Files
iris/src/rsc/task.rs
T

105 lines
3.5 KiB
Rust

use iris_core::HasState;
use std::{
pin::Pin,
sync::{
Arc,
mpsc::{Receiver as SyncReceiver, Sender as SyncSender, channel as sync_channel},
},
};
use tokio::{
runtime::Runtime,
sync::mpsc::{
UnboundedReceiver as AsyncReceiver, UnboundedSender as AsyncSender,
unbounded_channel as async_channel,
},
};
/// What a completed task nudges when it wants its result drawn. Shared
/// between backends rather than typed as `winit::window::Window` directly:
/// android-view has no `Window` at all, and the redraw request there is a
/// JNI call (`View::post_frame_callback`) rather than a method call on a
/// value this crate owns. Each backend supplies its own implementation --
/// `desktop/render.rs` for winit, `android/render.rs` for android-view --
/// and this module never needs to know which one it is holding.
pub trait RequestRedraw: Send + Sync + 'static {
fn request_redraw(&self);
}
pub type TaskMsgSender<Rsc> = SyncSender<Box<dyn TaskUpdate<Rsc>>>;
pub type TaskMsgReceiver<Rsc> = SyncReceiver<Box<dyn TaskUpdate<Rsc>>>;
pub trait TaskUpdate<Rsc: HasState>: FnOnce(&mut Rsc::State, &mut Rsc) + Send {}
impl<F: FnOnce(&mut Rsc::State, &mut Rsc) + Send, Rsc: HasState> TaskUpdate<Rsc> for F {}
pub struct Tasks<Rsc: HasState> {
start: AsyncSender<BoxTask>,
redraw: Arc<dyn RequestRedraw>,
msg_send: SyncSender<Box<dyn TaskUpdate<Rsc>>>,
}
pub struct TaskCtx<Rsc: HasState> {
send: TaskMsgSender<Rsc>,
}
impl<Rsc: HasState> TaskCtx<Rsc> {
pub fn update(&mut self, f: impl TaskUpdate<Rsc> + 'static) {
let _ = self.send.send(Box::new(f));
}
}
impl<Rsc: HasState + 'static> TaskCtx<Rsc> {
fn new(send: TaskMsgSender<Rsc>) -> Self {
Self { send }
}
}
type BoxTask = Pin<Box<dyn Future<Output = ()> + Send>>;
impl<Rsc: HasState> Tasks<Rsc> {
pub fn init(redraw: Arc<dyn RequestRedraw>) -> (Self, TaskMsgReceiver<Rsc>) {
let (start, start_recv) = async_channel();
let (msgs, msgs_recv) = sync_channel();
std::thread::spawn(|| {
let rt = Runtime::new().unwrap();
rt.block_on(listen(start_recv))
});
(
Self {
start,
msg_send: msgs,
redraw,
},
msgs_recv,
)
}
/// The same redraw handle `spawn`'s wrapper calls once, after a whole
/// task's future completes -- exposed so a caller running its own
/// longer-lived loop *inside* a spawned task (a live SSE follow, here)
/// can ask for a frame after each `TaskCtx::update`, not just at the
/// end. Without this a caller has no way to get a redraw mid-stream,
/// which is exactly the gap `iris/desktop-app`'s `app.rs` module doc
/// names for why it uses winit's `Proxy` instead of `Tasks` -- Android
/// has no `Proxy`, so this is what closes the same gap there.
pub fn redraw_handle(&self) -> Arc<dyn RequestRedraw> {
self.redraw.clone()
}
pub fn spawn<F: AsyncFnOnce(TaskCtx<Rsc>) + 'static + std::marker::Send>(&mut self, task: F)
where
F::CallOnceFuture: Send,
{
let send = self.msg_send.clone();
let redraw = self.redraw.clone();
let _ = self.start.send(Box::pin(async move {
task(TaskCtx::new(send)).await;
redraw.request_redraw();
}));
}
}
async fn listen(mut recv: AsyncReceiver<BoxTask>) {
while let Some(task) = recv.recv().await {
tokio::spawn(task);
}
}