impl timer-task-source, dedicated time-out mechanism for service-worker

components/script/task_source/timer.rs

@@ -0,0 +1,42 @@
+/* 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 crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
+use crate::task::{TaskCanceller, TaskOnce};
+use crate::task_source::{TaskSource, TaskSourceName};
+use msg::constellation_msg::PipelineId;
+use std::fmt;
+
+#[derive(JSTraceable)]
+/// https://html.spec.whatwg.org/multipage/#timer-task-source
+pub struct TimerTaskSource(pub Box<dyn ScriptChan + Send + 'static>, pub PipelineId);
+
+impl Clone for TimerTaskSource {
+    fn clone(&self) -> TimerTaskSource {
+        TimerTaskSource(self.0.clone(), self.1.clone())
+    }
+}
+
+impl fmt::Debug for TimerTaskSource {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "TimerTaskSource(...)")
+    }
+}
+
+impl TaskSource for TimerTaskSource {
+    const NAME: TaskSourceName = TaskSourceName::Timer;
+
+    fn queue_with_canceller<T>(&self, task: T, canceller: &TaskCanceller) -> Result<(), ()>
+    where
+        T: TaskOnce + 'static,
+    {
+        let msg = CommonScriptMsg::Task(
+            ScriptThreadEventCategory::TimerEvent,
+            Box::new(canceller.wrap_task(task)),
+            Some(self.1),
+            Self::NAME,
+        );
+        self.0.send(msg).map_err(|_| ())
+    }
+}