make eval copy

Cargo.lock

@@ -2529,6 +2529,7 @@ dependencies = [
  "exitcode",
  "futures-channel",
  "futures-util",
+ "generational-box",
  "global-hotkey",
  "infer 0.11.0",
  "muda",
@@ -2662,6 +2663,7 @@ dependencies = [
  "enumset",
  "euclid",
  "futures-channel",
+ "generational-box",
  "keyboard-types",
  "rfd",
  "serde",
@@ -2725,6 +2727,7 @@ dependencies = [
  "dioxus-interpreter-js",
  "futures-channel",
  "futures-util",
+ "generational-box",
  "minify-js",
  "once_cell",
  "pretty_env_logger",
@@ -2912,6 +2915,7 @@ dependencies = [
  "dioxus-signals",
  "fern",
  "fs_extra",
+ "generational-box",
  "http 0.2.11",
  "lru 0.10.1",
  "rustc-hash",
@@ -2962,6 +2966,7 @@ dependencies = [
  "dioxus-web",
  "futures-channel",
  "futures-util",
+ "generational-box",
  "gloo-dialogs",
  "gloo-timers",
  "js-sys",

packages/desktop/Cargo.toml

@@ -20,6 +20,7 @@ dioxus-html = { workspace = true, features = [
 dioxus-interpreter-js = { workspace = true, features = ["binary-protocol"] }
 dioxus-hot-reload = { workspace = true, optional = true }
 dioxus-cli-config = { workspace = true }
+generational-box = { workspace = true }
 
 serde = "1.0.136"
 serde_json = "1.0.79"

packages/desktop/src/eval.rs

@@ -1,7 +1,5 @@
-#![allow(clippy::await_holding_refcell_ref)]
-use async_trait::async_trait;
 use dioxus_html::prelude::{EvalError, EvalProvider, Evaluator};
-use std::{cell::RefCell, rc::Rc};
+use generational_box::{AnyStorage, GenerationalBox, UnsyncStorage};
 
 use crate::{query::Query, DesktopContext};
 
@@ -17,55 +15,57 @@ impl DesktopEvalProvider {
 }
 
 impl EvalProvider for DesktopEvalProvider {
-    fn new_evaluator(&self, js: String) -> Result<Box<dyn Evaluator>, EvalError> {
-        Ok(Box::new(DesktopEvaluator::new(
-            self.desktop_ctx.clone(),
-            js,
-        )))
+    fn new_evaluator(&self, js: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError> {
+        Ok(DesktopEvaluator::create(self.desktop_ctx.clone(), js))
     }
 }
 
 /// Represents a desktop-target's JavaScript evaluator.
 pub(crate) struct DesktopEvaluator {
-    query: Rc<RefCell<Query<serde_json::Value>>>,
+    query: Query<serde_json::Value>,
 }
 
 impl DesktopEvaluator {
     /// Creates a new evaluator for desktop-based targets.
-    pub fn new(desktop_ctx: DesktopContext, js: String) -> Self {
+    pub fn create(desktop_ctx: DesktopContext, js: String) -> GenerationalBox<Box<dyn Evaluator>> {
         let ctx = desktop_ctx.clone();
         let query = desktop_ctx.query.new_query(&js, ctx);
 
-        Self {
-            query: Rc::new(RefCell::new(query)),
-        }
+        // We create a generational box that is owned by the query slot so that when we drop the query slot, the generational box is also dropped.
+        let owner = UnsyncStorage::owner();
+        let query_id = query.id;
+        let query = owner.insert(Box::new(DesktopEvaluator { query }) as Box<dyn Evaluator>);
+        desktop_ctx.query.active_requests.slab.borrow_mut()[query_id].owner = Some(owner);
+
+        query
     }
 }
 
-#[async_trait(?Send)]
 impl Evaluator for DesktopEvaluator {
-    async fn join(&self) -> Result<serde_json::Value, EvalError> {
+    fn poll_join(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
         self.query
-            .borrow_mut()
-            .result()
-            .await
+            .poll_result(cx)
             .map_err(|e| EvalError::Communication(e.to_string()))
     }
 
