forked from mirrors/gecko-dev
92f175fd5a
This generalizes the work previously done for Promise job callbacks. There is now a microtask queue that correctly processes all queued microtasks after each turn of the event loop, as well as after a scripted callback finishes executing, and after a classic script executes. --- - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #4283 - [X] There are tests for these changes Source-Repo: https://github.com/servo/servo Source-Revision: cbcafd18f4cb5973948b081b4c104d99735e2789 --HG-- extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear extra : subtree_revision : 5175f700a2eff8f6bf1ef4b8a0f8d6a9aed1e78a
83 lines
3 KiB
Rust
83 lines
3 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
//! Implementation of [microtasks](https://html.spec.whatwg.org/multipage/#microtask) and
|
|
//! microtask queues. It is up to implementations of event loops to store a queue and
|
|
//! perform checkpoints at appropriate times, as well as enqueue microtasks as required.
|
|
|
|
use dom::bindings::callback::ExceptionHandling;
|
|
use dom::bindings::cell::DOMRefCell;
|
|
use dom::bindings::codegen::Bindings::PromiseBinding::PromiseJobCallback;
|
|
use dom::bindings::js::Root;
|
|
use dom::globalscope::GlobalScope;
|
|
use msg::constellation_msg::PipelineId;
|
|
use std::cell::Cell;
|
|
use std::mem;
|
|
use std::rc::Rc;
|
|
|
|
/// A collection of microtasks in FIFO order.
|
|
#[derive(JSTraceable, HeapSizeOf, Default)]
|
|
pub struct MicrotaskQueue {
|
|
/// The list of enqueued microtasks that will be invoked at the next microtask checkpoint.
|
|
microtask_queue: DOMRefCell<Vec<Microtask>>,
|
|
/// https://html.spec.whatwg.org/multipage/#performing-a-microtask-checkpoint
|
|
performing_a_microtask_checkpoint: Cell<bool>,
|
|
}
|
|
|
|
#[derive(JSTraceable, HeapSizeOf)]
|
|
pub enum Microtask {
|
|
Promise(EnqueuedPromiseCallback),
|
|
}
|
|
|
|
/// A promise callback scheduled to run during the next microtask checkpoint (#4283).
|
|
#[derive(JSTraceable, HeapSizeOf)]
|
|
pub struct EnqueuedPromiseCallback {
|
|
#[ignore_heap_size_of = "Rc has unclear ownership"]
|
|
pub callback: Rc<PromiseJobCallback>,
|
|
pub pipeline: PipelineId,
|
|
}
|
|
|
|
impl MicrotaskQueue {
|
|
/// Add a new microtask to this queue. It will be invoked as part of the next
|
|
/// microtask checkpoint.
|
|
pub fn enqueue(&self, job: Microtask) {
|
|
self.microtask_queue.borrow_mut().push(job);
|
|
}
|
|
|
|
/// https://html.spec.whatwg.org/multipage/#perform-a-microtask-checkpoint
|
|
/// Perform a microtask checkpoint, executing all queued microtasks until the queue is empty.
|
|
pub fn checkpoint<F>(&self, target_provider: F)
|
|
where F: Fn(PipelineId) -> Option<Root<GlobalScope>>
|
|
{
|
|
if self.performing_a_microtask_checkpoint.get() {
|
|
return;
|
|
}
|
|
|
|
// Step 1
|
|
self.performing_a_microtask_checkpoint.set(true);
|
|
|
|
// Steps 2-7
|
|
while !self.microtask_queue.borrow().is_empty() {
|
|
rooted_vec!(let mut pending_queue);
|
|
mem::swap(
|
|
&mut *pending_queue,
|
|
&mut *self.microtask_queue.borrow_mut());
|
|
|
|
for job in pending_queue.iter() {
|
|
match *job {
|
|
Microtask::Promise(ref job) => {
|
|
if let Some(target) = target_provider(job.pipeline) {
|
|
let _ = job.callback.Call_(&*target, ExceptionHandling::Report);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//TODO: Step 8 - notify about rejected promises
|
|
|
|
// Step 9
|
|
self.performing_a_microtask_checkpoint.set(false);
|
|
}
|
|
}
|