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Introduce PendingScript
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This moves scripts' loading results in Document, instead of maintaining them
behind a DOMRefCell in each HTMLScriptElement.
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@nox
nox committed Jan 11, 2017
1 parent 965370c commit 30f0553
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Showing 8 changed files with 193 additions and 82 deletions.
2 changes: 1 addition & 1 deletion components/script/dom/bindings/cell.rs
View file
Expand Up @@ -11,7 +11,7 @@ use style::thread_state;
///
/// This extends the API of `core::cell::RefCell` to allow unsafe access in
/// certain situations, with dynamic checking in debug builds.
#[derive(Clone, PartialEq, Debug, HeapSizeOf)]
#[derive(Clone, Debug, Default, HeapSizeOf, PartialEq)]
pub struct DOMRefCell<T> {
value: RefCell<T>,
}
Expand Down
203 changes: 140 additions & 63 deletions components/script/dom/document.rs
View file
Expand Up @@ -60,7 +60,7 @@ use dom::htmlheadelement::HTMLHeadElement;
use dom::htmlhtmlelement::HTMLHtmlElement;
use dom::htmliframeelement::HTMLIFrameElement;
use dom::htmlimageelement::HTMLImageElement;
use dom::htmlscriptelement::HTMLScriptElement;
use dom::htmlscriptelement::{HTMLScriptElement, ScriptResult};
use dom::htmltitleelement::HTMLTitleElement;
use dom::keyboardevent::KeyboardEvent;
use dom::location::Location;
Expand Down Expand Up @@ -118,7 +118,7 @@ use servo_url::ServoUrl;
use std::ascii::AsciiExt;
use std::borrow::ToOwned;
use std::cell::{Cell, Ref, RefMut};
use std::collections::HashMap;
use std::collections::{HashMap, VecDeque};
use std::collections::hash_map::Entry::{Occupied, Vacant};
use std::default::Default;
use std::iter::once;
Expand Down Expand Up @@ -220,15 +220,15 @@ pub struct Document {
/// The script element that is currently executing.
current_script: MutNullableJS<HTMLScriptElement>,
/// https://html.spec.whatwg.org/multipage/#pending-parsing-blocking-script
pending_parsing_blocking_script: MutNullableJS<HTMLScriptElement>,
pending_parsing_blocking_script: DOMRefCell<Option<PendingScript>>,
/// Number of stylesheets that block executing the next parser-inserted script
script_blocking_stylesheets_count: Cell<u32>,
/// https://html.spec.whatwg.org/multipage/#list-of-scripts-that-will-execute-when-the-document-has-finished-parsing
deferred_scripts: DOMRefCell<Vec<JS<HTMLScriptElement>>>,
deferred_scripts: PendingInOrderScriptVec,
/// https://html.spec.whatwg.org/multipage/#list-of-scripts-that-will-execute-in-order-as-soon-as-possible
asap_in_order_scripts_list: DOMRefCell<Vec<JS<HTMLScriptElement>>>,
asap_in_order_scripts_list: PendingInOrderScriptVec,
/// https://html.spec.whatwg.org/multipage/#set-of-scripts-that-will-execute-as-soon-as-possible
asap_scripts_set: DOMRefCell<Vec<JS<HTMLScriptElement>>>,
asap_scripts_set: DOMRefCell<VecDeque<PendingScript>>,
/// https://html.spec.whatwg.org/multipage/#concept-n-noscript
/// True if scripting is enabled for all scripts in this document
scripting_enabled: Cell<bool>,
Expand Down Expand Up @@ -1450,25 +1450,27 @@ impl Document {
changed
}

pub fn set_pending_parsing_blocking_script(&self, script: &HTMLScriptElement) {
pub fn set_pending_parsing_blocking_script(&self,
script: &HTMLScriptElement,
load: Option<ScriptResult>) {
assert!(!self.has_pending_parsing_blocking_script());
self.pending_parsing_blocking_script.set(Some(script));
*self.pending_parsing_blocking_script.borrow_mut() = Some(PendingScript::new_with_load(script, load));
}

pub fn has_pending_parsing_blocking_script(&self) -> bool {
self.pending_parsing_blocking_script.get().is_some()
self.pending_parsing_blocking_script.borrow().is_some()
}

