RawId::zip(index, epoch, backend), PhantomData)
}
#[inline]
pub fn unzip(self) -> (Index, Epoch, Backend) {
self.0.unzip()
}
}
impl<T> Copy for Id<T> where T: Marker {}
impl<T> Clone for Id<T>
where
T: Marker,
{
#[inline]
fn clone(&self) -> Self {
*self
}
}
impl<T> Debug for Id<T>
where
T: Marker,
{
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
let (index, epoch, backend) = self.unzip();
let backend = match backend {
Backend::Empty => "_",
Backend::Vulkan => "vk",
Backend::Metal => "mtl",
Backend::Dx12 => "d3d12",
Backend::Gl => "gl",
Backend::BrowserWebGpu => "webgpu",
};
write!(formatter, "Id({index},{epoch},{backend})")?;
Ok(())
}
}
impl<T> Hash for Id<T>
where
T: Marker,
{
#[inline]
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
self.0.hash(state);
}
}
impl<T> PartialEq for Id<T>
where
T: Marker,
{
#[inline]
fn eq(&self, other: &Self) -> bool {
self.0 == other.0
}
}
impl<T> Eq for Id<T> where T: Marker {}
impl<T> PartialOrd for Id<T>
where
T: Marker,
{
#[inline]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<T> Ord for Id<T>
where
T: Marker,
{
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
self.0.cmp(&other.0)
}
}
/// Marker trait used to determine which types uniquely identify a resource.
///
/// For example, `Device<A>` will have the same type of identifier as
/// `Device<B>` because `Device<T>` for any `T` defines the same maker type.
pub trait Marker: 'static + WasmNotSendSync {}
// This allows `()` to be used as a marker type for tests.
//
// We don't want these in production code, since they essentially remove type
// safety, like how identifiers across different types can be compared.
#[cfg(test)]
impl Marker for () {}
/// Define identifiers for each resource.
macro_rules! ids {
($(
$(#[$($meta:meta)*])*
pub type $name:ident $marker:ident;
)*) => {
/// Marker types for each resource.
pub mod markers {
$(
#[derive(Debug)]
pub enum $marker {}
impl super::Marker for $marker {}
)*
}
$(
$(#[$($meta)*])*
pub type $name = Id<self::markers::$marker>;
)*
}
}
ids! {
pub type AdapterId Adapter;
pub type SurfaceId Surface;
pub type DeviceId Device;
pub type QueueId Queue;
pub type BufferId Buffer;
pub type StagingBufferId StagingBuffer;
pub type TextureViewId TextureView;
pub type TextureId Texture;
pub type SamplerId Sampler;
pub type BindGroupLayoutId BindGroupLayout;
pub type PipelineLayoutId PipelineLayout;
pub type BindGroupId BindGroup;
pub type ShaderModuleId ShaderModule;
pub type RenderPipelineId RenderPipeline;
pub type ComputePipelineId ComputePipeline;
pub type CommandEncoderId CommandEncoder;
pub type CommandBufferId CommandBuffer;
pub type RenderPassEncoderId RenderPassEncoder;
pub type ComputePassEncoderId ComputePassEncoder;
pub type RenderBundleEncoderId RenderBundleEncoder;
pub type RenderBundleId RenderBundle;
pub type QuerySetId QuerySet;
}
impl CommandEncoderId {
pub fn into_command_buffer_id(self) -> CommandBufferId {
Id(self.0, PhantomData)
}
}
impl CommandBufferId {
pub fn into_command_encoder_id(self) -> CommandEncoderId {
Id(self.0, PhantomData)
}
}
impl DeviceId {
pub fn into_queue_id(self) -> QueueId {
Id(self.0, PhantomData)
}
}
#[test]
fn test_id_backend() {
for &b in &[
Backend::Empty,
Backend::Vulkan,
Backend::Metal,
Backend::Dx12,
Backend::Gl,
] {
let id = crate::id::Id::<()>::zip(1, 0, b);
let (_id, _epoch, backend) = id.unzip();
assert_eq!(id.backend(), b);
assert_eq!(backend, b);
}
}
#[test]
fn test_id() {
let last_index = ((1u64 << INDEX_BITS) - 1) as Index;
let indexes = [1, last_index / 2 - 1, last_index / 2 + 1, last_index];
let epochs = [1, EPOCH_MASK / 2 - 1, EPOCH_MASK / 2 + 1, EPOCH_MASK];
let backends = [
Backend::Empty,
Backend::Vulkan,
Backend::Metal,
Backend::Dx12,
Backend::Gl,
];
for &i in &indexes {
for &e in &epochs {
for &b in &backends {
let id = crate::id::Id::<()>::zip(i, e, b);
let (index, epoch, backend) = id.unzip();
assert_eq!(index, i);
assert_eq!(epoch, e);
assert_eq!(backend, b);
}
}
}
}