Auto merge of #14971 - asajeffrey:script-track-active-documents, r=cbrewster

Constellation informs script about documents becoming inactive, active or fully active.

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This PR replaces the current freeze/thaw mechanism by messages from the constellation to script informing it about when documents become inactive, active or fully active.

This means we can now implement |Document::is_active()| which is used in |document.write|.

This PR also changes how timers work: previously they were initialized running, and were then frozen/thawed. This means there was a transitory period when timers were running even though the document was not fully active. With this PR, timers are initially suspended, and are only resumed when the document is made fully active.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14876
- [X] These changes do not require tests because it's an interal refactoring.

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11 files changed, 78 insertions, 63 deletions

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 6d268823d77..6e0ce0d47dc 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -74,7 +74,7 @@ use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_layout_interface::OpaqueStyleAndLayoutData;
 use script_layout_interface::reporter::CSSErrorReporter;
 use script_layout_interface::rpc::LayoutRPC;
-use script_traits::{TimerEventId, TimerSource, TouchpadPressurePhase};
+use script_traits::{DocumentActivity, TimerEventId, TimerSource, TouchpadPressurePhase};
 use script_traits::{UntrustedNodeAddress, WindowSizeData, WindowSizeType};
 use serde::{Deserialize, Serialize};
 use servo_atoms::Atom;
@@ -327,7 +327,7 @@ unsafe_no_jsmanaged_fields!(TrustedPromise);
 unsafe_no_jsmanaged_fields!(PropertyDeclarationBlock);
 // These three are interdependent, if you plan to put jsmanaged data
 // in one of these make sure it is propagated properly to containing structs
-unsafe_no_jsmanaged_fields!(FrameId, FrameType, WindowSizeData, WindowSizeType, PipelineId);
+unsafe_no_jsmanaged_fields!(DocumentActivity, FrameId, FrameType, WindowSizeData, WindowSizeType, PipelineId);
 unsafe_no_jsmanaged_fields!(TimerEventId, TimerSource);
 unsafe_no_jsmanaged_fields!(TimelineMarkerType);
 unsafe_no_jsmanaged_fields!(WorkerId);
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 53aa4af882d..da4d715fe21 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -108,7 +108,8 @@ use origin::Origin;
 use script_layout_interface::message::{Msg, ReflowQueryType};
 use script_runtime::{CommonScriptMsg, ScriptThreadEventCategory};
 use script_thread::{MainThreadScriptMsg, Runnable};
-use script_traits::{AnimationState, CompositorEvent, MouseButton, MouseEventType, MozBrowserEvent};
+use script_traits::{AnimationState, CompositorEvent, DocumentActivity};
+use script_traits::{MouseButton, MouseEventType, MozBrowserEvent};
 use script_traits::{ScriptMsg as ConstellationMsg, TouchpadPressurePhase};
 use script_traits::{TouchEventType, TouchId};
 use script_traits::UntrustedNodeAddress;
@@ -191,7 +192,7 @@ pub struct Document {
     last_modified: Option<String>,
     encoding: Cell<EncodingRef>,
     is_html_document: bool,
-    is_fully_active: Cell<bool>,
+    activity: Cell<DocumentActivity>,
     url: DOMRefCell<ServoUrl>,
     quirks_mode: Cell<QuirksMode>,
     /// Caches for the getElement methods
@@ -387,17 +388,33 @@ impl Document {
         self.trigger_mozbrowser_event(MozBrowserEvent::SecurityChange(https_state));
     }
 
