# Objective
Simplify implementing some asset traits without Box::pin(async move{})
shenanigans.
Fixes (in part) https://github.com/bevyengine/bevy/issues/11308
## Solution
Use async-fn in traits when possible in all traits. Traits with return
position impl trait are not object safe however, and as AssetReader and
AssetWriter are both used with dynamic dispatch, you need a Boxed
version of these futures anyway.
In the future, Rust is [adding
](https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits.html)proc
macros to generate these traits automatically, and at some point in the
future dyn traits should 'just work'. Until then.... this seemed liked
the right approach given more ErasedXXX already exist, but, no clue if
there's plans here! Especially since these are public now, it's a bit of
an unfortunate API, and means this is a breaking change.
In theory this saves some performance when these traits are used with
static dispatch, but, seems like most code paths go through dynamic
dispatch, which boxes anyway.
I also suspect a bunch of the lifetime annotations on these function
could be simplified now as the BoxedFuture was often the only thing
returned which needed a lifetime annotation, but I'm not touching that
for now as traits + lifetimes can be so tricky.
This is a revival of
[pull/11362](https://github.com/bevyengine/bevy/pull/11362) after a
spectacular merge f*ckup, with updates to the latest Bevy. Just to recap
some discussion:
- Overall this seems like a win for code quality, especially when
implementing these traits, but a loss for having to deal with ErasedXXX
variants.
- `ConditionalSend` was the preferred name for the trait that might be
Send, to deal with wasm platforms.
- When reviewing be sure to disable whitespace difference, as that's 95%
of the PR.
## Changelog
- AssetReader, AssetWriter, AssetLoader, AssetSaver and Process now use
async-fn in traits rather than boxed futures.
## Migration Guide
- Custom implementations of AssetReader, AssetWriter, AssetLoader,
AssetSaver and Process should switch to async fn rather than returning a
bevy_utils::BoxedFuture.
- Simultaniously, to use dynamic dispatch on these traits you should
instead use dyn ErasedXXX.
# Objective
Make bevy_utils less of a compilation bottleneck. Tackle #11478.
## Solution
* Move all of the directly reexported dependencies and move them to
where they're actually used.
* Remove the UUID utilities that have gone unused since `TypePath` took
over for `TypeUuid`.
* There was also a extraneous bytemuck dependency on `bevy_core` that
has not been used for a long time (since `encase` became the primary way
to prepare GPU buffers).
* Remove the `all_tuples` macro reexport from bevy_ecs since it's
accessible from `bevy_utils`.
---
## Changelog
Removed: Many of the reexports from bevy_utils (petgraph, uuid, nonmax,
smallvec, and thiserror).
Removed: bevy_core's reexports of bytemuck.
## Migration Guide
bevy_utils' reexports of petgraph, uuid, nonmax, smallvec, and thiserror
have been removed.
bevy_core' reexports of bytemuck's types has been removed.
Add them as dependencies in your own crate instead.
# Objective
Currently the `missing_docs` lint is allowed-by-default and enabled at
crate level when their documentations is complete (see #3492).
This PR proposes to inverse this logic by making `missing_docs`
warn-by-default and mark crates with imcomplete docs allowed.
## Solution
Makes `missing_docs` warn at workspace level and allowed at crate level
when the docs is imcomplete.
# Objective
- Fixes#10518
## Solution
I've added a method to `LoadContext`, `load_direct_with_reader`, which
mirrors the behaviour of `load_direct` with a single key difference: it
is provided with the `Reader` by the caller, rather than getting it from
the contained `AssetServer`. This allows for an `AssetLoader` to process
its `Reader` stream, and then directly hand the results off to the
`LoadContext` to handle further loading. The outer `AssetLoader` can
control how the `Reader` is interpreted by providing a relevant
`AssetPath`.
For example, a Gzip decompression loader could process the asset
`images/my_image.png.gz` by decompressing the bytes, then handing the
decompressed result to the `LoadContext` with the new path
`images/my_image.png.gz/my_image.png`. This intuitively reflects the
nature of contained assets, whilst avoiding unintended behaviour, since
the generated path cannot be a real file path (a file and folder of the
same name cannot coexist in most file-systems).
