/* 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 https://mozilla.org/MPL/2.0/. */ // Work around https://github.com/rust-lang/rust/issues/62132 #![recursion_limit = "128"] //! The layout thread. Performs layout on the DOM, builds display lists and sends them to be //! painted. use lazy_static::lazy_static; use log::{debug, error, warn}; use app_units::Au; use crossbeam_channel::{select, Receiver, Sender}; use embedder_traits::resources::{self, Resource}; use euclid::{default::Size2D as UntypedSize2D, Point2D, Rect, Scale, Size2D}; use fnv::FnvHashMap; use fxhash::FxHashMap; use gfx::font_cache_thread::FontCacheThread; use gfx::font_context; use gfx_traits::{node_id_from_scroll_id, Epoch}; use ipc_channel::ipc::{self, IpcReceiver, IpcSender}; use ipc_channel::router::ROUTER; use layout::context::LayoutContext; use layout::display_list::{DisplayList, WebRenderImageInfo}; use layout::dom::DOMLayoutData; use layout::layout_debug; use layout::query::{ process_content_box_request, process_content_boxes_request, process_resolved_font_style_query, LayoutRPCImpl, LayoutThreadData, }; use layout::query::{process_element_inner_text_query, process_node_geometry_request}; use layout::query::{process_node_scroll_area_request, process_node_scroll_id_request}; use layout::query::{ process_offset_parent_query, process_resolved_style_request, process_text_index_request, }; use layout::traversal::RecalcStyle; use layout::{BoxTree, FragmentTree}; use layout_traits::LayoutThreadFactory; use malloc_size_of::{MallocSizeOf, MallocSizeOfOps}; use metrics::{PaintTimeMetrics, ProfilerMetadataFactory, ProgressiveWebMetric}; use msg::constellation_msg::{ BackgroundHangMonitor, BackgroundHangMonitorRegister, BrowsingContextId, HangAnnotation, LayoutHangAnnotation, MonitoredComponentId, MonitoredComponentType, PipelineId, TopLevelBrowsingContextId, }; use net_traits::image_cache::{ImageCache, UsePlaceholder}; use parking_lot::RwLock; use profile_traits::mem::{self as profile_mem, Report, ReportKind, ReportsChan}; use profile_traits::path; use profile_traits::time::{self as profile_time, profile, TimerMetadata}; use profile_traits::time::{TimerMetadataFrameType, TimerMetadataReflowType}; use script::layout_dom::{ServoLayoutDocument, ServoLayoutElement, ServoLayoutNode}; use script_layout_interface::message::{LayoutThreadInit, Msg, NodesFromPointQueryType}; use script_layout_interface::message::{QueryMsg, ReflowComplete, ReflowGoal, ScriptReflow}; use script_layout_interface::rpc::TextIndexResponse; use script_layout_interface::rpc::{LayoutRPC, OffsetParentResponse}; use script_traits::{ ConstellationControlMsg, DrawAPaintImageResult, IFrameSizeMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg, PaintWorkletError, Painter, ScrollState, UntrustedNodeAddress, WebrenderIpcSender, WindowSizeData, WindowSizeType, }; use servo_arc::Arc as ServoArc; use servo_atoms::Atom; use servo_config::opts::{self, DebugOptions}; use servo_url::{ImmutableOrigin, ServoUrl}; use std::cell::{Cell, RefCell}; use std::collections::HashMap; use std::ops::{Deref, DerefMut}; use std::process; use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering}; use std::sync::{Arc, Mutex, MutexGuard}; use std::thread; use std::time::Duration; use style::animation::DocumentAnimationSet; use style::context::{ QuirksMode, RegisteredSpeculativePainter, RegisteredSpeculativePainters, SharedStyleContext, }; use style::dom::{TElement, TNode}; use style::driver; use style::error_reporting::RustLogReporter; use style::global_style_data::{GLOBAL_STYLE_DATA, STYLE_THREAD_POOL}; use style::media_queries::{Device, MediaList, MediaType}; use style::properties::PropertyId; use style::selector_parser::SnapshotMap; use style::shared_lock::{SharedRwLock, SharedRwLockReadGuard, StylesheetGuards}; use style::stylesheets::{ DocumentStyleSheet, Origin, Stylesheet, StylesheetInDocument, UserAgentStylesheets, }; use style::stylist::Stylist; use style::thread_state::{self, ThreadState}; use style::traversal::DomTraversal; use style::traversal_flags::TraversalFlags; use style_traits::CSSPixel; use style_traits::DevicePixel; use style_traits::SpeculativePainter; use webrender_api::{units, HitTestFlags}; /// Information needed by the layout thread. pub struct LayoutThread { /// The ID of the pipeline that we belong to. id: PipelineId, /// The ID of the top-level browsing context that we belong to. top_level_browsing_context_id: TopLevelBrowsingContextId, /// The URL of the pipeline that we belong to. url: ServoUrl, /// Performs CSS selector matching and style resolution. stylist: Stylist, /// Is the current reflow of an iframe, as opposed to a root window? is_iframe: bool, /// The port on which we receive messages from the script thread. port: Receiver, /// The port on which we receive messages from the constellation. pipeline_port: Receiver, /// The port on which we receive messages from the font cache thread. font_cache_receiver: Receiver<()>, /// The channel on which the font cache can send messages to us. font_cache_sender: IpcSender<()>, /// A means of communication with the background hang monitor. background_hang_monitor: Box, /// The channel on which messages can be sent to the constellation. constellation_chan: IpcSender, /// The channel on which messages can be sent to the script thread. script_chan: IpcSender, /// The channel on which messages can be sent to the time profiler. time_profiler_chan: profile_time::ProfilerChan, /// The