-    // https://html.spec.whatwg.org/multipage/#fully-active
     pub fn is_fully_active(&self) -> bool {
-        self.is_fully_active.get()
-    }
-
-    pub fn fully_activate(&self) {
-        self.is_fully_active.set(true)
-    }
-
-    pub fn fully_deactivate(&self) {
-        self.is_fully_active.set(false)
+        self.activity.get() == DocumentActivity::FullyActive
+    }
+
+    pub fn is_active(&self) -> bool {
+        self.activity.get() != DocumentActivity::Inactive
+    }
+
+    pub fn set_activity(&self, activity: DocumentActivity) {
+        // This function should only be called on documents with a browsing context
+        assert!(self.browsing_context.is_some());
+        // Set the document's activity level, reflow if necessary, and suspend or resume timers.
+        if activity != self.activity.get() {
+            self.activity.set(activity);
+            if activity == DocumentActivity::FullyActive {
+                self.title_changed();
+                self.dirty_all_nodes();
+                self.window().reflow(
+                    ReflowGoal::ForDisplay,
+                    ReflowQueryType::NoQuery,
+                    ReflowReason::CachedPageNeededReflow
+                );
+                self.window().resume();
+            } else {
+                self.window().suspend();
+            }
+        }
     }
 
     pub fn origin(&self) -> &Origin {
@@ -1892,6 +1909,7 @@ impl Document {
                          is_html_document: IsHTMLDocument,
                          content_type: Option<DOMString>,
                          last_modified: Option<String>,
+                         activity: DocumentActivity,
                          source: DocumentSource,
                          doc_loader: DocumentLoader,
                          referrer: Option<String>,
@@ -1927,7 +1945,7 @@ impl Document {
             // https://dom.spec.whatwg.org/#concept-document-encoding
             encoding: Cell::new(UTF_8),
             is_html_document: is_html_document == IsHTMLDocument::HTMLDocument,
-            is_fully_active: Cell::new(false),
+            activity: Cell::new(activity),
             id_map: DOMRefCell::new(HashMap::new()),
             tag_map: DOMRefCell::new(HashMap::new()),
             tagns_map: DOMRefCell::new(HashMap::new()),
@@ -1995,6 +2013,7 @@ impl Document {
                          IsHTMLDocument::NonHTMLDocument,
                          None,
                          None,
+                         DocumentActivity::Inactive,
                          DocumentSource::NotFromParser,
                          docloader,
                          None,
@@ -2008,6 +2027,7 @@ impl Document {
                doctype: IsHTMLDocument,
                content_type: Option<DOMString>,
                last_modified: Option<String>,
+               activity: DocumentActivity,
                source: DocumentSource,
                doc_loader: DocumentLoader,
                referrer: Option<String>,
@@ -2020,6 +2040,7 @@ impl Document {
                                                                       doctype,
                                                                       content_type,
                                                                       last_modified,
+                                                                      activity,
                                                                       source,
                                                                       doc_loader,
                                                                       referrer,
@@ -2093,6 +2114,7 @@ impl Document {
                                         doctype,
                                         None,
                                         None,
+                                        DocumentActivity::Inactive,
                                         DocumentSource::NotFromParser,
                                         DocumentLoader::new(&self.loader()),
                                         None,
@@ -3249,8 +3271,7 @@ impl DocumentMethods for Document {
 
         // Step 2.
         // TODO: handle throw-on-dynamic-markup-insertion counter.
-        // FIXME: this should check for being active rather than fully active
-        if !self.is_fully_active() {
+        if !self.is_active() {
             // Step 3.
             return Ok(());
         }
diff --git a/components/script/dom/domimplementation.rs b/components/script/dom/domimplementation.rs
index 23521b94a09..45983c3292d 100644
--- a/components/script/dom/domimplementation.rs
+++ b/components/script/dom/domimplementation.rs
@@ -23,6 +23,7 @@ use dom::htmltitleelement::HTMLTitleElement;
 use dom::node::Node;
 use dom::text::Text;
 use dom::xmldocument::XMLDocument;
+use script_traits::DocumentActivity;
 
