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LibWeb: Pump the task queue when spinning until a goal condition

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This prevents goal conditions that rely on tasks that are currently in
flight on the task queue (or were just submitted) from blocking the
event loop until an IPC event fires to kick the native event loop.
This commit is contained in:
Andrew Kaster 2024-01-18 13:02:24 -07:00 • committed by Alexander Kalenik
parent 7d2635355d
commit 2cd93e6b58
Notes: sideshowbarker 2024-07-17 03:35:16 +09:00
1 changed files with 20 additions and 10 deletions
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30
Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp
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@ -5,6 +5,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibCore/EventLoop.h>
#include <LibJS/Runtime/VM.h>
#include <LibWeb/Bindings/MainThreadVM.h>
#include <LibWeb/DOM/Document.h>
@ -53,29 +54,38 @@ EventLoop& main_thread_event_loop()
// https://html.spec.whatwg.org/multipage/webappapis.html#spin-the-event-loop
void EventLoop::spin_until(JS::SafeFunction<bool()> goal_condition)
{
// FIXME: 1. Let task be the event loop's currently running task.
// FIXME: 2. Let task source be task's source.
// FIXME: The spec wants us to do the rest of the enclosing algorithm (i.e. the caller)
// in the context of the currently running task on entry. That's not possible with this implementation.
// 1. Let task be the event loop's currently running task.
// 2. Let task source be task's source.
// 3. Let old stack be a copy of the JavaScript execution context stack.
// 4. Empty the JavaScript execution context stack.
auto& vm = Bindings::main_thread_vm();
vm.save_execution_context_stack();
m_vm->save_execution_context_stack();
m_vm->clear_execution_context_stack();
// 5. Perform a microtask checkpoint.
perform_a_microtask_checkpoint();
// 6. In parallel:
// NOTE: We do these in reverse order here, but it shouldn't matter.
// 1. Wait until the condition goal is met.
// 2. Queue a task on task source to:
// 1. Replace the JavaScript execution context stack with old stack.
vm.restore_execution_context_stack();
// 2. Perform any steps that appear after this spin the event loop instance in the original algorithm.
// NOTE: This is achieved by returning from the function.
// 1. Wait until the condition goal is met.
Platform::EventLoopPlugin::the().spin_until(move(goal_condition));
Platform::EventLoopPlugin::the().spin_until([&] {
if (goal_condition())
return true;
if (m_task_queue.has_runnable_tasks()) {
schedule();
// FIXME: Remove the platform event loop plugin so that this doesn't look out of place
Core::EventLoop::current().wake();
}
return goal_condition();
});
m_vm->restore_execution_context_stack();
// 7. Stop task, allowing whatever algorithm that invoked it to resume.
// NOTE: This is achieved by returning from the function.