channel on which messages can be sent to the memory profiler. mem_profiler_chan: profile_mem::ProfilerChan, /// Reference to the script thread image cache. image_cache: Arc, /// Public interface to the font cache thread. font_cache_thread: FontCacheThread, /// Is this the first reflow in this LayoutThread? first_reflow: Cell, /// Starts at zero, and increased by one every time a layout completes. /// This can be used to easily check for invalid stale data. generation: Cell, /// The number of Web fonts that have been requested but not yet loaded. outstanding_web_fonts: Arc, /// The box tree. box_tree: RefCell>>, /// The fragment tree. fragment_tree: RefCell>>, /// A counter for epoch messages epoch: Cell, /// The size of the viewport. This may be different from the size of the screen due to viewport /// constraints. viewport_size: UntypedSize2D, /// A mutex to allow for fast, read-only RPC of layout's internal data /// structures, while still letting the LayoutThread modify them. /// /// All the other elements of this struct are read-only. rw_data: Arc>, webrender_image_cache: Arc>>, /// The executors for paint worklets. registered_painters: RegisteredPaintersImpl, /// Webrender interface. webrender_api: WebrenderIpcSender, /// Paint time metrics. paint_time_metrics: PaintTimeMetrics, /// The sizes of all iframes encountered during the last layout operation. last_iframe_sizes: RefCell>>, /// Flag that indicates if LayoutThread is busy handling a request. busy: Arc, /// Debug options, copied from configuration to this `LayoutThread` in order /// to avoid having to constantly access the thread-safe global options. debug: DebugOptions, } impl LayoutThreadFactory for LayoutThread { type Message = Msg; /// Spawns a new layout thread. fn create( id: PipelineId, top_level_browsing_context_id: TopLevelBrowsingContextId, url: ServoUrl, is_iframe: bool, chan: (Sender, Receiver), pipeline_port: IpcReceiver, background_hang_monitor_register: Box, constellation_chan: IpcSender, script_chan: IpcSender, image_cache: Arc, font_cache_thread: FontCacheThread, time_profiler_chan: profile_time::ProfilerChan, mem_profiler_chan: profile_mem::ProfilerChan, webrender_api_sender: WebrenderIpcSender, paint_time_metrics: PaintTimeMetrics, busy: Arc, window_size: WindowSizeData, ) { thread::Builder::new() .name(format!("Layout{}", id)) .spawn(move || { thread_state::initialize(ThreadState::LAYOUT); // In order to get accurate crash reports, we install the top-level bc id. TopLevelBrowsingContextId::install(top_level_browsing_context_id); { // Ensures layout thread is destroyed before we send shutdown message let sender = chan.0; let background_hang_monitor = background_hang_monitor_register .register_component( MonitoredComponentId(id, MonitoredComponentType::Layout), Duration::from_millis(1000), Duration::from_millis(5000), None, ); let layout = LayoutThread::new( id, top_level_browsing_context_id, url, is_iframe, chan.1, pipeline_port, background_hang_monitor, constellation_chan, script_chan, image_cache, font_cache_thread, time_profiler_chan, mem_profiler_chan.clone(), webrender_api_sender, paint_time_metrics, busy, window_size, ); let reporter_name = format!("layout-reporter-{}", id); mem_profiler_chan.run_with_memory_reporting( || { layout.start(); }, reporter_name, sender, Msg::CollectReports, ); } }) .expect("Thread spawning failed"); } } struct ScriptReflowResult { script_reflow: ScriptReflow, result: RefCell>, } impl Deref for ScriptReflowResult { type Target = ScriptReflow; fn deref(&self) -> &ScriptReflow { &self.script_reflow } } impl DerefMut for ScriptReflowResult { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.script_reflow } } impl ScriptReflowResult { fn new(script_reflow: ScriptReflow) -> ScriptReflowResult { ScriptReflowResult { script_reflow: script_reflow, result: RefCell::new(Some(Default::default())), } } } impl Drop for ScriptReflowResult { fn drop(&mut self) { self.script_reflow .script_join_chan .send(self.result.borrow_mut().take().unwrap()) .unwrap(); } } /// The `LayoutThread` `rw_data` lock must remain locked until the first reflow, /// as RPC calls don't make sense until then. Use this in combination with /// `LayoutThread::lock_rw_data` and `LayoutThread::return_rw_data`. pub enum RWGuard<'a> { /// If the lock was previously held, from when the thread started. Held(MutexGuard<'a, LayoutThreadData>), /// If the lock was just used, and has been returned since there has been /// a reflow already. Used(MutexGuard<'a, LayoutThreadData>), } impl<'a> Deref for RWGuard<'a> { type Target = LayoutThreadData; fn deref(&self) -> &LayoutThreadData { match *self { RWGuard::Held(ref x) => &**x, RWGuard::Used(ref x) => &**x, } } } impl<'a> DerefMut for RWGuard<'a> { fn deref_mut(&mut self) -> &mut LayoutThreadData { match *self { RWGuard::Held(ref mut x) => &mut **x, RWGuard::Used(ref mut x) => &mut **x, } } } struct RwData<'a, 'b: 'a> { rw_data: &'b Arc>, possibly_locked_rw_data: &'a mut Option>, } impl<'a, 'b: 'a> RwData<'a, 'b> { /// If no reflow has happened yet, this will just return the lock in /// `possibly_locked_rw_data`. Otherwise, it will acquire the `rw_data` lock. /// /// If you do not wish RPCs to remain blocked, just drop the `RWGuard` /// returned from this function. If you _do_ wish for them to remain blocked, /// use `block`. fn lock(&mut self) -> RWGuard<'b> { match self.possibly_locked_rw_data.take() { None => RWGuard::Used(self.rw_data.lock().unwrap()), Some(x) => RWGuard::Held(x), } } } fn add_font_face_rules( stylesheet: &Stylesheet, guard: &SharedRwLockReadGuard, device: &Device, font_cache_thread: &FontCacheThread, font_cache_sender: &IpcSender<()>, outstanding_web_fonts_counter: &Arc, load_webfonts_synchronously: bool, ) { if load_webfonts_synchronously { let (sender, receiver) = ipc::channel().unwrap(); stylesheet.effective_font_face_rules(&device, guard, |rule| { if let Some(font_face) = rule.font_face() { let effective_sources = font_face.effective_sources(); font_cache_thread.add_web_font( font_face.family().clone(), effective_sources, sender.clone(), ); receiver.recv().unwrap(); } }) } else { stylesheet.effective_font_face_rules(&device, guard, |rule| { if let Some(font_face) = rule.font_face() { let effective_sources = font_face.effective_sources(); outstanding_web_fonts_counter.fetch_add(1, Ordering::SeqCst); font_cache_thread.add_web_font( font_face.family().clone(), effective_sources, (*font_cache_sender).clone(), ); } }) } } impl LayoutThread { /// Creates a new `LayoutThread` structure. fn new( id: PipelineId, top_level_browsing_context_id: TopLevelBrowsingContextId, url: ServoUrl, is_iframe: bool, port: Receiver, pipeline_port: IpcReceiver, background_hang_monitor: Box, constellation_chan: IpcSender, script_chan: IpcSender, image_cache: Arc, font_cache_thread: FontCacheThread, time_profiler_chan: profile_time::ProfilerChan, mem_profiler_chan: profile_mem::ProfilerChan, webrender_api_sender: WebrenderIpcSender, paint_time_metrics: PaintTimeMetrics, busy: Arc, window_size: WindowSizeData, ) -> LayoutThread { // Let webrender know about this pipeline by sending an empty display list. webrender_api_sender.send_initial_transaction(id.to_webrender()); // The device pixel ratio is incorrect (it does not have the hidpi value), // but it will be set correctly when the initial reflow takes place. let device = Device::new( MediaType::screen(), QuirksMode::NoQuirks, window_size.initial_viewport, window_size.device_pixel_ratio, ); // Proxy IPC messages from the pipeline to the layout thread. let pipeline_receiver = ROUTER.route_ipc_receiver_to_new_crossbeam_receiver(pipeline_port); // Ask the router to proxy IPC messages from the font cache thread to the layout thread. let (ipc_font_cache_sender, ipc_font_cache_receiver) = ipc::channel().unwrap(); let font_cache_receiver = ROUTER.route_ipc_receiver_to_new_crossbeam_receiver(ipc_font_cache_receiver); LayoutThread { id, top_level_browsing_context_id: top_level_browsing_context_id, url, is_iframe, port, pipeline_port: pipeline_receiver, constellation_chan, script_chan: script_chan.clone(), background_hang_monitor, time_profiler_chan, mem_profiler_chan, registered_painters: RegisteredPaintersImpl(Default::default()), image_cache, font_cache_thread, first_reflow: Cell::new(true), font_cache_receiver, font_cache_sender: ipc_font_cache_sender, generation: Cell::new(0), outstanding_web_fonts: Arc::new(AtomicUsize::new(0)), box_tree: Default::default(), fragment_tree: Default::default(), // Epoch starts at 1 because of the initial display list for epoch 0 that we send to WR epoch: Cell::new(Epoch(1)), viewport_size: Size2D::new(Au(0), Au(0)), webrender_api: webrender_api_sender, stylist: Stylist::new(device, QuirksMode::NoQuirks), rw_data: Arc::new(Mutex::new(LayoutThreadData { display_list: None, content_box_response: None, content_boxes_response: Vec::new(), client_rect_response: Rect::zero(), scroll_id_response: None, scroll_area_response: Rect::zero(), resolved_style_response: String::new(), resolved_font_style_response: None, offset_parent_response: OffsetParentResponse::empty(), scroll_offsets: HashMap::new(), text_index_response: TextIndexResponse(None), nodes_from_point_response: vec![], element_inner_text_response: String::new(), inner_window_dimensions_response: None, })), webrender_image_cache: Default::default(), paint_time_metrics: paint_time_metrics, last_iframe_sizes: Default::default(), busy, debug: opts::get().debug.clone(), } } /// Starts listening on the port. fn start(mut self) { let rw_data = self.rw_data.clone(); let mut possibly_locked_rw_data = Some(rw_data.lock().unwrap()); let mut rw_data = RwData { rw_data: &rw_data, possibly_locked_rw_data: &mut possibly_locked_rw_data, }; while self.handle_request(&mut rw_data) { // Loop indefinitely. } } // Create a layout context for use in building display lists, hit testing, &c. fn build_layout_context<'a>( &'a self, guards: StylesheetGuards<'a>, snapshot_map: &'a SnapshotMap, origin: ImmutableOrigin, animation_timeline_value: f64, animations: &DocumentAnimationSet, stylesheets_changed: bool, use_rayon: bool, ) -> LayoutContext<'a> { let traversal_flags = match stylesheets_changed { true => TraversalFlags::ForCSSRuleChanges, false => TraversalFlags::empty(), }; LayoutContext { id: self.id, origin, style_context: SharedStyleContext { stylist: &self.stylist, options: GLOBAL_STYLE_DATA.options.clone(), guards, visited_styles_enabled: false, animations: animations.clone(), registered_speculative_painters: &self.registered_painters, current_time_for_animations: animation_timeline_value, traversal_flags, snapshot_map: snapshot_map, }, image_cache: self.image_cache.clone(), font_cache_thread: Mutex::new(self.font_cache_thread.clone()), webrender_image_cache: self.webrender_image_cache.clone(), pending_images: Mutex::new(vec![]), use_rayon, } } fn