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use std::marker::PhantomData;
use parking_lot::{RwLock, RwLockReadGuard, RwLockWriteGuard};
use wgt::Backend;
use crate::{
hub::{Access, Token},
id,
identity::{IdentityHandler, IdentityHandlerFactory},
resource::Resource,
storage::Storage,
};
#[derive(Debug)]
pub struct Registry<T: Resource, I: id::TypedId, F: IdentityHandlerFactory<I>> {
identity: F::Filter,
pub(crate) data: RwLock<Storage<T, I>>,
backend: Backend,
}
impl<T: Resource, I: id::TypedId, F: IdentityHandlerFactory<I>> Registry<T, I, F> {
pub(crate) fn new(backend: Backend, factory: &F) -> Self {
Self {
identity: factory.spawn(),
data: RwLock::new(Storage {
map: Vec::new(),
kind: T::TYPE,
_phantom: PhantomData,
}),
backend,
}
}
pub(crate) fn without_backend(factory: &F, kind: &'static str) -> Self {
Self {
identity: factory.spawn(),
data: RwLock::new(Storage {
map: Vec::new(),
kind,
_phantom: PhantomData,
}),
backend: Backend::Empty,
}
}
}
#[must_use]
pub(crate) struct FutureId<'a, I: id::TypedId, T> {
id: I,
data: &'a RwLock<Storage<T, I>>,
}
impl<I: id::TypedId + Copy, T> FutureId<'_, I, T> {
#[cfg(feature = "trace")]
pub fn id(&self) -> I {
self.id
}
pub fn into_id(self) -> I {
self.id
}
pub fn assign<'a, A: Access<T>>(self, value: T, _: &'a mut Token<A>) -> id::Valid<I> {
self.data.write().insert(self.id, value);
id::Valid(self.id)
}
pub fn assign_error<'a, A: Access<T>>(self, label: &str, _: &'a mut Token<A>) -> I {
self.data.write().insert_error(self.id, label);
self.id
}
}
impl<T: Resource, I: id::TypedId + Copy, F: IdentityHandlerFactory<I>> Registry<T, I, F> {
pub(crate) fn prepare(
&self,
id_in: <F::Filter as IdentityHandler<I>>::Input,
) -> FutureId<I, T> {
FutureId {
id: self.identity.process(id_in, self.backend),
data: &self.data,
}
}
/// Acquire read access to this `Registry`'s contents.
///
/// The caller must present a mutable reference to a `Token<A>`,
/// for some type `A` that comes before this `Registry`'s resource
/// type `T` in the lock ordering. A `Token<Root>` grants
/// permission to lock any field; see [`Token::root`].
///
/// Once the read lock is acquired, return a new `Token<T>`, along
/// with a read guard for this `Registry`'s [`Storage`], which can
/// be indexed by id to get at the actual resources.
///
/// The borrow checker ensures that the caller cannot again access
/// its `Token<A>` until it has dropped both the guard and the
/// `Token<T>`.
///
/// See the [`Hub`] type for more details on locking.
///
/// [`Hub`]: crate::hub::Hub
pub(crate) fn read<'a, A: Access<T>>(
&'a self,
_token: &'a mut Token<A>,
) -> (RwLockReadGuard<'a, Storage<T, I>>, Token<'a, T>) {
(self.data.read(), Token::new())
}
/// Acquire write access to this `Registry`'s contents.
///
/// The caller must present a mutable reference to a `Token<A>`,
/// for some type `A` that comes before this `Registry`'s resource
/// type `T` in the lock ordering. A `Token<Root>` grants
/// permission to lock any field; see [`Token::root`].
///
/// Once the lock is acquired, return a new `Token<T>`, along with
/// a write guard for this `Registry`'s [`Storage`], which can be
/// indexed by id to get at the actual resources.
///
/// The borrow checker ensures that the caller cannot again access
/// its `Token<A>` until it has dropped both the guard and the
/// `Token<T>`.
///
/// See the [`Hub`] type for more details on locking.
///
/// [`Hub`]: crate::hub::Hub
pub(crate) fn write<'a, A: Access<T>>(
&'a self,
_token: &'a mut Token<A>,
) -> (RwLockWriteGuard<'a, Storage<T, I>>, Token<'a, T>) {
(self.data.write(), Token::new())
}
/// Unregister the resource at `id`.
///
/// The caller must prove that it already holds a write lock for
/// this `Registry` by passing a mutable reference to this
/// `Registry`'s storage, obtained from the write guard returned
/// by a previous call to [`write`], as the `guard` parameter.
pub fn unregister_locked(&self, id: I, guard: &mut Storage<T, I>) -> Option<T> {
let value = guard.remove(id);
//Note: careful about the order here!
self.identity.free(id);
//Returning None is legal if it's an error ID
value
}
/// Unregister the resource at `id` and return its value, if any.
///
/// The caller must present a mutable reference to a `Token<A>`,
/// for some type `A` that comes before this `Registry`'s resource
/// type `T` in the lock ordering.
///
/// This returns a `Token<T>`, but it's almost useless, because it
/// doesn't return a lock guard to go with it: its only effect is
/// to make the token you passed to this function inaccessible.
/// However, the `Token<T>` can be used to satisfy some functions'
/// bureacratic expectations that you will have one available.
///
/// The borrow checker ensures that the caller cannot again access
/// its `Token<A>` until it has dropped both the guard and the
/// `Token<T>`.
///
/// See the [`Hub`] type for more details on locking.
///
/// [`Hub`]: crate::hub::Hub
pub(crate) fn unregister<'a, A: Access<T>>(
&self,
id: I,
_token: &'a mut Token<A>,
) -> (Option<T>, Token<'a, T>) {
let value = self.data.write().remove(id);
//Note: careful about the order here!
self.identity.free(id);
//Returning None is legal if it's an error ID
(value, Token::new())
}
pub fn label_for_resource(&self, id: I) -> String {
let guard = self.data.read();
let type_name = guard.kind;
match guard.get(id) {
Ok(res) => {
let label = res.label();
if label.is_empty() {
format!("<{}-{:?}>", type_name, id.unzip())
} else {
label.to_string()
}
}
Err(_) => format!(
"<Invalid-{} label={}>",
type_name,
guard.label_for_invalid_id(id)
),
}
}
}