Starting to mess with promises

Going to want async IO, I think. And it's a fun detail that I guess
I'm in charge of deciding when to run promise completion functions. :D

oden-js/src/context.rs

@@ -1,6 +1,6 @@
 use crate::{
-    callback::new_fn, conversion::RustFunction, module::Module, Atom, ClassID, Error, Result,
+    callback::new_fn, conversion::RustFunction, module::Module, Atom, ClassID, Error, Promise,
-    Runtime, Value, ValueRef, ValueResult,
+    Result, Runtime, Value, ValueRef, ValueResult,
 };
 use bitflags::bitflags;
 use oden_js_sys as sys;
@@ -34,6 +34,7 @@ pub struct ContextRef {
     pub(crate) ctx: *mut sys::JSContext,
 }
 
+// TODO: Should all these require mutability to enforce single-threadedness?
 impl ContextRef {
     pub(crate) fn from_raw(ctx: *mut sys::JSContext) -> Self {
         ContextRef { ctx }
@@ -277,6 +278,64 @@ impl ContextRef {
         Value::from_raw(v, self)
     }
 
+    /// Construct a new promise.
+    pub fn new_promise(&self) -> Result<Promise> {
+        unsafe {
+            let mut resolving_funcs: [sys::JSValue; 2] =
+                [sys::JS_MakeUndefined(), sys::JS_MakeUndefined()];
+            let val =
+                sys::JS_NewPromiseCapability(self.ctx, &mut resolving_funcs as *mut sys::JSValue);
+
+            if sys::JS_ValueGetTag(val) == sys::JS_TAG_EXCEPTION {
+                Err(self.exception_error())
+            } else {
+                Ok(Promise::new(
+                    Value::from_raw(val, self),
+                    Value::from_raw(resolving_funcs[0], self),
+                    Value::from_raw(resolving_funcs[1], self),
+                ))
+            }
+        }
+    }
+
+    /// Construct a new exception object, suitable for throwing.
+    pub fn new_error(&self, message: &str) -> Value {
+        let e = match self.new_string(message) {
+            Ok(e) => e,
+            Err(_) => match self.new_string("INTERNAL ERROR: Embedded NUL in message") {
+                Ok(e) => e,
+
+                // Faulting this hard is inexcusable.
+                Err(_) => return self.exception(),
+            },
+        };
+        unsafe {
+            let err = Value::from_raw(sys::JS_NewError(self.ctx), self);
+
+            // NOTE: Throughout this function we work at the lower-level
+            //       error handling stuff because the errors are easier to
+            //       manage. (We know how it can fail!)
+            if sys::JS_ValueGetTag(err.val) == sys::JS_TAG_EXCEPTION {
+                // GIVE UP; This is out of memory anyway things probably
+                // went wrong because of that. We'll return *that*
+                // exception.
+                return self.exception();
+            }
+
+            sys::JS_DupValue(self.ctx, e.val); // SetProperty takes ownership.
+            let prop = CString::new("message").unwrap();
+            if sys::JS_SetPropertyStr(self.ctx, err.val, prop.as_ptr(), e.val) == -1 {
+                // As before, we're just going to take the exception from
+                // the context, and drop the one we were trying to create
+                // on the floor.
+                return self.exception();
+            }
+
+            // We put the message in, we can return the value.
+            err
+        }
+    }
+
     /// Fetch the global object for the context.
     pub fn global_object(&self) -> ValueResult {
         self.check_exception(unsafe { sys::JS_GetGlobalObject(self.ctx) })
@@ -315,6 +374,23 @@ impl ContextRef {
 
         Error::Exception(exc, desc, stack)
     }
+
+    /// Process all pending async jobs. This includes all promise resolutions.
+    pub fn process_all_jobs(&self) -> Result<()> {
+        // TODO: SAFETY
+        // This is unsafe because multiple contexts can be sharing the same runtime and cause
+        // a race condition on the underlying runtime.
+        loop {
+            let mut ctx1: *mut sys::JSContext = std::ptr::null_mut();
+            let err = unsafe { sys::JS_ExecutePendingJob(sys::JS_GetRuntime(self.ctx), &mut ctx1) };
+            if err == 0 {
+                break;
+            } else if err < 0 {
+                return Err(ContextRef::from_raw(ctx1).exception_error());
+            }
+        }
+        Ok(())
+    }
 }
 
 #[derive(Debug)]

oden-js/src/lib.rs

@@ -8,6 +8,7 @@ mod class;
 mod context;
 mod conversion;
 pub mod module;
+mod promise;
 mod runtime;
 mod value;
 
@@ -15,6 +16,7 @@ pub use atom::{Atom, AtomRef};
 pub use class::{Class, ClassID};
 pub use context::{Context, ContextRef, EvalFlags};
 pub use conversion::*;
+pub use promise::Promise;
 pub use runtime::Runtime;
 pub use value::{Value, ValueRef, ValueType};
 
