bevy_asset/lib.rs
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//! In the context of game development, an "asset" is a piece of content that is loaded from disk and displayed in the game.
//! Typically, these are authored by artists and designers (in contrast to code),
//! are relatively large in size, and include everything from textures and models to sounds and music to levels and scripts.
//!
//! This presents two main challenges:
//! - Assets take up a lot of memory; simply storing a copy for each instance of an asset in the game would be prohibitively expensive.
//! - Loading assets from disk is slow, and can cause long load times and delays.
//!
//! These problems play into each other, for if assets are expensive to store in memory,
//! then larger game worlds will need to load them from disk as needed, ideally without a loading screen.
//!
//! As is common in Rust, non-blocking asset loading is done using `async`, with background tasks used to load assets while the game is running.
//! Bevy coordinates these tasks using the [`AssetServer`] resource, storing each loaded asset in a strongly-typed [`Assets<T>`] collection (also a resource).
//! [`Handle`]s serve as an id-based reference to entries in the [`Assets`] collection, allowing them to be cheaply shared between systems,
//! and providing a way to initialize objects (generally entities) before the required assets are loaded.
//! In short: [`Handle`]s are not the assets themselves, they just tell how to look them up!
//!
//! ## Loading assets
//!
//! The [`AssetServer`] is the main entry point for loading assets.
//! Typically, you'll use the [`AssetServer::load`] method to load an asset from disk, which returns a [`Handle`].
//! Note that this method does not attempt to reload the asset if it has already been loaded: as long as at least one handle has not been dropped,
//! calling [`AssetServer::load`] on the same path will return the same handle.
//! The handle that's returned can be used to instantiate various [`Component`](bevy_ecs::prelude::Component)s that require asset data to function,
//! which will then be spawned into the world as part of an entity.
//!
//! To avoid assets "popping" into existence, you may want to check that all of the required assets are loaded before transitioning to a new scene.
//! This can be done by checking the [`LoadState`] of the asset handle using [`AssetServer::is_loaded_with_dependencies`],
//! which will be `true` when the asset is ready to use.
//!
//! Keep track of what you're waiting on by using a [`HashSet`] of asset handles or similar data structure,
//! which iterate over and poll in your update loop, and transition to the new scene once all assets are loaded.
//! Bevy's built-in states system can be very helpful for this!
//!
//! # Modifying entities that use assets
//!
//! If we later want to change the asset data a given component uses (such as changing an entity's material), we have three options:
//!
//! 1. Change the handle stored on the responsible component to the handle of a different asset
//! 2. Despawn the entity and spawn a new one with the new asset data.
//! 3. Use the [`Assets`] collection to directly modify the current handle's asset data
//!
//! The first option is the most common: just query for the component that holds the handle, and mutate it, pointing to the new asset.
//! Check how the handle was passed in to the entity when it was spawned: if a mesh-related component required a handle to a mesh asset,
//! you'll need to find that component via a query and change the handle to the new mesh asset.
//! This is so commonly done that you should think about strategies for how to store and swap handles in your game.
//!
//! The second option is the simplest, but can be slow if done frequently,
//! and can lead to frustrating bugs as references to the old entity (such as what is targeting it) and other data on the entity are lost.
//! Generally, this isn't a great strategy.
//!
//! The third option has different semantics: rather than modifying the asset data for a single entity, it modifies the asset data for *all* entities using this handle.
//! While this might be what you want, it generally isn't!
//!
//! # Hot reloading assets
//!
//! Bevy supports asset hot reloading, allowing you to change assets on disk and see the changes reflected in your game without restarting.
//! When enabled, any changes to the underlying asset file will be detected by the [`AssetServer`], which will then reload the asset,
//! mutating the asset data in the [`Assets`] collection and thus updating all entities that use the asset.
//! While it has limited uses in published games, it is very useful when developing, as it allows you to iterate quickly.
//!
//! To enable asset hot reloading on desktop platforms, enable `bevy`'s `file_watcher` cargo feature.
//! To toggle it at runtime, you can use the `watch_for_changes_override` field in the [`AssetPlugin`] to enable or disable hot reloading.
//!
//! # Procedural asset creation
//!
//! Not all assets are loaded from disk: some are generated at runtime, such as procedural materials, sounds or even levels.
//! After creating an item of a type that implements [`Asset`], you can add it to the [`Assets`] collection using [`Assets::add`].
//! Once in the asset collection, this data can be operated on like any other asset.
//!
//! Note that, unlike assets loaded from a file path, no general mechanism currently exists to deduplicate procedural assets:
//! calling [`Assets::add`] for every entity that needs the asset will create a new copy of the asset for each entity,
//! quickly consuming memory.
//!
//! ## Handles and reference counting
//!
//! [`Handle`] (or their untyped counterpart [`UntypedHandle`]) are used to reference assets in the [`Assets`] collection,
//! and are the primary way to interact with assets in Bevy.
//! As a user, you'll be working with handles a lot!
//!
//! The most important thing to know about handles is that they are reference counted: when you clone a handle, you're incrementing a reference count.
//! When the object holding the handle is dropped (generally because an entity was despawned), the reference count is decremented.
//! When the reference count hits zero, the asset it references is removed from the [`Assets`] collection.
//!
//! This reference counting is a simple, largely automatic way to avoid holding onto memory for game objects that are no longer in use.
//! However, it can lead to surprising behavior if you're not careful!
//!
//! There are two categories of problems to watch out for:
//! - never dropping a handle, causing the asset to never be removed from memory
//! - dropping a handle too early, causing the asset to be removed from memory while it's still in use
//!
//! The first problem is less critical for beginners, as for tiny games, you can often get away with simply storing all of the assets in memory at once,
//! and loading them all at the start of the game.
//! As your game grows, you'll need to be more careful about when you load and unload assets,
//! segmenting them by level or area, and loading them on-demand.
//! This problem generally arises when handles are stored in a persistent "collection" or "manifest" of possible objects (generally in a resource),
//! which is convenient for easy access and zero-latency spawning, but can result in high but stable memory usage.
//!
//! The second problem is more concerning, and looks like your models or textures suddenly disappearing from the game.
//! Debugging reveals that the *entities* are still there, but nothing is rendering!
//! This is because the assets were removed from memory while they were still in use.
//! You were probably too aggressive with the use of weak handles (which don't increment the reference count of the asset): think through the lifecycle of your assets carefully!
//! As soon as an asset is loaded, you must ensure that at least one strong handle is held to it until all matching entities are out of sight of the player.
//!
//! # Asset dependencies
//!
//! Some assets depend on other assets to be loaded before they can be loaded themselves.
//! For example, a 3D model might require both textures and meshes to be loaded,
//! or a 2D level might require a tileset to be loaded.
//!
//! The assets that are required to load another asset are called "dependencies".
//! An asset is only considered fully loaded when it and all of its dependencies are loaded.
//! Asset dependencies can be declared when implementing the [`Asset`] trait by implementing the [`VisitAssetDependencies`] trait,
//! and the `#[dependency]` attribute can be used to automatically derive this implementation.
//!
//! # Custom asset types
//!
//! While Bevy comes with implementations for a large number of common game-oriented asset types (often behind off-by-default feature flags!),
//! implementing a custom asset type can be useful when dealing with unusual, game-specific, or proprietary formats.
//!
//! Defining a new asset type is as simple as implementing the [`Asset`] trait.
//! This requires [`TypePath`] for metadata about the asset type,
//! and [`VisitAssetDependencies`] to track asset dependencies.
//! In simple cases, you can derive [`Asset`] and [`Reflect`] and be done with it: the required supertraits will be implemented for you.
//!