 // https://dom.spec.whatwg.org/#domimplementation
 #[dom_struct]
@@ -83,6 +84,7 @@ impl DOMImplementationMethods for DOMImplementation {
                                    IsHTMLDocument::NonHTMLDocument,
                                    Some(DOMString::from(content_type)),
                                    None,
+                                   DocumentActivity::Inactive,
                                    DocumentSource::NotFromParser,
                                    loader);
         // Step 2-3.
@@ -129,6 +131,7 @@ impl DOMImplementationMethods for DOMImplementation {
                                 IsHTMLDocument::HTMLDocument,
                                 None,
                                 None,
+                                DocumentActivity::Inactive,
                                 DocumentSource::NotFromParser,
                                 loader,
                                 None,
diff --git a/components/script/dom/domparser.rs b/components/script/dom/domparser.rs
index c14bec8b594..54132ef94a9 100644
--- a/components/script/dom/domparser.rs
+++ b/components/script/dom/domparser.rs
@@ -19,6 +19,7 @@ use dom::document::{Document, IsHTMLDocument};
 use dom::document::DocumentSource;
 use dom::servoparser::ServoParser;
 use dom::window::Window;
+use script_traits::DocumentActivity;
 
 #[dom_struct]
 pub struct DOMParser {
@@ -65,6 +66,7 @@ impl DOMParserMethods for DOMParser {
                                              IsHTMLDocument::HTMLDocument,
                                              Some(content_type),
                                              None,
+                                             DocumentActivity::Inactive,
                                              DocumentSource::FromParser,
                                              loader,
                                              None,
@@ -82,6 +84,7 @@ impl DOMParserMethods for DOMParser {
                                              IsHTMLDocument::NonHTMLDocument,
                                              Some(content_type),
                                              None,
+                                             DocumentActivity::Inactive,
                                              DocumentSource::NotFromParser,
                                              loader,
                                              None,
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 71547c860bc..6931fca1822 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -65,6 +65,7 @@ use ref_slice::ref_slice;
 use script_layout_interface::{HTMLCanvasData, OpaqueStyleAndLayoutData, SVGSVGData};
 use script_layout_interface::{LayoutElementType, LayoutNodeType, TrustedNodeAddress};
 use script_layout_interface::message::Msg;
+use script_traits::DocumentActivity;
 use script_traits::UntrustedNodeAddress;
 use selectors::matching::{MatchingReason, matches};
 use selectors::parser::SelectorList;
@@ -1730,7 +1731,8 @@ impl Node {
                                              // https://github.com/whatwg/dom/issues/378
                                              document.origin().alias(),
                                              is_html_doc, None,
-                                             None, DocumentSource::NotFromParser, loader,
+                                             None, DocumentActivity::Inactive,
+                                             DocumentSource::NotFromParser, loader,
                                              None, None);
                 Root::upcast::<Node>(document)
             },
diff --git a/components/script/dom/servoparser/mod.rs b/components/script/dom/servoparser/mod.rs
index aaa36a2098b..d64704b2368 100644
--- a/components/script/dom/servoparser/mod.rs
+++ b/components/script/dom/servoparser/mod.rs
@@ -35,6 +35,7 @@ use network_listener::PreInvoke;
 use profile_traits::time::{TimerMetadata, TimerMetadataFrameType};
 use profile_traits::time::{TimerMetadataReflowType, ProfilerCategory, profile};
 use script_thread::ScriptThread;
+use script_traits::DocumentActivity;
 use servo_config::resource_files::read_resource_file;
 use servo_url::ServoUrl;
 use std::cell::Cell;
@@ -107,6 +108,7 @@ impl ServoParser {
                                      IsHTMLDocument::HTMLDocument,
                                      None,
                                      None,
+                                     DocumentActivity::Inactive,
                                      DocumentSource::FromParser,
                                      loader,
                                      None,
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index cb9d5abdf07..37c62543526 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -1488,21 +1488,17 @@ impl Window {
         None
     }
 
-    pub fn freeze(&self) {
+    pub fn suspend(&self) {
         self.upcast::<GlobalScope>().suspend();
         // A hint to the JS runtime that now would be a good time to
         // GC any unreachable objects generated by user script,
         // or unattached DOM nodes. Attached DOM nodes can't be GCd yet,
-        // as the document might be thawed later.
+        // as the document might be reactivated later.
         self.Gc();
     }
 