pub fn add_deferred_script(&self, script: &HTMLScriptElement) {
self.deferred_scripts.borrow_mut().push(JS::from_ref(script));
self.deferred_scripts.push(script);
}

pub fn add_asap_script(&self, script: &HTMLScriptElement) {
self.asap_scripts_set.borrow_mut().push(JS::from_ref(script));
self.asap_scripts_set.borrow_mut().push_back(PendingScript::new(script));
}

pub fn push_asap_in_order_script(&self, script: &HTMLScriptElement) {
self.asap_in_order_scripts_list.borrow_mut().push(JS::from_ref(script));
self.asap_in_order_scripts_list.push(script);
}

pub fn trigger_mozbrowser_event(&self, event: MozBrowserEvent) {
Expand Down Expand Up @@ -1573,12 +1575,22 @@ impl Document {
}

if let Some(parser) = self.get_current_parser() {
if let Some(script) = self.pending_parsing_blocking_script.get() {
if self.script_blocking_stylesheets_count.get() > 0 || !script.is_ready_to_be_executed() {
return;
}
self.pending_parsing_blocking_script.set(None);
parser.resume_with_pending_parsing_blocking_script(&script);
let ready_to_be_executed = match self.pending_parsing_blocking_script.borrow_mut().as_mut() {
Some(pending) => {
if self.script_blocking_stylesheets_count.get() > 0 {
return;
}
if let Some(pair) = pending.take_result() {
Some(pair)
} else {
return;
}
},
None => None,
};
if let Some((element, result)) = ready_to_be_executed {
*self.pending_parsing_blocking_script.borrow_mut() = None;
parser.resume_with_pending_parsing_blocking_script(&element, result);
}
} else if self.reflow_timeout.get().is_none() {
// If we don't have a parser, and the reflow timer has been reset, explicitly
Expand All @@ -1601,58 +1613,66 @@ impl Document {
}
}

/// https://html.spec.whatwg.org/multipage/#the-end step 3
/// https://html.spec.whatwg.org/multipage/#prepare-a-script step 22.d.
pub fn pending_parsing_blocking_script_loaded(&self, element: &HTMLScriptElement, result: ScriptResult) {
let mut blocking_script = self.pending_parsing_blocking_script.borrow_mut();
let entry = blocking_script.as_mut().unwrap();
assert!(&*entry.element == element);
entry.loaded(result);
}

/// https://html.spec.whatwg.org/multipage/#prepare-a-script step 22.d.
pub fn deferred_script_loaded(&self, element: &HTMLScriptElement, result: ScriptResult) {
self.deferred_scripts.loaded(element, result);
}

/// https://html.spec.whatwg.org/multipage/#the-end step 3.
pub fn process_deferred_scripts(&self) {
if self.ready_state.get() != DocumentReadyState::Interactive {
return;
}
// Part of substep 1.
if self.script_blocking_stylesheets_count.get() > 0 {
return;
}
let mut deferred_scripts = self.deferred_scripts.borrow_mut();
while !deferred_scripts.is_empty() {
{
let script = &*deferred_scripts[0];
// Part of substep 1.
if !script.is_ready_to_be_executed() {
return;
}
// Substep 2.
script.execute();
loop {
if self.script_blocking_stylesheets_count.get() > 0 {
return;
}
// Substep 3.
deferred_scripts.remove(0);
// Substep 4 (implicit).
}
// https://html.spec.whatwg.org/multipage/#the-end step 4.
self.maybe_dispatch_dom_content_loaded();
}

/// https://html.spec.whatwg.org/multipage/#the-end step 5 and the latter parts of
/// https://html.spec.whatwg.org/multipage/#prepare-a-script 20.d and 20.e.
pub fn process_asap_scripts(&self) {
// Execute the first in-order asap-executed script if it's ready, repeat as required.
// Re-borrowing the list for each step because it can also be borrowed under execute.
while self.asap_in_order_scripts_list.borrow().len() > 0 {
let script = Root::from_ref(&*self.asap_in_order_scripts_list.borrow()[0]);
if !script.is_ready_to_be_executed() {
if let Some((element, result)) = self.deferred_scripts.take_next_ready_to_be_executed() {
element.execute(result);
} else {
break;
}
script.execute();
self.asap_in_order_scripts_list.borrow_mut().remove(0);
}
if self.deferred_scripts.is_empty() {
// https://html.spec.whatwg.org/multipage/#the-end step 4.
self.maybe_dispatch_dom_content_loaded();
}
}