@@ -49,6 +51,20 @@ pub enum Error {
     ParseError(String, String),
 }
 
+impl Error {
+    // Convert the error into an exception-type object which can be
+    // thrown. This is *different* from try_into_value which just propagates
+    // the error.
+    pub fn to_js_error(&self, context: &ContextRef) -> Value {
+        if let Error::Exception(e, _, _) = self {
+            e.clone()
+        } else {
+            let message = self.to_string();
+            context.new_error(&message)
+        }
+    }
+}
+
 impl From<NulError> for Error {
     fn from(_: NulError) -> Self {
         Error::UnexpectedNul
@@ -75,35 +91,9 @@ pub(crate) fn throw_error(context: &ContextRef, error: Error) -> sys::JSValue {
 }
 
 pub(crate) fn throw_string(context: &ContextRef, message: String) -> sys::JSValue {
-    let ctx = context.ctx;
+    let err = context.new_error(&message);
-    match context.new_string(&message) {
+    unsafe {
-        Ok(e) => unsafe {
+        sys::JS_DupValue(context.ctx, err.val);
-            // Because context.new_string yields an owned Value, and will
+        sys::JS_Throw(context.ctx, err.val)
-            // clean it up on the way out, we need to explicitly DupValue a
-            // reference for the `Throw` to own.
-            let err = sys::JS_NewError(ctx);
-            if sys::JS_ValueGetTag(err) == sys::JS_TAG_EXCEPTION {
-                // GIVE UP; this is out of memory anyway things probably went
-                // wrong because of that.
-                return err;
-            }
-
-            sys::JS_DupValue(ctx, e.val); // SetProperty takes ownership.
-            let prop = CString::new("message").unwrap();
-            if sys::JS_SetPropertyStr(ctx, err, prop.as_ptr(), e.val) == -1 {
-                // Also an out of memory but we need to free the error object
-                // on our way out.
-                sys::JS_FreeValue(ctx, err);
-                return sys::JS_MakeException(); // JS_EXCEPTION
-            }
-
-            sys::JS_Throw(ctx, err)
-        },
-        Err(_) => unsafe {
-            sys::JS_Throw(
-                ctx,
-                sys::JS_NewString(ctx, "Errors within errors: embedded nulls in the description of the error that occurred".as_bytes().as_ptr() as *const i8),
-            )
-        },
     }
 }

oden-js/src/promise.rs

@@ -0,0 +1,34 @@
+use crate::{ContextRef, Value, ValueRef};
+
+#[derive(Debug, Clone)]
+pub struct Promise {
+    pub object: Value,
+    pub resolve_fn: Value,
+    pub reject_fn: Value,
+}
+
+impl Promise {
+    pub(crate) fn new(object: Value, resolve_fn: Value, reject_fn: Value) -> Self {
+        Promise {
+            object,
+            resolve_fn,
+            reject_fn,
+        }
+    }
+
+    pub fn dup(&self, ctx: &ContextRef) -> Self {
+        Promise {
+            object: self.object.dup(ctx),
+            resolve_fn: self.resolve_fn.dup(ctx),
+            reject_fn: self.reject_fn.dup(ctx),
+        }
+    }
+
+    pub fn resolve(self, context: &ContextRef, value: &ValueRef) {
+        let _ = self.resolve_fn.call(context, &[value]);
+    }
+
+    pub fn reject(self, context: &ContextRef, value: &ValueRef) {
+        let _ = self.reject_fn.call(context, &[value]);
+    }
+}

oden-js/src/value.rs

@@ -310,14 +310,16 @@ impl ValueRef {
         Ok(result)
     }
 
-    pub fn call(&self, ctx: &ContextRef) -> Result<Value> {
+    pub fn call(&self, ctx: &ContextRef, args: &[&ValueRef]) -> Result<Value> {
+        // TODO: There *must* be a way to avoid this allocation.
+        let mut args: Vec<sys::JSValue> = args.iter().map(|v| v.val).collect();
         unsafe {
             ctx.check_exception(sys::JS_Call(
                 ctx.ctx,
                 self.val,
                 sys::JS_MakeUndefined(),
-                0,
+                args.len() as i32,
-                std::ptr::null_mut(),
+                args.as_mut_ptr(),
             ))
         }
     }
@@ -345,9 +347,16 @@ impl Value {
     /// the runtime of the specified context, if not the context itself. This
     /// function makes no attempt to validate this.
     pub(crate) fn from_raw(val: sys::JSValue, ctx: &ContextRef) -> Self {
+        Value::from_raw_rt(
+            val,
+            Runtime::from_raw(unsafe { sys::JS_GetRuntime(ctx.ctx) }),
+        )
+    }
+
+    pub(crate) fn from_raw_rt(val: sys::JSValue, rt: Runtime) -> Self {
         Value {
             value: ValueRef::from_raw(val),
-            rt: Runtime::from_raw(unsafe { sys::JS_GetRuntime(ctx.ctx) }),
+            rt,
         }
     }
 