//! With a new asset type in place, we now need to figure out how to load it.
//! While [`AssetReader`](io::AssetReader) describes strategies to read asset bytes from various sources,
//! [`AssetLoader`] is the trait that actually turns those into your desired in-memory format.
//! Generally, (only) [`AssetLoader`] needs to be implemented for custom assets, as the [`AssetReader`](io::AssetReader) implementations are provided by Bevy.
//!
//! However, [`AssetLoader`] shouldn't be implemented for your asset type directly: instead, this is implemented for a "loader" type
//! that can store settings and any additional data required to load your asset, while your asset type is used as the [`AssetLoader::Asset`] associated type.
//! As the trait documentation explains, this allows various [`AssetLoader::Settings`] to be used to configure the loader.
//!
//! After the loader is implemented, it needs to be registered with the [`AssetServer`] using [`App::register_asset_loader`](AssetApp::register_asset_loader).
//! Once your asset type is loaded, you can use it in your game like any other asset type!
//!
//! If you want to save your assets back to disk, you should implement [`AssetSaver`](saver::AssetSaver) as well.
//! This trait mirrors [`AssetLoader`] in structure, and works in tandem with [`AssetWriter`](io::AssetWriter), which mirrors [`AssetReader`](io::AssetReader).
// FIXME(3492): remove once docs are ready
// FIXME(15321): solve CI failures, then replace with `#![expect()]`.
#![allow(missing_docs, reason = "Not all docs are written yet, see #3492.")]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
#![doc(
html_logo_url = "https://bevyengine.org/assets/icon.png",
html_favicon_url = "https://bevyengine.org/assets/icon.png"
)]
extern crate alloc;
pub mod io;
pub mod meta;
pub mod processor;
pub mod saver;
pub mod transformer;
/// The asset prelude.
///
/// This includes the most common types in this crate, re-exported for your convenience.
pub mod prelude {
#[doc(hidden)]
pub use crate::{
Asset, AssetApp, AssetEvent, AssetId, AssetMode, AssetPlugin, AssetServer, Assets,
DirectAssetAccessExt, Handle, UntypedHandle,
};
}
mod assets;
mod direct_access_ext;
mod event;
mod folder;
mod handle;
mod id;
mod loader;
mod loader_builders;
mod path;
mod reflect;
mod render_asset;
mod server;
pub use assets::*;
pub use bevy_asset_macros::Asset;
pub use direct_access_ext::DirectAssetAccessExt;
pub use event::*;
pub use folder::*;
pub use futures_lite::{AsyncReadExt, AsyncWriteExt};
pub use handle::*;
pub use id::*;
pub use loader::*;
pub use loader_builders::{
Deferred, DynamicTyped, Immediate, NestedLoader, StaticTyped, UnknownTyped,
};
pub use path::*;
pub use reflect::*;
pub use render_asset::*;
pub use server::*;
/// Rusty Object Notation, a crate used to serialize and deserialize bevy assets.
pub use ron;
use crate::{
io::{embedded::EmbeddedAssetRegistry, AssetSourceBuilder, AssetSourceBuilders, AssetSourceId},
processor::{AssetProcessor, Process},
};
use alloc::sync::Arc;
use bevy_app::{App, Last, Plugin, PreUpdate};
use bevy_ecs::{
reflect::AppTypeRegistry,
schedule::{IntoSystemConfigs, IntoSystemSetConfigs, SystemSet},
world::FromWorld,
};
use bevy_reflect::{FromReflect, GetTypeRegistration, Reflect, TypePath};
use bevy_utils::{tracing::error, HashSet};
use core::any::TypeId;
#[cfg(all(feature = "file_watcher", not(feature = "multi_threaded")))]
compile_error!(
"The \"file_watcher\" feature for hot reloading requires the \
\"multi_threaded\" feature to be functional.\n\
Consider either disabling the \"file_watcher\" feature or enabling \"multi_threaded\""
);
/// Provides "asset" loading and processing functionality. An [`Asset`] is a "runtime value" that is loaded from an [`AssetSource`],
/// which can be something like a filesystem, a network, etc.
///
/// Supports flexible "modes", such as [`AssetMode::Processed`] and
/// [`AssetMode::Unprocessed`] that enable using the asset workflow that best suits your project.
///
/// [`AssetSource`]: io::AssetSource
pub struct AssetPlugin {
/// The default file path to use (relative to the project root) for unprocessed assets.
pub file_path: String,
/// The default file path to use (relative to the project root) for processed assets.
pub processed_file_path: String,
/// If set, will override the default "watch for changes" setting. By default "watch for changes" will be `false` unless
/// the `watch` cargo feature is set. `watch` can be enabled manually, or it will be automatically enabled if a specific watcher
/// like `file_watcher` is enabled.
///
/// Most use cases should leave this set to [`None`] and enable a specific watcher feature such as `file_watcher` to enable
/// watching for dev-scenarios.
pub watch_for_changes_override: Option<bool>,
/// The [`AssetMode`] to use for this server.
pub mode: AssetMode,
/// How/If asset meta files should be checked.
pub meta_check: AssetMetaCheck,
}
/// Controls whether or not assets are pre-processed before being loaded.
///
/// This setting is controlled by setting [`AssetPlugin::mode`].
///
/// When building on web, asset preprocessing can cause problems due to the lack of filesystem access.
/// See [bevy#10157](https://github.com/bevyengine/bevy/issues/10157) for context.
#[derive(Debug)]
pub enum AssetMode {
/// Loads assets from their [`AssetSource`]'s default [`AssetReader`] without any "preprocessing".
///
/// [`AssetReader`]: io::AssetReader
/// [`AssetSource`]: io::AssetSource
Unprocessed,
/// Assets will be "pre-processed". This enables assets to be imported / converted / optimized ahead of time.
///
/// Assets will be read from their unprocessed [`AssetSource`] (defaults to the `assets` folder),
/// processed according to their [`AssetMeta`], and written to their processed [`AssetSource`] (defaults to the `imported_assets/Default` folder).
///
/// By default, this assumes the processor _has already been run_. It will load assets from their final processed [`AssetReader`].
///
/// When developing an app, you should enable the `asset_processor` cargo feature, which will run the asset processor at startup. This should generally
/// be used in combination with the `file_watcher` cargo feature, which enables hot-reloading of assets that have changed. When both features are enabled,
/// changes to "original/source assets" will be detected, the asset will be re-processed, and then the final processed asset will be hot-reloaded in the app.
///
/// [`AssetMeta`]: meta::AssetMeta
/// [`AssetSource`]: io::AssetSource
/// [`AssetReader`]: io::AssetReader
Processed,
}
/// Configures how / if meta files will be checked. If an asset's meta file is not checked, the default meta for the asset
/// will be used.
#[derive(Debug, Default, Clone)]
pub enum AssetMetaCheck {
/// Always check if assets have meta files. If the meta does not exist, the default meta will be used.
#[default]
Always,
/// Only look up meta files for the provided paths. The default meta will be used for any paths not contained in this set.
Paths(HashSet<AssetPath<'static>>),
/// Never check if assets have meta files and always use the default meta. If meta files exist, they will be ignored and the default meta will be used.