notify_activity_to_hang_monitor(&self, request: &Msg) { let hang_annotation = match request { Msg::AddStylesheet(..) => LayoutHangAnnotation::AddStylesheet, Msg::RemoveStylesheet(..) => LayoutHangAnnotation::RemoveStylesheet, Msg::SetQuirksMode(..) => LayoutHangAnnotation::SetQuirksMode, Msg::Reflow(..) => LayoutHangAnnotation::Reflow, Msg::GetRPC(..) => LayoutHangAnnotation::GetRPC, Msg::CollectReports(..) => LayoutHangAnnotation::CollectReports, Msg::PrepareToExit(..) => LayoutHangAnnotation::PrepareToExit, Msg::ExitNow => LayoutHangAnnotation::ExitNow, Msg::GetCurrentEpoch(..) => LayoutHangAnnotation::GetCurrentEpoch, Msg::GetWebFontLoadState(..) => LayoutHangAnnotation::GetWebFontLoadState, Msg::CreateLayoutThread(..) => LayoutHangAnnotation::CreateLayoutThread, Msg::SetFinalUrl(..) => LayoutHangAnnotation::SetFinalUrl, Msg::SetScrollStates(..) => LayoutHangAnnotation::SetScrollStates, Msg::RegisterPaint(..) => LayoutHangAnnotation::RegisterPaint, Msg::SetNavigationStart(..) => LayoutHangAnnotation::SetNavigationStart, }; self.background_hang_monitor .notify_activity(HangAnnotation::Layout(hang_annotation)); } /// Receives and dispatches messages from the script and constellation threads fn handle_request<'a, 'b>(&mut self, possibly_locked_rw_data: &mut RwData<'a, 'b>) -> bool { enum Request { FromPipeline(LayoutControlMsg), FromScript(Msg), FromFontCache, } // Notify the background-hang-monitor we are waiting for an event. self.background_hang_monitor.notify_wait(); let request = select! { recv(self.pipeline_port) -> msg => Request::FromPipeline(msg.unwrap()), recv(self.port) -> msg => Request::FromScript(msg.unwrap()), recv(self.font_cache_receiver) -> msg => { msg.unwrap(); Request::FromFontCache } }; self.busy.store(true, Ordering::Relaxed); let result = match request { Request::FromPipeline(LayoutControlMsg::SetScrollStates(new_scroll_states)) => self .handle_request_helper( Msg::SetScrollStates(new_scroll_states), possibly_locked_rw_data, ), Request::FromPipeline(LayoutControlMsg::GetCurrentEpoch(sender)) => { self.handle_request_helper(Msg::GetCurrentEpoch(sender), possibly_locked_rw_data) }, Request::FromPipeline(LayoutControlMsg::GetWebFontLoadState(sender)) => self .handle_request_helper(Msg::GetWebFontLoadState(sender), possibly_locked_rw_data), Request::FromPipeline(LayoutControlMsg::ExitNow) => { self.handle_request_helper(Msg::ExitNow, possibly_locked_rw_data) }, Request::FromPipeline(LayoutControlMsg::PaintMetric(epoch, paint_time)) => { self.paint_time_metrics.maybe_set_metric(epoch, paint_time); true }, Request::FromScript(msg) => self.handle_request_helper(msg, possibly_locked_rw_data), Request::FromFontCache => { let _rw_data = possibly_locked_rw_data.lock(); self.outstanding_web_fonts.fetch_sub(1, Ordering::SeqCst); font_context::invalidate_font_caches(); self.script_chan .send(ConstellationControlMsg::WebFontLoaded(self.id)) .unwrap(); true }, }; self.busy.store(false, Ordering::Relaxed); result } /// Receives and dispatches messages from other threads. fn handle_request_helper<'a, 'b>( &mut self, request: Msg, possibly_locked_rw_data: &mut RwData<'a, 'b>, ) -> bool { self.notify_activity_to_hang_monitor(&request); match request { Msg::AddStylesheet(stylesheet, before_stylesheet) => { let guard = stylesheet.shared_lock.read(); self.handle_add_stylesheet(&stylesheet, &guard); match before_stylesheet { Some(insertion_point) => self.stylist.insert_stylesheet_before( DocumentStyleSheet(stylesheet.clone()), DocumentStyleSheet(insertion_point), &guard, ), None => self .stylist .append_stylesheet(DocumentStyleSheet(stylesheet.clone()), &guard), } }, Msg::RemoveStylesheet(stylesheet) => { let guard = stylesheet.shared_lock.read(); self.stylist .remove_stylesheet(DocumentStyleSheet(stylesheet.clone()), &guard); }, Msg::SetQuirksMode(mode) => self.handle_set_quirks_mode(mode), Msg::GetRPC(response_chan) => { response_chan .send(Box::new(LayoutRPCImpl(self.rw_data.clone())) as Box) .unwrap(); }, Msg::Reflow(data) => { let mut data = ScriptReflowResult::new(data); profile( profile_time::ProfilerCategory::LayoutPerform, self.profiler_metadata(), self.time_profiler_chan.clone(), || self.handle_reflow(&mut data, possibly_locked_rw_data), ); }, Msg::SetScrollStates(new_scroll_states) => { self.set_scroll_states(new_scroll_states, possibly_locked_rw_data); }, Msg::CollectReports(reports_chan) => { self.collect_reports(reports_chan, possibly_locked_rw_data); }, Msg::GetCurrentEpoch(sender) => { let _rw_data = possibly_locked_rw_data.lock(); sender.send(self.epoch.get()).unwrap(); }, Msg::GetWebFontLoadState(sender) => { let _rw_data = possibly_locked_rw_data.lock(); let outstanding_web_fonts = self.outstanding_web_fonts.load(Ordering::SeqCst); sender.send(outstanding_web_fonts != 0).unwrap(); }, Msg::CreateLayoutThread(info) => self.create_layout_thread(info), Msg::SetFinalUrl(final_url) => { self.url = final_url; }, Msg::RegisterPaint(_name, _properties, _painter) => {}, Msg::PrepareToExit(response_chan) => { self.prepare_to_exit(response_chan); return false; }, // Receiving the Exit message at this stage only happens when layout is undergoing a "force exit". Msg::ExitNow => { debug!