@@ -394,6 +403,15 @@ impl fmt::Debug for Value {
     }
 }
 
+impl Clone for Value {
+    fn clone(&self) -> Self {
+        unsafe {
+            sys::JS_DupValueRT(self.rt.rt, self.val);
+        }
+        Value::from_raw_rt(self.val, self.rt.clone())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/lib.rs

@@ -178,22 +178,6 @@ impl State {
                 label: Some("sprite_bind_group_layout"),
             });
 
-        // TODO: DELETE THIS
-        // let sprite_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
-        //     layout: &sprite_bind_group_layout,
-        //     entries: &[
-        //         wgpu::BindGroupEntry {
-        //             binding: 0,
-        //             resource: wgpu::BindingResource::TextureView(&diffuse_texture.view),
-        //         },
-        //         wgpu::BindGroupEntry {
-        //             binding: 1,
-        //             resource: wgpu::BindingResource::Sampler(&diffuse_texture.sampler),
-        //         },
-        //     ],
-        //     label: Some("diffuse_bind_group"),
-        // });
-
         let screen_uniform = ScreenUniforms::new(size.width, size.height);
         let screen_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
             label: Some("Screen Uniform Buffer"),
@@ -205,7 +189,7 @@ impl State {
             device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                 entries: &[wgpu::BindGroupLayoutEntry {
                     binding: 0,
-                    visibility: wgpu::ShaderStages::VERTEX,
+                    visibility: wgpu::ShaderStages::VERTEX | wgpu::ShaderStages::FRAGMENT,
                     ty: wgpu::BindingType::Buffer {
                         ty: wgpu::BufferBindingType::Uniform,
                         has_dynamic_offset: false,
@@ -225,28 +209,28 @@ impl State {
             label: Some("camera_bind_group"),
         });
 
-        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+        let sprite_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
-            label: Some("Shader"),
+            label: Some("Sprite Shader"),
-            source: wgpu::ShaderSource::Wgsl(include_str!("shader.wgsl").into()),
+            source: wgpu::ShaderSource::Wgsl(include_str!("sprite_shader.wgsl").into()),
         });
 
-        let render_pipeline_layout =
+        let sprite_pipeline_layout =
             device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
-                label: Some("Render Pipeline Layout"),
+                label: Some("Sprite Pipeline Layout"),
                 bind_group_layouts: &[&sprite_bind_group_layout, &screen_uniform_bind_group_layout],
                 push_constant_ranges: &[],
             });
 
-        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+        let sprite_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
-            label: Some("Render Pipeline"),
+            label: Some("Sprite Pipeline"),
-            layout: Some(&render_pipeline_layout),
+            layout: Some(&sprite_pipeline_layout),
             vertex: wgpu::VertexState {
-                module: &shader,
+                module: &sprite_shader,
                 entry_point: "vs_main",
                 buffers: &[Vertex::desc()],
             },
             fragment: Some(wgpu::FragmentState {
-                module: &shader,
+                module: &sprite_shader,
                 entry_point: "fs_main",
                 targets: &[Some(wgpu::ColorTargetState {
                     format: config.format,
@@ -292,7 +276,7 @@ impl State {
             queue,
             config,
             size,
-            render_pipeline,
+            render_pipeline: sprite_pipeline,
             vertex_buffer,
             max_vertices,
             sprite_bind_group_layout,
@@ -529,7 +513,7 @@ pub async fn run() {
 
     let mut state = State::new(window).await;
 
-    let context = script::ScriptContext::new();
+    let mut context = script::ScriptContext::new();
     context.init();
 
     event_loop.run(move |event, _, control_flow| {

src/script.rs

@@ -1,9 +1,11 @@
 use oden_js::{
     module::loader::{ModuleLoader, ModuleSource},
-    Context, ContextRef, Result, Runtime, Value,
+    Context, ContextRef, Promise, Result, Runtime, Value, ValueResult,
 };
+use std::collections::HashMap;
 use std::ffi::OsStr;
 use std::path::Path;
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::mpsc::{channel, Receiver};
 