-    pub fn thaw(&self) {
+    pub fn resume(&self) {
         self.upcast::<GlobalScope>().resume();
-
-        // Push the document title to the compositor since we are
-        // activating this document due to a navigation.
-        self.Document().title_changed();
     }
 
     pub fn need_emit_timeline_marker(&self, timeline_type: TimelineMarkerType) -> bool {
diff --git a/components/script/dom/xmldocument.rs b/components/script/dom/xmldocument.rs
index 87c639742f6..593749c4499 100644
--- a/components/script/dom/xmldocument.rs
+++ b/components/script/dom/xmldocument.rs
@@ -17,6 +17,7 @@ use dom::node::Node;
 use dom::window::Window;
 use js::jsapi::{JSContext, JSObject};
 use origin::Origin;
+use script_traits::DocumentActivity;
 use servo_url::ServoUrl;
 
 // https://dom.spec.whatwg.org/#xmldocument
@@ -33,6 +34,7 @@ impl XMLDocument {
                      is_html_document: IsHTMLDocument,
                      content_type: Option<DOMString>,
                      last_modified: Option<String>,
+                     activity: DocumentActivity,
                      source: DocumentSource,
                      doc_loader: DocumentLoader) -> XMLDocument {
         XMLDocument {
@@ -43,6 +45,7 @@ impl XMLDocument {
                                               is_html_document,
                                               content_type,
                                               last_modified,
+                                              activity,
                                               source,
                                               doc_loader,
                                               None,
@@ -57,6 +60,7 @@ impl XMLDocument {
                doctype: IsHTMLDocument,
                content_type: Option<DOMString>,
                last_modified: Option<String>,
+               activity: DocumentActivity,
                source: DocumentSource,
                doc_loader: DocumentLoader)
                -> Root<XMLDocument> {
@@ -68,6 +72,7 @@ impl XMLDocument {
                                            doctype,
                                            content_type,
                                            last_modified,
+                                           activity,
                                            source,
                                            doc_loader),
             window,
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index 95a8ba0c3ad..f42afe87f8b 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -58,6 +58,7 @@ use net_traits::CoreResourceMsg::Fetch;
 use net_traits::request::{CredentialsMode, Destination, RequestInit, RequestMode};
 use net_traits::trim_http_whitespace;
 use network_listener::{NetworkListener, PreInvoke};
+use script_traits::DocumentActivity;
 use servo_atoms::Atom;
 use servo_config::prefs::PREFS;
 use servo_url::ServoUrl;
@@ -1228,6 +1229,7 @@ impl XMLHttpRequest {
                       is_html_document,
                       content_type,
                       None,
+                      DocumentActivity::Inactive,
                       DocumentSource::FromParser,
                       docloader,
                       None,
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 9bab1679aa6..2bdb75a486f 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -83,7 +83,8 @@ use profile_traits::time::{self, ProfilerCategory, profile};
 use script_layout_interface::message::{self, NewLayoutThreadInfo, ReflowQueryType};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory, EnqueuedPromiseCallback};
 use script_runtime::{ScriptPort, StackRootTLS, get_reports, new_rt_and_cx, PromiseJobQueue};
-use script_traits::{CompositorEvent, ConstellationControlMsg, DiscardBrowsingContext, EventResult};
+use script_traits::{CompositorEvent, ConstellationControlMsg};
+use script_traits::{DocumentActivity, DiscardBrowsingContext, EventResult};
 use script_traits::{InitialScriptState, LayoutMsg, LoadData, MouseButton, MouseEventType, MozBrowserEvent};
 use script_traits::{NewLayoutInfo, ScriptMsg as ConstellationMsg};
 use script_traits::{ScriptThreadFactory, TimerEvent, TimerEventRequest, TimerSource};
@@ -148,8 +149,8 @@ struct InProgressLoad {
     window_size: Option<WindowSizeData>,
     /// Channel to the layout thread associated with this pipeline.
     layout_chan: Sender<message::Msg>,
-    /// Window is frozen (navigated away while loading for example).
-    is_frozen: bool,
+    /// The activity level of the document (inactive, active or fully active).
+    activity: DocumentActivity,
     /// Window is visible.
     is_visible: bool,
     /// The requested URL of the load.
@@ -172,7 +173,7 @@ impl InProgressLoad {
             parent_info: parent_info,
             layout_chan: layout_chan,
             window_size: window_size,
-            is_frozen: false,
+            activity: DocumentActivity::FullyActive,
             is_visible: true,
             url: url,
             origin: origin,
@@ -963,10 +964,8 @@ impl ScriptThread {
                 self.handle_resize_inactive_msg(id, new_size),
             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::SetDocumentActivity(pipeline_id, activity) =>
+                self.handle_set_document_activity_msg(pipeline_id, activity),
             ConstellationControlMsg::ChangeFrameVisibilityStatus(pipeline_id, visible) =>
                 self.handle_visibility_change_msg(pipeline_id, visible),
             ConstellationControlMsg::NotifyVisibilityChange(parent_pipeline_id, frame_id, visible) =>
@@ -1303,37 +1302,20 @@ impl ScriptThread {
         warn!("change visibility message sent to nonexistent pipeline");
     }
 