Never,
}
impl Default for AssetPlugin {
fn default() -> Self {
Self {
mode: AssetMode::Unprocessed,
file_path: Self::DEFAULT_UNPROCESSED_FILE_PATH.to_string(),
processed_file_path: Self::DEFAULT_PROCESSED_FILE_PATH.to_string(),
watch_for_changes_override: None,
meta_check: AssetMetaCheck::default(),
}
}
}
impl AssetPlugin {
const DEFAULT_UNPROCESSED_FILE_PATH: &'static str = "assets";
/// NOTE: this is in the Default sub-folder to make this forward compatible with "import profiles"
/// and to allow us to put the "processor transaction log" at `imported_assets/log`
const DEFAULT_PROCESSED_FILE_PATH: &'static str = "imported_assets/Default";
}
impl Plugin for AssetPlugin {
fn build(&self, app: &mut App) {
let embedded = EmbeddedAssetRegistry::default();
{
let mut sources = app
.world_mut()
.get_resource_or_init::<AssetSourceBuilders>();
sources.init_default_source(
&self.file_path,
(!matches!(self.mode, AssetMode::Unprocessed))
.then_some(self.processed_file_path.as_str()),
);
embedded.register_source(&mut sources);
}
{
let mut watch = cfg!(feature = "watch");
if let Some(watch_override) = self.watch_for_changes_override {
watch = watch_override;
}
match self.mode {
AssetMode::Unprocessed => {
let mut builders = app.world_mut().resource_mut::<AssetSourceBuilders>();
let sources = builders.build_sources(watch, false);
app.insert_resource(AssetServer::new_with_meta_check(
sources,
AssetServerMode::Unprocessed,
self.meta_check.clone(),
watch,
));
}
AssetMode::Processed => {
#[cfg(feature = "asset_processor")]
{
let mut builders = app.world_mut().resource_mut::<AssetSourceBuilders>();
let processor = AssetProcessor::new(&mut builders);
let mut sources = builders.build_sources(false, watch);
sources.gate_on_processor(processor.data.clone());
// the main asset server shares loaders with the processor asset server
app.insert_resource(AssetServer::new_with_loaders(
sources,
processor.server().data.loaders.clone(),
AssetServerMode::Processed,
AssetMetaCheck::Always,
watch,
))
.insert_resource(processor)
.add_systems(bevy_app::Startup, AssetProcessor::start);
}
#[cfg(not(feature = "asset_processor"))]
{
let mut builders = app.world_mut().resource_mut::<AssetSourceBuilders>();
let sources = builders.build_sources(false, watch);
app.insert_resource(AssetServer::new_with_meta_check(
sources,
AssetServerMode::Processed,
AssetMetaCheck::Always,
watch,
));
}
}
}
}
app.insert_resource(embedded)
.init_asset::<LoadedFolder>()
.init_asset::<LoadedUntypedAsset>()
.init_asset::<()>()
.add_event::<UntypedAssetLoadFailedEvent>()
.configure_sets(PreUpdate, TrackAssets.after(handle_internal_asset_events))
// `handle_internal_asset_events` requires the use of `&mut World`,
// and as a result has ambiguous system ordering with all other systems in `PreUpdate`.
// This is virtually never a real problem: asset loading is async and so anything that interacts directly with it
// needs to be robust to stochastic delays anyways.
.add_systems(PreUpdate, handle_internal_asset_events.ambiguous_with_all())
.register_type::<AssetPath>();
}
}
/// Declares that this type is an asset,
/// which can be loaded and managed by the [`AssetServer`] and stored in [`Assets`] collections.
///
/// Generally, assets are large, complex, and/or expensive to load from disk, and are often authored by artists or designers.
///
/// [`TypePath`] is largely used for diagnostic purposes, and should almost always be implemented by deriving [`Reflect`] on your type.
/// [`VisitAssetDependencies`] is used to track asset dependencies, and an implementation is automatically generated when deriving [`Asset`].
#[diagnostic::on_unimplemented(
message = "`{Self}` is not an `Asset`",
label = "invalid `Asset`",
note = "consider annotating `{Self}` with `#[derive(Asset)]`"
)]
pub trait Asset: VisitAssetDependencies + TypePath + Send + Sync + 'static {}
/// This trait defines how to visit the dependencies of an asset.
/// For example, a 3D model might require both textures and meshes to be loaded.
///
/// Note that this trait is automatically implemented when deriving [`Asset`].
pub trait VisitAssetDependencies {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId));
}
impl<A: Asset> VisitAssetDependencies for Handle<A> {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
visit(self.id().untyped());
}
}
impl<A: Asset> VisitAssetDependencies for Option<Handle<A>> {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
if let Some(handle) = self {
visit(handle.id().untyped());
}
}
}
impl VisitAssetDependencies for UntypedHandle {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
visit(self.id());
}
}
impl VisitAssetDependencies for Option<UntypedHandle> {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
if let Some(handle) = self {
visit(handle.id());
}
}
}
impl<A: Asset> VisitAssetDependencies for Vec<Handle<A>> {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
for dependency in self {
visit(dependency.id().untyped());
}
}
}
impl VisitAssetDependencies for Vec<UntypedHandle> {
fn visit_dependencies(&self, visit: &mut impl FnMut(UntypedAssetId)) {
for dependency in self {
visit(dependency.id());
}
}
}
/// Adds asset-related builder methods to [`App`].
pub trait AssetApp {
/// Registers the given `loader` in the [`App`]'s [`AssetServer`].
fn register_asset_loader<L: AssetLoader>(&mut self, loader: L) -> &mut Self;
/// Registers the given `processor` in the [`App`]'s [`AssetProcessor`].
fn register_asset_processor<P: Process>(&mut self, processor: P) -> &mut Self;
/// Registers the given [`AssetSourceBuilder`] with the given `id`.
///
/// Note that asset sources must be registered before adding [`AssetPlugin`] to your application,
/// since registered asset sources are built at that point and not after.
fn register_asset_source(
&mut self,
id: impl Into<AssetSourceId<'static>>,
source: AssetSourceBuilder,
) -> &mut Self;
/// Sets the default asset processor for the given `extension`.
fn set_default_asset_processor<P: Process>(&mut self, extension: &str) -> &mut Self;
/// Initializes the given loader in the [`App`]'s [`AssetServer`].
fn init_asset_loader<L: AssetLoader + FromWorld>(&mut self) -> &mut Self;
/// Initializes the given [`Asset`] in the [`App`] by:
/// * Registering the [`Asset`] in the [`AssetServer`]
/// * Initializing the [`AssetEvent`] resource for the [`Asset`]
/// * Adding other relevant systems and resources for the [`Asset`]
/// * Ignoring schedule ambiguities in [`Assets`] resource. Any time a system takes
/// mutable access to this resource this causes a conflict, but they rarely actually
/// modify the same underlying asset.
fn init_asset<A: Asset>(&mut self) -> &mut Self;
/// Registers the asset type `T` using `[App::register]`,
/// and adds [`ReflectAsset`] type data to `T` and [`ReflectHandle`] type data to [`Handle<T>`] in the type registry.