     /// Sends a message to the evaluated JavaScript.
     fn send(&self, data: serde_json::Value) -> Result<(), EvalError> {
-        if let Err(e) = self.query.borrow_mut().send(data) {
+        if let Err(e) = self.query.send(data) {
             return Err(EvalError::Communication(e.to_string()));
         }
         Ok(())
     }
 
     /// Gets an UnboundedReceiver to receive messages from the evaluated JavaScript.
-    async fn recv(&mut self) -> Result<serde_json::Value, EvalError> {
+    fn poll_recv(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
         self.query
-            .borrow_mut()
-            .recv()
-            .await
+            .poll_recv(cx)
             .map_err(|e| EvalError::Communication(e.to_string()))
     }
 }

packages/desktop/src/query.rs

@@ -1,7 +1,8 @@
 use std::{cell::RefCell, rc::Rc};
 
 use crate::DesktopContext;
-use futures_util::StreamExt;
+use futures_util::{FutureExt, StreamExt};
+use generational_box::Owner;
 use serde::{de::DeserializeOwned, Deserialize};
 use serde_json::Value;
 use slab::Slab;
@@ -43,8 +44,8 @@ let dioxus = {
 
 /// Tracks what query ids are currently active
 
-struct SharedSlab<T = ()> {
-    slab: Rc<RefCell<Slab<T>>>,
+pub(crate) struct SharedSlab<T = ()> {
+    pub slab: Rc<RefCell<Slab<T>>>,
 }
 
 impl<T> Clone for SharedSlab<T> {
@@ -63,9 +64,10 @@ impl<T> Default for SharedSlab<T> {
     }
 }
 
-struct QueryEntry {
+pub(crate) struct QueryEntry {
     channel_sender: futures_channel::mpsc::UnboundedSender<Value>,
     return_sender: Option<futures_channel::oneshot::Sender<Value>>,
+    pub owner: Option<Owner>,
 }
 
 const QUEUE_NAME: &str = "__msg_queues";
@@ -73,7 +75,7 @@ const QUEUE_NAME: &str = "__msg_queues";
 /// Handles sending and receiving arbitrary queries from the webview. Queries can be resolved non-sequentially, so we use ids to track them.
 #[derive(Clone, Default)]
 pub(crate) struct QueryEngine {
-    active_requests: SharedSlab<QueryEntry>,
+    pub active_requests: SharedSlab<QueryEntry>,
 }
 
 impl QueryEngine {
@@ -88,6 +90,7 @@ impl QueryEngine {
         let request_id = self.active_requests.slab.borrow_mut().insert(QueryEntry {
             channel_sender: tx,
             return_sender: Some(return_tx),
+            owner: None,
         });
 
         // start the query
@@ -161,7 +164,7 @@ pub(crate) struct Query<V: DeserializeOwned> {
     slab: SharedSlab<QueryEntry>,
     receiver: futures_channel::mpsc::UnboundedReceiver<Value>,
     return_receiver: Option<futures_channel::oneshot::Receiver<Value>>,
-    id: usize,
+    pub id: usize,
     phantom: std::marker::PhantomData<V>,
 }
 
@@ -198,9 +201,14 @@ impl<V: DeserializeOwned> Query<V> {
         Ok(())
     }
 
-    /// Receive a message from the query
-    pub async fn recv(&mut self) -> Result<Value, QueryError> {
-        self.receiver.next().await.ok_or(QueryError::Recv)
+    /// Poll the query for a message
+    pub fn poll_recv(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<Value, QueryError>> {
+        self.receiver
+            .poll_next_unpin(cx)
+            .map(|result| result.ok_or(QueryError::Recv))
     }
 
