ruby fibers POC

Cargo.toml

@@ -35,6 +35,7 @@ magnus = { version = "0.7.1", optional = true }
 rb-sys = { version = "0.9", default-features = false, features = ["link-ruby", "ruby-static"], optional = true }
 crossbeam-channel = "0.5.15"
 libc = "0.2.172"
+tempfile = "3.20.0"
 
 [[example]]
 name = "call_function_from_rust_rhai"

assets/examples/ruby/promises.rb

@@ -1,3 +1,2 @@
-get_player_name.and_then do |name|
-  puts name
-end
+puts get_player_name.await
+quit

examples/ruby/promises.rs

@@ -9,7 +9,8 @@ fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
         .add_scripting::<RubyRuntime>(|builder| {
-            builder.add_function(
+            builder
+                .add_function(
                     String::from("get_player_name"),
                     |player_names: Query<&Name, With<Player>>| {
                         player_names
@@ -17,7 +18,10 @@ fn main() {
                             .expect("Missing player_names")
                             .to_string()
                     },
-            );
+                )
+                .add_function(String::from("quit"), |mut exit: EventWriter<AppExit>| {
+                    exit.write(AppExit::Success);
+                });
         })
         .add_systems(Startup, startup)
         .run();

src/runtimes/ruby.rs

@@ -1,11 +1,15 @@
 use std::{
     collections::HashMap,
     ffi::CString,
+    io::Write,
     sync::{Arc, Condvar, LazyLock, Mutex},
     thread::{self, JoinHandle},
 };
 
-use ::magnus::{typed_data::Inspect, value::Opaque};
+use ::magnus::{
+    typed_data::Inspect,
+    value::{self, Opaque},
+};
 use bevy::{
     asset::Asset,
     ecs::{component::Component, entity::Entity, resource::Resource, schedule::ScheduleLabel},
@@ -19,7 +23,7 @@ use magnus::{
     value::{Lazy, ReprValue},
 };
 use magnus::{method, prelude::*};
-use rb_sys::{VALUE, ruby_init_stack};
+use rb_sys::{VALUE, rb_load, ruby_init_stack};
 use serde::Deserialize;
 
 use crate::{
@@ -174,6 +178,25 @@ fn then(r_self: magnus::Value) -> magnus::Value {
         .into_value()
 }
 
+fn await_promise(r_self: magnus::Value) -> magnus::Value {
+    let promise: &Promise<(), RubyValue> =
+        TryConvert::try_convert(r_self).expect("Couldn't convert self to Promise");
+    let ruby =
+        Ruby::get().expect("Failed to get a handle to Ruby API when registering Promise callback");
+    let fiber = Opaque::from(ruby.fiber_current());
+    promise
+        .clone()
+        .then(RubyValue::new(
+            ruby.proc_from_fn(move |ruby, args, _| {
+                let fiber = ruby.get_inner(fiber);
+                fiber.resume::<_, magnus::Value>(args).unwrap();
+            })
+            .as_value(),
+        ))
+        .into_value();
+    ruby.fiber_yield::<_, magnus::Value>(()).unwrap()
+}
+
 #[derive(Clone, Debug)]
 #[magnus::wrap(class = "Bevy::Entity")]
 pub struct BevyEntity(pub Entity);
@@ -266,6 +289,7 @@ impl Default for RubyRuntime {
 
                 let promise = module.define_class("Promise", ruby.class_object())?;
                 promise.define_method("and_then", magnus::method!(then, 0))?;
+                promise.define_method("await", magnus::method!(await_promise, 0))?;
 
                 let vec3 = module.define_class("Vec3", ruby.class_object())?;
                 vec3.define_singleton_method("new", function!(BevyVec3::new, 3))?;
@@ -392,10 +416,35 @@ impl Runtime for RubyRuntime {
     ) -> Result<Self::ScriptData, crate::ScriptingError> {
         let script = script.0.clone();
         self.execute_in_thread(Box::new(move |ruby: &Ruby| {
+            let p = Opaque::from(ruby.proc_from_fn(move |ruby, _args, _block| {
                 Self::with_current_entity(ruby, entity, || {
-                ruby.eval::<magnus::value::Value>(&script)
-                    .map_err(<magnus::Error as Into<ScriptingError>>::into)
-            })?;
+                    let mut tmpfile = tempfile::NamedTempFile::new().unwrap();
+                    tmpfile.write(script.as_bytes()).unwrap();
+                    unsafe {
+                        let file = rb_sys::rb_str_new_cstr(
+                            CString::new(tmpfile.path().to_str().unwrap())
+                                .unwrap()
+                                .into_raw(),
+                        );
+                        rb_load(file, 1);
+                    };
+                    // ruby.eval::<magnus::value::Value>(&script)
+                    //     .map_err(<magnus::Error as Into<ScriptingError>>::into)
+                    Ok::<(), ScriptingError>(())
+                })
+                .unwrap();
+            }));
+            let fiber = ruby
+                .fiber_new_from_fn(Default::default(), move |ruby, _args, _block| {
+                    let p = ruby.get_inner(p);
+
+                    p.call::<_, value::Value>(()).unwrap();
+
+                    Ok(())
+                })
+                .unwrap();
+            fiber.resume::<_, value::Value>(()).unwrap();
+
             Ok::<Self::ScriptData, ScriptingError>(RubyScriptData)
         }))
     }