///
/// This enables reflection code to access assets. For detailed information, see the docs on [`ReflectAsset`] and [`ReflectHandle`].
fn register_asset_reflect<A>(&mut self) -> &mut Self
where
A: Asset + Reflect + FromReflect + GetTypeRegistration;
/// Preregisters a loader for the given extensions, that will block asset loads until a real loader
/// is registered.
fn preregister_asset_loader<L: AssetLoader>(&mut self, extensions: &[&str]) -> &mut Self;
}
impl AssetApp for App {
fn register_asset_loader<L: AssetLoader>(&mut self, loader: L) -> &mut Self {
self.world()
.resource::<AssetServer>()
.register_loader(loader);
self
}
fn register_asset_processor<P: Process>(&mut self, processor: P) -> &mut Self {
if let Some(asset_processor) = self.world().get_resource::<AssetProcessor>() {
asset_processor.register_processor(processor);
}
self
}
fn register_asset_source(
&mut self,
id: impl Into<AssetSourceId<'static>>,
source: AssetSourceBuilder,
) -> &mut Self {
let id = AssetSourceId::from_static(id);
if self.world().get_resource::<AssetServer>().is_some() {
error!("{} must be registered before `AssetPlugin` (typically added as part of `DefaultPlugins`)", id);
}
{
let mut sources = self
.world_mut()
.get_resource_or_init::<AssetSourceBuilders>();
sources.insert(id, source);
}
self
}
fn set_default_asset_processor<P: Process>(&mut self, extension: &str) -> &mut Self {
if let Some(asset_processor) = self.world().get_resource::<AssetProcessor>() {
asset_processor.set_default_processor::<P>(extension);
}
self
}
fn init_asset_loader<L: AssetLoader + FromWorld>(&mut self) -> &mut Self {
let loader = L::from_world(self.world_mut());
self.register_asset_loader(loader)
}
fn init_asset<A: Asset>(&mut self) -> &mut Self {
let assets = Assets::<A>::default();
self.world()
.resource::<AssetServer>()
.register_asset(&assets);
if self.world().contains_resource::<AssetProcessor>() {
let processor = self.world().resource::<AssetProcessor>();
// The processor should have its own handle provider separate from the Asset storage
// to ensure the id spaces are entirely separate. Not _strictly_ necessary, but
// desirable.
processor
.server()
.register_handle_provider(AssetHandleProvider::new(
TypeId::of::<A>(),
Arc::new(AssetIndexAllocator::default()),
));
}
self.insert_resource(assets)
.allow_ambiguous_resource::<Assets<A>>()
.add_event::<AssetEvent<A>>()
.add_event::<AssetLoadFailedEvent<A>>()
.register_type::<Handle<A>>()
.add_systems(
Last,
Assets::<A>::asset_events
.run_if(Assets::<A>::asset_events_condition)
.in_set(AssetEvents),
)
.add_systems(PreUpdate, Assets::<A>::track_assets.in_set(TrackAssets))
}
fn register_asset_reflect<A>(&mut self) -> &mut Self
where
A: Asset + Reflect + FromReflect + GetTypeRegistration,
{
let type_registry = self.world().resource::<AppTypeRegistry>();
{
let mut type_registry = type_registry.write();
type_registry.register::<A>();
type_registry.register::<Handle<A>>();
type_registry.register_type_data::<A, ReflectAsset>();
type_registry.register_type_data::<Handle<A>, ReflectHandle>();
}
self
}
fn preregister_asset_loader<L: AssetLoader>(&mut self, extensions: &[&str]) -> &mut Self {
self.world_mut()
.resource_mut::<AssetServer>()
.preregister_loader::<L>(extensions);
self
}
}
/// A system set that holds all "track asset" operations.
#[derive(SystemSet, Hash, Debug, PartialEq, Eq, Clone)]
pub struct TrackAssets;
/// A system set where events accumulated in [`Assets`] are applied to the [`AssetEvent`] [`Events`] resource.
///
/// [`Events`]: bevy_ecs::event::Events
#[derive(Debug, Hash, PartialEq, Eq, Clone, SystemSet)]
pub struct AssetEvents;
#[cfg(test)]
mod tests {
use crate::{
self as bevy_asset,
folder::LoadedFolder,
handle::Handle,
io::{
gated::{GateOpener, GatedReader},
memory::{Dir, MemoryAssetReader},
AssetReader, AssetReaderError, AssetSource, AssetSourceId, Reader,
},
loader::{AssetLoader, LoadContext},
Asset, AssetApp, AssetEvent, AssetId, AssetLoadError, AssetLoadFailedEvent, AssetPath,
AssetPlugin, AssetServer, Assets,
};
use alloc::sync::Arc;
use bevy_app::{App, Update};
use bevy_core::TaskPoolPlugin;
use bevy_ecs::{
event::EventCursor,
prelude::*,
schedule::{LogLevel, ScheduleBuildSettings},
};
use bevy_log::LogPlugin;
use bevy_reflect::TypePath;
use bevy_utils::{Duration, HashMap};
use derive_more::derive::{Display, Error, From};
use serde::{Deserialize, Serialize};
use std::path::Path;
#[derive(Asset, TypePath, Debug, Default)]
pub struct CoolText {
pub text: String,
pub embedded: String,
#[dependency]
pub dependencies: Vec<Handle<CoolText>>,
#[dependency]
pub sub_texts: Vec<Handle<SubText>>,
}
#[derive(Asset, TypePath, Debug)]
pub struct SubText {
text: String,
}
#[derive(Serialize, Deserialize)]
pub struct CoolTextRon {
text: String,
dependencies: Vec<String>,
embedded_dependencies: Vec<String>,
sub_texts: Vec<String>,
}
#[derive(Default)]
pub struct CoolTextLoader;
#[derive(Error, Display, Debug, From)]
pub enum CoolTextLoaderError {
#[display("Could not load dependency: {dependency}")]
CannotLoadDependency { dependency: AssetPath<'static> },
#[display("A RON error occurred during loading")]
RonSpannedError(ron::error::SpannedError),
#[display("An IO error occurred during loading")]
Io(std::io::Error),
}
impl AssetLoader for CoolTextLoader {
type Asset = CoolText;
type Settings = ();
type Error = CoolTextLoaderError;
async fn load(
&self,
reader: &mut dyn Reader,
_settings: &Self::Settings,
load_context: &mut LoadContext<'_>,
) -> Result<Self::Asset, Self::Error> {
let mut bytes = Vec::new();
reader.read_to_end(&mut bytes).await?;
let mut ron: CoolTextRon = ron::de::from_bytes(&bytes)?;
let mut embedded = String::new();
for dep in ron.embedded_dependencies {
let loaded = load_context
.loader()
.immediate()
.load::<CoolText>(&dep)
.await
.map_err(|_| Self::Error::CannotLoadDependency {
dependency: dep.into(),
})?;
let cool = loaded.get();
embedded.push_str(&cool.text);
}
Ok(CoolText {
text: ron.text,
embedded,
dependencies: ron
.dependencies
.iter()
.map(|p| load_context.load(p))
.collect(),
sub_texts: ron
.sub_texts
.drain(..)
.map(|text| load_context.add_labeled_asset(text.clone(), SubText { text }))
.collect(),
})
}
fn extensions(&self) -> &[&str] {
&["cool.ron"]
}
}
/// A dummy [`CoolText`] asset reader that only succeeds after `failure_count` times it's read from for each asset.
