task: move Scheduler into a trait, define static-sized scheduler implementation, expose as a system task runner in platform

src/task.rs

@@ -77,25 +77,35 @@ impl ScheduledTask {
 }
 
 #[derive(Debug)]
-pub struct Scheduler {
-    tasks: Vec<ScheduledTask>,
+pub struct FixedSizeScheduler<const TASK_COUNT: usize> {
+    tasks: [Option<ScheduledTask>; TASK_COUNT],
 }
 
-impl Scheduler {
-    pub fn new(tasks: Vec<Box<dyn Task>>) -> Self {
-        let mut scheduled = Vec::new();
+impl<const TASK_COUNT: usize> FixedSizeScheduler<TASK_COUNT> {
+    pub fn new(tasks: [Box<dyn Task>; TASK_COUNT]) -> Self {
+        let mut scheduled = [const { None }; TASK_COUNT];
+        let mut idx = 0;
         for task in tasks {
-            log::info!("Scheduling task {} {:?}", task.name(), task);
-            scheduled.push(ScheduledTask::new(task));
+            scheduled[idx] = Some(ScheduledTask::new(task));
+            idx += 1;
         }
-        Scheduler {
+        FixedSizeScheduler {
             tasks: scheduled
         }
     }
+}
 
-    pub fn tick(&mut self) {
-        for task in &mut self.tasks {
-            task.tick();
+impl<const TASK_COUNT: usize> Scheduler for FixedSizeScheduler<TASK_COUNT> {
+    fn tick(&mut self) {
+        for slot in &mut self.tasks {
+            match slot {
+                Some(task) => task.tick(),
+                _ => ()
+            }
         }
     }
 }
+
+pub trait Scheduler {
+    fn tick(&mut self);
+}