     /// Receive the result of the query
@@ -210,6 +218,17 @@ impl<V: DeserializeOwned> Query<V> {
             None => Err(QueryError::Finished),
         }
     }
+
+    /// Poll the query for a result
+    pub fn poll_result(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<Value, QueryError>> {
+        match self.return_receiver.as_mut() {
+            Some(receiver) => receiver.poll_unpin(cx).map_err(|_| QueryError::Recv),
+            None => std::task::Poll::Ready(Err(QueryError::Finished)),
+        }
+    }
 }
 
 impl<V: DeserializeOwned> Drop for Query<V> {

packages/html/Cargo.toml

@@ -13,6 +13,7 @@ keywords = ["dom", "ui", "gui", "react"]
 dioxus-core = { workspace = true }
 dioxus-rsx = { workspace = true, features = ["hot_reload"], optional = true }
 dioxus-html-internal-macro = { workspace = true }
+generational-box = { workspace = true }
 serde = { version = "1", features = ["derive"], optional = true }
 serde_repr = { version = "0.1", optional = true }
 wasm-bindgen = { workspace = true, optional = true }

packages/html/src/eval.rs

@@ -1,26 +1,32 @@
 #![allow(clippy::await_holding_refcell_ref)]
 
-use async_trait::async_trait;
 use dioxus_core::prelude::*;
-use std::future::{Future, IntoFuture};
+use generational_box::GenerationalBox;
+use std::future::{poll_fn, Future, IntoFuture};
 use std::pin::Pin;
 use std::rc::Rc;
+use std::task::{Context, Poll};
 
 /// A struct that implements EvalProvider is sent through [`ScopeState`]'s provide_context function
 /// so that [`use_eval`] can provide a platform agnostic interface for evaluating JavaScript code.
 pub trait EvalProvider {
-    fn new_evaluator(&self, js: String) -> Result<Box<dyn Evaluator>, EvalError>;
+    fn new_evaluator(&self, js: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError>;
 }
 
 /// The platform's evaluator.
-#[async_trait(?Send)]
 pub trait Evaluator {
     /// Sends a message to the evaluated JavaScript.
     fn send(&self, data: serde_json::Value) -> Result<(), EvalError>;
     /// Receive any queued messages from the evaluated JavaScript.
-    async fn recv(&mut self) -> Result<serde_json::Value, EvalError>;
+    fn poll_recv(
+        &mut self,
+        context: &mut Context<'_>,
+    ) -> Poll<Result<serde_json::Value, EvalError>>;
     /// Gets the return value of the JavaScript
-    async fn join(&self) -> Result<serde_json::Value, EvalError>;
+    fn poll_join(
+        &mut self,
+        context: &mut Context<'_>,
+    ) -> Poll<Result<serde_json::Value, EvalError>>;
 }
 
 type EvalCreator = Rc<dyn Fn(&str) -> Result<UseEval, EvalError>>;
@@ -54,28 +60,36 @@ pub fn eval(script: &str) -> Result<UseEval, EvalError> {
 
 /// A wrapper around the target platform's evaluator.
 pub struct UseEval {
-    evaluator: Box<dyn Evaluator + 'static>,
+    evaluator: GenerationalBox<Box<dyn Evaluator>>,
 }
 
 impl UseEval {
     /// Creates a new UseEval
-    pub fn new(evaluator: Box<dyn Evaluator + 'static>) -> Self {
+    pub fn new(evaluator: GenerationalBox<Box<dyn Evaluator + 'static>>) -> Self {
         Self { evaluator }
     }
 
     /// Sends a [`serde_json::Value`] to the evaluated JavaScript.
     pub fn send(&self, data: serde_json::Value) -> Result<(), EvalError> {
-        self.evaluator.send(data)
+        self.evaluator.read().send(data)
     }
 
