script/dom/workers/
abstractworkerglobalscope.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5use crossbeam_channel::{Receiver, select};
6use devtools_traits::DevtoolScriptControlMsg;
7use rustc_hash::FxHashSet;
8
9use crate::dom::bindings::conversions::DerivedFrom;
10use crate::dom::bindings::reflector::DomObject;
11use crate::dom::dedicatedworkerglobalscope::AutoWorkerReset;
12use crate::dom::globalscope::GlobalScope;
13use crate::dom::worker::TrustedWorkerAddress;
14use crate::dom::workerglobalscope::WorkerGlobalScope;
15use crate::realms::enter_realm;
16use crate::task_queue::{QueuedTaskConversion, TaskQueue};
17
18pub(crate) trait WorkerEventLoopMethods {
19    type WorkerMsg: QueuedTaskConversion + Send;
20    type ControlMsg;
21    type Event;
22    fn task_queue(&self) -> &TaskQueue<Self::WorkerMsg>;
23    fn handle_event(&self, event: Self::Event, cx: &mut js::context::JSContext) -> bool;
24    fn handle_worker_post_event(
25        &self,
26        worker: &TrustedWorkerAddress,
27    ) -> Option<AutoWorkerReset<'_>>;
28    fn from_control_msg(msg: Self::ControlMsg) -> Self::Event;
29    fn from_worker_msg(msg: Self::WorkerMsg) -> Self::Event;
30    fn from_devtools_msg(msg: DevtoolScriptControlMsg) -> Self::Event;
31    fn from_timer_msg() -> Self::Event;
32    fn control_receiver(&self) -> &Receiver<Self::ControlMsg>;
33}
34
35// https://html.spec.whatwg.org/multipage/#worker-event-loop
36pub(crate) fn run_worker_event_loop<T, WorkerMsg, Event>(
37    worker_scope: &T,
38    worker: Option<&TrustedWorkerAddress>,
39    cx: &mut js::context::JSContext,
40) where
41    WorkerMsg: QueuedTaskConversion + Send,
42    T: WorkerEventLoopMethods<WorkerMsg = WorkerMsg, Event = Event>
43        + DerivedFrom<WorkerGlobalScope>
44        + DerivedFrom<GlobalScope>
45        + DomObject,
46{
47    let scope = worker_scope.upcast::<WorkerGlobalScope>();
48    let task_queue = worker_scope.task_queue();
49
50    let never = crossbeam_channel::never();
51    let devtools_receiver = scope.devtools_receiver().unwrap_or(&never);
52
53    let event = select! {
54        recv(worker_scope.control_receiver()) -> msg => T::from_control_msg(msg.unwrap()),
55        recv(task_queue.select()) -> msg => {
56            task_queue.take_tasks(msg.unwrap(), &FxHashSet::default());
57            T::from_worker_msg(task_queue.recv().unwrap())
58        },
59        // RoutedReceivers have two results
60        recv(devtools_receiver) -> msg => T::from_devtools_msg(msg.unwrap().unwrap()),
61        recv(scope.timer_scheduler().wait_channel()) -> _ => T::from_timer_msg(),
62    };
63
64    scope.timer_scheduler().dispatch_completed_timers();
65
66    let mut sequential = vec![event];
67
68    // https://html.spec.whatwg.org/multipage/#worker-event-loop
69    // Once the WorkerGlobalScope's closing flag is set to true,
70    // the event loop's task queues must discard any further tasks
71    // that would be added to them
72    // (tasks already on the queue are unaffected except where otherwise specified).
73    while !scope.is_closing() {
74        // Batch all events that are ready.
75        // The task queue will throttle non-priority tasks if necessary.
76        match task_queue.take_tasks_and_recv(&FxHashSet::default()) {
77            Err(_) => match devtools_receiver.try_recv() {
78                Ok(message) => sequential.push(T::from_devtools_msg(message.unwrap())),
79                Err(_) => break,
80            },
81            Ok(ev) => sequential.push(T::from_worker_msg(ev)),
82        }
83    }
84
85    // Step 3
86    for event in sequential {
87        let _realm = enter_realm(worker_scope);
88        if !worker_scope.handle_event(event, cx) {
89            // Shutdown
90            return;
91        }
92        // Step 6
93        let _ar = match worker {
94            Some(worker) => worker_scope.handle_worker_post_event(worker),
95            None => None,
96        };
97        scope.perform_a_microtask_checkpoint(cx);
98    }
99    worker_scope
100        .upcast::<GlobalScope>()
101        .perform_a_dom_garbage_collection_checkpoint();
102}
script/dom/workers/abstractworkerglobalscope.rs

script/dom/workers/
abstractworkerglobalscope.rs
