Add some conveniences to Clock and thread. Allow atomic load on booleans.

lib/std/experimental/FrameScheduler.c3

@@ -0,0 +1,94 @@
+module std::experimental::scheduler(<Event>);
+import std::collections, std::thread, std::time;
+
+struct DelayedSchedulerEvent @local
+{
+	inline Event event;
+	Clock execution_time;
+}
+
+fn int DelayedSchedulerEvent.compare_to(self, DelayedSchedulerEvent other) @local
+{
+	switch
+	{
+		case self.execution_time < other.execution_time: return -1;
+		case self.execution_time > other.execution_time: return 1;
+		default: return 0;
+	}
+}
+
+struct FrameScheduler
+{
+	PriorityQueue{DelayedSchedulerEvent} delayed_events;
+	List{Event} events;
+	List{Event} pending_events;
+	bool pending;
+	Mutex mtx;
+}
+
+fn void FrameScheduler.init(&self)
+{
+	self.events.new_init();
+	self.pending_events.new_init();
+	self.delayed_events.new_init();
+	(void)self.mtx.init();
+	bool pending;
+}
+
+macro void FrameScheduler.@destroy(&self; @destruct(Event e))
+{
+	foreach (e : self.events) @destruct(e);
+	foreach (e : self.pending_events) @destruct(e);
+	foreach (e : self.delayed_events.heap) @destruct(e.event);
+	self.events.free();
+	self.pending_events.free();
+	self.delayed_events.free();
+	(void)self.mtx.destroy();
+}
+
+fn void FrameScheduler.queue_delayed_event(&self, Event event, Duration delay)
+{
+	self.mtx.@in_lock()
+	{
+		self.delayed_events.push({ event, clock::now().add_duration(delay)});
+		@atomic_store(self.pending, true);
+	};
+}
+
+fn bool FrameScheduler.has_delayed(&self)
+{
+	self.mtx.@in_lock()
+    {
+        return @ok(self.delayed_events.first());
+    };
+}
+
+fn void FrameScheduler.queue_event(&self, Event event)
+{
+	self.mtx.@in_lock()
+	{
+		self.pending_events.push(event);
+		@atomic_store(self.pending, true);
+	};
+}
+fn Event! FrameScheduler.pop_event(&self)
+{
+	while (true)
+	{
+		if (try event = self.events.pop()) return event;
+    	if (!@atomic_load(self.pending)) return IteratorResult.NO_MORE_ELEMENT?;
+        self.mtx.@in_lock()
+        {
+            self.events.add_all(&self.pending_events);
+            self.pending_events.clear();
+            Clock c = clock::now();
+            while (try top = self.delayed_events.first())
+            {
+                if (top.execution_time > c) break;
+                self.events.push(self.delayed_events.pop()!!);
+            }
+            @atomic_store(self.pending, self.delayed_events.len() > 0);
+            if (!self.events.len()) return IteratorResult.NO_MORE_ELEMENT?;
+        };
+	}
+}