     /// Gets an UnboundedReceiver to receive messages from the evaluated JavaScript.
     pub async fn recv(&mut self) -> Result<serde_json::Value, EvalError> {
-        self.evaluator.recv().await
+        poll_fn(|cx| match self.evaluator.try_write() {
+            Ok(mut evaluator) => evaluator.poll_recv(cx),
+            Err(_) => Poll::Ready(Err(EvalError::Finished)),
+        })
+        .await
     }
 
     /// Gets the return value of the evaluated JavaScript.
     pub async fn join(self) -> Result<serde_json::Value, EvalError> {
-        self.evaluator.join().await
+        poll_fn(|cx| match self.evaluator.try_write() {
+            Ok(mut evaluator) => evaluator.poll_join(cx),
+            Err(_) => Poll::Ready(Err(EvalError::Finished)),
+        })
+        .await
     }
 }
 
@@ -92,7 +106,7 @@ impl IntoFuture for UseEval {
 #[derive(Debug)]
 pub enum EvalError {
     /// The platform does not support evaluating JavaScript.
-    Unspported,
+    Unsupported,
 
     /// The provided JavaScript has already been ran.
     Finished,

packages/liveview/Cargo.toml

@@ -29,6 +29,7 @@ dioxus-core = { workspace = true, features = ["serialize"] }
 dioxus-interpreter-js = { workspace = true, features = ["binary-protocol"] }
 dioxus-hot-reload = { workspace = true, optional = true }
 dioxus-cli-config = { workspace = true }
+generational-box = { workspace = true }
 
 # warp
 warp = { version = "0.3.3", optional = true }

packages/liveview/src/eval.rs

@@ -1,9 +1,7 @@
-#![allow(clippy::await_holding_refcell_ref)]
-
-use async_trait::async_trait;
 use dioxus_core::ScopeId;
 use dioxus_html::prelude::{EvalError, EvalProvider, Evaluator};
-use std::{cell::RefCell, rc::Rc};
+use generational_box::{AnyStorage, GenerationalBox, UnsyncStorage};
+use std::rc::Rc;
 
 use crate::query::{Query, QueryEngine};
 
@@ -14,48 +12,51 @@ pub fn init_eval() {
     ScopeId::ROOT.provide_context(provider);
 }
 
-/// Reprents the desktop-target's provider of evaluators.
+/// Reprints the desktop-target's provider of evaluators.
 pub struct DesktopEvalProvider {
     query: QueryEngine,
 }
 
 impl EvalProvider for DesktopEvalProvider {
-    fn new_evaluator(&self, js: String) -> Result<Box<dyn Evaluator>, EvalError> {
-        Ok(Box::new(DesktopEvaluator::new(self.query.clone(), js)))
+    fn new_evaluator(&self, js: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError> {
+        Ok(DesktopEvaluator::create(self.query.clone(), js))
     }
 }
 
 /// Reprents a desktop-target's JavaScript evaluator.
 pub(crate) struct DesktopEvaluator {
-    query: Rc<RefCell<Query<serde_json::Value>>>,
+    query: Query<serde_json::Value>,
 }
 
 impl DesktopEvaluator {
     /// Creates a new evaluator for desktop-based targets.
-    pub fn new(query: QueryEngine, js: String) -> Self {
-        let query = query.new_query(&js);
+    pub fn create(query_engine: QueryEngine, js: String) -> GenerationalBox<Box<dyn Evaluator>> {
+        let query = query_engine.new_query(&js);
+        // We create a generational box that is owned by the query slot so that when we drop the query slot, the generational box is also dropped.
+        let owner = UnsyncStorage::owner();
+        let query_id = query.id;
+        let query = owner.insert(Box::new(DesktopEvaluator { query }) as Box<dyn Evaluator>);
+        query_engine.active_requests.slab.borrow_mut()[query_id].owner = Some(owner);
 
-        Self {
-            query: Rc::new(RefCell::new(query)),
-        }
+        query
     }
 }
 
