use the graph system dispatcher to execute systems, make it easier to add systems

src/ecs/mod.rs

@@ -9,48 +9,40 @@ pub mod components;
 
 /// A trait that represents a simple system
 pub trait SimpleSystem {
+    fn setup(&mut self, world: &mut World) -> anyhow::Result<()> {
+        Ok(())
+    }
+
     // todo: make async?
     fn execute_mut(&mut self, world: &mut World) -> anyhow::Result<()>;
 }
 
-pub type SystemFn = dyn Fn(&mut World) -> anyhow::Result<()>;
+impl<S> SimpleSystem for S
-
+    where S: FnMut(&mut World) -> anyhow::Result<()>
-pub struct SystemFnExecutor {
+{
-    systems: HashMap<String, Box<SystemFn>>,
-}
-
-impl SystemFnExecutor {
-    pub fn new() -> Self {
-        Self {
-            systems: HashMap::new(),
-        }
-    }
-
-    pub fn with_systems(systems: HashMap<String, Box<SystemFn>>) -> Self {
-        Self {
-            systems,
-        }
-    }
-
-    pub fn add_system(&mut self, system_label: &str, system: Box<SystemFn>) {
-        self.systems.insert(system_label.to_string(), system);
-    }
-
-    pub fn remove_system(&mut self, system_label: &str) {
-        self.systems.remove(&system_label.to_string());
-    }
-}
-
-impl SimpleSystem for SystemFnExecutor {
     fn execute_mut(&mut self, world: &mut World) -> anyhow::Result<()> {
-        for system in self.systems.iter() {
+        self(world)
-            let system_fn = system.1.as_ref();
-            let res = system_fn(world);
-
-            // log an error returned by the system
-            if let Err(e) = res {
-                warn!("System execution of {} resulted in an error! '{}'", system.0, e);
     }
+}
+
+/// A system that executes a batch of systems in order that they were given.
+pub struct BatchedSystem {
+    systems: Vec<Box<dyn SimpleSystem>>,
+}
+
+impl BatchedSystem {
+    /// Create a new BatchedSystems. The systems will be executed in the order given.
+    pub fn new(systems: Vec<Box<dyn SimpleSystem>>) -> Self {
+        Self {
+            systems
+        }
+    }
+}
+
+impl SimpleSystem for BatchedSystem {
+    fn execute_mut(&mut self, world: &mut World) -> anyhow::Result<()> {
+        for system in self.systems.iter_mut() {
+            system.execute_mut(world)?;
         }
 
         Ok(())
@@ -67,12 +59,16 @@ struct SystemGraphEdge {
     
 }
 
-pub struct SystemGraphExecutor {
+/// Dispatcher for multiple systems.
+/// 
+/// This struct uses a graph for finding executing systems with dependencies.
+/// At some point this will be multithreaded.
+pub struct SystemDispatcher {
     graph: StableDiGraph<SystemGraphNode, SystemGraphEdge>,
     node_refs: HashMap<String, NodeIndex>,
 }
 
-impl Default for SystemGraphExecutor {
+impl Default for SystemDispatcher {
     fn default() -> Self {
         Self {
             graph: StableDiGraph::new(),
@@ -81,7 +77,7 @@ impl Default for SystemGraphExecutor {
     }
 }
 
-impl SystemGraphExecutor {
+impl SystemDispatcher {
     pub fn new() -> Self {
         Self::default()
     }
@@ -92,11 +88,11 @@ impl SystemGraphExecutor {
     /// and will cause a panic later on in the engine.
     /// 
     /// TODO: Return false if a cycle was created, making it impossible to know when to dispatch them. This will mean that the System would not of had been added.
-    pub fn add_system(&mut self, name: String, system: Box<dyn SimpleSystem>, dependencies: &[String]) -> bool {
+    pub fn add_system(&mut self, name: String, system: Box<dyn SimpleSystem>, dependencies: Vec<String>) -> bool {
         let added_index =
             self.graph.add_node(SystemGraphNode {
                 name: name.clone(),
-                dependent_on: dependencies.clone().to_vec(),
+                dependent_on: dependencies.clone(),
                 system,
             });
 