#[derive(Default, Clone)]
pub struct UnstableMemoryAssetReader {
pub attempt_counters: Arc<std::sync::Mutex<HashMap<Box<Path>, usize>>>,
pub load_delay: Duration,
memory_reader: MemoryAssetReader,
failure_count: usize,
}
impl UnstableMemoryAssetReader {
pub fn new(root: Dir, failure_count: usize) -> Self {
Self {
load_delay: Duration::from_millis(10),
memory_reader: MemoryAssetReader { root },
attempt_counters: Default::default(),
failure_count,
}
}
}
impl AssetReader for UnstableMemoryAssetReader {
async fn is_directory<'a>(&'a self, path: &'a Path) -> Result<bool, AssetReaderError> {
self.memory_reader.is_directory(path).await
}
async fn read_directory<'a>(
&'a self,
path: &'a Path,
) -> Result<Box<bevy_asset::io::PathStream>, AssetReaderError> {
self.memory_reader.read_directory(path).await
}
async fn read_meta<'a>(
&'a self,
path: &'a Path,
) -> Result<impl Reader + 'a, AssetReaderError> {
self.memory_reader.read_meta(path).await
}
async fn read<'a>(&'a self, path: &'a Path) -> Result<impl Reader + 'a, AssetReaderError> {
let attempt_number = {
let mut attempt_counters = self.attempt_counters.lock().unwrap();
if let Some(existing) = attempt_counters.get_mut(path) {
*existing += 1;
*existing
} else {
attempt_counters.insert(path.into(), 1);
1
}
};
if attempt_number <= self.failure_count {
let io_error = std::io::Error::new(
std::io::ErrorKind::ConnectionRefused,
format!(
"Simulated failure {attempt_number} of {}",
self.failure_count
),
);
let wait = self.load_delay;
return async move {
std::thread::sleep(wait);
Err(AssetReaderError::Io(io_error.into()))
}
.await;
}
self.memory_reader.read(path).await
}
}
fn test_app(dir: Dir) -> (App, GateOpener) {
let mut app = App::new();
let (gated_memory_reader, gate_opener) = GatedReader::new(MemoryAssetReader { root: dir });
app.register_asset_source(
AssetSourceId::Default,
AssetSource::build().with_reader(move || Box::new(gated_memory_reader.clone())),
)
.add_plugins((
TaskPoolPlugin::default(),
LogPlugin::default(),
AssetPlugin::default(),
));
(app, gate_opener)
}
pub fn run_app_until(app: &mut App, mut predicate: impl FnMut(&mut World) -> Option<()>) {
for _ in 0..LARGE_ITERATION_COUNT {
app.update();
if predicate(app.world_mut()).is_some() {
return;
}
}
panic!("Ran out of loops to return `Some` from `predicate`");
}
const LARGE_ITERATION_COUNT: usize = 10000;
fn get<A: Asset>(world: &World, id: AssetId<A>) -> Option<&A> {
world.resource::<Assets<A>>().get(id)
}
#[derive(Resource, Default)]
struct StoredEvents(Vec<AssetEvent<CoolText>>);
fn store_asset_events(
mut reader: EventReader<AssetEvent<CoolText>>,
mut storage: ResMut<StoredEvents>,
) {
storage.0.extend(reader.read().cloned());
}
#[test]
fn load_dependencies() {
// The particular usage of GatedReader in this test will cause deadlocking if running single-threaded
#[cfg(not(feature = "multi_threaded"))]
panic!("This test requires the \"multi_threaded\" feature, otherwise it will deadlock.\ncargo test --package bevy_asset --features multi_threaded");
let dir = Dir::default();
let a_path = "a.cool.ron";
let a_ron = r#"
(
text: "a",
dependencies: [
"foo/b.cool.ron",
"c.cool.ron",
],
embedded_dependencies: [],
sub_texts: [],
)"#;
let b_path = "foo/b.cool.ron";
let b_ron = r#"
(
text: "b",
dependencies: [],
embedded_dependencies: [],
sub_texts: [],
)"#;
let c_path = "c.cool.ron";
let c_ron = r#"
(
text: "c",
dependencies: [
"d.cool.ron",
],
embedded_dependencies: ["a.cool.ron", "foo/b.cool.ron"],
sub_texts: ["hello"],
)"#;
let d_path = "d.cool.ron";
let d_ron = r#"
(
text: "d",
dependencies: [],
embedded_dependencies: [],
sub_texts: [],
)"#;
dir.insert_asset_text(Path::new(a_path), a_ron);
dir.insert_asset_text(Path::new(b_path), b_ron);
dir.insert_asset_text(Path::new(c_path), c_ron);
dir.insert_asset_text(Path::new(d_path), d_ron);
#[derive(Resource)]
struct IdResults {
b_id: AssetId<CoolText>,
c_id: AssetId<CoolText>,
d_id: AssetId<CoolText>,
}
let (mut app, gate_opener) = test_app(dir);
app.init_asset::<CoolText>()
.init_asset::<SubText>()
.init_resource::<StoredEvents>()
.register_asset_loader(CoolTextLoader)
.add_systems(Update, store_asset_events);
let asset_server = app.world().resource::<AssetServer>().clone();
let handle: Handle<CoolText> = asset_server.load(a_path);
let a_id = handle.id();
app.update();
{
let a_text = get::<CoolText>(app.world(), a_id);
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert!(a_text.is_none(), "a's asset should not exist yet");
assert!(a_load.is_loading());
assert!(a_deps.is_loading());
assert!(a_rec_deps.is_loading());
}
// Allow "a" to load ... wait for it to finish loading and validate results
// Dependencies are still gated so they should not be loaded yet
gate_opener.open(a_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert_eq!(a_text.text, "a");
assert_eq!(a_text.dependencies.len(), 2);
assert!(a_load.is_loaded());
assert!(a_deps.is_loading());
assert!(a_rec_deps.is_loading());
let b_id = a_text.dependencies[0].id();
let b_text = get::<CoolText>(world, b_id);
let (b_load, b_deps, b_rec_deps) = asset_server.get_load_states(b_id).unwrap();
assert!(b_text.is_none(), "b component should not exist yet");
assert!(b_load.is_loading());
assert!(b_deps.is_loading());
assert!(b_rec_deps.is_loading());
let c_id = a_text.dependencies[1].id();
let c_text = get::<CoolText>(world, c_id);
let (c_load, c_deps, c_rec_deps) = asset_server.get_load_states(c_id).unwrap();
assert!(c_text.is_none(), "c component should not exist yet");
assert!(c_load.is_loading());
assert!(c_deps.is_loading());
assert!(c_rec_deps.is_loading());
Some(())
});
// Allow "b" to load ... wait for it to finish loading and validate results
// "c" should not be loaded yet
gate_opener.open(b_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert_eq!(a_text.text, "a");
assert_eq!(a_text.dependencies.len(), 2);
assert!(a_load.is_loaded());
assert!(a_deps.is_loading());
assert!(a_rec_deps.is_loading());
let b_id = a_text.dependencies[0].id();
let b_text = get::<CoolText>(world, b_id)?;
let (b_load, b_deps, b_rec_deps) = asset_server.get_load_states(b_id).unwrap();
assert_eq!(b_text.text, "b");
assert!(b_load.is_loaded());
assert!(b_deps.is_loaded());
assert!(b_rec_deps.is_loaded());
let c_id = a_text.dependencies[1].id();
let c_text = get::<CoolText>(world, c_id);
let (c_load, c_deps, c_rec_deps) = asset_server.get_load_states(c_id).unwrap();
assert!(c_text.is_none(), "c component should not exist yet");
assert!(c_load.is_loading());
assert!(c_deps.is_loading());
assert!(c_rec_deps.is_loading());
Some(())
});
// Allow "c" to load ... wait for it to finish loading and validate results
// all "a" dependencies should be loaded now
gate_opener.open(c_path);
// Re-open a and b gates to allow c to load embedded deps (gates are closed after each load)
