bd489068c6
# Objective - Adjust `bevy_utils` to make it `no_std` compatible - Partially replaces #6581 - Contributes to #8161 - Contributes to #6370 ## Solution Added `alloc` and `std` features to `bevy_utils` (`std` is enabled by default), allowing the crate's use in `no_std` contexts. ## Testing - CI passed locally. - Used `bevy_utils` in a `no_std` crate as an experiment and compiled successfully. ## Migration Guide If you were importing `bevy_utils` and setting `default_features` to `false`, but relying on elements which are now gated behind the `std` or `alloc` features, include the relevant feature in your `Cargo.toml`. ## Notes - Bevy already includes a single `no_std` crate, `bevy_ptr`, so there is precedent for this change. - As `bevy_utils` is widely used across the rest of Bevy, further work to make Bevy `no_std` compatible would be blocked on this crate, if such work was to be undertaken. - Most of the changes in this PR are just the removal of an unnecessary call to `to_string()` within unit tests.
80 lines
2.6 KiB
Rust
80 lines
2.6 KiB
Rust
#[cfg(all(feature = "alloc", not(feature = "std")))]
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use alloc::vec::Vec;
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use core::{cell::RefCell, ops::DerefMut};
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use thread_local::ThreadLocal;
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/// A cohesive set of thread-local values of a given type.
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///
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/// Mutable references can be fetched if `T: Default` via [`Parallel::scope`].
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#[derive(Default)]
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pub struct Parallel<T: Send> {
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locals: ThreadLocal<RefCell<T>>,
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}
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/// A scope guard of a `Parallel`, when this struct is dropped ,the value will writeback to its `Parallel`
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impl<T: Send> Parallel<T> {
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/// Gets a mutable iterator over all of the per-thread queues.
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pub fn iter_mut(&mut self) -> impl Iterator<Item = &'_ mut T> {
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self.locals.iter_mut().map(RefCell::get_mut)
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}
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/// Clears all of the stored thread local values.
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pub fn clear(&mut self) {
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self.locals.clear();
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}
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}
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impl<T: Default + Send> Parallel<T> {
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/// Retrieves the thread-local value for the current thread and runs `f` on it.
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///
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/// If there is no thread-local value, it will be initialized to its default.
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pub fn scope<R>(&self, f: impl FnOnce(&mut T) -> R) -> R {
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let mut cell = self.locals.get_or_default().borrow_mut();
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let ret = f(cell.deref_mut());
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ret
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}
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/// Mutably borrows the thread-local value.
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///
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/// If there is no thread-local value, it will be initialized to it's default.
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pub fn borrow_local_mut(&self) -> impl DerefMut<Target = T> + '_ {
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self.locals.get_or_default().borrow_mut()
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}
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}
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impl<T, I> Parallel<I>
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where
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I: IntoIterator<Item = T> + Default + Send + 'static,
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{
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/// Drains all enqueued items from all threads and returns an iterator over them.
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///
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/// Unlike [`Vec::drain`], this will piecemeal remove chunks of the data stored.
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/// If iteration is terminated part way, the rest of the enqueued items in the same
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/// chunk will be dropped, and the rest of the undrained elements will remain.
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///
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/// The ordering is not guaranteed.
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pub fn drain(&mut self) -> impl Iterator<Item = T> + '_ {
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self.locals.iter_mut().flat_map(|item| item.take())
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}
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}
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#[cfg(feature = "alloc")]
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impl<T: Send> Parallel<Vec<T>> {
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/// Collect all enqueued items from all threads and appends them to the end of a
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/// single Vec.
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///
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/// The ordering is not guaranteed.
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pub fn drain_into(&mut self, out: &mut Vec<T>) {
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let size = self
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.locals
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.iter_mut()
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.map(|queue| queue.get_mut().len())
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.sum();
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out.reserve(size);
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for queue in self.locals.iter_mut() {
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out.append(queue.get_mut());
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}
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}
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}
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