-    /// Handles freeze message
-    fn handle_freeze_msg(&self, id: PipelineId) {
+    /// Handles activity change message
+    fn handle_set_document_activity_msg(&self, id: PipelineId, activity: DocumentActivity) {
+        debug!("Setting activity of {} to be {:?}.", id, activity);
         let document = self.documents.borrow().find_document(id);
         if let Some(document) = document {
-            document.window().freeze();
-            document.fully_deactivate();
+            document.set_activity(activity);
             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;
+            load.activity = activity;
             return;
         }
-        warn!("freeze sent to nonexistent pipeline");
-    }
-
-    /// Handles thaw message
-    fn handle_thaw_msg(&self, id: PipelineId) {
-        let document = self.documents.borrow().find_document(id);
-        if let Some(document) = document {
-            self.rebuild_and_force_reflow(&document, ReflowReason::CachedPageNeededReflow);
-            document.window().thaw();
-            document.fully_activate();
-            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;
-        }
-        warn!("thaw sent to nonexistent pipeline");
+        warn!("change of activity sent to nonexistent pipeline");
     }
 
     fn handle_focus_iframe_msg(&self,
@@ -1759,16 +1741,13 @@ impl ScriptThread {
                                      is_html_document,
                                      content_type,
                                      last_modified,
+                                     incomplete.activity,
                                      DocumentSource::FromParser,
                                      loader,
                                      referrer,
                                      referrer_policy);
         document.set_ready_state(DocumentReadyState::Loading);
 
-        if !incomplete.is_frozen {
-            document.fully_activate();
-        }
-
         self.documents.borrow_mut().insert(incomplete.pipeline_id, &*document);
 
         window.init_document(&document);
@@ -1822,8 +1801,8 @@ impl ScriptThread {
             ServoParser::parse_html_document(&document, parse_input, final_url);
         }
 
-        if incomplete.is_frozen {
-            window.upcast::<GlobalScope>().suspend();
+        if incomplete.activity != DocumentActivity::FullyActive {
+            window.suspend();
         }
 
         if !incomplete.is_visible {
diff --git a/components/script/timers.rs b/components/script/timers.rs
index 881fe9b6034..c1f0a1de6c4 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -233,6 +233,7 @@ impl OneshotTimers {
             return warn!("Suspending an already suspended timer.");
         }
 
+        debug!("Suspending timers.");
         self.suspended_since.set(Some(precise_time_ms()));
         self.invalidate_expected_event_id();
     }
@@ -244,6 +245,7 @@ impl OneshotTimers {
             None => return warn!("Resuming an already resumed timer."),
         };
 
+        debug!("Resuming timers.");
         self.suspension_offset.set(self.suspension_offset.get() + additional_offset);
         self.suspended_since.set(None);
 
@@ -252,7 +254,7 @@ impl OneshotTimers {
 
     fn schedule_timer_call(&self) {
         if self.suspended_since.get().is_some() {
-            // The timer will be scheduled when the pipeline is thawed.
+            // The timer will be scheduled when the pipeline is fully activated.
             return;
         }