```rust
#[derive(Asset, TypePath)]
pub struct GzAsset {
pub uncompressed: ErasedLoadedAsset,
}
#[derive(Default)]
pub struct GzAssetLoader;
impl AssetLoader for GzAssetLoader {
type Asset = GzAsset;
type Settings = ();
type Error = GzAssetLoaderError;
fn load<'a>(
&'a self,
reader: &'a mut Reader,
_settings: &'a (),
load_context: &'a mut LoadContext,
) -> BoxedFuture<'a, Result<Self::Asset, Self::Error>> {
Box::pin(async move {
let compressed_path = load_context.path();
let file_name = compressed_path
.file_name()
.ok_or(GzAssetLoaderError::IndeterminateFilePath)?
.to_string_lossy();
let uncompressed_file_name = file_name
.strip_suffix(".gz")
.ok_or(GzAssetLoaderError::IndeterminateFilePath)?;
let contained_path = compressed_path.join(uncompressed_file_name);
let mut bytes_compressed = Vec::new();
reader.read_to_end(&mut bytes_compressed).await?;
let mut decoder = GzDecoder::new(bytes_compressed.as_slice());
let mut bytes_uncompressed = Vec::new();
decoder.read_to_end(&mut bytes_uncompressed)?;
// Now that we have decompressed the asset, let's pass it back to the
// context to continue loading
let mut reader = VecReader::new(bytes_uncompressed);
let uncompressed = load_context
.load_direct_with_reader(&mut reader, contained_path)
.await?;
Ok(GzAsset { uncompressed })
})
}
fn extensions(&self) -> &[&str] {
&["gz"]
}
}
```
Because this example is so prudent, I've included an
`asset_decompression` example which implements this exact behaviour:
```rust
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.init_asset::<GzAsset>()
.init_asset_loader::<GzAssetLoader>()
.add_systems(Startup, setup)
.add_systems(Update, decompress::<Image>)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn(Camera2dBundle::default());
commands.spawn((
Compressed::<Image> {
compressed: asset_server.load("data/compressed_image.png.gz"),
..default()
},
Sprite::default(),
TransformBundle::default(),
VisibilityBundle::default(),
));
}
fn decompress<A: Asset>(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut compressed_assets: ResMut<Assets<GzAsset>>,
query: Query<(Entity, &Compressed<A>)>,
) {
for (entity, Compressed { compressed, .. }) in query.iter() {
let Some(GzAsset { uncompressed }) = compressed_assets.remove(compressed) else {
continue;
};
let uncompressed = uncompressed.take::<A>().unwrap();
commands
.entity(entity)
.remove::<Compressed<A>>()
.insert(asset_server.add(uncompressed));
}
}
```
A key limitation to this design is how to type the internally loaded
asset, since the example `GzAssetLoader` is unaware of the internal
asset type `A`. As such, in this example I store the contained asset as
an `ErasedLoadedAsset`, and leave it up to the consumer of the `GzAsset`
to handle typing the final result, which is the purpose of the
`decompress` system. This limitation can be worked around by providing
type information to the `GzAssetLoader`, such as `GzAssetLoader<Image,
ImageAssetLoader>`, but this would require registering the asset loader
for every possible decompression target.
Aside from this limitation, nested asset containerisation works as an
end user would expect; if the user registers a `TarAssetLoader`, and a
`GzAssetLoader`, then they can load assets with compound
containerisation, such as `images.tar.gz`.
---
## Changelog
- Added `LoadContext::load_direct_with_reader`
- Added `asset_decompression` example
## Notes
- While I believe my implementation of a Gzip asset loader is
reasonable, I haven't included it as a public feature of `bevy_asset` to
keep the scope of this PR as focussed as possible.
- I have included `flate2` as a `dev-dependency` for the example; it is
not included in the main dependency graph.
