script/dom/performance/
performanceobserver.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5use std::cell::Cell;
6use std::rc::Rc;
7
8use dom_struct::dom_struct;
9use js::context::JSContext;
10use js::rust::{HandleObject, MutableHandleValue};
11use script_bindings::cell::DomRefCell;
12use script_bindings::reflector::{Reflector, reflect_dom_object_with_proto_and_cx};
13
14use super::performance::PerformanceEntryList;
15use super::performanceentry::{EntryType, PerformanceEntry};
16use super::performanceobserverentrylist::PerformanceObserverEntryList;
17use crate::dom::bindings::callback::ExceptionHandling;
18use crate::dom::bindings::codegen::Bindings::PerformanceBinding::PerformanceEntryList as DOMPerformanceEntryList;
19use crate::dom::bindings::codegen::Bindings::PerformanceObserverBinding::{
20    PerformanceObserverCallback, PerformanceObserverInit, PerformanceObserverMethods,
21};
22use crate::dom::bindings::error::{Error, Fallible};
23use crate::dom::bindings::reflector::DomGlobal;
24use crate::dom::bindings::root::DomRoot;
25use crate::dom::console::Console;
26use crate::dom::globalscope::GlobalScope;
27
28#[derive(Clone, Copy, JSTraceable, MallocSizeOf, PartialEq)]
29enum ObserverType {
30    Undefined,
31    Single,
32    Multiple,
33}
34
35#[dom_struct]
36pub(crate) struct PerformanceObserver {
37    reflector_: Reflector,
38    #[conditional_malloc_size_of]
39    callback: Rc<PerformanceObserverCallback>,
40    entries: DomRefCell<DOMPerformanceEntryList>,
41    observer_type: Cell<ObserverType>,
42}
43
44impl PerformanceObserver {
45    fn new_inherited(
46        callback: Rc<PerformanceObserverCallback>,
47        entries: DomRefCell<DOMPerformanceEntryList>,
48    ) -> PerformanceObserver {
49        PerformanceObserver {
50            reflector_: Reflector::new(),
51            callback,
52            entries,
53            observer_type: Cell::new(ObserverType::Undefined),
54        }
55    }
56
57    pub(crate) fn new(
58        cx: &mut JSContext,
59        global: &GlobalScope,
60        callback: Rc<PerformanceObserverCallback>,
61        entries: DOMPerformanceEntryList,
62    ) -> DomRoot<PerformanceObserver> {
63        Self::new_with_proto(cx, global, None, callback, entries)
64    }
65
66    #[cfg_attr(crown, expect(crown::unrooted_must_root))]
67    fn new_with_proto(
68        cx: &mut JSContext,
69        global: &GlobalScope,
70        proto: Option<HandleObject>,
71        callback: Rc<PerformanceObserverCallback>,
72        entries: DOMPerformanceEntryList,
73    ) -> DomRoot<PerformanceObserver> {
74        let observer = PerformanceObserver::new_inherited(callback, DomRefCell::new(entries));
75        reflect_dom_object_with_proto_and_cx(Box::new(observer), global, proto, cx)
76    }
77
78    /// Buffer a new performance entry.
79    pub(crate) fn queue_entry(&self, entry: &PerformanceEntry) {
80        self.entries.borrow_mut().push(DomRoot::from_ref(entry));
81    }
82
83    /// Trigger performance observer callback with the list of performance entries
84    /// buffered since the last callback call.
85    pub(crate) fn notify(&self, cx: &mut JSContext) {
86        if self.entries.borrow().is_empty() {
87            return;
88        }
89        let entry_list = PerformanceEntryList::new(self.entries.borrow_mut().drain(..).collect());
90        let observer_entry_list = PerformanceObserverEntryList::new(cx, &self.global(), entry_list);
91        // using self both as thisArg and as the second formal argument
92        let _ = self.callback.Call_(
93            cx,
94            self,
95            &observer_entry_list,
96            self,
97            ExceptionHandling::Report,
98        );
99    }
100
101    pub(crate) fn callback(&self) -> Rc<PerformanceObserverCallback> {
102        self.callback.clone()
103    }
104
105    pub(crate) fn entries(&self) -> DOMPerformanceEntryList {
106        self.entries.borrow().clone()
107    }
108
109    pub(crate) fn set_entries(&self, entries: DOMPerformanceEntryList) {
110        *self.entries.borrow_mut() = entries;
111    }
112}
113
114impl PerformanceObserverMethods<crate::DomTypeHolder> for PerformanceObserver {
115    /// <https://w3c.github.io/performance-timeline/#dom-performanceobserver-constructor>
116    fn Constructor(
117        cx: &mut js::context::JSContext,
118        global: &GlobalScope,
119        proto: Option<HandleObject>,
120        callback: Rc<PerformanceObserverCallback>,
121    ) -> Fallible<DomRoot<PerformanceObserver>> {
122        Ok(PerformanceObserver::new_with_proto(
123            cx,
124            global,
125            proto,
126            callback,
127            Vec::new(),
128        ))
129    }
130
131    /// <https://w3c.github.io/performance-timeline/#supportedentrytypes-attribute>
132    fn SupportedEntryTypes(cx: &mut JSContext, global: &GlobalScope, retval: MutableHandleValue) {
133        // While this is exposed through a method of PerformanceObserver,
134        // it is specified as associated with the global scope.
