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Lower level io methods for AssetServer. #13493

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52 changes: 49 additions & 3 deletions crates/bevy_asset/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -452,12 +452,19 @@ mod tests {
event::ManualEventReader,
schedule::{LogLevel, ScheduleBuildSettings},
};
use bevy_log::LogPlugin;
use bevy_log::{error, LogPlugin};
use bevy_reflect::TypePath;
use bevy_tasks::AsyncComputeTaskPool;
use bevy_utils::{Duration, HashMap};
use futures_lite::AsyncReadExt;
use serde::{Deserialize, Serialize};
use std::{path::Path, sync::Arc};
use std::{
path::Path,
sync::{
atomic::{AtomicBool, Ordering},
Arc,
},
};
use thiserror::Error;

#[derive(Asset, TypePath, Debug, Default)]
Expand Down Expand Up @@ -1481,9 +1488,48 @@ mod tests {
..Default::default()
});
});
}

#[test]
fn stream_io() {
// 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: [],
)"#;
dir.insert_asset_text(Path::new(a_path), a_ron);

// running schedule does not error on ambiguity between the 2 uses_assets systems
app.world_mut().run_schedule(Update);
let (mut app, gate) = test_app(dir);
let asset_server = app.world().resource::<AssetServer>().clone();
let lock = Arc::new(AtomicBool::new(false));
let lock_check = lock.clone();
let final_check = lock.clone();
gate.open(a_path);
AsyncComputeTaskPool::get()
.spawn(async move {
let mut reader = Vec::new();
asset_server.read_stream(a_path, &mut reader).await.unwrap();
assert_eq!(reader, a_ron.as_bytes());
lock.store(true, Ordering::Release);
})
.detach();
run_app_until(&mut app, |_| {
lock_check.load(Ordering::Acquire).then_some(())
});
assert!(final_check.load(Ordering::Acquire));
}

// validate the Asset derive macro for various asset types
Expand Down
86 changes: 85 additions & 1 deletion crates/bevy_asset/src/server/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@ use crate::{
folder::LoadedFolder,
io::{
AssetReaderError, AssetSource, AssetSourceEvent, AssetSourceId, AssetSources,
ErasedAssetReader, MissingAssetSourceError, MissingProcessedAssetReaderError, Reader,
AssetWriterError, ErasedAssetReader, MissingAssetSourceError, MissingAssetWriterError,
MissingProcessedAssetReaderError, MissingProcessedAssetWriterError, Reader,
},
loader::{AssetLoader, ErasedAssetLoader, LoadContext, LoadedAsset},
meta::{
Expand All @@ -22,6 +23,7 @@ use bevy_tasks::IoTaskPool;
use bevy_utils::tracing::{error, info};
use bevy_utils::{CowArc, HashSet};
use crossbeam_channel::{Receiver, Sender};
use futures_io::{AsyncRead, AsyncWrite};
use futures_lite::StreamExt;
use info::*;
use loaders::*;
Expand Down Expand Up @@ -1104,6 +1106,60 @@ impl AssetServer {
})
})
}

/// Low level function that reads a file from an [`AssetSource`] into an [`AsyncWrite`].
///
/// # Example
///
/// ```
/// # use bevy_asset::AssetServer;
/// # async fn read(asset_server: &AssetServer) {
/// let mut vec = Vec::new();
/// asset_server.read_stream("config/config.json", &mut vec).await;
/// # }
/// ```
pub async fn read_stream(
&self,
path: impl Into<AssetPath<'static>>,
sink: impl AsyncWrite,
) -> Result<(), AssetReadError> {
let path: AssetPath = path.into();
let source = self.get_source(path.source())?;
let asset_reader = match self.data.mode {
AssetServerMode::Unprocessed { .. } => source.reader(),
AssetServerMode::Processed { .. } => source.processed_reader()?,
};
let reader = asset_reader.read(path.path()).await?;
futures_lite::io::copy(reader, sink).await?;
Ok(())
}

/// Low level function that writes to a file from an [`AssetSource`] from an [`AsyncRead`].
///
/// # Example
///
/// ```
/// # use bevy_asset::AssetServer;
/// # async fn write(asset_server: &AssetServer) {
/// let mut json = br#"{"bevy": "awesome"}"#;
/// asset_server.write_stream("config/config.json", json.as_slice()).await;
/// # }
/// ```
pub async fn write_stream(
&self,
path: impl Into<AssetPath<'static>>,
stream: impl AsyncRead,
) -> Result<(), AssetWriteError> {
let path: AssetPath = path.into();
let source = self.get_source(path.source())?;
let asset_writer = match self.data.mode {
AssetServerMode::Unprocessed { .. } => source.writer()?,
AssetServerMode::Processed { .. } => source.processed_writer()?,
};
let writer = asset_writer.write(path.path()).await?;
futures_lite::io::copy(stream, writer).await?;
Ok(())
}
}

/// A system that manages internal [`AssetServer`] events, such as finalizing asset loads.
Expand Down Expand Up @@ -1338,6 +1394,34 @@ pub enum AssetLoadError {
},
}

/// An error that occurs during an [`AssetServer::read_stream`].
#[derive(Error, Debug)]
pub enum AssetReadError {
#[error(transparent)]
MissingAssetSourceError(#[from] MissingAssetSourceError),
#[error(transparent)]
MissingProcessedAssetReaderError(#[from] MissingProcessedAssetReaderError),
#[error(transparent)]
AssetReaderError(#[from] AssetReaderError),
#[error(transparent)]
IoError(#[from] std::io::Error),
}

/// An error that occurs during an [`AssetServer::write_stream`].
#[derive(Error, Debug)]
pub enum AssetWriteError {
#[error(transparent)]
MissingAssetSourceError(#[from] MissingAssetSourceError),
#[error(transparent)]
MissingAssetWriterError(#[from] MissingAssetWriterError),
#[error(transparent)]
MissingProcessedAssetWriterError(#[from] MissingProcessedAssetWriterError),
#[error(transparent)]
AssetWriterError(#[from] AssetWriterError),
#[error(transparent)]
IoError(#[from] std::io::Error),
}

#[derive(Error, Debug, Clone)]
#[error("Failed to load asset '{path}' with asset loader '{loader_name}': {error}")]
pub struct AssetLoaderError {
Expand Down