/* 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/. */
//! The script thread is the thread that owns the DOM in memory, runs JavaScript, and spawns parsing
//! and layout threads. It's in charge of processing events for all same-origin pages in a frame
//! tree, and manages the entire lifetime of pages in the frame tree from initial request to
//! teardown.
//!
//! Page loads follow a two-step process. When a request for a new page load is received, the
//! network request is initiated and the relevant data pertaining to the new page is stashed.
//! While the non-blocking request is ongoing, the script thread is free to process further events,
//! noting when they pertain to ongoing loads (such as resizes/viewport adjustments). When the
//! initial response is received for an ongoing load, the second phase starts - the frame tree
//! entry is created, along with the Window and Document objects, and the appropriate parser
//! takes over the response body. Once parsing is complete, the document lifecycle for loading
//! a page runs its course and the script thread returns to processing events in the main event
//! loop.
use devtools;
use devtools_traits::CSSError;
use devtools_traits::{DevtoolScriptControlMsg, DevtoolsPageInfo};
use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
use document_loader::DocumentLoader;
use dom::bindings::cell::DOMRefCell;
use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
use dom::bindings::conversions::{FromJSValConvertible, StringificationBehavior};
use dom::bindings::global::GlobalRef;
use dom::bindings::inheritance::Castable;
use dom::bindings::js::{JS, MutNullableHeap, Root, RootCollection};
use dom::bindings::js::{RootCollectionPtr, RootedReference};
use dom::bindings::refcounted::{LiveDOMReferences, Trusted};
use dom::bindings::trace::JSTraceable;
use dom::bindings::utils::WRAP_CALLBACKS;
use dom::browsingcontext::{BrowsingContext, IterableContext};
use dom::document::{Document, DocumentProgressHandler, DocumentSource, FocusType, IsHTMLDocument};
use dom::element::Element;
use dom::event::{Event, EventBubbles, EventCancelable};
use dom::htmlanchorelement::HTMLAnchorElement;
use dom::node::{Node, NodeDamage, window_from_node};
use dom::servohtmlparser::ParserContext;
use dom::uievent::UIEvent;
use dom::window::{ReflowReason, ScriptHelpers, Window};
use dom::worker::TrustedWorkerAddress;
use euclid::Rect;
use euclid::point::Point2D;
use gfx_traits::LayerId;
use hyper::header::{ContentType, HttpDate};
use hyper::header::{Headers, LastModified};
use hyper::method::Method;
use hyper::mime::{Mime, SubLevel, TopLevel};
use ipc_channel::ipc::{self, IpcSender};
use ipc_channel::router::ROUTER;
use js::glue::GetWindowProxyClass;
use js::jsapi::{DOMProxyShadowsResult, HandleId, HandleObject, RootedValue};
use js::jsapi::{JSContext, JS_SetWrapObjectCallbacks, JSTracer, SetWindowProxyClass};
use js::jsval::UndefinedValue;
use js::rust::Runtime;
use layout_interface::{ReflowQueryType};
use layout_interface::{self, LayoutChan, NewLayoutThreadInfo, ScriptLayoutChan};
use mem::heap_size_of_self_and_children;
use msg::constellation_msg::{LoadData, PanicMsg, PipelineId, PipelineNamespace};
use msg::constellation_msg::{SubpageId, WindowSizeData, WindowSizeType};
use msg::webdriver_msg::WebDriverScriptCommand;
use net_traits::LoadData as NetLoadData;
use net_traits::bluetooth_thread::BluetoothMethodMsg;
use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheResult, ImageCacheThread};
use net_traits::{AsyncResponseTarget, CoreResourceMsg, LoadConsumer, LoadContext, Metadata, ResourceThreads};
use net_traits::{RequestSource, CustomResponse, CustomResponseSender, IpcSend};
use network_listener::NetworkListener;
use parse::ParserRoot;
use parse::html::{ParseContext, parse_html};
use parse::xml::{self, parse_xml};
use profile_traits::mem::{self, OpaqueSender, Report, ReportKind, ReportsChan};
use profile_traits::time::{self, ProfilerCategory, profile};
use script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
use script_runtime::{ScriptPort, StackRootTLS, new_rt_and_cx, get_reports};
use script_traits::CompositorEvent::{KeyEvent, MouseButtonEvent, MouseMoveEvent, ResizeEvent};
use script_traits::CompositorEvent::{TouchEvent, TouchpadPressureEvent};
use script_traits::{CompositorEvent, ConstellationControlMsg, EventResult};
use script_traits::{InitialScriptState, MouseButton, MouseEventType, MozBrowserEvent, NewLayoutInfo};
use script_traits::{LayoutMsg, OpaqueScriptLayoutChannel, ScriptMsg as ConstellationMsg};
use script_traits::{ScriptThreadFactory, ScriptToCompositorMsg, TimerEvent, TimerEventRequest, TimerSource};
use script_traits::{TouchEventType, TouchId};
use std::any::Any;
use std::borrow::ToOwned;
use std::cell::{Cell, RefCell};
use std::collections::HashSet;
use std::option::Option;
use std::rc::Rc;
use std::result::Result;
use std::sync::atomic::{Ordering, AtomicBool};
use std::sync::mpsc::{Receiver, Select, Sender, channel};
use std::sync::{Arc, Mutex};
use style::context::ReflowGoal;
use task_source::TaskSource;
use task_source::dom_manipulation::{DOMManipulationTaskSource, DOMManipulationTask};
use task_source::file_reading::FileReadingTaskSource;
use task_source::history_traversal::HistoryTraversalTaskSource;
use task_source::networking::NetworkingTaskSource;
use task_source::user_interaction::{UserInteractionTaskSource, UserInteractionTask};
use time::Tm;
use url::{Url, Position};
use util::opts;
use util::str::DOMString;
use util::thread;
use util::thread_state;
use webdriver_handlers;
thread_local!(pub static STACK_ROOTS: Cell> = Cell::new(None));
thread_local!(static SCRIPT_THREAD_ROOT: RefCell > = RefCell::new(None));
pub unsafe fn trace_thread(tr: *mut JSTracer) {
SCRIPT_THREAD_ROOT.with(|root| {
if let Some(script_thread) = *root.borrow() {
debug!("tracing fields of ScriptThread");
(*script_thread).trace(tr);
}
});
}
/// A document load that is in the process of fetching the requested resource. Contains
/// data that will need to be present when the document and frame tree entry are created,
/// but is only easily available at initiation of the load and on a push basis (so some
/// data will be updated according to future resize events, viewport changes, etc.)
#[derive(JSTraceable)]
struct InProgressLoad {
/// The pipeline which requested this load.
pipeline_id: PipelineId,
/// The parent pipeline and child subpage associated with this load, if any.
parent_info: Option<(PipelineId, SubpageId)>,
/// The current window size associated with this pipeline.
window_size: Option,
/// Channel to the layout thread associated with this pipeline.
layout_chan: LayoutChan,
/// The current viewport clipping rectangle applying to this pipeline, if any.
clip_rect: Option>,
/// Window is frozen (navigated away while loading for example).
is_frozen: bool,
/// The requested URL of the load.
url: Url,
}
impl InProgressLoad {
/// Create a new InProgressLoad object.
fn new(id: PipelineId,
parent_info: Option<(PipelineId, SubpageId)>,
layout_chan: LayoutChan,
window_size: Option,
url: Url) -> InProgressLoad {
InProgressLoad {
pipeline_id: id,
parent_info: parent_info,
layout_chan: layout_chan,
window_size: window_size,
clip_rect: None,
is_frozen: false,
url: url,
}
}
}
/// Encapsulated state required to create cancellable runnables from non-script threads.
pub struct RunnableWrapper {
pub cancelled: Arc,
}
impl RunnableWrapper {
pub fn wrap_runnable(&self, runnable: T) -> Box {
box CancellableRunnable {
cancelled: self.cancelled.clone(),
inner: box runnable,
}
}
}
/// A runnable that can be discarded by toggling a shared flag.
pub struct CancellableRunnable {
cancelled: Arc,
inner: Box,
}
impl Runnable for CancellableRunnable {
fn is_cancelled(&self) -> bool {
self.cancelled.load(Ordering::Relaxed)
}
fn handler(self: Box>) {
self.inner.handler()
}
}
pub trait Runnable {
fn is_cancelled(&self) -> bool { false }
fn handler(self: Box);
}
pub trait MainThreadRunnable {
fn handler(self: Box, script_thread: &ScriptThread);
}
enum MixedMessage {
FromConstellation(ConstellationControlMsg),
FromScript(MainThreadScriptMsg),
FromDevtools(DevtoolScriptControlMsg),
FromImageCache(ImageCacheResult),
FromScheduler(TimerEvent),
FromNetwork(IpcSender>),
}
/// Messages used to control the script event loop
pub enum MainThreadScriptMsg {
/// Common variants associated with the script messages
Common(CommonScriptMsg),
/// Notify a document that all pending loads are complete.
DocumentLoadsComplete(PipelineId),
/// Notifies the script that a window associated with a particular pipeline
/// should be closed (only dispatched to ScriptThread).
ExitWindow(PipelineId),
/// Begins a content-initiated load on the specified pipeline (only
/// dispatched to ScriptThread).