let mut idx = 0;
// Re-borrowing the set for each step because it can also be borrowed under execute.
while idx < self.asap_scripts_set.borrow().len() {
let script = Root::from_ref(&*self.asap_scripts_set.borrow()[idx]);
if !script.is_ready_to_be_executed() {
idx += 1;
continue;
}
script.execute();
self.asap_scripts_set.borrow_mut().swap_remove(idx);
/// https://html.spec.whatwg.org/multipage/#the-end step 3.
/// https://html.spec.whatwg.org/multipage/#prepare-a-script step 22.d.
pub fn asap_script_loaded(&self, element: &HTMLScriptElement, result: ScriptResult) {
let mut scripts = self.asap_scripts_set.borrow_mut();
let idx = scripts.iter().position(|entry| &*entry.element == element).unwrap();
scripts.swap(0, idx);
scripts[0].loaded(result);
}

/// https://html.spec.whatwg.org/multipage/#the-end step 3.
/// https://html.spec.whatwg.org/multipage/#prepare-a-script step 22.c.
pub fn asap_in_order_script_loaded(&self,
element: &HTMLScriptElement,
result: ScriptResult) {
self.asap_in_order_scripts_list.loaded(element, result);
}

fn process_asap_scripts(&self) {
let pair = self.asap_scripts_set.borrow_mut().front_mut().and_then(PendingScript::take_result);
if let Some((element, result)) = pair {
self.asap_scripts_set.borrow_mut().pop_front();
element.execute(result);
}
while let Some((element, result)) = self.asap_in_order_scripts_list.take_next_ready_to_be_executed() {
element.execute(result);
}
}

Expand Down Expand Up @@ -1889,9 +1909,9 @@ impl Document {
current_script: Default::default(),
pending_parsing_blocking_script: Default::default(),
script_blocking_stylesheets_count: Cell::new(0u32),
deferred_scripts: DOMRefCell::new(vec![]),
asap_in_order_scripts_list: DOMRefCell::new(vec![]),
asap_scripts_set: DOMRefCell::new(vec![]),
deferred_scripts: Default::default(),
asap_in_order_scripts_list: Default::default(),
asap_scripts_set: Default::default(),
scripting_enabled: Cell::new(browsing_context.is_some()),
animation_frame_ident: Cell::new(0),
animation_frame_list: DOMRefCell::new(vec![]),
Expand Down Expand Up @@ -3379,3 +3399,60 @@ impl AnimationFrameCallback {
}
}
}

#[derive(Default, HeapSizeOf, JSTraceable)]
#[must_root]
struct PendingInOrderScriptVec {
scripts: DOMRefCell<VecDeque<PendingScript>>,
}

impl PendingInOrderScriptVec {
fn is_empty(&self) -> bool {
self.scripts.borrow().is_empty()
}
fn push(&self, element: &HTMLScriptElement) {
self.scripts.borrow_mut().push_back(PendingScript::new(element));
}

fn loaded(&self, element: &HTMLScriptElement, result: ScriptResult) {
let mut scripts = self.scripts.borrow_mut();
let mut entry = scripts.iter_mut().find(|entry| &*entry.element == element).unwrap();
entry.loaded(result);
}

fn take_next_ready_to_be_executed(&self) -> Option<(Root<HTMLScriptElement>, ScriptResult)> {
let mut scripts = self.scripts.borrow_mut();
let pair = scripts.front_mut().and_then(PendingScript::take_result);
if pair.is_none() {
return None;
}
scripts.pop_front();
pair
}
}

#[derive(HeapSizeOf, JSTraceable)]
#[must_root]
struct PendingScript {
element: JS<HTMLScriptElement>,
load: Option<ScriptResult>,
}

impl PendingScript {
fn new(element: &HTMLScriptElement) -> Self {
Self { element: JS::from_ref(element), load: None }
}

fn new_with_load(element: &HTMLScriptElement, load: Option<ScriptResult>) -> Self {
Self { element: JS::from_ref(element), load }
}

fn loaded(&mut self, result: ScriptResult) {
assert!(self.load.is_none());
self.load = Some(result);
}

fn take_result(&mut self) -> Option<(Root<HTMLScriptElement>, ScriptResult)> {
self.load.take().map(|result| (Root::from_ref(&*self.element), result))
}
}

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