gate_opener.open(a_path);
gate_opener.open(b_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert_eq!(a_text.text, "a");
assert_eq!(a_text.embedded, "");
assert_eq!(a_text.dependencies.len(), 2);
assert!(a_load.is_loaded());
let b_id = a_text.dependencies[0].id();
let b_text = get::<CoolText>(world, b_id)?;
let (b_load, b_deps, b_rec_deps) = asset_server.get_load_states(b_id).unwrap();
assert_eq!(b_text.text, "b");
assert_eq!(b_text.embedded, "");
assert!(b_load.is_loaded());
assert!(b_deps.is_loaded());
assert!(b_rec_deps.is_loaded());
let c_id = a_text.dependencies[1].id();
let c_text = get::<CoolText>(world, c_id)?;
let (c_load, c_deps, c_rec_deps) = asset_server.get_load_states(c_id).unwrap();
assert_eq!(c_text.text, "c");
assert_eq!(c_text.embedded, "ab");
assert!(c_load.is_loaded());
assert!(
c_deps.is_loading(),
"c deps should not be loaded yet because d has not loaded"
);
assert!(
c_rec_deps.is_loading(),
"c rec deps should not be loaded yet because d has not loaded"
);
let sub_text_id = c_text.sub_texts[0].id();
let sub_text = get::<SubText>(world, sub_text_id)
.expect("subtext should exist if c exists. it came from the same loader");
assert_eq!(sub_text.text, "hello");
let (sub_text_load, sub_text_deps, sub_text_rec_deps) =
asset_server.get_load_states(sub_text_id).unwrap();
assert!(sub_text_load.is_loaded());
assert!(sub_text_deps.is_loaded());
assert!(sub_text_rec_deps.is_loaded());
let d_id = c_text.dependencies[0].id();
let d_text = get::<CoolText>(world, d_id);
let (d_load, d_deps, d_rec_deps) = asset_server.get_load_states(d_id).unwrap();
assert!(d_text.is_none(), "d component should not exist yet");
assert!(d_load.is_loading());
assert!(d_deps.is_loading());
assert!(d_rec_deps.is_loading());
assert!(
a_deps.is_loaded(),
"If c has been loaded, the a deps should all be considered loaded"
);
assert!(
a_rec_deps.is_loading(),
"d is not loaded, so a's recursive deps should still be loading"
);
world.insert_resource(IdResults { b_id, c_id, d_id });
Some(())
});
gate_opener.open(d_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let (_a_load, _a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
let c_id = a_text.dependencies[1].id();
let c_text = get::<CoolText>(world, c_id)?;
let (c_load, c_deps, c_rec_deps) = asset_server.get_load_states(c_id).unwrap();
assert_eq!(c_text.text, "c");
assert_eq!(c_text.embedded, "ab");
let d_id = c_text.dependencies[0].id();
let d_text = get::<CoolText>(world, d_id)?;
let (d_load, d_deps, d_rec_deps) = asset_server.get_load_states(d_id).unwrap();
assert_eq!(d_text.text, "d");
assert_eq!(d_text.embedded, "");
assert!(c_load.is_loaded());
assert!(c_deps.is_loaded());
assert!(c_rec_deps.is_loaded());
assert!(d_load.is_loaded());
assert!(d_deps.is_loaded());
assert!(d_rec_deps.is_loaded());
assert!(
a_rec_deps.is_loaded(),
"d is loaded, so a's recursive deps should be loaded"
);
Some(())
});
{
let mut texts = app.world_mut().resource_mut::<Assets<CoolText>>();
let a = texts.get_mut(a_id).unwrap();
a.text = "Changed".to_string();
}
drop(handle);
app.update();
assert_eq!(
app.world().resource::<Assets<CoolText>>().len(),
0,
"CoolText asset entities should be despawned when no more handles exist"
);
app.update();
// this requires a second update because the parent asset was freed in the previous app.update()
assert_eq!(
app.world().resource::<Assets<SubText>>().len(),
0,
"SubText asset entities should be despawned when no more handles exist"
);
let events = app.world_mut().remove_resource::<StoredEvents>().unwrap();
let id_results = app.world_mut().remove_resource::<IdResults>().unwrap();
let expected_events = vec![
AssetEvent::Added { id: a_id },
AssetEvent::LoadedWithDependencies {
id: id_results.b_id,
},
AssetEvent::Added {
id: id_results.b_id,
},
AssetEvent::Added {
id: id_results.c_id,
},
AssetEvent::LoadedWithDependencies {
id: id_results.d_id,
},
AssetEvent::LoadedWithDependencies {
id: id_results.c_id,
},
AssetEvent::LoadedWithDependencies { id: a_id },
AssetEvent::Added {
id: id_results.d_id,
},
AssetEvent::Modified { id: a_id },
AssetEvent::Unused { id: a_id },
AssetEvent::Removed { id: a_id },
AssetEvent::Unused {
id: id_results.b_id,
},
AssetEvent::Removed {
id: id_results.b_id,
},
AssetEvent::Unused {
id: id_results.c_id,
},
AssetEvent::Removed {
id: id_results.c_id,
},
AssetEvent::Unused {
id: id_results.d_id,
},
AssetEvent::Removed {
id: id_results.d_id,
},
];
assert_eq!(events.0, expected_events);
}
#[test]
fn failure_load_states() {
// The particular usage of GatedReader in this test will cause deadlocking if running single-threaded
#[cfg(not(feature = "multi_threaded"))]
panic!("This test requires the \"multi_threaded\" feature, otherwise it will deadlock.\ncargo test --package bevy_asset --features multi_threaded");
let dir = Dir::default();
let a_path = "a.cool.ron";
let a_ron = r#"
(
text: "a",
dependencies: [
"b.cool.ron",
"c.cool.ron",
],
embedded_dependencies: [],
sub_texts: []
)"#;
let b_path = "b.cool.ron";
let b_ron = r#"
(
text: "b",
dependencies: [],
embedded_dependencies: [],
sub_texts: []
)"#;
let c_path = "c.cool.ron";
let c_ron = r#"
(
text: "c",
dependencies: [
"d.cool.ron",
],
embedded_dependencies: [],
sub_texts: []
)"#;
let d_path = "d.cool.ron";
let d_ron = r#"
(
text: "d",
dependencies: [],
OH NO THIS ASSET IS MALFORMED
embedded_dependencies: [],
sub_texts: []
)"#;
dir.insert_asset_text(Path::new(a_path), a_ron);
dir.insert_asset_text(Path::new(b_path), b_ron);
dir.insert_asset_text(Path::new(c_path), c_ron);
dir.insert_asset_text(Path::new(d_path), d_ron);
let (mut app, gate_opener) = test_app(dir);
app.init_asset::<CoolText>()
.register_asset_loader(CoolTextLoader);
let asset_server = app.world().resource::<AssetServer>().clone();
let handle: Handle<CoolText> = asset_server.load(a_path);
let a_id = handle.id();
{
let other_handle: Handle<CoolText> = asset_server.load(a_path);
assert_eq!(
other_handle, handle,
"handles from consecutive load calls should be equal"
);
assert_eq!(
other_handle.id(),
handle.id(),
"handle ids from consecutive load calls should be equal"
);
}
gate_opener.open(a_path);
gate_opener.open(b_path);
gate_opener.open(c_path);
gate_opener.open(d_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
let b_id = a_text.dependencies[0].id();
let b_text = get::<CoolText>(world, b_id)?;
let (b_load, b_deps, b_rec_deps) = asset_server.get_load_states(b_id).unwrap();
let c_id = a_text.dependencies[1].id();
let c_text = get::<CoolText>(world, c_id)?;
let (c_load, c_deps, c_rec_deps) = asset_server.get_load_states(c_id).unwrap();
let d_id = c_text.dependencies[0].id();
let d_text = get::<CoolText>(world, d_id);
let (d_load, d_deps, d_rec_deps) = asset_server.get_load_states(d_id).unwrap();
if !d_load.is_failed() {
// wait until d has exited the loading state