Navigate(PipelineId, LoadData),
/// Tasks that originate from the DOM manipulation task source
DOMManipulation(DOMManipulationTask),
/// Tasks that originate from the user interaction task source
UserInteraction(UserInteractionTask),
}
impl OpaqueSender for Box {
fn send(&self, msg: CommonScriptMsg) {
ScriptChan::send(&**self, msg).unwrap();
}
}
impl ScriptPort for Receiver {
fn recv(&self) -> Result {
self.recv().map_err(|_| ())
}
}
impl ScriptPort for Receiver {
fn recv(&self) -> Result {
match self.recv() {
Ok(MainThreadScriptMsg::Common(script_msg)) => Ok(script_msg),
Ok(_) => panic!("unexpected main thread event message!"),
_ => Err(()),
}
}
}
impl ScriptPort for Receiver<(TrustedWorkerAddress, CommonScriptMsg)> {
fn recv(&self) -> Result {
self.recv().map(|(_, msg)| msg).map_err(|_| ())
}
}
impl ScriptPort for Receiver<(TrustedWorkerAddress, MainThreadScriptMsg)> {
fn recv(&self) -> Result {
match self.recv().map(|(_, msg)| msg) {
Ok(MainThreadScriptMsg::Common(script_msg)) => Ok(script_msg),
Ok(_) => panic!("unexpected main thread event message!"),
_ => Err(()),
}
}
}
/// Encapsulates internal communication of shared messages within the script thread.
#[derive(JSTraceable)]
pub struct SendableMainThreadScriptChan(pub Sender);
impl ScriptChan for SendableMainThreadScriptChan {
fn send(&self, msg: CommonScriptMsg) -> Result<(), ()> {
self.0.send(msg).map_err(|_| ())
}
fn clone(&self) -> Box {
box SendableMainThreadScriptChan((&self.0).clone())
}
}
/// Encapsulates internal communication of main thread messages within the script thread.
#[derive(JSTraceable)]
pub struct MainThreadScriptChan(pub Sender);
impl ScriptChan for MainThreadScriptChan {
fn send(&self, msg: CommonScriptMsg) -> Result<(), ()> {
self.0.send(MainThreadScriptMsg::Common(msg)).map_err(|_| ())
}
fn clone(&self) -> Box {
box MainThreadScriptChan((&self.0).clone())
}
}
impl OpaqueSender for Sender {
fn send(&self, msg: CommonScriptMsg) {
self.send(MainThreadScriptMsg::Common(msg)).unwrap()
}
}
/// Information for an entire page. Pages are top-level browsing contexts and can contain multiple
/// frames.
#[derive(JSTraceable)]
// ScriptThread instances are rooted on creation, so this is okay
#[allow(unrooted_must_root)]
pub struct ScriptThread {
/// A handle to the information pertaining to page layout
browsing_context: MutNullableHeap>,
/// A list of data pertaining to loads that have not yet received a network response
incomplete_loads: DOMRefCell>,
/// A handle to the image cache thread.
image_cache_thread: ImageCacheThread,
/// A handle to the resource thread. This is an `Arc` to avoid running out of file descriptors if
/// there are many iframes.
resource_threads: ResourceThreads,
/// A handle to the bluetooth thread.
bluetooth_thread: IpcSender,
/// The port on which the script thread receives messages (load URL, exit, etc.)
port: Receiver,
/// A channel to hand out to script thread-based entities that need to be able to enqueue
/// events in the event queue.
chan: MainThreadScriptChan,
/// A handle to network event messages
custom_message_chan: IpcSender,
/// The port which receives a sender from the network
custom_message_port: Receiver,
dom_manipulation_task_source: DOMManipulationTaskSource,
user_interaction_task_source: UserInteractionTaskSource,
networking_task_source: NetworkingTaskSource,
history_traversal_task_source: HistoryTraversalTaskSource,
file_reading_task_source: FileReadingTaskSource,
/// A channel to hand out to threads that need to respond to a message from the script thread.
control_chan: IpcSender,
/// The port on which the constellation and layout threads can communicate with the
/// script thread.
control_port: Receiver,
/// For communicating load url messages to the constellation
constellation_chan: IpcSender,
/// For communicating layout messages to the constellation
layout_to_constellation_chan: IpcSender,
/// A handle to the compositor for communicating ready state messages.
compositor: IpcSender,
/// The port on which we receive messages from the image cache
image_cache_port: Receiver,
/// The channel on which the image cache can send messages to ourself.
image_cache_channel: ImageCacheChan,
/// For providing contact with the time profiler.
time_profiler_chan: time::ProfilerChan,
/// For providing contact with the memory profiler.
mem_profiler_chan: mem::ProfilerChan,
/// For providing instructions to an optional devtools server.
devtools_chan: Option>,
/// For receiving commands from an optional devtools server. Will be ignored if
/// no such server exists.
devtools_port: Receiver,
devtools_sender: IpcSender,
/// The JavaScript runtime.
js_runtime: Rc,
/// The topmost element over the mouse.
topmost_mouse_over_target: MutNullableHeap>,
/// List of pipelines that have been owned and closed by this script thread.
closed_pipelines: DOMRefCell>,
scheduler_chan: IpcSender,
timer_event_chan: Sender,
timer_event_port: Receiver,
content_process_shutdown_chan: IpcSender<()>,
panic_chan: IpcSender,
}
/// In the event of thread panic, all data on the stack runs its destructor. However, there
/// are no reachable, owning pointers to the DOM memory, so it never gets freed by default
/// when the script thread fails. The ScriptMemoryFailsafe uses the destructor bomb pattern
/// to forcibly tear down the JS compartments for pages associated with the failing ScriptThread.
struct ScriptMemoryFailsafe<'a> {
owner: Option<&'a ScriptThread>,
}
impl<'a> ScriptMemoryFailsafe<'a> {
fn neuter(&mut self) {
self.owner = None;
}
fn new(owner: &'a ScriptThread) -> ScriptMemoryFailsafe<'a> {
ScriptMemoryFailsafe {
owner: Some(owner),
}
}
}
impl<'a> Drop for ScriptMemoryFailsafe<'a> {
#[allow(unrooted_must_root)]
fn drop(&mut self) {
match self.owner {
Some(owner) => {
let context = owner.browsing_context.get();
for context in context.iter() {
let window = context.active_window();
window.clear_js_runtime_for_script_deallocation();
}
}
None => (),
}
}
}
impl ScriptThreadFactory for ScriptThread {
fn create_layout_channel() -> OpaqueScriptLayoutChannel {
let (chan, port) = channel();
ScriptLayoutChan::new(chan, port)
}
fn clone_layout_channel(pair: &OpaqueScriptLayoutChannel)
-> Box {
box pair.sender() as Box
}
fn create(state: InitialScriptState,
layout_chan: &OpaqueScriptLayoutChannel,
load_data: LoadData) {
let panic_chan = state.panic_chan.clone();
let (script_chan, script_port) = channel();
let layout_chan = LayoutChan(layout_chan.sender());
let pipeline_id = state.id;
thread::spawn_named_with_send_on_panic(format!("ScriptThread {:?}", state.id),
thread_state::SCRIPT,
move || {
PipelineNamespace::install(state.pipeline_namespace_id);
let roots = RootCollection::new();
let _stack_roots_tls = StackRootTLS::new(&roots);
let id = state.id;
let parent_info = state.parent_info;
let mem_profiler_chan = state.mem_profiler_chan.clone();
let window_size = state.window_size;
let script_thread = ScriptThread::new(state,
script_port,
script_chan.clone());
SCRIPT_THREAD_ROOT.with(|root| {
*root.borrow_mut() = Some(&script_thread as *const _);
});
let mut failsafe = ScriptMemoryFailsafe::new(&script_thread);
let new_load = InProgressLoad::new(id, parent_info, layout_chan, window_size,
load_data.url.clone());
script_thread.start_page_load(new_load, load_data);
let reporter_name = format!("script-reporter-{}", id);
mem_profiler_chan.run_with_memory_reporting(|| {
script_thread.start();
let _ = script_thread.compositor.send(ScriptToCompositorMsg::Exited);
let _ = script_thread.content_process_shutdown_chan.send(());
}, reporter_name, script_chan, CommonScriptMsg::CollectReports);
// This must always be the very last operation performed before the thread completes
failsafe.neuter();
}, Some(pipeline_id), panic_chan);
}
}
pub unsafe extern "C" fn shadow_check_callback(_cx: *mut JSContext,
_object: HandleObject, _id: HandleId) -> DOMProxyShadowsResult {
// XXX implement me
DOMProxyShadowsResult::ShadowCheckFailed
}
impl ScriptThread {
pub fn page_fetch_complete(id: &PipelineId, subpage: Option<&SubpageId>, metadata: Option)
-> Option {
SCRIPT_THREAD_ROOT.with(|root| {
let script_thread = unsafe { &*root.borrow().unwrap() };
script_thread.handle_page_fetch_complete(id, subpage, metadata)
})
}
pub fn parsing_complete(id: PipelineId) {
SCRIPT_THREAD_ROOT.with(|root| {
let script_thread = unsafe { &*root.borrow().unwrap() };
script_thread.handle_parsing_complete(id);
});
}
pub fn process_event(msg: CommonScriptMsg) {
SCRIPT_THREAD_ROOT.with(|root| {
if let Some(script_thread) = *root.borrow() {
let script_thread = unsafe { &*script_thread };
script_thread.handle_msg_from_script(MainThreadScriptMsg::Common(msg));
}
});
}
// https://html.spec.whatwg.org/multipage/#await-a-stable-state
pub fn await_stable_state(task: T) {
//TODO use microtasks when they exist
SCRIPT_THREAD_ROOT.with(|root| {
if let Some(script_thread) = *root.borrow() {
let script_thread = unsafe { &*script_thread };
let _ = script_thread.chan.send(CommonScriptMsg::RunnableMsg(
ScriptThreadEventCategory::DomEvent,
box task));
}
});
}
/// Creates a new script thread.