-#[async_trait(?Send)]
 impl Evaluator for DesktopEvaluator {
     /// # Panics
     /// This will panic if the query is currently being awaited.
-    async fn join(&self) -> Result<serde_json::Value, EvalError> {
+    fn poll_join(
+        &mut self,
+        context: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
         self.query
-            .borrow_mut()
-            .result()
-            .await
+            .poll_result(context)
             .map_err(|e| EvalError::Communication(e.to_string()))
     }
 
     /// Sends a message to the evaluated JavaScript.
     fn send(&self, data: serde_json::Value) -> Result<(), EvalError> {
-        if let Err(e) = self.query.borrow_mut().send(data) {
+        if let Err(e) = self.query.send(data) {
             return Err(EvalError::Communication(e.to_string()));
         }
         Ok(())
@@ -65,11 +66,12 @@ impl Evaluator for DesktopEvaluator {
     ///
     /// # Panics
     /// This will panic if the query is currently being awaited.
-    async fn recv(&mut self) -> Result<serde_json::Value, EvalError> {
+    fn poll_recv(
+        &mut self,
+        context: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
         self.query
-            .borrow_mut()
-            .recv()
-            .await
+            .poll_recv(context)
             .map_err(|e| EvalError::Communication(e.to_string()))
     }
 }

packages/liveview/src/query.rs

@@ -1,5 +1,7 @@
 use std::{cell::RefCell, rc::Rc};
 
+use futures_util::FutureExt;
+use generational_box::{Owner, UnsyncStorage};
 use serde::{de::DeserializeOwned, Deserialize};
 use serde_json::Value;
 use slab::Slab;
@@ -42,8 +44,8 @@ let dioxus = {
 
 /// Tracks what query ids are currently active
 
-struct SharedSlab<T = ()> {
-    slab: Rc<RefCell<Slab<T>>>,
+pub(crate) struct SharedSlab<T = ()> {
+    pub(crate) slab: Rc<RefCell<Slab<T>>>,
 }
 
 impl<T> Clone for SharedSlab<T> {
@@ -62,9 +64,10 @@ impl<T> Default for SharedSlab<T> {
     }
 }
 
-struct QueryEntry {
+pub(crate) struct QueryEntry {
     channel_sender: tokio::sync::mpsc::UnboundedSender<Value>,
     return_sender: Option<tokio::sync::oneshot::Sender<Value>>,
+    pub(crate) owner: Option<Owner<UnsyncStorage>>,
 }
 
 const QUEUE_NAME: &str = "__msg_queues";
@@ -72,7 +75,7 @@ const QUEUE_NAME: &str = "__msg_queues";
 /// Handles sending and receiving arbitrary queries from the webview. Queries can be resolved non-sequentially, so we use ids to track them.
 #[derive(Clone)]
 pub(crate) struct QueryEngine {
-    active_requests: SharedSlab<QueryEntry>,
+    pub(crate) active_requests: SharedSlab<QueryEntry>,
     query_tx: tokio::sync::mpsc::UnboundedSender<String>,
 }
 
@@ -91,6 +94,7 @@ impl QueryEngine {
         let request_id = self.active_requests.slab.borrow_mut().insert(QueryEntry {
             channel_sender: tx,
             return_sender: Some(return_tx),
+            owner: None,
         });
 
         // start the query
@@ -162,7 +166,7 @@ pub(crate) struct Query<V: DeserializeOwned> {
     query_engine: QueryEngine,
     pub receiver: tokio::sync::mpsc::UnboundedReceiver<Value>,
     pub return_receiver: Option<tokio::sync::oneshot::Receiver<Value>>,
-    id: usize,
+    pub id: usize,
     phantom: std::marker::PhantomData<V>,
 }
 
@@ -198,12 +202,14 @@ impl<V: DeserializeOwned> Query<V> {
         Ok(())
     }
 
-    /// Receive a message from the query
-    pub async fn recv(&mut self) -> Result<Value, QueryError> {
+    /// Poll the query for a message
+    pub fn poll_recv(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<Value, QueryError>> {
         self.receiver
-            .recv()
-            .await
-            .ok_or(QueryError::Recv(RecvError::Closed))
+            .poll_recv(cx)
+            .map(|result| result.ok_or(QueryError::Recv(RecvError::Closed)))
     }
 