("layout: ExitNow received"); self.exit_now(); return false; }, Msg::SetNavigationStart(time) => { self.paint_time_metrics.set_navigation_start(time); }, } true } fn collect_reports<'a, 'b>( &self, reports_chan: ReportsChan, possibly_locked_rw_data: &mut RwData<'a, 'b>, ) { let mut reports = vec![]; // Servo uses vanilla jemalloc, which doesn't have a // malloc_enclosing_size_of function. let mut ops = MallocSizeOfOps::new(servo_allocator::usable_size, None, None); // FIXME(njn): Just measuring the display tree for now. let rw_data = possibly_locked_rw_data.lock(); let display_list = rw_data.display_list.as_ref(); let formatted_url = &format!("url({})", self.url); reports.push(Report { path: path![formatted_url, "layout-thread", "display-list"], kind: ReportKind::ExplicitJemallocHeapSize, size: display_list.map_or(0, |sc| sc.size_of(&mut ops)), }); reports.push(Report { path: path![formatted_url, "layout-thread", "stylist"], kind: ReportKind::ExplicitJemallocHeapSize, size: self.stylist.size_of(&mut ops), }); reports_chan.send(reports); } fn create_layout_thread(&self, info: LayoutThreadInit) { LayoutThread::create( info.id, self.top_level_browsing_context_id, info.url.clone(), info.is_parent, info.layout_pair, info.pipeline_port, info.background_hang_monitor_register, info.constellation_chan, info.script_chan.clone(), info.image_cache.clone(), self.font_cache_thread.clone(), self.time_profiler_chan.clone(), self.mem_profiler_chan.clone(), self.webrender_api.clone(), info.paint_time_metrics, info.layout_is_busy, info.window_size, ); } /// Enters a quiescent state in which no new messages will be processed until an `ExitNow` is /// received. A pong is immediately sent on the given response channel. fn prepare_to_exit(&mut self, response_chan: Sender<()>) { response_chan.send(()).unwrap(); loop { match self.port.recv().unwrap() { Msg::ExitNow => { debug!("layout thread is exiting..."); self.exit_now(); break; }, Msg::CollectReports(_) => { // Just ignore these messages at this point. }, _ => panic!("layout: unexpected message received after `PrepareToExitMsg`"), } } } fn exit_now(&mut self) { self.background_hang_monitor.unregister(); } fn handle_add_stylesheet(&self, stylesheet: &Stylesheet, guard: &SharedRwLockReadGuard) { // Find all font-face rules and notify the font cache of them. // GWTODO: Need to handle unloading web fonts. if stylesheet.is_effective_for_device(self.stylist.device(), &guard) { add_font_face_rules( &*stylesheet, &guard, self.stylist.device(), &self.font_cache_thread, &self.font_cache_sender, &self.outstanding_web_fonts, self.debug.load_webfonts_synchronously, ); } } /// Sets quirks mode for the document, causing the quirks mode stylesheet to be used. fn handle_set_quirks_mode<'a, 'b>(&mut self, quirks_mode: QuirksMode) { self.stylist.set_quirks_mode(quirks_mode); } /// The high-level routine that performs layout threads. fn handle_reflow<'a, 'b>( &mut self, data: &mut ScriptReflowResult, possibly_locked_rw_data: &mut RwData<'a, 'b>, ) { let document = unsafe { ServoLayoutNode::::new(&data.document) }; let document = document.as_document().unwrap(); let mut rw_data = possibly_locked_rw_data.lock(); let root_element = match document.root_element() { None => { // Since we cannot compute anything, give spec-required placeholders. debug!("layout: No root node: bailing"); match data.reflow_goal { ReflowGoal::LayoutQuery(ref query_msg, _) => match query_msg { &QueryMsg::ContentBoxQuery(_) => { rw_data.content_box_response = None; }, &QueryMsg::ContentBoxesQuery(_) => { rw_data.content_boxes_response = Vec::new(); }, &QueryMsg::NodesFromPointQuery(..) => { rw_data.nodes_from_point_response = Vec::new(); }, &QueryMsg::ClientRectQuery(_) => { rw_data.client_rect_response = Rect::zero(); }, &QueryMsg::NodeScrollGeometryQuery(_) => { rw_data.scroll_area_response = Rect::zero(); }, &QueryMsg::NodeScrollIdQuery(_) => { rw_data.scroll_id_response = None; }, &QueryMsg::ResolvedStyleQuery(_, _, _) => { rw_data.resolved_style_response = String::new(); }, &QueryMsg::ResolvedFontStyleQuery(_, _, _) => { rw_data.resolved_font_style_response = None; }, &QueryMsg::OffsetParentQuery(_) => { rw_data.offset_parent_response = OffsetParentResponse::empty(); }, &QueryMsg::StyleQuery => {}, &QueryMsg::TextIndexQuery(..) => { rw_data.text_index_response = TextIndexResponse(None); }, &QueryMsg::ElementInnerTextQuery(_) => { rw_data.element_inner_text_response = String::new(); }, &QueryMsg::InnerWindowDimensionsQuery(browsing_context_id) => { rw_data.inner_window_dimensions_response = self .last_iframe_sizes .borrow() .get(&browsing_context_id) .cloned(); }, }, ReflowGoal::Full | ReflowGoal::TickAnimations | ReflowGoal::UpdateScrollNode(_) => {}, } return; }, Some(x) => x, }; let initial_viewport = data.window_size.initial_viewport; let device_pixel_ratio = data.window_size.device_pixel_ratio; let current_screen_size = Size2D::new( Au::from_f32_px(initial_viewport.width), Au::from_f32_px(initial_viewport.height), ); let origin = data.origin.clone(); // Calculate the actual viewport as per DEVICE-ADAPT ยง 6 // If the entire flow tree is invalid, then it will be reflowed anyhow. let document_shared_lock = document.style_shared_lock(); let author_guard = document_shared_lock.read(); let ua_stylesheets = &*UA_STYLESHEETS; let ua_or_user_guard = ua_stylesheets.shared_lock.read(); let guards = StylesheetGuards { author: &author_guard, ua_or_user: &ua_or_user_guard, }; let device = Device::new( MediaType::screen(), self.stylist.quirks_mode(), initial_viewport, device_pixel_ratio, ); let sheet_origins_affected_by_device_change = self.stylist.set_device(device, &guards); self.stylist .force_stylesheet_origins_dirty(sheet_origins_affected_by_device_change); self.viewport_size = current_screen_size; if self.first_reflow.get() { for stylesheet in &ua_stylesheets.user_or_user_agent_stylesheets { self.stylist .append_stylesheet(stylesheet.clone(), &ua_or_user_guard); self.handle_add_stylesheet(&stylesheet.0, &ua_or_user_guard); } if self.stylist.quirks_mode() != QuirksMode::NoQuirks { self.stylist.append_stylesheet( ua_stylesheets.quirks_mode_stylesheet.clone(), &ua_or_user_guard, ); self.handle_add_stylesheet( &ua_stylesheets.quirks_mode_stylesheet.0, &ua_or_user_guard, ); } } if data.stylesheets_changed { self.stylist .force_stylesheet_origins_dirty(Origin::Author.into()); } // Flush shadow roots stylesheets if dirty. document.flush_shadow_roots_stylesheets(&mut self.stylist, guards.author.clone()); let restyles = std::mem::take(&mut data.pending_restyles); debug!("Draining restyles: {}", restyles.len()); let mut map = SnapshotMap::new(); let elements_with_snapshot: Vec<_> = restyles .iter() .filter(|r| r.1.snapshot.is_some()) .map(|r| unsafe { ServoLayoutNode::::new(&r.0) .as_element() .unwrap() }) .collect(); for (el, restyle) in restyles { let el = unsafe { ServoLayoutNode::::new(&el) .as_element() .unwrap() }; // If we haven't styled this node yet, we don't need to track a // restyle. let mut style_data = match el.mutate_data() { Some(d) => d, None => { unsafe { el.unset_snapshot_flags() }; continue; }, }; if let Some(s) = restyle.snapshot { unsafe { el.set_has_snapshot() }; map.insert(el.as_node().opaque(), s); } // Stash the data on the element for processing by the style system. style_data.hint.insert(restyle.hint.into()); style_data.damage = restyle.damage; debug!("Noting restyle for {:?}: {:?}", el, style_data); } self.stylist.flush(&guards, Some(root_element), Some(&map)); let rayon_pool = STYLE_THREAD_POOL.lock().unwrap(); let rayon_pool = rayon_pool.pool(); let rayon_pool = rayon_pool.as_ref(); // Create a layout context for use throughout the following passes. let mut layout_context = self.build_layout_context( guards.clone(), &map, origin, data.animation_timeline_value, &data.animations, data.stylesheets_changed, rayon_pool.is_some(), ); let dirty_root = unsafe { ServoLayoutNode::::new(&data.dirty_root.unwrap()) .as_element() .unwrap() }; let traversal = RecalcStyle::new(layout_context); let token = { let shared = DomTraversal::>::shared_context(&traversal); RecalcStyle::pre_traverse(dirty_root, shared) }; if token.should_traverse() { let dirty_root: ServoLayoutNode = driver::traverse_dom(&traversal, token, rayon_pool).as_node(); let root_node = root_element.as_node(); let mut box_tree = self.box_tree.borrow_mut(); let box_tree = &mut *box_tree; let mut build_box_tree = || { if !BoxTree::update(traversal.context(), dirty_root) { *box_tree = Some(Arc::new(BoxTree::construct(traversal.context(), root_node))); } }; if let Some(pool) = rayon_pool { pool.install(build_box_tree) } else { build_box_tree() }; let viewport_size = Size2D::new( self.viewport_size.width.to_f32_px(), self.viewport_size.height.to_f32_px(), ); let run_layout = || { box_tree .as_ref() .unwrap() .layout(traversal.context(), viewport_size) }; let fragment_tree = Arc::new(if let Some(pool) = rayon_pool { pool.install(run_layout) } else { run_layout() }); *self.fragment_tree.borrow_mut() = Some(fragment_tree); } layout_context = traversal.destroy(); for element in elements_with_snapshot { unsafe { element.unset_snapshot_flags() } } if self.debug.dump_style_tree { println!( "{:?}", style::dom::ShowSubtreeDataAndPrimaryValues(root_element.as_node()) ); } if self.debug.dump_rule_tree { layout_context .style_context .stylist .rule_tree() .dump_stdout(&guards); } // GC the rule tree if some heuristics are met. layout_context.style_context.stylist.rule_tree().maybe_gc(); // Perform post-style recalculation layout passes. if let Some(root) = &*self.fragment_tree.borrow() { self.perform_post_style_recalc_layout_passes( root.clone(), &data.reflow_goal, Some(&document), &mut layout_context, ); } self.first_reflow.set(false); self.respond_to_query_if_necessary( &data.reflow_goal, &mut *rw_data, &mut layout_context, data.result.borrow_mut().as_mut().unwrap(), ); } fn respond_to_query_if_necessary( &self, reflow_goal: &ReflowGoal, rw_data: &mut LayoutThreadData, context: &mut LayoutContext, reflow_result: &mut ReflowComplete, ) { reflow_result.pending_images = std::mem::replace(&mut *context.pending_images.lock().unwrap(), vec![]); match *reflow_goal { ReflowGoal::LayoutQuery(ref querymsg, _) => match querymsg { &QueryMsg::ContentBoxQuery(node) => { rw_data.content_box_response = process_content_box_request(node, self.fragment_tree.borrow().clone()); }, &QueryMsg::ContentBoxesQuery(node) => { rw_data.content_boxes_response = process_content_boxes_request(node); }, &QueryMsg::TextIndexQuery(node, point_in_node) => { let point_in_node = Point2D::new( Au::from_f32_px(point_in_node.x), Au::from_f32_px(point_in_node.y), ); rw_data.text_index_response = process_text_index_request(node, point_in_node); }, &QueryMsg::ClientRectQuery(node) => { rw_data.client_rect_response = process_node_geometry_request(node, self.fragment_tree.borrow().clone()); }, &QueryMsg::NodeScrollGeometryQuery(node) => { rw_data.scroll_area_response = process_node_scroll_area_request(node, self.fragment_tree.borrow().clone()); }, &QueryMsg::NodeScrollIdQuery(node) => { let node = unsafe { ServoLayoutNode::::new(&node) }; rw_data.scroll_id_response = Some(process_node_scroll_id_request(self.id, node)); }, &QueryMsg::ResolvedStyleQuery(node, ref pseudo, ref property) => { let node = unsafe { ServoLayoutNode::::new(&node) }; let fragment_tree = self.fragment_tree.borrow().clone(); rw_data.resolved_style_response = process_resolved_style_request( context, node, pseudo, property, fragment_tree, ); }, &QueryMsg::ResolvedFontStyleQuery(node, ref property, ref value) => { let node = unsafe { ServoLayoutNode::::new(&node) }; rw_data.resolved_font_style_response = process_resolved_font_style_query(node, property, value); }, &QueryMsg::OffsetParentQuery(node) => { rw_data.offset_parent_response = process_offset_parent_query(node, self.fragment_tree.borrow().clone()); }, &QueryMsg::StyleQuery => {}, &QueryMsg::NodesFromPointQuery(client_point, ref reflow_goal) => { let mut flags = match reflow_goal { &NodesFromPointQueryType::Topmost => HitTestFlags::empty(), &NodesFromPointQueryType::All => HitTestFlags::FIND_ALL, }; // The point we get is not relative to the entire WebRender scene, but to this // particular pipeline, so we need to tell WebRender about that. flags.insert(HitTestFlags::POINT_RELATIVE_TO_PIPELINE_VIEWPORT); let client_point = units::WorldPoint::from_untyped(client_point); let results = self.webrender_api.hit_test( Some(self.id.to_webrender()), client_point, flags, ); rw_data.nodes_from_point_response = results.iter().map(|result| result.node).collect() }, &QueryMsg::ElementInnerTextQuery(node) => { let node = unsafe { ServoLayoutNode::::new(&node) }; rw_data.element_inner_text_response = process_element_inner_text_query(node); }, &QueryMsg::InnerWindowDimensionsQuery(_browsing_context_id) => { // TODO(jdm): port the iframe sizing code from layout2013's display // builder in order to support query iframe sizing. rw_data.inner_window_dimensions_response = None; }, }, ReflowGoal::UpdateScrollNode(scroll_state) => { self.update_scroll_node_state(&scroll_state, rw_data); }, ReflowGoal::Full | ReflowGoal::TickAnimations => {}, } } fn update_scroll_node_state(&self, state: &ScrollState, rw_data: &mut LayoutThreadData) { rw_data .scroll_offsets .insert(state.scroll_id, state.scroll_offset); let point = Point2D::new(-state.scroll_offset.x, -state.scroll_offset.y); self.webrender_api .send_scroll_node(units::LayoutPoint::from_untyped(point), state.scroll_id); } fn set_scroll_states<'a, 'b>( &mut self, new_scroll_states: Vec, possibly_locked_rw_data: &mut RwData<'a, 'b>, ) { let mut rw_data = possibly_locked_rw_data.lock(); let mut script_scroll_states = vec![]; let mut layout_scroll_states = HashMap::new(); for new_state in &new_scroll_states { let offset = new_state.scroll_offset; layout_scroll_states.insert(new_state.scroll_id, offset); if new_state.scroll_id.is_root() { script_scroll_states.push((UntrustedNodeAddress::from_id(0), offset)) } else if let Some(node_id) = node_id_from_scroll_id(new_state.scroll_id.0 as usize) { script_scroll_states.push((UntrustedNodeAddress::from_id(node_id), offset)) } } let _ = self .script_chan .send(ConstellationControlMsg::SetScrollState( self.id, script_scroll_states, )); rw_data.scroll_offsets = layout_scroll_states } fn perform_post_style_recalc_layout_passes( &self, fragment_tree: Arc, reflow_goal: &ReflowGoal, document: Option<&ServoLayoutDocument>, context: &mut LayoutContext, ) { Self::cancel_animations_for_nodes_not_in_fragment_tree( &context.style_context.animations, &fragment_tree, ); if self.debug.trace_layout { if let Some(box_tree) = &*self.box_tree.borrow() { layout_debug::begin_trace(box_tree.clone(), fragment_tree.clone()); } } if !reflow_goal.needs_display() { // Defer the paint step until the next ForDisplay. // // We need to tell the document about this so it doesn't // incorrectly suppress reflows. See #13131. document .expect("No document in a non-display reflow?") .needs_paint_from_layout(); return; } if let Some(document) = document { document.will_paint(); } let mut epoch = self.epoch.get(); epoch.next(); self.epoch.set(epoch); let viewport_size = units::LayoutSize::from_untyped(Size2D::new( self.viewport_size.width.to_f32_px(), self.viewport_size.height.to_f32_px(), )); let mut display_list = DisplayList::new( viewport_size, fragment_tree.scrollable_overflow(), self.id.to_webrender(), epoch.into(), ); // `dump_serialized_display_list` doesn't actually print anything. It sets up // the display list for printing the serialized version when `finalize()` is called. // We need to call this before adding any display items so that they are printed // during `finalize()`. if self.debug.dump_display_list { display_list.wr.dump_serialized_display_list(); } // Build the root stacking context. This turns the `FragmentTree` into a // tree of fragments in CSS painting order and also creates all // applicable spatial and clip nodes. let root_stacking_context = display_list.build_stacking_context_tree(&fragment_tree); // Build the rest of the display list which inclues all of the WebRender primitives. let (iframe_sizes, is_contentful) = display_list.build(context, &fragment_tree, &root_stacking_context); if self.debug.dump_flow_tree { fragment_tree.print(); } debug!