pub fn new(state: InitialScriptState,
port: Receiver,
chan: Sender)
-> ScriptThread {
let runtime = unsafe { new_rt_and_cx() };
unsafe {
JS_SetWrapObjectCallbacks(runtime.rt(),
&WRAP_CALLBACKS);
SetWindowProxyClass(runtime.rt(), GetWindowProxyClass());
}
// Ask the router to proxy IPC messages from the devtools to us.
let (ipc_devtools_sender, ipc_devtools_receiver) = ipc::channel().unwrap();
let devtools_port = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_devtools_receiver);
let (ipc_custom_resp_chan, ipc_custom_resp_port) = ipc::channel().unwrap();
let custom_msg_port = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_custom_resp_port);
// Ask the router to proxy IPC messages from the image cache thread to us.
let (ipc_image_cache_channel, ipc_image_cache_port) = ipc::channel().unwrap();
let image_cache_port =
ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_image_cache_port);
let (timer_event_chan, timer_event_port) = channel();
// Ask the router to proxy IPC messages from the control port to us.
let control_port = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(state.control_port);
ScriptThread {
browsing_context: MutNullableHeap::new(None),
incomplete_loads: DOMRefCell::new(vec!()),
image_cache_thread: state.image_cache_thread,
image_cache_channel: ImageCacheChan(ipc_image_cache_channel),
image_cache_port: image_cache_port,
resource_threads: state.resource_threads,
bluetooth_thread: state.bluetooth_thread,
port: port,
custom_message_chan: ipc_custom_resp_chan,
custom_message_port: custom_msg_port,
chan: MainThreadScriptChan(chan.clone()),
dom_manipulation_task_source: DOMManipulationTaskSource(chan.clone()),
user_interaction_task_source: UserInteractionTaskSource(chan.clone()),
networking_task_source: NetworkingTaskSource(chan.clone()),
history_traversal_task_source: HistoryTraversalTaskSource(chan.clone()),
file_reading_task_source: FileReadingTaskSource(chan),
control_chan: state.control_chan,
control_port: control_port,
constellation_chan: state.constellation_chan,
layout_to_constellation_chan: state.layout_to_constellation_chan,
compositor: state.compositor,
time_profiler_chan: state.time_profiler_chan,
mem_profiler_chan: state.mem_profiler_chan,
panic_chan: state.panic_chan,
devtools_chan: state.devtools_chan,
devtools_port: devtools_port,
devtools_sender: ipc_devtools_sender,
js_runtime: Rc::new(runtime),
topmost_mouse_over_target: MutNullableHeap::new(Default::default()),
closed_pipelines: DOMRefCell::new(HashSet::new()),
scheduler_chan: state.scheduler_chan,
timer_event_chan: timer_event_chan,
timer_event_port: timer_event_port,
content_process_shutdown_chan: state.content_process_shutdown_chan,
}
}
// Return the root browsing context in the frame tree. Panics if it doesn't exist.
pub fn root_browsing_context(&self) -> Root {
self.browsing_context.get().unwrap()
}
fn root_browsing_context_exists(&self) -> bool {
self.browsing_context.get().is_some()
}
/// Find a child browsing context of the root context by pipeline id. Returns `None` if the
/// root context does not exist or the child context cannot be found.
fn find_child_context(&self, pipeline_id: PipelineId) -> Option> {
self.browsing_context.get().and_then(|context| context.find(pipeline_id))
}
pub fn get_cx(&self) -> *mut JSContext {
self.js_runtime.cx()
}
/// Starts the script thread. After calling this method, the script thread will loop receiving
/// messages on its port.
pub fn start(&self) {
while self.handle_msgs() {
// Go on...
}
}
/// Handle incoming control messages.
fn handle_msgs(&self) -> bool {
use self::MixedMessage::{FromConstellation, FromDevtools, FromImageCache};
use self::MixedMessage::{FromScheduler, FromScript, FromNetwork};
// Handle pending resize events.
// Gather them first to avoid a double mut borrow on self.
let mut resizes = vec!();
let context = self.browsing_context.get();
if let Some(context) = context {
for context in context.iter() {
// Only process a resize if layout is idle.
let window = context.active_window();
let resize_event = window.steal_resize_event();
match resize_event {
Some(size) => resizes.push((window.pipeline(), size)),
None => ()
}
}
}
for (id, (size, size_type)) in resizes {
self.handle_event(id, ResizeEvent(size, size_type));
}
// Store new resizes, and gather all other events.
let mut sequential = vec!();
// Receive at least one message so we don't spinloop.
let mut event = {
let sel = Select::new();
let mut script_port = sel.handle(&self.port);
let mut control_port = sel.handle(&self.control_port);
let mut timer_event_port = sel.handle(&self.timer_event_port);
let mut devtools_port = sel.handle(&self.devtools_port);
let mut image_cache_port = sel.handle(&self.image_cache_port);
let mut custom_message_port = sel.handle(&self.custom_message_port);
unsafe {
script_port.add();
control_port.add();
timer_event_port.add();
if self.devtools_chan.is_some() {
devtools_port.add();
}
image_cache_port.add();
custom_message_port.add();
}
let ret = sel.wait();
if ret == script_port.id() {
FromScript(self.port.recv().unwrap())
} else if ret == control_port.id() {
FromConstellation(self.control_port.recv().unwrap())
} else if ret == timer_event_port.id() {
FromScheduler(self.timer_event_port.recv().unwrap())
} else if ret == devtools_port.id() {
FromDevtools(self.devtools_port.recv().unwrap())
} else if ret == image_cache_port.id() {
FromImageCache(self.image_cache_port.recv().unwrap())
} else if ret == custom_message_port.id() {
FromNetwork(self.custom_message_port.recv().unwrap())
} else {
panic!("unexpected select result")
}
};
// Squash any pending resize, reflow, animation tick, and mouse-move events in the queue.
let mut mouse_move_event_index = None;
let mut animation_ticks = HashSet::new();
loop {
match event {
// This has to be handled before the ResizeMsg below,
// otherwise the page may not have been added to the
// child list yet, causing the find() to fail.
FromConstellation(ConstellationControlMsg::AttachLayout(
new_layout_info)) => {
self.profile_event(ScriptThreadEventCategory::AttachLayout, || {
self.handle_new_layout(new_layout_info);
})
}
FromConstellation(ConstellationControlMsg::Resize(id, size, size_type)) => {
self.profile_event(ScriptThreadEventCategory::Resize, || {
self.handle_resize(id, size, size_type);
})
}
FromConstellation(ConstellationControlMsg::Viewport(id, rect)) => {
self.profile_event(ScriptThreadEventCategory::SetViewport, || {
self.handle_viewport(id, rect);
})
}
FromConstellation(ConstellationControlMsg::TickAllAnimations(
pipeline_id)) => {
if !animation_ticks.contains(&pipeline_id) {
animation_ticks.insert(pipeline_id);
sequential.push(event);
}
}
FromConstellation(ConstellationControlMsg::SendEvent(
_,
MouseMoveEvent(_))) => {
match mouse_move_event_index {
None => {
mouse_move_event_index = Some(sequential.len());
sequential.push(event);
}
Some(index) => {
sequential[index] = event
}
}
}
_ => {
sequential.push(event);
}
}
// If any of our input sources has an event pending, we'll perform another iteration
// and check for more resize events. If there are no events pending, we'll move
// on and execute the sequential non-resize events we've seen.
match self.control_port.try_recv() {
Err(_) => match self.port.try_recv() {
Err(_) => match self.timer_event_port.try_recv() {
Err(_) => match self.devtools_port.try_recv() {
Err(_) => match self.image_cache_port.try_recv() {
Err(_) => match self.custom_message_port.try_recv() {
Err(_) => break,
Ok(ev) => event = FromNetwork(ev)
},
Ok(ev) => event = FromImageCache(ev),
},
Ok(ev) => event = FromDevtools(ev),
},
Ok(ev) => event = FromScheduler(ev),
},
Ok(ev) => event = FromScript(ev),
},
Ok(ev) => event = FromConstellation(ev),
}
}
// Process the gathered events.
for msg in sequential {
let category = self.categorize_msg(&msg);
let result = self.profile_event(category, move || {
match msg {
FromConstellation(ConstellationControlMsg::ExitPipeline(id)) => {
if self.handle_exit_pipeline_msg(id) {
return Some(false)
}
},
FromConstellation(inner_msg) => self.handle_msg_from_constellation(inner_msg),
FromScript(inner_msg) => self.handle_msg_from_script(inner_msg),
FromNetwork(inner_msg) => self.handle_msg_from_network(inner_msg),
FromScheduler(inner_msg) => self.handle_timer_event(inner_msg),
FromDevtools(inner_msg) => self.handle_msg_from_devtools(inner_msg),
FromImageCache(inner_msg) => self.handle_msg_from_image_cache(inner_msg),
}
None
});
if let Some(retval) = result {
return retval
}
}
// Issue batched reflows on any pages that require it (e.g. if images loaded)
// TODO(gw): In the future we could probably batch other types of reflows
// into this loop too, but for now it's only images.