return None;
}
assert!(d_text.is_none());
assert!(d_load.is_failed());
assert!(d_deps.is_failed());
assert!(d_rec_deps.is_failed());
assert_eq!(a_text.text, "a");
assert!(a_load.is_loaded());
assert!(a_deps.is_loaded());
assert!(a_rec_deps.is_failed());
assert_eq!(b_text.text, "b");
assert!(b_load.is_loaded());
assert!(b_deps.is_loaded());
assert!(b_rec_deps.is_loaded());
assert_eq!(c_text.text, "c");
assert!(c_load.is_loaded());
assert!(c_deps.is_failed());
assert!(c_rec_deps.is_failed());
assert!(asset_server.load_state(a_id).is_loaded());
assert!(asset_server.dependency_load_state(a_id).is_loaded());
assert!(asset_server
.recursive_dependency_load_state(a_id)
.is_failed());
assert!(asset_server.is_loaded(a_id));
assert!(asset_server.is_loaded_with_direct_dependencies(a_id));
assert!(!asset_server.is_loaded_with_dependencies(a_id));
Some(())
});
}
#[test]
fn dependency_load_states() {
// The particular usage of GatedReader in this test will cause deadlocking if running single-threaded
#[cfg(not(feature = "multi_threaded"))]
panic!("This test requires the \"multi_threaded\" feature, otherwise it will deadlock.\ncargo test --package bevy_asset --features multi_threaded");
let a_path = "a.cool.ron";
let a_ron = r#"
(
text: "a",
dependencies: [
"b.cool.ron",
"c.cool.ron",
],
embedded_dependencies: [],
sub_texts: []
)"#;
let b_path = "b.cool.ron";
let b_ron = r#"
(
text: "b",
dependencies: [],
MALFORMED
embedded_dependencies: [],
sub_texts: []
)"#;
let c_path = "c.cool.ron";
let c_ron = r#"
(
text: "c",
dependencies: [],
embedded_dependencies: [],
sub_texts: []
)"#;
let dir = Dir::default();
dir.insert_asset_text(Path::new(a_path), a_ron);
dir.insert_asset_text(Path::new(b_path), b_ron);
dir.insert_asset_text(Path::new(c_path), c_ron);
let (mut app, gate_opener) = test_app(dir);
app.init_asset::<CoolText>()
.register_asset_loader(CoolTextLoader);
let asset_server = app.world().resource::<AssetServer>().clone();
let handle: Handle<CoolText> = asset_server.load(a_path);
let a_id = handle.id();
gate_opener.open(a_path);
run_app_until(&mut app, |world| {
let _a_text = get::<CoolText>(world, a_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert!(a_load.is_loaded());
assert!(a_deps.is_loading());
assert!(a_rec_deps.is_loading());
Some(())
});
gate_opener.open(b_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let b_id = a_text.dependencies[0].id();
let (b_load, _b_deps, _b_rec_deps) = asset_server.get_load_states(b_id).unwrap();
if !b_load.is_failed() {
// wait until b fails
return None;
}
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert!(a_load.is_loaded());
assert!(a_deps.is_failed());
assert!(a_rec_deps.is_failed());
Some(())
});
gate_opener.open(c_path);
run_app_until(&mut app, |world| {
let a_text = get::<CoolText>(world, a_id)?;
let c_id = a_text.dependencies[1].id();
// wait until c loads
let _c_text = get::<CoolText>(world, c_id)?;
let (a_load, a_deps, a_rec_deps) = asset_server.get_load_states(a_id).unwrap();
assert!(a_load.is_loaded());
assert!(
a_deps.is_failed(),
"Successful dependency load should not overwrite a previous failure"
);
assert!(
a_rec_deps.is_failed(),
"Successful dependency load should not overwrite a previous failure"
);
Some(())
});
}
const SIMPLE_TEXT: &str = r#"
(
text: "dep",
dependencies: [],
embedded_dependencies: [],
sub_texts: [],
)"#;
#[test]
fn keep_gotten_strong_handles() {
let dir = Dir::default();
dir.insert_asset_text(Path::new("dep.cool.ron"), SIMPLE_TEXT);
let (mut app, _) = test_app(dir);
app.init_asset::<CoolText>()
.init_asset::<SubText>()
.init_resource::<StoredEvents>()
.register_asset_loader(CoolTextLoader)
.add_systems(Update, store_asset_events);
let id = {
let handle = {
let mut texts = app.world_mut().resource_mut::<Assets<CoolText>>();
let handle = texts.add(CoolText::default());
texts.get_strong_handle(handle.id()).unwrap()
};
app.update();
{
let text = app.world().resource::<Assets<CoolText>>().get(&handle);
assert!(text.is_some());
}
handle.id()
};
// handle is dropped
app.update();
assert!(
app.world().resource::<Assets<CoolText>>().get(id).is_none(),
"asset has no handles, so it should have been dropped last update"
);
}
#[test]
fn manual_asset_management() {
// The particular usage of GatedReader in this test will cause deadlocking if running single-threaded
#[cfg(not(feature = "multi_threaded"))]
panic!("This test requires the \"multi_threaded\" feature, otherwise it will deadlock.\ncargo test --package bevy_asset --features multi_threaded");
let dir = Dir::default();
let dep_path = "dep.cool.ron";
dir.insert_asset_text(Path::new(dep_path), SIMPLE_TEXT);
let (mut app, gate_opener) = test_app(dir);
app.init_asset::<CoolText>()
.init_asset::<SubText>()
.init_resource::<StoredEvents>()
.register_asset_loader(CoolTextLoader)
.add_systems(Update, store_asset_events);
let hello = "hello".to_string();
let empty = "".to_string();
let id = {
let handle = {
let mut texts = app.world_mut().resource_mut::<Assets<CoolText>>();
texts.add(CoolText {
text: hello.clone(),
embedded: empty.clone(),
dependencies: vec![],
sub_texts: Vec::new(),
})
};
app.update();
{
let text = app
.world()
.resource::<Assets<CoolText>>()
.get(&handle)
.unwrap();
assert_eq!(text.text, hello);
}
handle.id()
};
// handle is dropped
app.update();
assert!(
app.world().resource::<Assets<CoolText>>().get(id).is_none(),
"asset has no handles, so it should have been dropped last update"
);
// remove event is emitted
app.update();
let events = core::mem::take(&mut app.world_mut().resource_mut::<StoredEvents>().0);
let expected_events = vec![
AssetEvent::Added { id },
AssetEvent::Unused { id },
AssetEvent::Removed { id },
];
assert_eq!(events, expected_events);
let dep_handle = app.world().resource::<AssetServer>().load(dep_path);
let a = CoolText {
text: "a".to_string(),
embedded: empty,
// this dependency is behind a manual load gate, which should prevent 'a' from emitting a LoadedWithDependencies event
dependencies: vec![dep_handle.clone()],
sub_texts: Vec::new(),
};
let a_handle = app.world().resource::<AssetServer>().load_asset(a);
app.update();
// TODO: ideally it doesn't take two updates for the added event to emit
app.update();
let events = core::mem::take(&mut app.world_mut().resource_mut::<StoredEvents>().0);
let expected_events = vec![AssetEvent::Added { id: a_handle.id() }];
assert_eq!(events, expected_events);
gate_opener.open(dep_path);
loop {
app.update();
let events = core::mem::take(&mut app.world_mut().resource_mut::<StoredEvents>().0);
if events.is_empty() {
continue;
}
let expected_events = vec![
AssetEvent::LoadedWithDependencies {
id: dep_handle.id(),
},
AssetEvent::LoadedWithDependencies { id: a_handle.id() },
];
assert_eq!(events, expected_events);
break;
}
app.update();
let events = core::mem::take(&mut app.world_mut().resource_mut::<StoredEvents>().0);