("Layout done!"); // Observe notifications about rendered frames if needed right before // sending the display list to WebRender in order to set time related // Progressive Web Metrics. self.paint_time_metrics .maybe_observe_paint_time(self, epoch, is_contentful); self.webrender_api .send_display_list(display_list.compositor_info, display_list.wr.finalize().1); self.update_iframe_sizes(iframe_sizes); if self.debug.trace_layout { layout_debug::end_trace(self.generation.get()); } self.generation.set(self.generation.get() + 1); } /// Returns profiling information which is passed to the time profiler. fn profiler_metadata(&self) -> Option { Some(TimerMetadata { url: self.url.to_string(), iframe: if self.is_iframe { TimerMetadataFrameType::IFrame } else { TimerMetadataFrameType::RootWindow }, incremental: if self.first_reflow.get() { TimerMetadataReflowType::FirstReflow } else { TimerMetadataReflowType::Incremental }, }) } /// Cancel animations for any nodes which have been removed from fragment tree. /// TODO(mrobinson): We should look into a way of doing this during flow tree construction. /// This also doesn't yet handles nodes that have been reparented. fn cancel_animations_for_nodes_not_in_fragment_tree( animations: &DocumentAnimationSet, root: &FragmentTree, ) { // Assume all nodes have been removed until proven otherwise. let mut animations = animations.sets.write(); let mut invalid_nodes = animations.keys().cloned().collect(); root.remove_nodes_in_fragment_tree_from_set(&mut invalid_nodes); // Cancel animations for any nodes that are no longer in the fragment tree. for node in &invalid_nodes { if let Some(state) = animations.get_mut(node) { state.cancel_all_animations(); } } } /// Update the recorded iframe sizes of the contents of this layout thread and /// when these sizes changes, send a message to the constellation informing it /// of the new sizes. fn update_iframe_sizes( &self, new_iframe_sizes: FnvHashMap>, ) { let old_iframe_sizes = std::mem::replace(&mut *self.last_iframe_sizes.borrow_mut(), new_iframe_sizes); if self.last_iframe_sizes.borrow().is_empty() { return; } let size_messages: Vec<_> = self .last_iframe_sizes .borrow() .iter() .filter_map(|(browsing_context_id, size)| { match old_iframe_sizes.get(&browsing_context_id) { Some(old_size) if old_size != size => Some(IFrameSizeMsg { browsing_context_id: *browsing_context_id, size: *size, type_: WindowSizeType::Resize, }), None => Some(IFrameSizeMsg { browsing_context_id: *browsing_context_id, size: *size, type_: WindowSizeType::Initial, }), _ => None, } }) .collect(); if !size_messages.is_empty() { let msg = ConstellationMsg::IFrameSizes(size_messages); if let Err(e) = self.constellation_chan.send(msg) { warn!("Layout resize to constellation failed ({}).", e); } } } } impl ProfilerMetadataFactory for LayoutThread { fn new_metadata(&self) -> Option { self.profiler_metadata() } } fn get_ua_stylesheets() -> Result { fn parse_ua_stylesheet( shared_lock: &SharedRwLock, filename: &str, content: &[u8], ) -> Result { Ok(DocumentStyleSheet(ServoArc::new(Stylesheet::from_bytes( content, ServoUrl::parse(&format!("chrome://resources/{:?}", filename)).unwrap(), None, None, Origin::UserAgent, MediaList::empty(), shared_lock.clone(), None, None, QuirksMode::NoQuirks, )))) } let shared_lock = &GLOBAL_STYLE_DATA.shared_lock; // FIXME: presentational-hints.css should be at author origin with zero specificity. // (Does it make a difference?) let mut user_or_user_agent_stylesheets = vec![ parse_ua_stylesheet( &shared_lock, "user-agent.css", &resources::read_bytes(Resource::UserAgentCSS), )?, parse_ua_stylesheet( &shared_lock, "servo.css", &resources::read_bytes(Resource::ServoCSS), )?, parse_ua_stylesheet( &shared_lock, "presentational-hints.css", &resources::read_bytes(Resource::PresentationalHintsCSS), )?, ]; for &(ref contents, ref url) in &opts::get().user_stylesheets { user_or_user_agent_stylesheets.push(DocumentStyleSheet(ServoArc::new( Stylesheet::from_bytes( &contents, url.clone(), None, None, Origin::User, MediaList::empty(), shared_lock.clone(), None, Some(&RustLogReporter), QuirksMode::NoQuirks, ), ))); } let quirks_mode_stylesheet = parse_ua_stylesheet( &shared_lock, "quirks-mode.css", &resources::read_bytes(Resource::QuirksModeCSS), )?; Ok(UserAgentStylesheets { shared_lock: shared_lock.clone(), user_or_user_agent_stylesheets: user_or_user_agent_stylesheets, quirks_mode_stylesheet: quirks_mode_stylesheet, }) } lazy_static! { static ref UA_STYLESHEETS: UserAgentStylesheets = { match get_ua_stylesheets() { Ok(stylesheets) => stylesheets, Err(filename) => { error!("Failed to load UA stylesheet {}!", filename); process::exit(1); }, } }; } struct RegisteredPainterImpl { painter: Box, name: Atom, // FIXME: Should be a PrecomputedHashMap. properties: FxHashMap, } impl SpeculativePainter for RegisteredPainterImpl { fn speculatively_draw_a_paint_image( &self, properties: Vec<(Atom, String)>, arguments: Vec, ) { self.painter .speculatively_draw_a_paint_image(properties, arguments); } } impl RegisteredSpeculativePainter for RegisteredPainterImpl { fn properties(&self) -> &FxHashMap { &self.properties } fn name(&self) -> Atom { self.name.clone() } } impl Painter for RegisteredPainterImpl { fn draw_a_paint_image( &self, size: Size2D, device_pixel_ratio: Scale, properties: Vec<(Atom, String)>, arguments: Vec, ) -> Result { self.painter .draw_a_paint_image(size, device_pixel_ratio, properties, arguments) } } struct RegisteredPaintersImpl(FnvHashMap); impl RegisteredSpeculativePainters for RegisteredPaintersImpl { fn get(&self, name: &Atom) -> Option<&dyn RegisteredSpeculativePainter> { self.0 .get(&name) .map(|painter| painter as &dyn RegisteredSpeculativePainter) } }