let context = self.browsing_context.get();
if let Some(context) = context {
for context in context.iter() {
let window = context.active_window();
let pending_reflows = window.get_pending_reflow_count();
if pending_reflows > 0 {
window.reflow(ReflowGoal::ForDisplay,
ReflowQueryType::NoQuery,
ReflowReason::ImageLoaded);
} else {
// Reflow currently happens when explicitly invoked by code that
// knows the document could have been modified. This should really
// be driven by the compositor on an as-needed basis instead, to
// minimize unnecessary work.
window.reflow(ReflowGoal::ForDisplay,
ReflowQueryType::NoQuery,
ReflowReason::MissingExplicitReflow);
}
}
}
true
}
fn categorize_msg(&self, msg: &MixedMessage) -> ScriptThreadEventCategory {
match *msg {
MixedMessage::FromConstellation(ref inner_msg) => {
match *inner_msg {
ConstellationControlMsg::SendEvent(_, _) =>
ScriptThreadEventCategory::DomEvent,
_ => ScriptThreadEventCategory::ConstellationMsg
}
},
MixedMessage::FromDevtools(_) => ScriptThreadEventCategory::DevtoolsMsg,
MixedMessage::FromImageCache(_) => ScriptThreadEventCategory::ImageCacheMsg,
MixedMessage::FromScript(ref inner_msg) => {
match *inner_msg {
MainThreadScriptMsg::Common(CommonScriptMsg::RunnableMsg(ref category, _)) =>
*category,
_ => ScriptThreadEventCategory::ScriptEvent
}
},
MixedMessage::FromScheduler(_) => ScriptThreadEventCategory::TimerEvent,
MixedMessage::FromNetwork(_) => ScriptThreadEventCategory::NetworkEvent
}
}
fn profile_event(&self, category: ScriptThreadEventCategory, f: F) -> R
where F: FnOnce() -> R {
if opts::get().profile_script_events {
let profiler_cat = match category {
ScriptThreadEventCategory::AttachLayout => ProfilerCategory::ScriptAttachLayout,
ScriptThreadEventCategory::ConstellationMsg => ProfilerCategory::ScriptConstellationMsg,
ScriptThreadEventCategory::DevtoolsMsg => ProfilerCategory::ScriptDevtoolsMsg,
ScriptThreadEventCategory::DocumentEvent => ProfilerCategory::ScriptDocumentEvent,
ScriptThreadEventCategory::DomEvent => ProfilerCategory::ScriptDomEvent,
ScriptThreadEventCategory::FileRead => ProfilerCategory::ScriptFileRead,
ScriptThreadEventCategory::FormPlannedNavigation => ProfilerCategory::ScriptPlannedNavigation,
ScriptThreadEventCategory::ImageCacheMsg => ProfilerCategory::ScriptImageCacheMsg,
ScriptThreadEventCategory::InputEvent => ProfilerCategory::ScriptInputEvent,
ScriptThreadEventCategory::NetworkEvent => ProfilerCategory::ScriptNetworkEvent,
ScriptThreadEventCategory::Resize => ProfilerCategory::ScriptResize,
ScriptThreadEventCategory::ScriptEvent => ProfilerCategory::ScriptEvent,
ScriptThreadEventCategory::UpdateReplacedElement => {
ProfilerCategory::ScriptUpdateReplacedElement
}
ScriptThreadEventCategory::StylesheetLoad => ProfilerCategory::ScriptStylesheetLoad,
ScriptThreadEventCategory::SetViewport => ProfilerCategory::ScriptSetViewport,
ScriptThreadEventCategory::TimerEvent => ProfilerCategory::ScriptTimerEvent,
ScriptThreadEventCategory::WebSocketEvent => ProfilerCategory::ScriptWebSocketEvent,
ScriptThreadEventCategory::WorkerEvent => ProfilerCategory::ScriptWorkerEvent,
};
profile(profiler_cat, None, self.time_profiler_chan.clone(), f)
} else {
f()
}
}
fn handle_msg_from_constellation(&self, msg: ConstellationControlMsg) {
match msg {
ConstellationControlMsg::AttachLayout(_) =>
panic!("should have handled AttachLayout already"),
ConstellationControlMsg::Navigate(pipeline_id, subpage_id, load_data) =>
self.handle_navigate(pipeline_id, Some(subpage_id), load_data),
ConstellationControlMsg::SendEvent(id, event) =>
self.handle_event(id, event),
ConstellationControlMsg::ResizeInactive(id, new_size) =>
self.handle_resize_inactive_msg(id, new_size),
ConstellationControlMsg::Viewport(..) =>
panic!("should have handled Viewport already"),
ConstellationControlMsg::Resize(..) =>
panic!("should have handled Resize already"),
ConstellationControlMsg::ExitPipeline(..) =>
panic!("should have handled ExitPipeline already"),
ConstellationControlMsg::GetTitle(pipeline_id) =>
self.handle_get_title_msg(pipeline_id),
ConstellationControlMsg::Freeze(pipeline_id) =>
self.handle_freeze_msg(pipeline_id),
ConstellationControlMsg::Thaw(pipeline_id) =>
self.handle_thaw_msg(pipeline_id),
ConstellationControlMsg::MozBrowserEvent(parent_pipeline_id,
subpage_id,
event) =>
self.handle_mozbrowser_event_msg(parent_pipeline_id,
subpage_id,
event),
ConstellationControlMsg::UpdateSubpageId(containing_pipeline_id,
old_subpage_id,
new_subpage_id,
new_pipeline_id) =>
self.handle_update_subpage_id(containing_pipeline_id,
old_subpage_id,
new_subpage_id,
new_pipeline_id),
ConstellationControlMsg::FocusIFrame(containing_pipeline_id, subpage_id) =>
self.handle_focus_iframe_msg(containing_pipeline_id, subpage_id),
ConstellationControlMsg::WebDriverScriptCommand(pipeline_id, msg) =>
self.handle_webdriver_msg(pipeline_id, msg),
ConstellationControlMsg::TickAllAnimations(pipeline_id) =>
self.handle_tick_all_animations(pipeline_id),
ConstellationControlMsg::WebFontLoaded(pipeline_id) =>
self.handle_web_font_loaded(pipeline_id),
ConstellationControlMsg::DispatchFrameLoadEvent {
target: pipeline_id, parent: containing_id } =>
self.handle_frame_load_event(containing_id, pipeline_id),
ConstellationControlMsg::FramedContentChanged(containing_pipeline_id, subpage_id) =>
self.handle_framed_content_changed(containing_pipeline_id, subpage_id),
ConstellationControlMsg::ReportCSSError(pipeline_id, filename, line, column, msg) =>
self.handle_css_error_reporting(pipeline_id, filename, line, column, msg),
}
}
fn handle_msg_from_script(&self, msg: MainThreadScriptMsg) {
match msg {
MainThreadScriptMsg::Navigate(id, load_data) =>
self.handle_navigate(id, None, load_data),
MainThreadScriptMsg::ExitWindow(id) =>
self.handle_exit_window_msg(id),
MainThreadScriptMsg::DocumentLoadsComplete(id) =>
self.handle_loads_complete(id),
MainThreadScriptMsg::Common(CommonScriptMsg::RunnableMsg(_, runnable)) => {
// The category of the runnable is ignored by the pattern, however
// it is still respected by profiling (see categorize_msg).
