1 files changed, 117 insertions, 0 deletions
diff --git a/components/script/dom/performanceobserver.rs b/components/script/dom/performanceobserver.rs
new file mode 100644
index 00000000000..e0d2e49a57b
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+++ b/components/script/dom/performanceobserver.rs
@@ -0,0 +1,117 @@
+/* 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/. */
+
+use dom::bindings::callback::ExceptionHandling;
+use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::PerformanceBinding::PerformanceEntryList as DOMPerformanceEntryList;
+use dom::bindings::codegen::Bindings::PerformanceObserverBinding;
+use dom::bindings::codegen::Bindings::PerformanceObserverBinding::PerformanceObserverCallback;
+use dom::bindings::codegen::Bindings::PerformanceObserverBinding::PerformanceObserverInit;
+use dom::bindings::codegen::Bindings::PerformanceObserverBinding::PerformanceObserverMethods;
+use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
+use dom::bindings::error::{Error, Fallible};
+use dom::bindings::js::Root;
+use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
+use dom::bindings::str::DOMString;
+use dom::globalscope::GlobalScope;
+use dom::performance::PerformanceEntryList;
+use dom::performanceentry::PerformanceEntry;
+use dom::performanceobserverentrylist::PerformanceObserverEntryList;
+use dom_struct::dom_struct;
+use std::rc::Rc;
+
+/// List of allowed performance entry types.
+const VALID_ENTRY_TYPES: &'static [&'static str] = &[
+    // "mark", XXX User Timing API
+    // "measure", XXX User Timing API
+    // "resource", XXX Resource Timing API
+    // "server", XXX Server Timing API
+    // "paint", XXX Paint Timing API
+];
+
+#[dom_struct]
+pub struct PerformanceObserver {
+    reflector_: Reflector,
+    #[ignore_heap_size_of = "can't measure Rc values"]
+    callback: Rc<PerformanceObserverCallback>,
+    entries: DOMRefCell<DOMPerformanceEntryList>,
+}
+
+impl PerformanceObserver {
+    fn new_inherited(callback: Rc<PerformanceObserverCallback>,
+                     entries: DOMRefCell<DOMPerformanceEntryList>)
+        -> PerformanceObserver {
+        PerformanceObserver {
+            reflector_: Reflector::new(),
+            callback,
+            entries,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(global: &GlobalScope,
+           callback: Rc<PerformanceObserverCallback>,
+           entries: DOMPerformanceEntryList)
+        -> Root<PerformanceObserver> {
+        let observer = PerformanceObserver::new_inherited(callback, DOMRefCell::new(entries));
+        reflect_dom_object(box observer, global, PerformanceObserverBinding::Wrap)
+    }
+
+    pub fn Constructor(global: &GlobalScope, callback: Rc<PerformanceObserverCallback>)
+        -> Fallible<Root<PerformanceObserver>> {
+        Ok(PerformanceObserver::new(global, callback, Vec::new()))
+    }
+
+    /// Buffer a new performance entry.
+    pub fn queue_entry(&self, entry: &PerformanceEntry) {
+        self.entries.borrow_mut().push(Root::from_ref(entry));
+    }
+
+    /// Trigger performance observer callback with the list of performance entries
+    /// buffered since the last callback call.
+    pub fn notify(&self) {
+        let entries = self.entries.borrow();
+        if entries.is_empty() {
+            return;
+        }
+        let mut entries = entries.clone();
+        let global = self.global();
+        let entry_list = PerformanceEntryList::new(entries.drain(..).collect());
+        let observer_entry_list = PerformanceObserverEntryList::new(&global, entry_list);
+        let _ = self.callback.Call__(&observer_entry_list, self, ExceptionHandling::Report);
+    }
+
+    pub fn callback(&self) -> Rc<PerformanceObserverCallback> {
+        self.callback.clone()
+    }
+
+    pub fn entries(&self) -> DOMPerformanceEntryList {
+        self.entries.borrow().clone()
+    }
+}
+
+impl PerformanceObserverMethods for PerformanceObserver {
+    // https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()
+    fn Observe(&self, options: &PerformanceObserverInit) -> Fallible<()> {
+        // Make sure the client is asking to observe events from allowed entry types.
+        let entry_types = options.entryTypes.iter()
+                                            .filter(|e| VALID_ENTRY_TYPES.contains(&e.as_ref()))
+                                            .map(|e| e.clone())
+                                            .collect::<Vec<DOMString>>();
+        // There must be at least one valid entry type.
+        if entry_types.is_empty() {
+            return Err((Error::Type("entryTypes cannot be empty".to_string())));
+        }
+
+        let performance = self.global().as_window().Performance();
+        performance.add_observer(self, entry_types);
+        Ok(())
+    }
+
+    // https://w3c.github.io/performance-timeline/#dom-performanceobserver-disconnect()
+    fn Disconnect(&self) {
+        self.global().as_window().Performance().remove_observer(self);
+        self.entries.borrow_mut().clear();
+    }
+}