@@ -106,7 +102,7 @@ impl SystemGraphExecutor {
         // find the dependencies in node_refs and add edges directed towards the new node
         for depend in dependencies.into_iter() {
             let idx = self.node_refs
-                .get(depend)
+                .get(&depend)
                 .expect("Dependency not found!");
 
             self.graph.add_edge(idx.clone(), added_index, SystemGraphEdge { });
@@ -115,7 +111,7 @@ impl SystemGraphExecutor {
         true
     }
 
-    pub(crate) fn execute_mut(&mut self, world: &mut World) {
+    pub(crate) fn execute_systems(&mut self, world: &mut World) {
         let mut topo = Topo::new(&self.graph);
 
         while let Some(nx) = topo.next(&self.graph) {
@@ -125,6 +121,10 @@ impl SystemGraphExecutor {
                 Ok(()) => {},
                 Err(e) => {
                     warn!("System execution of {} resulted in an error! '{}'.", node.name, e);
+
+                    // TODO: Find some way to stop traversing down a topopath in the graph executor and continue down a different one.
+                    // This might require a custom topopath implementation (preferably iterative). It would have to ensure that it
+                    // doesn't run other systems that are dependent on that failed system.
                     return;
                 }
             }
@@ -132,9 +132,9 @@ impl SystemGraphExecutor {
     }
 }
 
-impl SimpleSystem for SystemGraphExecutor {
+impl SimpleSystem for SystemDispatcher {
     fn execute_mut(&mut self, world: &mut World) -> anyhow::Result<()> {
-        SystemGraphExecutor::execute_mut(self, world);
+        self.execute_systems(world);
 
         Ok(())
     }

src/game.rs

@@ -4,7 +4,7 @@ use async_std::{task::block_on, sync::Mutex};
 
 use hecs::World;
 use instant::Instant;
-use tracing::{metadata::LevelFilter, info, debug, warn};
+use tracing::{metadata::LevelFilter, info, debug, warn, error};
 use tracing_subscriber::{
     layer::{Layer, SubscriberExt},
     filter::FilterFn,
@@ -13,7 +13,7 @@ use tracing_subscriber::{
 
 use winit::{window::{WindowBuilder, Window}, event::{Event, WindowEvent, KeyboardInput, ElementState, VirtualKeyCode}, event_loop::{EventLoop, ControlFlow}};
 
-use crate::{render::{renderer::{Renderer, BasicRenderer}, render_job::RenderJob}, input_event::InputEvent, ecs::{components::{mesh::MeshComponent, transform::TransformComponent}, SystemFnExecutor, SimpleSystem, SystemGraphExecutor}};
+use crate::{render::{renderer::{Renderer, BasicRenderer}, render_job::RenderJob}, input_event::InputEvent, ecs::{components::{mesh::MeshComponent, transform::TransformComponent}, SimpleSystem, SystemDispatcher}};
 
 struct TickCounter {
     counter: u32,
@@ -76,20 +76,20 @@ struct GameLoop {
     
     world: Arc<Mutex<World>>,
     /// higher priority systems
-    engine_systems: Vec<Box<dyn SimpleSystem>>,
+    engine_sys_dispatcher: SystemDispatcher,
-    systems: Vec<Box<dyn SimpleSystem>>,
+    user_sys_dispatcher: SystemDispatcher,
     fps_counter: TickCounter,
 }
 
 impl GameLoop {
-    pub async fn new(window: Arc<Window>, world: Arc<Mutex<World>>, user_systems: Vec<Box<dyn SimpleSystem>>) -> GameLoop {
+    pub async fn new(window: Arc<Window>, world: Arc<Mutex<World>>, user_systems: SystemDispatcher) -> GameLoop {
         Self {
             window: Arc::clone(&window),
             renderer: Box::new(BasicRenderer::create_with_window(window).await),
 
             world,
-            engine_systems: vec![],
+            engine_sys_dispatcher: SystemDispatcher::new(),
-            systems: user_systems,
+            user_sys_dispatcher: user_systems,
             fps_counter: TickCounter::new(),
         }
     }
@@ -105,13 +105,20 @@ impl GameLoop {
     async fn update(&mut self) {
         let mut world = self.world.lock().await;
 
