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denoland-deno/core/examples/schedule_task.rs
Matt Mastracci a1764f7690
refactor(core): Improve ergonomics of managing ASCII strings (#18498)
This is a follow-on to the earlier work in reducing string copies,
mainly focused on ensuring that ASCII strings are easy to provide to the
JS runtime.

While we are replacing a 16-byte reference in a number of places with a
24-byte structure (measured via `std::mem::size_of`), the reduction in
copies wins out over the additional size of the arguments passed into
functions.

Benchmarking shows approximately the same if not slightly less wallclock
time/instructions retired, but I believe this continues to open up
further refactoring opportunities.
2023-04-04 06:46:31 -06:00

69 lines
1.9 KiB
Rust

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
use deno_core::anyhow::Error;
use deno_core::op;
use deno_core::Extension;
use deno_core::JsRuntime;
use deno_core::OpState;
use deno_core::RuntimeOptions;
use futures::channel::mpsc;
use futures::stream::StreamExt;
use std::task::Poll;
// This is a hack to make the `#[op]` macro work with
// deno_core examples.
// You can remove this:
use deno_core::*;
type Task = Box<dyn FnOnce()>;
fn main() {
let my_ext = Extension::builder("my_ext")
.ops(vec![op_schedule_task::decl()])
.event_loop_middleware(|state_rc, cx| {
let mut state = state_rc.borrow_mut();
let recv = state.borrow_mut::<mpsc::UnboundedReceiver<Task>>();
let mut ref_loop = false;
while let Poll::Ready(Some(call)) = recv.poll_next_unpin(cx) {
call();
ref_loop = true; // `call` can callback into runtime and schedule new callbacks :-)
}
ref_loop
})
.state(move |state| {
let (tx, rx) = mpsc::unbounded::<Task>();
state.put(tx);
state.put(rx);
})
.build();
// Initialize a runtime instance
let mut js_runtime = JsRuntime::new(RuntimeOptions {
extensions: vec![my_ext],
..Default::default()
});
let runtime = tokio::runtime::Builder::new_current_thread()
.enable_all()
.build()
.unwrap();
let future = async move {
// Schedule 10 tasks.
js_runtime
.execute_script_static(
"<usage>",
r#"for (let i = 1; i <= 10; i++) Deno.core.ops.op_schedule_task(i);"#,
)
.unwrap();
js_runtime.run_event_loop(false).await
};
runtime.block_on(future).unwrap();
}
#[op]
fn op_schedule_task(state: &mut OpState, i: u8) -> Result<(), Error> {
let tx = state.borrow_mut::<mpsc::UnboundedSender<Task>>();
tx.unbounded_send(Box::new(move || println!("Hello, world! x{i}")))
.expect("unbounded_send failed");
Ok(())
}