     /// Receive the result of the query
@@ -215,6 +221,19 @@ impl<V: DeserializeOwned> Query<V> {
             None => Err(QueryError::Finished),
         }
     }
+
+    /// Poll the query for a result
+    pub fn poll_result(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<Value, QueryError>> {
+        match self.return_receiver.as_mut() {
+            Some(receiver) => receiver
+                .poll_unpin(cx)
+                .map_err(|_| QueryError::Recv(RecvError::Closed)),
+            None => std::task::Poll::Ready(Err(QueryError::Finished)),
+        }
+    }
 }
 
 impl<V: DeserializeOwned> Drop for Query<V> {

packages/ssr/Cargo.toml

@@ -11,6 +11,7 @@ keywords = ["dom", "ui", "gui", "react", "ssr"]
 [dependencies]
 dioxus-core = { workspace = true, features = ["serialize"] }
 dioxus-html = { workspace = true, features = ["eval"]}
+generational-box = { workspace = true }
 askama_escape = "0.10.3"
 thiserror = "1.0.23"
 rustc-hash = "1.1.0"

packages/ssr/src/eval.rs

@@ -1,6 +1,7 @@
 use async_trait::async_trait;
 use dioxus_core::ScopeId;
 use dioxus_html::prelude::{EvalError, EvalProvider, Evaluator};
+use generational_box::{AnyStorage, GenerationalBox, UnsyncStorage};
 use std::rc::Rc;
 
 /// Provides the SSREvalProvider through [`cx.provide_context`].
@@ -12,8 +13,9 @@ pub fn init_eval() {
 /// Reprents the ssr-target's provider of evaluators.
 pub struct SSREvalProvider;
 impl EvalProvider for SSREvalProvider {
-    fn new_evaluator(&self, _: String) -> Result<Box<dyn Evaluator>, EvalError> {
-        Ok(Box::new(SSREvaluator) as Box<dyn Evaluator + 'static>)
+    fn new_evaluator(&self, _: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError> {
+        let owner = UnsyncStorage::owner();
+        Ok(owner.insert(Box::new(SSREvaluator) as Box<dyn Evaluator + 'static>))
     }
 }
 
@@ -23,20 +25,22 @@ pub struct SSREvaluator;
 // In ssr rendering we never run or resolve evals.
 #[async_trait(?Send)]
 impl Evaluator for SSREvaluator {
-    /// Runs the evaluated JavaScript.
-    async fn join(&self) -> Result<serde_json::Value, EvalError> {
-        std::future::pending::<()>().await;
-        unreachable!()
-    }
-
     /// Sends a message to the evaluated JavaScript.
     fn send(&self, _el: serde_json::Value) -> Result<(), EvalError> {
         Ok(())
     }
 
-    /// Gets an UnboundedReceiver to receive messages from the evaluated JavaScript.
-    async fn recv(&mut self) -> Result<serde_json::Value, EvalError> {
-        std::future::pending::<()>().await;
-        unreachable!()
+    fn poll_recv(
+        &mut self,
+        _cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
+        std::task::Poll::Pending
+    }
+
+    fn poll_join(
+        &mut self,
+        _cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
+        std::task::Poll::Pending
     }
 }

packages/web/Cargo.toml

@@ -16,6 +16,7 @@ dioxus-interpreter-js = { workspace = true, features = [
     "minimal_bindings",
     "webonly",
 ] }
+generational-box = { workspace = true }
 
 js-sys = "0.3.56"
 wasm-bindgen = { workspace = true }

packages/web/src/eval.rs

@@ -1,10 +1,10 @@
-use async_trait::async_trait;
 use dioxus_core::ScopeId;
 use dioxus_html::prelude::{EvalError, EvalProvider, Evaluator};
 use futures_util::StreamExt;
+use generational_box::{AnyStorage, GenerationalBox, UnsyncStorage};
 use js_sys::Function;
 use serde_json::Value;
-use std::{cell::RefCell, rc::Rc, str::FromStr};
+use std::{rc::Rc, str::FromStr};
 use wasm_bindgen::prelude::*;
 
