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/*
* Copyright 2022 Google Inc. All Rights Reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#![doc = include_str!("../README.md")]
// Note: `atomics` is whitelisted in `target_feature` detection, but `bulk-memory` isn't,
// so we can check only presence of the former. This should be enough to catch most common
// mistake (forgetting to pass `RUSTFLAGS` altogether).
#[cfg(all(not(doc), not(target_feature = "atomics")))]
compile_error!("Did you forget to enable `atomics` and `bulk-memory` features as outlined in wasm-bindgen-rayon README?");
use crossbeam_channel::{bounded, Receiver, Sender};
use js_sys::Promise;
use rayon::{ThreadBuilder, ThreadPoolBuilder};
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsValue;
#[cfg(feature = "no-bundler")]
use js_sys::JsString;
// Naming is a workaround for https://github.com/rustwasm/wasm-bindgen/issues/2429
// and https://github.com/rustwasm/wasm-bindgen/issues/1762.
#[allow(non_camel_case_types)]
#[wasm_bindgen]
#[doc(hidden)]
pub struct wbg_rayon_PoolBuilder {
num_threads: usize,
sender: Sender<ThreadBuilder>,
receiver: Receiver<ThreadBuilder>,
}
#[cfg_attr(
not(feature = "no-bundler"),
wasm_bindgen(module = "/src/workerHelpers.js")
)]
#[cfg_attr(
feature = "no-bundler",
wasm_bindgen(module = "/src/workerHelpers.no-bundler.js")
)]
extern "C" {
#[wasm_bindgen(js_name = startWorkers)]
fn start_workers(module: JsValue, memory: JsValue, builder: wbg_rayon_PoolBuilder) -> Promise;
}
#[cfg(not(feature = "no-bundler"))]
fn _ensure_worker_emitted() {
// Just ensure that the worker is emitted into the output folder, but don't actually use the URL.
wasm_bindgen::link_to!(module = "/src/workerHelpers.worker.js");
}
#[wasm_bindgen]
impl wbg_rayon_PoolBuilder {
fn new(num_threads: usize) -> Self {
let (sender, receiver) = bounded(num_threads);
Self {
num_threads,
sender,
receiver,
}
}
#[cfg(feature = "no-bundler")]
#[wasm_bindgen(js_name = mainJS)]
pub fn main_js(&self) -> JsString {
#[wasm_bindgen]
extern "C" {
#[wasm_bindgen(js_namespace = ["import", "meta"], js_name = url)]
static URL: JsString;
}
URL.clone()
}
#[wasm_bindgen(js_name = numThreads)]
pub fn num_threads(&self) -> usize {
self.num_threads
}
pub fn receiver(&self) -> *const Receiver<ThreadBuilder> {
&self.receiver
}
// This should be called by the JS side once all the Workers are spawned.
// Important: it must take `self` by reference, otherwise
// `start_worker_thread` will try to receive a message on a moved value.
pub fn build(&mut self) {
ThreadPoolBuilder::new()
.num_threads(self.num_threads)
// We could use postMessage here instead of Rust channels,
// but currently we can't due to a Chrome bug that will cause
// the main thread to lock up before it even sends the message:
// https://bugs.chromium.org/p/chromium/issues/detail?id=1075645
.spawn_handler(move |thread| {
// Note: `send` will return an error if there are no receivers.
// We can use it because all the threads are spawned and ready to accept
// messages by the time we call `build()` to instantiate spawn handler.
self.sender.send(thread).unwrap_throw();
Ok(())
})
.build_global()
.unwrap_throw();
}
}
#[wasm_bindgen(js_name = initThreadPool)]
#[doc(hidden)]
pub fn init_thread_pool(num_threads: usize) -> Promise {
start_workers(
wasm_bindgen::module(),
wasm_bindgen::memory(),
wbg_rayon_PoolBuilder::new(num_threads),
)
}
#[wasm_bindgen]
#[allow(clippy::not_unsafe_ptr_arg_deref)]
#[doc(hidden)]
pub fn wbg_rayon_start_worker(receiver: *const Receiver<ThreadBuilder>)
where
// Statically assert that it's safe to accept `Receiver` from another thread.
Receiver<ThreadBuilder>: Sync,
{
// This is safe, because we know it came from a reference to PoolBuilder,
// allocated on the heap by wasm-bindgen and dropped only once all the
// threads are running.
//
// The only way to violate safety is if someone externally calls
// `exports.wbg_rayon_start_worker(garbageValue)`, but then no Rust tools
// would prevent us from issues anyway.
let receiver = unsafe { &*receiver };
// Wait for a task (`ThreadBuilder`) on the channel, and, once received,
// start executing it.
//
// On practice this will start running Rayon's internal event loop.
receiver.recv().unwrap_throw().run()
}