if !runnable.is_cancelled() {
runnable.handler()
}
}
MainThreadScriptMsg::Common(CommonScriptMsg::RefcountCleanup(addr)) =>
LiveDOMReferences::cleanup(addr),
MainThreadScriptMsg::Common(CommonScriptMsg::CollectReports(reports_chan)) =>
self.collect_reports(reports_chan),
MainThreadScriptMsg::DOMManipulation(task) =>
task.handle_task(self),
MainThreadScriptMsg::UserInteraction(task) =>
task.handle_task(),
}
}
fn handle_timer_event(&self, timer_event: TimerEvent) {
let TimerEvent(source, id) = timer_event;
let pipeline_id = match source {
TimerSource::FromWindow(pipeline_id) => pipeline_id,
TimerSource::FromWorker => panic!("Worker timeouts must not be sent to script thread"),
};
let context = self.root_browsing_context();
let context = context.find(pipeline_id).expect("ScriptThread: received fire timer msg for a
pipeline ID not associated with this script thread. This is a bug.");
let window = context.active_window();
window.handle_fire_timer(id);
}
fn handle_msg_from_devtools(&self, msg: DevtoolScriptControlMsg) {
let context = self.root_browsing_context();
match msg {
DevtoolScriptControlMsg::EvaluateJS(id, s, reply) => {
let window = get_browsing_context(&context, id).active_window();
let global_ref = GlobalRef::Window(window.r());
devtools::handle_evaluate_js(&global_ref, s, reply)
},
DevtoolScriptControlMsg::GetRootNode(id, reply) =>
devtools::handle_get_root_node(&context, id, reply),
DevtoolScriptControlMsg::GetDocumentElement(id, reply) =>
devtools::handle_get_document_element(&context, id, reply),
DevtoolScriptControlMsg::GetChildren(id, node_id, reply) =>
devtools::handle_get_children(&context, id, node_id, reply),
DevtoolScriptControlMsg::GetLayout(id, node_id, reply) =>
devtools::handle_get_layout(&context, id, node_id, reply),
DevtoolScriptControlMsg::GetCachedMessages(pipeline_id, message_types, reply) =>
devtools::handle_get_cached_messages(pipeline_id, message_types, reply),
DevtoolScriptControlMsg::ModifyAttribute(id, node_id, modifications) =>
devtools::handle_modify_attribute(&context, id, node_id, modifications),
DevtoolScriptControlMsg::WantsLiveNotifications(id, to_send) => {
let window = get_browsing_context(&context, id).active_window();
let global_ref = GlobalRef::Window(window.r());
devtools::handle_wants_live_notifications(&global_ref, to_send)
},
DevtoolScriptControlMsg::SetTimelineMarkers(_pipeline_id, marker_types, reply) =>
devtools::handle_set_timeline_markers(&context, marker_types, reply),
DevtoolScriptControlMsg::DropTimelineMarkers(_pipeline_id, marker_types) =>
devtools::handle_drop_timeline_markers(&context, marker_types),
DevtoolScriptControlMsg::RequestAnimationFrame(pipeline_id, name) =>
devtools::handle_request_animation_frame(&context, pipeline_id, name),
}
}
fn handle_msg_from_image_cache(&self, msg: ImageCacheResult) {
msg.responder.unwrap().respond(msg.image_response);
}
fn handle_msg_from_network(&self, msg: IpcSender>) {
// We may detect controlling service workers here
// We send None as default
let _ = msg.send(None);
}
fn handle_webdriver_msg(&self, pipeline_id: PipelineId, msg: WebDriverScriptCommand) {
let context = self.root_browsing_context();
match msg {
WebDriverScriptCommand::ExecuteScript(script, reply) =>
webdriver_handlers::handle_execute_script(&context, pipeline_id, script, reply),
WebDriverScriptCommand::FindElementCSS(selector, reply) =>
webdriver_handlers::handle_find_element_css(&context, pipeline_id, selector, reply),
WebDriverScriptCommand::FindElementsCSS(selector, reply) =>
webdriver_handlers::handle_find_elements_css(&context, pipeline_id, selector, reply),
WebDriverScriptCommand::FocusElement(element_id, reply) =>
webdriver_handlers::handle_focus_element(&context, pipeline_id, element_id, reply),
WebDriverScriptCommand::GetActiveElement(reply) =>
webdriver_handlers::handle_get_active_element(&context, pipeline_id, reply),
WebDriverScriptCommand::GetElementTagName(node_id, reply) =>
webdriver_handlers::handle_get_name(&context, pipeline_id, node_id, reply),
WebDriverScriptCommand::GetElementAttribute(node_id, name, reply) =>
webdriver_handlers::handle_get_attribute(&context, pipeline_id, node_id, name, reply),
WebDriverScriptCommand::GetElementCSS(node_id, name, reply) =>
webdriver_handlers::handle_get_css(&context, pipeline_id, node_id, name, reply),
WebDriverScriptCommand::GetElementRect(node_id, reply) =>
webdriver_handlers::handle_get_rect(&context, pipeline_id, node_id, reply),
WebDriverScriptCommand::GetElementText(node_id, reply) =>
webdriver_handlers::handle_get_text(&context, pipeline_id, node_id, reply),
WebDriverScriptCommand::GetFrameId(frame_id, reply) =>
webdriver_handlers::handle_get_frame_id(&context, pipeline_id, frame_id, reply),
WebDriverScriptCommand::GetUrl(reply) =>
webdriver_handlers::handle_get_url(&context, pipeline_id, reply),
WebDriverScriptCommand::IsEnabled(element_id, reply) =>
webdriver_handlers::handle_is_enabled(&context, pipeline_id, element_id, reply),
WebDriverScriptCommand::IsSelected(element_id, reply) =>
webdriver_handlers::handle_is_selected(&context, pipeline_id, element_id, reply),
WebDriverScriptCommand::GetTitle(reply) =>
webdriver_handlers::handle_get_title(&context, pipeline_id, reply),
WebDriverScriptCommand::ExecuteAsyncScript(script, reply) =>
webdriver_handlers::handle_execute_async_script(&context, pipeline_id, script, reply),
}
}
fn handle_resize(&self, id: PipelineId, size: WindowSizeData, size_type: WindowSizeType) {
if let Some(ref context) = self.find_child_context(id) {
let window = context.active_window();
window.set_resize_event(size, size_type);
return;
}
let mut loads = self.incomplete_loads.borrow_mut();
if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
load.window_size = Some(size);
return;
}
panic!("resize sent to nonexistent pipeline");
}
fn handle_viewport(&self, id: PipelineId, rect: Rect) {
let context = self.browsing_context.get();
if let Some(context) = context {
if let Some(inner_context) = context.find(id) {
let window = inner_context.active_window();
if window.set_page_clip_rect_with_new_viewport(rect) {
let context = get_browsing_context(&context, id);
self.rebuild_and_force_reflow(&context, ReflowReason::Viewport);
}
return;
}
}
let mut loads = self.incomplete_loads.borrow_mut();
if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
load.clip_rect = Some(rect);
return;
}
panic!("Page rect message sent to nonexistent pipeline");
}
fn handle_new_layout(&self, new_layout_info: NewLayoutInfo) {
let NewLayoutInfo {
containing_pipeline_id,
new_pipeline_id,
subpage_id,
load_data,
paint_chan,
panic_chan,
pipeline_port,
layout_shutdown_chan,
content_process_shutdown_chan,
} = new_layout_info;
let layout_pair = ScriptThread::create_layout_channel();
let layout_chan = LayoutChan(*ScriptThread::clone_layout_channel(
&layout_pair).downcast::>().unwrap());
let layout_creation_info = NewLayoutThreadInfo {
id: new_pipeline_id,
url: load_data.url.clone(),
is_parent: false,
layout_pair: layout_pair,
pipeline_port: pipeline_port,
constellation_chan: self.layout_to_constellation_chan.clone(),
panic_chan: panic_chan,
paint_chan: paint_chan,
script_chan: self.control_chan.clone(),
image_cache_thread: self.image_cache_thread.clone(),
layout_shutdown_chan: layout_shutdown_chan,
content_process_shutdown_chan: content_process_shutdown_chan,
};
let context = self.root_browsing_context();
let parent_context = context.find(containing_pipeline_id).expect("ScriptThread: received a layout
whose parent has a PipelineId which does not correspond to a pipeline in the script
thread's browsing context tree. This is a bug.");
let parent_window = parent_context.active_window();
// Tell layout to actually spawn the thread.
parent_window.layout_chan()
.0
.send(layout_interface::Msg::CreateLayoutThread(layout_creation_info))
.unwrap();
// Kick off the fetch for the new resource.