 pub mod graphics;
@@ -37,6 +39,21 @@ impl ModuleLoader for Loader {
     }
 }
 
+#[derive(Eq, PartialEq, Hash, Debug, Clone, Copy)]
+pub struct PromiseHandle(u64);
+
+impl PromiseHandle {
+    pub fn new() -> Self {
+        static NEXT_ID: AtomicU64 = AtomicU64::new(0);
+        PromiseHandle(NEXT_ID.fetch_add(1, Ordering::SeqCst))
+    }
+}
+
+pub enum ScriptEvent {
+    AddPromise(PromiseHandle, Promise),
+    CompletePromise(PromiseHandle, Box<dyn FnOnce(&ContextRef) -> ValueResult>),
+}
+
 pub struct ScriptContext {
     context: Context,
     init: Value,
@@ -46,6 +63,9 @@ pub struct ScriptContext {
     gfx: graphics::GraphicsAPI,
     _assets: assets::AssetsAPI,
     gfx_receive: Receiver<graphics::GraphicsCommand>,
+
+    script_receive: Receiver<ScriptEvent>,
+    promises: HashMap<PromiseHandle, Promise>,
 }
 
 impl ScriptContext {
@@ -58,6 +78,7 @@ impl ScriptContext {
         context.add_intrinsic_operators();
 
         let (gfx_send, gfx_receive) = channel();
+        let (script_send, script_receive) = channel();
 
         let gfx = graphics::GraphicsAPI::define(&context, gfx_send.clone())
             .expect("Graphics module should load without error");
@@ -89,6 +110,9 @@ impl ScriptContext {
             gfx_receive,
 
             _assets: assets,
+
+            script_receive,
+            promises: HashMap::new(),
         }
     }
 
@@ -96,18 +120,52 @@ impl ScriptContext {
     //       We would want a bi-directional gate for frames to not let the
     //       game thread go to fast probably? And to discard whole frames &c.
 
-    pub fn init(&self) {
+    pub fn init(&mut self) {
-        self.init.call(&self.context).expect("Exception in init");
+        self.init
+            .call(&self.context, &[])
+            .expect("Exception in init");
     }
 
-    pub fn update(&self) {
+    pub fn update(&mut self) {
+        // Handle any promises that have completed before calling update.
+        while let Ok(event) = self.script_receive.try_recv() {
+            match event {
+                // TODO: Capture debugging information.
+                ScriptEvent::AddPromise(handle, promise) => {
+                    self.promises.insert(handle, promise);
+                }
+                ScriptEvent::CompletePromise(handle, value_producer) => {
+                    if let Some(promise) = self.promises.remove(&handle) {
+                        let result = value_producer(&self.context);
+                        match result {
+                            Ok(v) => {
+                                promise.resolve(&self.context, &v);
+                            }
+                            Err(e) => {
+                                let error = e.to_js_error(&self.context);
+                                promise.reject(&self.context, &error);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        // Tell the runtime to process all pending "jobs".
+        self.context
+            .process_all_jobs()
+            .expect("Error processing async jobs");
+
+        // Now run the update function.
         self.update
-            .call(&self.context)
+            .call(&self.context, &[])
             .expect("Exception in update");
     }
 
-    pub fn render(&self) -> Vec<graphics::GraphicsCommand> {
+    pub fn render(&mut self) -> Vec<graphics::GraphicsCommand> {
-        self.draw.call(&self.context).expect("Exception in draw");
+        self.draw
+            .call(&self.context, &[])
+            .expect("Exception in draw");
         self.gfx.end_frame();
 
         let mut commands = Vec::new();

src/shader.wgsl

@@ -48,13 +48,30 @@ const RES = vec2f(320.0, 240.0); // The logical resolution of the screen.
   return out;
 }
 
-// Fragment shader
+// Fragment shader....
 
 @group(0) @binding(0) var t_diffuse : texture_2d<f32>;
 @group(0) @binding(1) var s_diffuse : sampler;
 
 @fragment fn fs_main(in : VertexOutput)->@location(0) vec4<f32> {
+  // The "screen" is centered in the window, so anything outside of the
+  // screen borders should be black. But *where are they*?
+  let RES_AR = RES.x / RES.y; // The aspect ratio of the logical screen.
+  let screen_ar = screen.resolution.x / screen.resolution.y;
+  var black_mod = 1.0;
+  if (screen_ar > RES_AR) {
+    // Wider than tall, bars are on the left and right.
+    let active_width = screen.resolution.y * RES_AR;
+    let half_delta = (screen.resolution.x - active_width) / 2.0;
+    if (in.clip_position.x < half_delta ||
+        in.clip_position.x > half_delta + active_width) {
+      black_mod = 0.0;
+    }
+  } else {
+    // Taller than wide, bars are on top and bottom.
+  }
+
   let dims = vec2f(textureDimensions(t_diffuse));
 
-  return textureSample(t_diffuse, s_diffuse, in.tex_coords / dims);
+  return black_mod * textureSample(t_diffuse, s_diffuse, in.tex_coords / dims);
 }