1cded6ac60
# Objective Memory usage optimisation ## Solution `HashMap` and `HashSet`'s keys are immutable. So using mutable types like `String`, `Vec<T>`, or `PathBuf` as a key is a waste of memory: they have an extra `usize` for their capacity and may have spare capacity. This PR replaces these types by their immutable equivalents `Box<str>`, `Box<[T]>`, and `Box<Path>`. For more context, I recommend watching the [Use Arc Instead of Vec](https://www.youtube.com/watch?v=A4cKi7PTJSs) video. --------- Co-authored-by: James Liu <contact@jamessliu.com>
97 lines
2.9 KiB
Rust
97 lines
2.9 KiB
Rust
use crate::io::{AssetReader, AssetReaderError, PathStream, Reader};
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use bevy_utils::{BoxedFuture, HashMap};
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use crossbeam_channel::{Receiver, Sender};
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use parking_lot::RwLock;
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use std::{path::Path, sync::Arc};
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/// A "gated" reader that will prevent asset reads from returning until
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/// a given path has been "opened" using [`GateOpener`].
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///
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/// This is built primarily for unit tests.
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pub struct GatedReader<R: AssetReader> {
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reader: R,
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gates: Arc<RwLock<HashMap<Box<Path>, (Sender<()>, Receiver<()>)>>>,
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}
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impl<R: AssetReader + Clone> Clone for GatedReader<R> {
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fn clone(&self) -> Self {
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Self {
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reader: self.reader.clone(),
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gates: self.gates.clone(),
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}
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}
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}
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/// Opens path "gates" for a [`GatedReader`].
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pub struct GateOpener {
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gates: Arc<RwLock<HashMap<Box<Path>, (Sender<()>, Receiver<()>)>>>,
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}
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impl GateOpener {
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/// Opens the `path` "gate", allowing a _single_ [`AssetReader`] operation to return for that path.
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/// If multiple operations are expected, call `open` the expected number of calls.
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pub fn open<P: AsRef<Path>>(&self, path: P) {
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let mut gates = self.gates.write();
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let gates = gates
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.entry_ref(path.as_ref())
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.or_insert_with(crossbeam_channel::unbounded);
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gates.0.send(()).unwrap();
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}
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}
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impl<R: AssetReader> GatedReader<R> {
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/// Creates a new [`GatedReader`], which wraps the given `reader`. Also returns a [`GateOpener`] which
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/// can be used to open "path gates" for this [`GatedReader`].
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pub fn new(reader: R) -> (Self, GateOpener) {
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let gates = Arc::new(RwLock::new(HashMap::new()));
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(
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Self {
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reader,
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gates: gates.clone(),
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},
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GateOpener { gates },
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)
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}
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}
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impl<R: AssetReader> AssetReader for GatedReader<R> {
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fn read<'a>(
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&'a self,
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path: &'a Path,
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) -> BoxedFuture<'a, Result<Box<Reader<'a>>, AssetReaderError>> {
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let receiver = {
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let mut gates = self.gates.write();
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let gates = gates
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.entry_ref(path.as_ref())
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.or_insert_with(crossbeam_channel::unbounded);
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gates.1.clone()
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};
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Box::pin(async move {
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receiver.recv().unwrap();
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let result = self.reader.read(path).await?;
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Ok(result)
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})
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}
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fn read_meta<'a>(
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&'a self,
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path: &'a Path,
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) -> BoxedFuture<'a, Result<Box<Reader<'a>>, AssetReaderError>> {
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self.reader.read_meta(path)
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}
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fn read_directory<'a>(
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&'a self,
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path: &'a Path,
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) -> BoxedFuture<'a, Result<Box<PathStream>, AssetReaderError>> {
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self.reader.read_directory(path)
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}
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fn is_directory<'a>(
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&'a self,
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path: &'a Path,
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) -> BoxedFuture<'a, Result<bool, AssetReaderError>> {
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self.reader.is_directory(path)
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}
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}
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