Removed the session history from BrowsingContext.

components/script/dom/browsingcontext.rs

@@ -3,12 +3,10 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::cell::DOMRefCell;
-use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::conversions::{ToJSValConvertible, root_from_handleobject};
-use dom::bindings::js::{JS, Root, RootedReference};
+use dom::bindings::js::{JS, MutNullableHeap, Root, RootedReference};
 use dom::bindings::proxyhandler::{fill_property_descriptor, get_property_descriptor};
 use dom::bindings::reflector::{Reflectable, MutReflectable, Reflector};
-use dom::bindings::str::DOMString;
 use dom::bindings::trace::JSTraceable;
 use dom::bindings::utils::WindowProxyHandler;
 use dom::bindings::utils::get_array_index_from_id;
@@ -28,9 +26,12 @@ use js::jsapi::{ObjectOpResult, PropertyDescriptor};
 use js::jsval::{UndefinedValue, PrivateValue};
 use msg::constellation_msg::PipelineId;
 use std::cell::Cell;
-use url::Url;
 
 #[dom_struct]
+// NOTE: the browsing context for a window is managed in two places:
+// here, in script, but also in the constellation. The constellation
+// manages the session history, which in script is accessed through
+// History objects, messaging the constellation.
 pub struct BrowsingContext {
     reflector: Reflector,
 
@@ -40,15 +41,15 @@ pub struct BrowsingContext {
     /// Indicates if reflow is required when reloading.
     needs_reflow: Cell<bool>,
 
-    /// Stores this context's session history
-    history: DOMRefCell<Vec<SessionHistoryEntry>>,
-
-    /// The index of the active session history entry
-    active_index: Cell<usize>,
-
     /// Stores the child browsing contexts (ex. iframe browsing context)
     children: DOMRefCell<Vec<JS<BrowsingContext>>>,
 
+    /// The current active document.
+    /// Note that the session history is stored in the constellation,
+    /// in the script thread we just track the current active document.
+    active_document: MutNullableHeap<JS<Document>>,
+
+    /// The containing iframe element, if this is a same-origin iframe
     frame_element: Option<JS<Element>>,
 }
 
@@ -58,9 +59,8 @@ impl BrowsingContext {
             reflector: Reflector::new(),
             id: id,
             needs_reflow: Cell::new(true),
-            history: DOMRefCell::new(vec![]),
-            active_index: Cell::new(0),
             children: DOMRefCell::new(vec![]),
+            active_document: Default::default(),
             frame_element: frame_element.map(JS::from_ref),
         }
     }
@@ -90,29 +90,16 @@ impl BrowsingContext {
         }
     }
 
-    pub fn init(&self, document: &Document) {
+    pub fn set_active_document(&self, document: &Document) {
-        assert!(self.history.borrow().is_empty());
+        self.active_document.set(Some(document))
-        assert_eq!(self.active_index.get(), 0);
-        self.history.borrow_mut().push(SessionHistoryEntry::new(document, document.url().clone(), document.Title()));
-    }
-
-    pub fn push_history(&self, document: &Document) {
-        let mut history = self.history.borrow_mut();
-        // Clear all session history entries after the active index
-        history.drain((self.active_index.get() + 1)..);
-        history.push(SessionHistoryEntry::new(document, document.url().clone(), document.Title()));
-        self.active_index.set(self.active_index.get() + 1);
-        assert_eq!(self.active_index.get(), history.len() - 1);
     }
 
     pub fn active_document(&self) -> Root<Document> {
-        Root::from_ref(&self.history.borrow()[self.active_index.get()].document)
+        self.active_document.get().expect("No active document.")
     }
 
     pub fn maybe_active_document(&self) -> Option<Root<Document>> {
-        self.history.borrow().get(self.active_index.get()).map(|entry| {
+        self.active_document.get()
-            Root::from_ref(&*entry.document)
-        })
     }
 
     pub fn active_window(&self) -> Root<Window> {
@@ -167,9 +154,8 @@ impl BrowsingContext {
         }).map(|context| context.active_window())
     }
 
-    pub fn clear_session_history(&self) {
+    pub fn unset_active_document(&self) {
-        self.active_index.set(0);
+        self.active_document.set(None)
-        self.history.borrow_mut().clear();
     }
 
     pub fn iter(&self) -> ContextIterator {
@@ -208,27 +194,6 @@ impl Iterator for ContextIterator {
     }
 }
 
-// This isn't a DOM struct, just a convenience struct
-// without a reflector, so we don't mark this as #[dom_struct]
-#[must_root]
-#[privatize]
-#[derive(JSTraceable, HeapSizeOf)]
-pub struct SessionHistoryEntry {
-    document: JS<Document>,
-    url: Url,
-    title: DOMString,
-}
-
-impl SessionHistoryEntry {
-    fn new(document: &Document, url: Url, title: DOMString) -> SessionHistoryEntry {
-        SessionHistoryEntry {
-            document: JS::from_ref(document),
-            url: url,
-            title: title,
-        }
-    }
-}
-
 #[allow(unsafe_code)]
 unsafe fn GetSubframeWindow(cx: *mut JSContext,
                             proxy: HandleObject,

components/script/script_thread.rs

@@ -1655,8 +1655,6 @@ impl ScriptThread {
             }
         }
 
-        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);
@@ -1675,7 +1673,6 @@ impl ScriptThread {
             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)
         };
 
@@ -1741,11 +1738,7 @@ impl ScriptThread {
                                      loader,
                                      referrer,
                                      referrer_policy);
-        if using_new_context {
+        browsing_context.set_active_document(&document);
-            browsing_context.init(&document);
-        } else {
-            browsing_context.push_history(&document);
-        }
         document.set_ready_state(DocumentReadyState::Loading);
 
         self.constellation_chan
@@ -2238,7 +2231,7 @@ fn shut_down_layout(context_tree: &BrowsingContext) {
         window.clear_js_runtime();
 
         // Sever the connection between the global and the DOM tree
-        context.clear_session_history();
+        context.unset_active_document();
     }
 
     // Destroy the layout thread. If there were node leaks, layout will now crash safely.