let new_load = InProgressLoad::new(new_pipeline_id, Some((containing_pipeline_id, subpage_id)),
layout_chan, parent_window.window_size(),
load_data.url.clone());
self.start_page_load(new_load, load_data);
}
fn handle_loads_complete(&self, pipeline: PipelineId) {
let context = get_browsing_context(&self.root_browsing_context(), pipeline);
let doc = context.active_document();
let doc = doc.r();
if doc.loader().is_blocked() {
return;
}
doc.mut_loader().inhibit_events();
// https://html.spec.whatwg.org/multipage/#the-end step 7
let handler = box DocumentProgressHandler::new(Trusted::new(doc));
self.dom_manipulation_task_source.queue(DOMManipulationTask::DocumentProgress(handler)).unwrap();
self.constellation_chan.send(ConstellationMsg::LoadComplete(pipeline)).unwrap();
}
fn collect_reports(&self, reports_chan: ReportsChan) {
let mut urls = vec![];
let mut dom_tree_size = 0;
let mut reports = vec![];
if let Some(root_context) = self.browsing_context.get() {
for it_context in root_context.iter() {
let current_url = it_context.active_document().url().to_string();
for child in it_context.active_document().upcast::().traverse_preorder() {
dom_tree_size += heap_size_of_self_and_children(&*child);
}
let window = it_context.active_window();
dom_tree_size += heap_size_of_self_and_children(&*window);
reports.push(Report {
path: path![format!("url({})", current_url), "dom-tree"],
kind: ReportKind::ExplicitJemallocHeapSize,
size: dom_tree_size,
});
urls.push(current_url);
}
}
let path_seg = format!("url({})", urls.join(", "));
reports.extend(get_reports(self.get_cx(), path_seg));
reports_chan.send(reports);
}
/// Handles freeze message
fn handle_freeze_msg(&self, id: PipelineId) {
if let Some(root_context) = self.browsing_context.get() {
if let Some(ref inner_context) = root_context.find(id) {
let window = inner_context.active_window();
window.freeze();
return;
}
}
let mut loads = self.incomplete_loads.borrow_mut();
if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
load.is_frozen = true;
return;
}
panic!("freeze sent to nonexistent pipeline");
}
/// Handles thaw message
fn handle_thaw_msg(&self, id: PipelineId) {
if let Some(inner_context) = self.root_browsing_context().find(id) {
let needed_reflow = inner_context.set_reflow_status(false);
if needed_reflow {
self.rebuild_and_force_reflow(&inner_context, ReflowReason::CachedPageNeededReflow);
}
let window = inner_context.active_window();
window.thaw();
return;
}
let mut loads = self.incomplete_loads.borrow_mut();
if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
load.is_frozen = false;
return;
}
panic!("thaw sent to nonexistent pipeline");
}
fn handle_focus_iframe_msg(&self,
parent_pipeline_id: PipelineId,
subpage_id: SubpageId) {
let borrowed_context = self.root_browsing_context();
let context = borrowed_context.find(parent_pipeline_id).unwrap();
let doc = context.active_document();
let frame_element = doc.find_iframe(subpage_id);
if let Some(ref frame_element) = frame_element {
doc.begin_focus_transaction();
doc.request_focus(frame_element.upcast());
doc.commit_focus_transaction(FocusType::Parent);
}
}
fn handle_framed_content_changed(&self,
parent_pipeline_id: PipelineId,
subpage_id: SubpageId) {
let root_context = self.root_browsing_context();
let context = root_context.find(parent_pipeline_id).unwrap();
let doc = context.active_document();
let frame_element = doc.find_iframe(subpage_id);
if let Some(ref frame_element) = frame_element {
frame_element.upcast::().dirty(NodeDamage::OtherNodeDamage);
let window = context.active_window();
window.reflow(ReflowGoal::ForDisplay,
ReflowQueryType::NoQuery,
ReflowReason::FramedContentChanged);
}
}
/// Handles a mozbrowser event, for example see:
/// https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadstart
fn handle_mozbrowser_event_msg(&self,
parent_pipeline_id: PipelineId,
subpage_id: SubpageId,
event: MozBrowserEvent) {
let borrowed_context = self.root_browsing_context();
let frame_element = borrowed_context.find(parent_pipeline_id).and_then(|context| {
let doc = context.active_document();
doc.find_iframe(subpage_id)
});
if let Some(ref frame_element) = frame_element {
frame_element.dispatch_mozbrowser_event(event);
}
}
fn handle_update_subpage_id(&self,
containing_pipeline_id: PipelineId,
old_subpage_id: SubpageId,
new_subpage_id: SubpageId,
new_pipeline_id: PipelineId) {
let borrowed_context = self.root_browsing_context();
let frame_element = borrowed_context.find(containing_pipeline_id).and_then(|context| {
let doc = context.active_document();
doc.find_iframe(old_subpage_id)
});
frame_element.unwrap().update_subpage_id(new_subpage_id, new_pipeline_id);
}
/// Window was resized, but this script was not active, so don't reflow yet
fn handle_resize_inactive_msg(&self, id: PipelineId, new_size: WindowSizeData) {
let context = self.root_browsing_context();
let context = context.find(id).expect("Received resize message for PipelineId not associated
with a browsing context in the browsing context tree. This is a bug.");
let window = context.active_window();
window.set_window_size(new_size);
context.set_reflow_status(true);
}
/// We have gotten a window.close from script, which we pass on to the compositor.
/// We do not shut down the script thread now, because the compositor will ask the
/// constellation to shut down the pipeline, which will clean everything up
/// normally. If we do exit, we will tear down the DOM nodes, possibly at a point
/// where layout is still accessing them.
fn handle_exit_window_msg(&self, _: PipelineId) {
debug!("script thread handling exit window msg");
// TODO(tkuehn): currently there is only one window,
// so this can afford to be naive and just shut down the
// compositor. In the future it'll need to be smarter.
self.compositor.send(ScriptToCompositorMsg::Exit).unwrap();
}
/// We have received notification that the response associated with a load has completed.
/// Kick off the document and frame tree creation process using the result.
fn handle_page_fetch_complete(&self, id: &PipelineId, subpage: Option<&SubpageId>,
metadata: Option) -> Option {
let idx = self.incomplete_loads.borrow().iter().position(|load| {
load.pipeline_id == *id && load.parent_info.as_ref().map(|info| &info.1) == subpage
});
// The matching in progress load structure may not exist if
// the pipeline exited before the page load completed.
match idx {
Some(idx) => {
let load = self.incomplete_loads.borrow_mut().remove(idx);
metadata.map(|meta| self.load(meta, load))
}
None => {
assert!(self.closed_pipelines.borrow().contains(id));
None
}
}
}
/// Handles a request for the window title.
fn handle_get_title_msg(&self, pipeline_id: PipelineId) {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
document.send_title_to_compositor();
}
/// Handles a request to exit the script thread and shut down layout.
/// Returns true if the script thread should shut down and false otherwise.
fn handle_exit_pipeline_msg(&self, id: PipelineId) -> bool {
self.closed_pipelines.borrow_mut().insert(id);
// Check if the exit message is for an in progress load.
let idx = self.incomplete_loads.borrow().iter().position(|load| {
load.pipeline_id == id
});
if let Some(idx) = idx {
let load = self.incomplete_loads.borrow_mut().remove(idx);
// Tell the layout thread to begin shutting down, and wait until it
// processed this message.
let (response_chan, response_port) = channel();
let LayoutChan(chan) = load.layout_chan;
if chan.send(layout_interface::Msg::PrepareToExit(response_chan)).is_ok() {
debug!("shutting down layout for page {:?}", id);
response_port.recv().unwrap();
chan.send(layout_interface::Msg::ExitNow).ok();
}
let has_pending_loads = self.incomplete_loads.borrow().len() > 0;
let has_root_context = self.root_browsing_context_exists();
// Exit if no pending loads and no root context
return !has_pending_loads && !has_root_context;
}
// If root is being exited, shut down all contexts
let context = self.root_browsing_context();
let window = context.active_window();
if window.pipeline() == id {
debug!("shutting down layout for root context {:?}", id);
shut_down_layout(&context);
return true
}
// otherwise find just the matching context and exit all sub-contexts
if let Some(ref mut child_context) = context.remove(id) {
shut_down_layout(&child_context);
}
false
}
/// Handles when layout thread finishes all animation in one tick
fn handle_tick_all_animations(&self, id: PipelineId) {
let context = get_browsing_context(&self.root_browsing_context(), id);
let document = context.active_document();
document.run_the_animation_frame_callbacks();
}
/// Handles a Web font being loaded. Does nothing if the page no longer exists.
fn handle_web_font_loaded(&self, pipeline_id: PipelineId) {
if let Some(context) = self.find_child_context(pipeline_id) {
self.rebuild_and_force_reflow(&context, ReflowReason::WebFontLoaded);
}
}
/// Notify the containing document of a child frame that has completed loading.
fn handle_frame_load_event(&self, containing_pipeline: PipelineId, id: PipelineId) {
let context = get_browsing_context(&self.root_browsing_context(), containing_pipeline);
let document = context.active_document();
if let Some(iframe) = document.find_iframe_by_pipeline(id) {
iframe.iframe_load_event_steps(id);
}
}
/// The entry point to document loading. Defines bindings, sets up the window and document
/// objects, parses HTML and CSS, and kicks off initial layout.
fn load(&self, metadata: Metadata, incomplete: InProgressLoad) -> ParserRoot {
let final_url = metadata.final_url.clone();
{
// send the final url to the layout thread.
let LayoutChan(ref chan) = incomplete.layout_chan;
chan.send(layout_interface::Msg::SetFinalUrl(final_url.clone())).unwrap();
// update the pipeline url
self.constellation_chan
.send(ConstellationMsg::SetFinalUrl(incomplete.pipeline_id, final_url.clone()))
.unwrap();
}
debug!("ScriptThread: loading {} on pipeline {:?}", incomplete.url, incomplete.pipeline_id);
let frame_element = incomplete.parent_info.and_then(|(parent_id, subpage_id)| {
// The root context may not exist yet, if the parent of this frame
// exists in a different script thread.
let root_context = self.browsing_context.get();
// In the case a parent id exists but the matching context
// cannot be found, this means the context exists in a different
// script thread (due to origin) so it shouldn't be returned.