135        global.supported_performance_entry_types(cx, retval)
136    }
137
138    /// <https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()>
139    fn Observe(&self, cx: &mut JSContext, options: &PerformanceObserverInit) -> Fallible<()> {
140        // Step 1 is self
141
142        // Step 2 is self.global()
143
144        // Step 3
145        if options.entryTypes.is_none() && options.type_.is_none() {
146            return Err(Error::Syntax(None));
147        }
148
149        // Step 4
150        if options.entryTypes.is_some() && (options.buffered.is_some() || options.type_.is_some()) {
151            return Err(Error::Syntax(None));
152        }
153
154        // If this point is reached, then one of options.entryTypes or options.type_
155        // is_some, but not both.
156
157        // Step 5
158        match self.observer_type.get() {
159            ObserverType::Undefined => {
160                if options.entryTypes.is_some() {
161                    self.observer_type.set(ObserverType::Multiple);
162                } else {
163                    self.observer_type.set(ObserverType::Single);
164                }
165            },
166            ObserverType::Single => {
167                if options.entryTypes.is_some() {
168                    return Err(Error::InvalidModification(None));
169                }
170            },
171            ObserverType::Multiple => {
172                if options.type_.is_some() {
173                    return Err(Error::InvalidModification(None));
174                }
175            },
176        }
177
178        // The entryTypes and type paths diverge here
179        const NO_VALID_ENTRY_TYPE: &str = "No valid entry type provided to observe().";
180        if let Some(entry_types) = &options.entryTypes {
181            // Steps 6.1 - 6.2
182            let entry_types = entry_types
183                .iter()
184                .filter_map(|e| EntryType::try_from(&*e.str()).ok())
185                .collect::<Vec<EntryType>>();
186
187            // Step 6.3
188            if entry_types.is_empty() {
189                Console::internal_warn(cx, &self.global(), NO_VALID_ENTRY_TYPE.to_string());
190                return Ok(());
191            }
192
193            // Steps 6.4-6.5
194            // This never pre-fills buffered entries, and
195            // any existing types are replaced.
196            self.global()
197                .performance()
198                .add_multiple_type_observer(self, entry_types);
199            Ok(())
200        } else if let Some(entry_type) = &options.type_ {
201            // Step 7.2
202            let Ok(entry_type) = EntryType::try_from(&*entry_type.str()) else {
203                Console::internal_warn(cx, &self.global(), NO_VALID_ENTRY_TYPE.to_string());
204                return Ok(());
205            };
206
207            // Steps 7.3-7.5
208            // This may pre-fill buffered entries, and
209            // existing types are appended to.
210            self.global().performance().add_single_type_observer(
211                self,
212                entry_type,
213                options.buffered.unwrap_or(false),
214            );
215            Ok(())
216        } else {
217            // Step 7.1
218            unreachable!()
219        }
220    }
221
222    /// <https://w3c.github.io/performance-timeline/#dom-performanceobserver-disconnect>
223    fn Disconnect(&self) {
224        self.global().performance().remove_observer(self);
225        self.entries.borrow_mut().clear();
226    }
227
228    /// <https://w3c.github.io/performance-timeline/#takerecords-method>
229    fn TakeRecords(&self) -> Vec<DomRoot<PerformanceEntry>> {
230        let mut entries = self.entries.borrow_mut();
231        let taken = entries
232            .iter()
233            .map(|entry| DomRoot::from_ref(&**entry))
234            .collect();
235        entries.clear();
236        taken
237    }
238}
script/dom/performance/performanceobserver.rs

script/dom/performance/
performanceobserver.rs