 /// Provides the WebEvalProvider through [`cx.provide_context`].
@@ -16,8 +16,8 @@ pub fn init_eval() {
 /// Represents the web-target's provider of evaluators.
 pub struct WebEvalProvider;
 impl EvalProvider for WebEvalProvider {
-    fn new_evaluator(&self, js: String) -> Result<Box<dyn Evaluator>, EvalError> {
-        WebEvaluator::new(js).map(|eval| Box::new(eval) as Box<dyn Evaluator + 'static>)
+    fn new_evaluator(&self, js: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError> {
+        WebEvaluator::create(js)
     }
 }
 
@@ -30,19 +30,23 @@ const PROMISE_WRAPPER: &str = r#"
     "#;
 
 /// Represents a web-target's JavaScript evaluator.
-pub struct WebEvaluator {
+struct WebEvaluator {
     dioxus: Dioxus,
     channel_receiver: futures_channel::mpsc::UnboundedReceiver<serde_json::Value>,
-    result: RefCell<Option<serde_json::Value>>,
+    result: Option<serde_json::Value>,
 }
 
 impl WebEvaluator {
     /// Creates a new evaluator for web-based targets.
-    pub fn new(js: String) -> Result<Self, EvalError> {
+    fn create(js: String) -> Result<GenerationalBox<Box<dyn Evaluator>>, EvalError> {
         let (mut channel_sender, channel_receiver) = futures_channel::mpsc::unbounded();
+        let owner = UnsyncStorage::owner();
+        let invalid = owner.invalid();
 
         // This Rc cloning mess hurts but it seems to work..
         let recv_value = Closure::<dyn FnMut(JsValue)>::new(move |data| {
+            // Drop the owner when the sender is dropped.
+            let _ = &owner;
             match serde_wasm_bindgen::from_value::<serde_json::Value>(data) {
                 Ok(data) => _ = channel_sender.start_send(data),
                 Err(e) => {
@@ -84,19 +88,27 @@ impl WebEvaluator {
             }
         };
 
-        Ok(Self {
+        invalid.set(Box::new(Self {
             dioxus,
             channel_receiver,
-            result: RefCell::new(Some(result)),
-        })
+            result: Some(result),
+        }) as Box<dyn Evaluator + 'static>);
+
+        Ok(invalid)
     }
 }
 
-#[async_trait(?Send)]
 impl Evaluator for WebEvaluator {
     /// Runs the evaluated JavaScript.
-    async fn join(&self) -> Result<serde_json::Value, EvalError> {
-        self.result.take().ok_or(EvalError::Finished)
+    fn poll_join(
+        &mut self,
+        _cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
+        if let Some(result) = self.result.take() {
+            std::task::Poll::Ready(Ok(result))
+        } else {
+            std::task::Poll::Ready(Err(EvalError::Finished))
+        }
     }
 
     /// Sends a message to the evaluated JavaScript.
@@ -111,11 +123,15 @@ impl Evaluator for WebEvaluator {
     }
 
     /// Gets an UnboundedReceiver to receive messages from the evaluated JavaScript.
-    async fn recv(&mut self) -> Result<serde_json::Value, EvalError> {
-        self.channel_receiver
-            .next()
-            .await
-            .ok_or_else(|| EvalError::Communication("failed to receive data from js".to_string()))
+    fn poll_recv(
+        &mut self,
+        context: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
+        self.channel_receiver.poll_next_unpin(context).map(|poll| {
+            poll.ok_or_else(|| {
+                EvalError::Communication("failed to receive data from js".to_string())
+            })
+        })
     }
 }