// TODO: window.parent will continue to return self in that
// case, which is wrong. We should be returning an object that
// denies access to most properties (per
// https://github.com/servo/servo/issues/3939#issuecomment-62287025).
root_context.and_then(|root_context| {
root_context.find(parent_id).and_then(|context| {
let doc = context.active_document();
doc.find_iframe(subpage_id)
})
})
});
let MainThreadScriptChan(ref sender) = self.chan;
let DOMManipulationTaskSource(ref dom_sender) = self.dom_manipulation_task_source;
let UserInteractionTaskSource(ref user_sender) = self.user_interaction_task_source;
let NetworkingTaskSource(ref network_sender) = self.networking_task_source;
let HistoryTraversalTaskSource(ref history_sender) = self.history_traversal_task_source;
let FileReadingTaskSource(ref file_sender) = self.file_reading_task_source;
let (ipc_timer_event_chan, ipc_timer_event_port) = ipc::channel().unwrap();
ROUTER.route_ipc_receiver_to_mpsc_sender(ipc_timer_event_port,
self.timer_event_chan.clone());
// Create the window and document objects.
let window = Window::new(self.js_runtime.clone(),
MainThreadScriptChan(sender.clone()),
DOMManipulationTaskSource(dom_sender.clone()),
UserInteractionTaskSource(user_sender.clone()),
NetworkingTaskSource(network_sender.clone()),
HistoryTraversalTaskSource(history_sender.clone()),
FileReadingTaskSource(file_sender.clone()),
self.image_cache_channel.clone(),
self.custom_message_chan.clone(),
self.compositor.clone(),
self.image_cache_thread.clone(),
self.resource_threads.clone(),
self.bluetooth_thread.clone(),
self.mem_profiler_chan.clone(),
self.time_profiler_chan.clone(),
self.devtools_chan.clone(),
self.constellation_chan.clone(),
self.control_chan.clone(),
self.scheduler_chan.clone(),
self.panic_chan.clone(),
ipc_timer_event_chan,
incomplete.layout_chan,
incomplete.pipeline_id,
incomplete.parent_info,
incomplete.window_size);
let frame_element = frame_element.r().map(Castable::upcast);
enum ContextToRemove {
Root,
Child(PipelineId),
None,
}
struct AutoContextRemover<'a> {
context: ContextToRemove,
script_thread: &'a ScriptThread,
neutered: bool,
}
impl<'a> AutoContextRemover<'a> {
fn new(script_thread: &'a ScriptThread, context: ContextToRemove) -> AutoContextRemover<'a> {
AutoContextRemover {
context: context,
script_thread: script_thread,
neutered: false,
}
}
fn neuter(&mut self) {
self.neutered = true;
}
}
impl<'a> Drop for AutoContextRemover<'a> {
fn drop(&mut self) {
if !self.neutered {
match self.context {
ContextToRemove::Root => {
self.script_thread.browsing_context.set(None)
},
ContextToRemove::Child(id) => {
self.script_thread.root_browsing_context().remove(id).unwrap();
},
ContextToRemove::None => {},
}
}
}
}
let mut using_new_context = true;
let (browsing_context, context_to_remove) = if !self.root_browsing_context_exists() {
// Create a new context tree entry. This will become the root context.
let new_context = BrowsingContext::new(&window, frame_element, incomplete.pipeline_id);
// We have a new root frame tree.
self.browsing_context.set(Some(&new_context));
(new_context, ContextToRemove::Root)
} else if let Some((parent, _)) = incomplete.parent_info {
// Create a new context tree entry. This will be a child context.
let new_context = BrowsingContext::new(&window, frame_element, incomplete.pipeline_id);
let root_context = self.root_browsing_context();
// TODO(gw): This find will fail when we are sharing script threads
// between cross origin iframes in the same TLD.
let parent_context = root_context.find(parent)
.expect("received load for child context with missing parent");
parent_context.push_child_context(&*new_context);
(new_context, ContextToRemove::Child(incomplete.pipeline_id))
} else {
using_new_context = false;
(self.root_browsing_context(), ContextToRemove::None)
};
window.init_browsing_context(&browsing_context);
let mut context_remover = AutoContextRemover::new(self, context_to_remove);
let last_modified = metadata.headers.as_ref().and_then(|headers| {
headers.get().map(|&LastModified(HttpDate(ref tm))| dom_last_modified(tm))
});
let content_type = metadata.content_type.as_ref().and_then(|&ContentType(ref mimetype)| {
match *mimetype {
Mime(TopLevel::Application, SubLevel::Xml, _) |
Mime(TopLevel::Application, SubLevel::Ext(_), _) |
Mime(TopLevel::Text, SubLevel::Xml, _) |
Mime(TopLevel::Text, SubLevel::Plain, _) => Some(DOMString::from(mimetype.to_string())),
_ => None,
}
});
let loader = DocumentLoader::new_with_thread(Arc::new(self.resource_threads.sender()),
Some(browsing_context.pipeline()),
Some(incomplete.url.clone()));
let is_html_document = match metadata.content_type {
Some(ContentType(Mime(TopLevel::Application, SubLevel::Xml, _))) |
Some(ContentType(Mime(TopLevel::Text, SubLevel::Xml, _))) =>
IsHTMLDocument::NonHTMLDocument,
_ => IsHTMLDocument::HTMLDocument,
};
let document = Document::new(window.r(),
Some(&browsing_context),
Some(final_url.clone()),
is_html_document,
content_type,
last_modified,
DocumentSource::FromParser,
loader);
if using_new_context {
browsing_context.init(&document);
} else {
browsing_context.push_history(&document);
}
document.set_ready_state(DocumentReadyState::Loading);
self.constellation_chan
.send(ConstellationMsg::ActivateDocument(incomplete.pipeline_id))
.unwrap();
// Notify devtools that a new script global exists.
self.notify_devtools(document.Title(), final_url.clone(), (browsing_context.pipeline(), None));
let is_javascript = incomplete.url.scheme() == "javascript";
let parse_input = if is_javascript {
use url::percent_encoding::percent_decode;
// Turn javascript: URL into JS code to eval, according to the steps in
// https://html.spec.whatwg.org/multipage/#javascript-protocol
// This slice of the URL’s serialization is equivalent to (5.) to (7.):
// Start with the scheme data of the parsed URL;
// append question mark and query component, if any;
// append number sign and fragment component if any.
let encoded = &incomplete.url[Position::BeforePath..];
// Percent-decode (8.) and UTF-8 decode (9.)
let script_source = percent_decode(encoded.as_bytes()).decode_utf8_lossy();
// Script source is ready to be evaluated (11.)
unsafe {
let mut jsval = RootedValue::new(self.get_cx(), UndefinedValue());
window.evaluate_js_on_global_with_result(&script_source, jsval.handle_mut());
let strval = DOMString::from_jsval(self.get_cx(),
jsval.handle(),
StringificationBehavior::Empty);
strval.unwrap_or(DOMString::new())
}
} else {
DOMString::new()
};
document.set_https_state(metadata.https_state);
let is_xml = match metadata.content_type {
Some(ContentType(Mime(TopLevel::Application, SubLevel::Ext(ref sub_level), _)))
if sub_level.ends_with("+xml") => true,
Some(ContentType(Mime(TopLevel::Application, SubLevel::Xml, _))) |
Some(ContentType(Mime(TopLevel::Text, SubLevel::Xml, _))) => true,
_ => false,
};
if is_xml {
parse_xml(document.r(),
parse_input,
final_url,
xml::ParseContext::Owner(Some(incomplete.pipeline_id)));
} else {
parse_html(document.r(),
parse_input,
final_url,
ParseContext::Owner(Some(incomplete.pipeline_id)));
}
if incomplete.is_frozen {
window.freeze();
}
context_remover.neuter();
document.get_current_parser().unwrap()
}
fn notify_devtools(&self, title: DOMString, url: Url, ids: (PipelineId, Option)) {
if let Some(ref chan) = self.devtools_chan {
let page_info = DevtoolsPageInfo {
title: String::from(title),
url: url,
};
chan.send(ScriptToDevtoolsControlMsg::NewGlobal(
ids,
self.devtools_sender.clone(),
page_info)).unwrap();
}
}
fn scroll_fragment_point(&self, pipeline_id: PipelineId, element: &Element) {
// FIXME(#8275, pcwalton): This is pretty bogus when multiple layers are involved.
// Really what needs to happen is that this needs to go through layout to ask which
// layer the element belongs to, and have it send the scroll message to the
// compositor.
let rect = element.upcast::().bounding_content_box();
// In order to align with element edges, we snap to unscaled pixel boundaries, since the
// paint thread currently does the same for drawing elements. This is important for pages
// that require pixel perfect scroll positioning for proper display (like Acid2). Since we
// don't have the device pixel ratio here, this might not be accurate, but should work as
// long as the ratio is a whole number. Once #8275 is fixed this should actually take into
// account the real device pixel ratio.
let point = Point2D::new(rect.origin.x.to_nearest_px() as f32,
rect.origin.y.to_nearest_px() as f32);
self.compositor.send(ScriptToCompositorMsg::ScrollFragmentPoint(
pipeline_id, LayerId::null(), point, false)).unwrap();
}
/// Reflows non-incrementally, rebuilding the entire layout tree in the process.
fn rebuild_and_force_reflow(&self, context: &BrowsingContext, reason: ReflowReason) {
let document = context.active_document();
document.dirty_all_nodes();
let window = window_from_node(document.r());
window.reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, reason);
}
/// This is the main entry point for receiving and dispatching DOM events.
