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Delay iframe and script element processing until the DOM is stable.

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This commit is contained in:
Josh Matthews 2018-12-09 23:52:42 -05:00
parent 14b0de30db
commit fc2d810bce
4 changed files with 59 additions and 21 deletions
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44
components/script/dom/document.rs
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@ -101,6 +101,7 @@ use crate::dom::windowproxy::WindowProxy;
use crate::fetch::FetchCanceller;
use crate::script_runtime::{CommonScriptMsg, ScriptThreadEventCategory};
use crate::script_thread::{MainThreadScriptMsg, ScriptThread};
use crate::task::TaskBox;
use crate::task_source::{TaskSource, TaskSourceName};
use crate::timers::OneshotTimerCallback;
use devtools_traits::ScriptToDevtoolsControlMsg;
@ -410,8 +411,11 @@ pub struct Document {
responsive_images: DomRefCell<Vec<Dom<HTMLImageElement>>>,
/// Number of redirects for the document load
redirect_count: Cell<u16>,
///
/// Number of outstanding requests to prevent JS or layout from running.
script_and_layout_blockers: Cell<u32>,
/// List of tasks to execute as soon as last script/layout blocker is removed.
#[ignore_malloc_size_of = "Measuring trait objects is hard"]
delayed_tasks: DomRefCell<Vec<Box<dyn TaskBox>>>,
}
#[derive(JSTraceable, MallocSizeOf)]
@ -2698,24 +2702,48 @@ impl Document {
responsive_images: Default::default(),
redirect_count: Cell::new(0),
script_and_layout_blockers: Cell::new(0),
delayed_tasks: Default::default(),
}
}
/// Prevent any JS or layout from running until the corresponding call to
/// `remove_script_and_layout_blocker`. Used to isolate periods in which
/// the DOM is in an unstable state and should not be exposed to arbitrary
/// web content. Any attempts to invoke content JS or query layout during
/// that time will trigger a panic. `add_delayed_task` will cause the
/// provided task to be executed as soon as the last blocker is removed.
pub fn add_script_and_layout_blocker(&self) {
self.script_and_layout_blockers.set(
self.script_and_layout_blockers.get() + 1
);
self.script_and_layout_blockers
.set(self.script_and_layout_blockers.get() + 1);
}
/// Terminate the period in which JS or layout is disallowed from running.
/// If no further blockers remain, any delayed tasks in the queue will
/// be executed in queue order until the queue is empty.
pub fn remove_script_and_layout_blocker(&self) {
assert!(self.script_and_layout_blockers.get() > 0);
self.script_and_layout_blockers.set(
self.script_and_layout_blockers.get() - 1
);
self.script_and_layout_blockers
.set(self.script_and_layout_blockers.get() - 1);
while self.script_and_layout_blockers.get() == 0 && !self.delayed_tasks.borrow().is_empty()
{
let task = self.delayed_tasks.borrow_mut().remove(0);
task.run_box();
}
}
/// Enqueue a task to run as soon as any JS and layout blockers are removed.
pub fn add_delayed_task<T: 'static + TaskBox>(&self, task: T) {
self.delayed_tasks.borrow_mut().push(Box::new(task));
}
/// Assert that the DOM is in a state that will allow running content JS or
/// performing a layout operation.
pub fn ensure_safe_to_run_script_or_layout(&self) {
assert_eq!(self.script_and_layout_blockers.get(), 0);
assert_eq!(
self.script_and_layout_blockers.get(),
0,
"Attempt to use script or layout while DOM not in a stable state"
);
}
// https://dom.spec.whatwg.org/#dom-document-document