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

src/platform/esp32.rs

@@ -18,6 +18,7 @@ use rgb::Rgb;
 
 use super::Board;
 
+use crate::task::FixedSizeScheduler;
 use crate::task::Task;
 use crate::buffers::{Pixbuf, SurfacePool};
 use crate::mappings::StrideMapping;
@@ -34,12 +35,14 @@ use crate::buffers::SimpleSurface as SurfaceType;
 pub struct Esp32Board<'a> {
     output: Option<<Self as Board>::Output>,
     surfaces: Option<SurfacePool<SurfaceType>>,
-    tasks: Option<Vec<Box<dyn Task>>>
+    sys_loop: EspSystemEventLoop,
+    modem: Option<Modem>,
 }
 
 impl<'a> Board for Esp32Board<'a> {
     type Output = StrideOutput<[Rgb<u8>; 310], FastWs2812Esp32Rmt<'a>>;
     type Surfaces = SurfacePool<SurfaceType>;
+    type Scheduler = FixedSizeScheduler<2>;
     
     fn take() -> Self {
         // It is necessary to call this function once. Otherwise some patches to the runtime
@@ -51,7 +54,6 @@ impl<'a> Board for Esp32Board<'a> {
 
         let peripherals = Peripherals::take().unwrap();
         let sys_loop = EspSystemEventLoop::take().unwrap();
-        let nvs = EspDefaultNvsPartition::take().unwrap();
 
         let channel = peripherals.rmt.channel0;
         let pins = peripherals.pins;
@@ -74,10 +76,6 @@ impl<'a> Board for Esp32Board<'a> {
             }
         };
 
-        let tasks: Vec<Box<dyn Task>> = vec![
-            Box::new(WifiTask::new(peripherals.modem, sys_loop.clone(), &nvs)),
-        ];
-
         const POWER_VOLTS : u32 = 5;
         const POWER_MA : u32 = 500;
         const MAX_POWER_MW : u32 = POWER_VOLTS * POWER_MA;
@@ -92,7 +90,8 @@ impl<'a> Board for Esp32Board<'a> {
         Esp32Board {
             surfaces: Some(SurfacePool::new()),
             output: Some(output),
-            tasks: Some(tasks),
+            modem: Some(peripherals.modem),
+            sys_loop: sys_loop.clone(),
         }
     }
 
@@ -104,8 +103,11 @@ impl<'a> Board for Esp32Board<'a> {
         self.surfaces.take().unwrap()
     }
 
-    fn system_tasks(&mut self) -> Vec<Box<dyn Task>> {
-        self.tasks.take().unwrap()
+    fn system_tasks(&mut self) -> Self::Scheduler {
+        let nvs = EspDefaultNvsPartition::take().unwrap();
+        FixedSizeScheduler::new([
+            Box::new(WifiTask::new(self.modem.take().unwrap(), self.sys_loop.clone(), &nvs)),
+        ])
     }
 }
 

src/platform/mod.rs

@@ -9,14 +9,15 @@ pub mod esp32;
 pub type DefaultBoard = esp32::Esp32Board;
 
 use crate::render::{Output, Surfaces};
-use crate::task::Task;
+use crate::task::Scheduler;
 
 pub trait Board {
     type Output: Output;
     type Surfaces: Surfaces;
+    type Scheduler: Scheduler;
 
     fn take() -> Self;
     fn output(&mut self) -> Self::Output;
     fn surfaces(&mut self) -> Self::Surfaces;
-    fn system_tasks(&mut self) -> Vec<Box<dyn Task>>;
+    fn system_tasks(&mut self) -> Self::Scheduler;
 }