///
/// TODO: Actually perform DOM event dispatch.
fn handle_event(&self, pipeline_id: PipelineId, event: CompositorEvent) {
// DOM events can only be handled if there's a root browsing context.
if !self.root_browsing_context_exists() {
return;
}
match event {
ResizeEvent(new_size, size_type) => {
self.handle_resize_event(pipeline_id, new_size, size_type);
}
MouseButtonEvent(event_type, button, point) => {
self.handle_mouse_event(pipeline_id, event_type, button, point);
}
MouseMoveEvent(point) => {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
// Get the previous target temporarily
let prev_mouse_over_target = self.topmost_mouse_over_target.get();
document.handle_mouse_move_event(self.js_runtime.rt(), point,
&self.topmost_mouse_over_target);
// Short-circuit if nothing changed
if self.topmost_mouse_over_target.get() == prev_mouse_over_target {
return;
}
let mut state_already_changed = false;
// Notify Constellation about the topmost anchor mouse over target.
if let Some(target) = self.topmost_mouse_over_target.get() {
if let Some(anchor) = target.upcast::()
.inclusive_ancestors()
.filter_map(Root::downcast::)
.next() {
let status = anchor.upcast::()
.get_attribute(&ns!(), &atom!("href"))
.and_then(|href| {
let value = href.value();
let url = document.url();
url.join(&value).map(|url| url.to_string()).ok()
});
let event = ConstellationMsg::NodeStatus(status);
self.constellation_chan.send(event).unwrap();
state_already_changed = true;
}
}
// We might have to reset the anchor state
if !state_already_changed {
if let Some(target) = prev_mouse_over_target {
if let Some(_) = target.upcast::()
.inclusive_ancestors()
.filter_map(Root::downcast::)
.next() {
let event = ConstellationMsg::NodeStatus(None);
self.constellation_chan.send(event).unwrap();
}
}
}
}
TouchEvent(event_type, identifier, point) => {
let handled = self.handle_touch_event(pipeline_id, event_type, identifier, point);
match event_type {
TouchEventType::Down => {
if handled {
// TODO: Wait to see if preventDefault is called on the first touchmove event.
self.compositor
.send(ScriptToCompositorMsg::TouchEventProcessed(
EventResult::DefaultAllowed)).unwrap();
} else {
self.compositor
.send(ScriptToCompositorMsg::TouchEventProcessed(
EventResult::DefaultPrevented)).unwrap();
}
}
_ => {
// TODO: Calling preventDefault on a touchup event should prevent clicks.
}
}
}
TouchpadPressureEvent(point, pressure, phase) => {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
document.r().handle_touchpad_pressure_event(self.js_runtime.rt(), point, pressure, phase);
}
KeyEvent(key, state, modifiers) => {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
document.dispatch_key_event(key, state, modifiers, &self.compositor);
}
}
}
fn handle_mouse_event(&self,
pipeline_id: PipelineId,
mouse_event_type: MouseEventType,
button: MouseButton,
point: Point2D) {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
document.handle_mouse_event(self.js_runtime.rt(), button, point, mouse_event_type);
}
fn handle_touch_event(&self,
pipeline_id: PipelineId,
event_type: TouchEventType,
identifier: TouchId,
point: Point2D)
-> bool {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
document.handle_touch_event(self.js_runtime.rt(), event_type, identifier, point)
}
/// https://html.spec.whatwg.org/multipage/#navigating-across-documents
/// The entry point for content to notify that a new load has been requested
/// for the given pipeline (specifically the "navigate" algorithm).
fn handle_navigate(&self, pipeline_id: PipelineId, subpage_id: Option, load_data: LoadData) {
// Step 8.
{
let nurl = &load_data.url;
if let Some(fragment) = nurl.fragment() {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let document = context.active_document();
let document = document.r();
let url = document.url();
if &url[..Position::AfterQuery] == &nurl[..Position::AfterQuery] &&
load_data.method == Method::Get {
match document.find_fragment_node(fragment) {
Some(ref node) => {
self.scroll_fragment_point(pipeline_id, node.r());
}
None => {}
}
return;
}
}
}
match subpage_id {
Some(subpage_id) => {
let root_context = self.root_browsing_context();
let iframe = root_context.find(pipeline_id).and_then(|context| {
let doc = context.active_document();
doc.find_iframe(subpage_id)
});
if let Some(iframe) = iframe.r() {
iframe.navigate_or_reload_child_browsing_context(Some(load_data));
}
}
None => {
self.constellation_chan
.send(ConstellationMsg::LoadUrl(pipeline_id, load_data))
.unwrap();
}
}
}
fn handle_resize_event(&self, pipeline_id: PipelineId, new_size: WindowSizeData, size_type: WindowSizeType) {
let context = get_browsing_context(&self.root_browsing_context(), pipeline_id);
let window = context.active_window();
window.set_window_size(new_size);
window.force_reflow(ReflowGoal::ForDisplay,
ReflowQueryType::NoQuery,
ReflowReason::WindowResize);
let document = context.active_document();
let fragment_node = window.steal_fragment_name()
.and_then(|name| document.find_fragment_node(&*name));
match fragment_node {
Some(ref node) => self.scroll_fragment_point(pipeline_id, node.r()),
None => {}
}
// http://dev.w3.org/csswg/cssom-view/#resizing-viewports
// https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#event-type-resize
if size_type == WindowSizeType::Resize {
let uievent = UIEvent::new(window.r(),
DOMString::from("resize"), EventBubbles::DoesNotBubble,
EventCancelable::NotCancelable, Some(window.r()),
0i32);
uievent.upcast::().fire(window.upcast());
}
}
/// Initiate a non-blocking fetch for a specified resource. Stores the InProgressLoad
/// argument until a notification is received that the fetch is complete.
fn start_page_load(&self, incomplete: InProgressLoad, mut load_data: LoadData) {
let id = incomplete.pipeline_id.clone();
let subpage = incomplete.parent_info.clone().map(|p| p.1);
let context = Arc::new(Mutex::new(ParserContext::new(id, subpage, load_data.url.clone())));
let (action_sender, action_receiver) = ipc::channel().unwrap();
let listener = NetworkListener {
context: context,
script_chan: self.chan.clone(),
};
ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
listener.notify(message.to().unwrap());
});
let response_target = AsyncResponseTarget {
sender: action_sender,
};
if load_data.url.scheme() == "javascript" {
load_data.url = Url::parse("about:blank").unwrap();
}
self.resource_threads.send(CoreResourceMsg::Load(NetLoadData {
context: LoadContext::Browsing,
url: load_data.url,
method: load_data.method,
headers: Headers::new(),
preserved_headers: load_data.headers,
data: load_data.data,
cors: None,
pipeline_id: Some(id),
credentials_flag: true,
referrer_policy: load_data.referrer_policy,
referrer_url: load_data.referrer_url,
source: RequestSource::Window(self.custom_message_chan.clone())
}, LoadConsumer::Listener(response_target), None)).unwrap();
self.incomplete_loads.borrow_mut().push(incomplete);
}
fn handle_parsing_complete(&self, id: PipelineId) {
let parent_context = self.root_browsing_context();
let context = match parent_context.find(id) {
Some(context) => context,
None => return,
};
let document = context.active_document();
let final_url = document.url();
// https://html.spec.whatwg.org/multipage/#the-end step 1
document.set_ready_state(DocumentReadyState::Interactive);
// TODO: Execute step 2 here.
// Kick off the initial reflow of the page.
debug!("kicking off initial reflow of {:?}", final_url);
document.disarm_reflow_timeout();
document.upcast::().dirty(NodeDamage::OtherNodeDamage);
let window = window_from_node(document.r());
window.reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, ReflowReason::FirstLoad);
// No more reflow required
context.set_reflow_status(false);
// https://html.spec.whatwg.org/multipage/#the-end steps 3-4.
document.process_deferred_scripts();
window.set_fragment_name(final_url.fragment().map(str::to_owned));
}
fn handle_css_error_reporting(&self, pipeline_id: PipelineId, filename: String,
line: usize, column: usize, msg: String) {
let parent_context = self.root_browsing_context();
let context = match parent_context.find(pipeline_id) {
Some(context) => context,
None => return,
};
let document = context.active_document();
let css_error = CSSError {
filename: filename,
line: line,
column: column,
msg: msg
};
document.report_css_error(css_error.clone());
let window = context.active_window();
if window.live_devtools_updates() {
if let Some(ref chan) = self.devtools_chan {
chan.send(ScriptToDevtoolsControlMsg::ReportCSSError(
pipeline_id,
css_error)).unwrap();
}
}
}
}
impl Drop for ScriptThread {
fn drop(&mut self) {
SCRIPT_THREAD_ROOT.with(|root| {
*root.borrow_mut() = None;
});
}
}
/// Shuts down layout for the given browsing context tree.
fn shut_down_layout(context_tree: &BrowsingContext) {
let mut channels = vec!();
for context in context_tree.iter() {
// Tell the layout thread to begin shutting down, and wait until it
// processed this message.
let (response_chan, response_port) = channel();
let window = context.active_window();
let LayoutChan(chan) = window.layout_chan().clone();
if chan.send(layout_interface::Msg::PrepareToExit(response_chan)).is_ok() {
channels.push(chan);
response_port.recv().unwrap();
}
}
// Drop our references to the JSContext and DOM objects.
for context in context_tree.iter() {
let window = context.active_window();
window.clear_js_runtime();
// Sever the connection between the global and the DOM tree
context.clear_session_history();
}
// Destroy the layout thread. If there were node leaks, layout will now crash safely.
for chan in channels {
chan.send(layout_interface::Msg::ExitNow).ok();
}
}
pub fn get_browsing_context(context: &BrowsingContext,
pipeline_id: PipelineId)
-> Root {
context.find(pipeline_id).expect("ScriptThread: received an event \
message for a layout channel that is not associated with this script thread.\
This is a bug.")
}
fn dom_last_modified(tm: &Tm) -> String {
tm.to_local().strftime("%m/%d/%Y %H:%M:%S").unwrap().to_string()
}