let expected_events = vec![AssetEvent::Added {
id: dep_handle.id(),
}];
assert_eq!(events, expected_events);
}
#[test]
fn load_folder() {
// The particular usage of GatedReader in this test will cause deadlocking if running single-threaded
#[cfg(not(feature = "multi_threaded"))]
panic!("This test requires the \"multi_threaded\" feature, otherwise it will deadlock.\ncargo test --package bevy_asset --features multi_threaded");
let dir = Dir::default();
let a_path = "text/a.cool.ron";
let a_ron = r#"
(
text: "a",
dependencies: [
"b.cool.ron",
],
embedded_dependencies: [],
sub_texts: [],
)"#;
let b_path = "b.cool.ron";
let b_ron = r#"
(
text: "b",
dependencies: [],
embedded_dependencies: [],
sub_texts: [],
)"#;
let c_path = "text/c.cool.ron";
let c_ron = r#"
(
text: "c",
dependencies: [
],
embedded_dependencies: [],
sub_texts: [],
)"#;
dir.insert_asset_text(Path::new(a_path), a_ron);
dir.insert_asset_text(Path::new(b_path), b_ron);
dir.insert_asset_text(Path::new(c_path), c_ron);
let (mut app, gate_opener) = test_app(dir);
app.init_asset::<CoolText>()
.init_asset::<SubText>()
.register_asset_loader(CoolTextLoader);
let asset_server = app.world().resource::<AssetServer>().clone();
let handle: Handle<LoadedFolder> = asset_server.load_folder("text");
gate_opener.open(a_path);
gate_opener.open(b_path);
gate_opener.open(c_path);
let mut reader = EventCursor::default();
run_app_until(&mut app, |world| {
let events = world.resource::<Events<AssetEvent<LoadedFolder>>>();
let asset_server = world.resource::<AssetServer>();
let loaded_folders = world.resource::<Assets<LoadedFolder>>();
let cool_texts = world.resource::<Assets<CoolText>>();
for event in reader.read(events) {
if let AssetEvent::LoadedWithDependencies { id } = event {
if *id == handle.id() {
let loaded_folder = loaded_folders.get(&handle).unwrap();
let a_handle: Handle<CoolText> =
asset_server.get_handle("text/a.cool.ron").unwrap();
let c_handle: Handle<CoolText> =
asset_server.get_handle("text/c.cool.ron").unwrap();
let mut found_a = false;
let mut found_c = false;
for asset_handle in &loaded_folder.handles {
if asset_handle.id() == a_handle.id().untyped() {
found_a = true;
} else if asset_handle.id() == c_handle.id().untyped() {
found_c = true;
}
}
assert!(found_a);
assert!(found_c);
assert_eq!(loaded_folder.handles.len(), 2);
let a_text = cool_texts.get(&a_handle).unwrap();
let b_text = cool_texts.get(&a_text.dependencies[0]).unwrap();
let c_text = cool_texts.get(&c_handle).unwrap();
assert_eq!("a", a_text.text);
assert_eq!("b", b_text.text);
assert_eq!("c", c_text.text);
return Some(());
}
}
}
None
});
}
/// Tests that `AssetLoadFailedEvent<A>` events are emitted and can be used to retry failed assets.
#[test]
fn load_error_events() {
#[derive(Resource, Default)]
struct ErrorTracker {
tick: u64,
failures: usize,
queued_retries: Vec<(AssetPath<'static>, AssetId<CoolText>, u64)>,
finished_asset: Option<AssetId<CoolText>>,
}
fn asset_event_handler(
mut events: EventReader<AssetEvent<CoolText>>,
mut tracker: ResMut<ErrorTracker>,
) {
for event in events.read() {
if let AssetEvent::LoadedWithDependencies { id } = event {
tracker.finished_asset = Some(*id);
}
}
}
fn asset_load_error_event_handler(
server: Res<AssetServer>,
mut errors: EventReader<AssetLoadFailedEvent<CoolText>>,
mut tracker: ResMut<ErrorTracker>,
) {
// In the real world, this would refer to time (not ticks)
tracker.tick += 1;
// Retry loading past failed items
let now = tracker.tick;
tracker
.queued_retries
.retain(|(path, old_id, retry_after)| {
if now > *retry_after {
let new_handle = server.load::<CoolText>(path);
assert_eq!(&new_handle.id(), old_id);
false
} else {
true
}
});
// Check what just failed
for error in errors.read() {
let (load_state, _, _) = server.get_load_states(error.id).unwrap();
assert!(load_state.is_failed());
assert_eq!(*error.path.source(), AssetSourceId::Name("unstable".into()));
match &error.error {
AssetLoadError::AssetReaderError(read_error) => match read_error {
AssetReaderError::Io(_) => {
tracker.failures += 1;
if tracker.failures <= 2 {
// Retry in 10 ticks
tracker.queued_retries.push((
error.path.clone(),
error.id,
now + 10,
));
} else {
panic!(
"Unexpected failure #{} (expected only 2)",
tracker.failures
);
}
}
_ => panic!("Unexpected error type {:?}", read_error),
},
_ => panic!("Unexpected error type {:?}", error.error),
}
}
}
let a_path = "text/a.cool.ron";
let a_ron = r#"
(
text: "a",
dependencies: [],
embedded_dependencies: [],
sub_texts: [],
)"#;
let dir = Dir::default();
dir.insert_asset_text(Path::new(a_path), a_ron);
let unstable_reader = UnstableMemoryAssetReader::new(dir, 2);
let mut app = App::new();
app.register_asset_source(
"unstable",
AssetSource::build().with_reader(move || Box::new(unstable_reader.clone())),
)
.add_plugins((
TaskPoolPlugin::default(),
LogPlugin::default(),
AssetPlugin::default(),
))
.init_asset::<CoolText>()
.register_asset_loader(CoolTextLoader)
.init_resource::<ErrorTracker>()
.add_systems(
Update,
(asset_event_handler, asset_load_error_event_handler).chain(),
);
let asset_server = app.world().resource::<AssetServer>().clone();
let a_path = format!("unstable://{a_path}");
let a_handle: Handle<CoolText> = asset_server.load(a_path);
let a_id = a_handle.id();
run_app_until(&mut app, |world| {
let tracker = world.resource::<ErrorTracker>();
match tracker.finished_asset {
Some(asset_id) => {
assert_eq!(asset_id, a_id);
let assets = world.resource::<Assets<CoolText>>();
let result = assets.get(asset_id).unwrap();
assert_eq!(result.text, "a");
Some(())
}
None => None,
}
});
}
#[test]
fn ignore_system_ambiguities_on_assets() {
let mut app = App::new();
app.add_plugins(AssetPlugin::default())
.init_asset::<CoolText>();
fn uses_assets(_asset: ResMut<Assets<CoolText>>) {}
app.add_systems(Update, (uses_assets, uses_assets));
app.edit_schedule(Update, |s| {
s.set_build_settings(ScheduleBuildSettings {
ambiguity_detection: LogLevel::Error,
..Default::default()
});
});
// running schedule does not error on ambiguity between the 2 uses_assets systems
app.world_mut().run_schedule(Update);
}
// validate the Asset derive macro for various asset types
#[derive(Asset, TypePath)]
pub struct TestAsset;
#[allow(dead_code)]
#[derive(Asset, TypePath)]
pub enum EnumTestAsset {
Unnamed(#[dependency] Handle<TestAsset>),
Named {
#[dependency]
handle: Handle<TestAsset>,
#[dependency]
vec_handles: Vec<Handle<TestAsset>>,
#[dependency]
embedded: TestAsset,
},
StructStyle(#[dependency] TestAsset),
Empty,
}
#[allow(dead_code)]
#[derive(Asset, TypePath)]
pub struct StructTestAsset {
#[dependency]
handle: Handle<TestAsset>,
#[dependency]
embedded: TestAsset,
}
#[allow(dead_code)]
#[derive(Asset, TypePath)]
pub struct TupleTestAsset(#[dependency] Handle<TestAsset>);
}