-        for esystem in self.engine_systems.iter_mut() {
+        if let Err(e) = self.engine_sys_dispatcher.execute_mut(&mut world) {
+            error!("Error when executing engine ecs systems: '{}'", e);
+        }
+
+        if let Err(e) = self.user_sys_dispatcher.execute_mut(&mut world) {
+            error!("Error when executing user ecs systems: '{}'", e);
+        }
+        /* for esystem in self.engine_systems.iter_mut() {
             esystem.execute_mut(&mut world).unwrap();
         }
 
         for system in self.systems.iter_mut() {
             system.execute_mut(&mut world).unwrap();
-        }
+        } */
     }
 
     async fn input_update(&mut self, event: &InputEvent) -> Option<ControlFlow> {
@@ -218,14 +225,14 @@ impl GameLoop {
 
 pub struct Game {
     world: Option<Arc<Mutex<World>>>,
-    systems: Option<Vec<Box<dyn SimpleSystem>>>
+    system_dispatcher: Option<SystemDispatcher>
 }
 
 impl Default for Game {
     fn default() -> Self {
         Self {
             world: None,
-            systems: Some(vec![]),
+            system_dispatcher: Some(SystemDispatcher::new()),
         }
     }
 }
@@ -259,12 +266,18 @@ impl Game {
         self
     }
 
-    pub fn with_system<S>(&mut self, system: S) -> &mut Self
+    pub fn with_system<S>(&mut self, name: &str, system: S, depends: &[&str]) -> &mut Self
     where
         S: SimpleSystem + 'static
     {
-        let systems = self.systems.as_mut().unwrap();
+
-        systems.push(Box::new(system));
+        let depends: Vec<String> = depends
+            .iter()
+            .map(|s| s.to_string())
+            .collect();
+
+        let dispatcher = self.system_dispatcher.as_mut().unwrap();
+        dispatcher.add_system(name.to_string(), Box::new(system), depends);
 
         self
     }
@@ -275,7 +288,7 @@ impl Game {
         let event_loop = EventLoop::new();
         let window = Arc::new(WindowBuilder::new().build(&event_loop).unwrap());
 
-        let systems = self.systems.take().unwrap();
+        let systems = self.system_dispatcher.take().unwrap();
 
         let mut g_loop = GameLoop::new(Arc::clone(&window), world, systems).await;
 

src/main.rs

@@ -12,12 +12,10 @@ use game::Game;
 use hecs::World;
 use tracing::debug;
 
-use crate::ecs::SystemFnExecutor;
 use crate::render::material::Material;
 use crate::render::texture::Texture;
 use crate::ecs::components::camera::CameraComponent;
 use crate::math::{Angle, Transform};
-//use specs::*;
 
 #[derive(Debug, Default)]
 struct Point2d {
@@ -101,32 +99,8 @@ async fn main() {
         Ok(())
     };
     
-    let mut fn_exec = SystemFnExecutor::new();
-    fn_exec.add_system("jiggle", Box::new(jiggle_system));
-    
     Game::initialize().await
         .with_world(world)
-        .with_system(fn_exec)
+        .with_system("jiggle", jiggle_system, &[])
         .run().await;
-
-    /* world.register::<Point2d>();
-    world.register::<Point3d>();
-
-    world.create_entity()
-        .with(Point2d::new(10, 10))
-        .with(Point3d::new(50, 50, 50))
-        .build();
-
-    let mut dispatcher = DispatcherBuilder::new().with(TestingSystem, "testing_system", &[]).build();
-    dispatcher.setup(&mut world);
-
-    //dispatcher.dispatch(&mut world);
-
-    Game::initialize().await
-        .with_world(world)
-        .with_dispatcher(dispatcher)
-        .run().await; */
-
-    /* let mut game = Game::initialize().await;
-    game.run().await; */
 }