fix: don't have Rc cycles in DioxusElement or Queries (#3618)

Author: jkelleyrtp

packages/desktop/src/document.rs

@@ -88,8 +88,7 @@ pub(crate) struct DesktopEvaluator {
 impl DesktopEvaluator {
     /// Creates a new evaluator for desktop-based targets.
     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);
+        let query = desktop_ctx.query.new_query(&js, desktop_ctx.clone());
 
         // 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();

packages/desktop/src/element.rs

@@ -1,21 +1,24 @@
+use std::rc::Rc;
+
 use dioxus_core::ElementId;
 use dioxus_html::{
     geometry::{PixelsRect, PixelsSize, PixelsVector2D},
     MountedResult, RenderedElementBacking,
 };
 
-use crate::{desktop_context::DesktopContext, query::QueryEngine};
+use crate::{desktop_context::DesktopContext, query::QueryEngine, WeakDesktopContext};
 
 #[derive(Clone)]
 /// A mounted element passed to onmounted events
 pub struct DesktopElement {
     id: ElementId,
-    webview: DesktopContext,
+    webview: WeakDesktopContext,
     query: QueryEngine,
 }
 
 impl DesktopElement {
     pub(crate) fn new(id: ElementId, webview: DesktopContext, query: QueryEngine) -> Self {
+        let webview = Rc::downgrade(&webview);
         Self { id, webview, query }
     }
 }
@@ -28,10 +31,13 @@ macro_rules! scripted_getter {
             Box<dyn futures_util::Future<Output = dioxus_html::MountedResult<$output_type>>>,
         > {
             let script = format!($script, id = self.id.0);
-
+            let webview = self
+                .webview
+                .upgrade()
+                .expect("Webview should be alive if the element is being queried");
             let fut = self
                 .query
-                .new_query::<Option<$output_type>>(&script, self.webview.clone())
+                .new_query::<Option<$output_type>>(&script, webview)
                 .resolve();
             Box::pin(async move {
                 match fut.await {
@@ -80,11 +86,11 @@ impl RenderedElementBacking for DesktopElement {
             self.id.0,
             serde_json::to_string(&behavior).expect("Failed to serialize ScrollBehavior")
         );
-
-        let fut = self
-            .query
-            .new_query::<bool>(&script, self.webview.clone())
-            .resolve();
+        let webview = self
+            .webview
+            .upgrade()
+            .expect("Webview should be alive if the element is being queried");
+        let fut = self.query.new_query::<bool>(&script, webview).resolve();
         Box::pin(async move {
             match fut.await {
                 Ok(true) => Ok(()),
@@ -106,11 +112,11 @@ impl RenderedElementBacking for DesktopElement {
             "return window.interpreter.setFocus({}, {});",
             self.id.0, focus
         );
-
-        let fut = self
-            .query
-            .new_query::<bool>(&script, self.webview.clone())
-            .resolve();
+        let webview = self
+            .webview
+            .upgrade()
+            .expect("Webview should be alive if the element is being queried");
+        let fut = self.query.new_query::<bool>(&script, webview).resolve();
 
         Box::pin(async move {
             match fut.await {

packages/desktop/src/query.rs

@@ -1,4 +1,4 @@
-use crate::DesktopContext;
+use crate::{DesktopContext, WeakDesktopContext};
 use futures_util::{FutureExt, StreamExt};
 use generational_box::Owner;
 use serde::{de::DeserializeOwned, Deserialize};
@@ -107,7 +107,7 @@ impl QueryEngine {
             id: request_id,
             receiver: rx,
             return_receiver: Some(return_rx),
-            desktop: context,
+            desktop: Rc::downgrade(&context),
             phantom: std::marker::PhantomData,
         }
     }
@@ -140,7 +140,7 @@ impl QueryEngine {
 }
 
 pub(crate) struct Query<V: DeserializeOwned> {
-    desktop: DesktopContext,
+    desktop: WeakDesktopContext,
     receiver: futures_channel::mpsc::UnboundedReceiver<Value>,
     return_receiver: Option<futures_channel::oneshot::Receiver<Result<Value, String>>>,
     pub id: usize,
@@ -161,7 +161,8 @@ impl<V: DeserializeOwned> Query<V> {
         let data = message.to_string();
         let script = format!(r#"window.getQuery({queue_id}).rustSend({data});"#);
 
-        self.desktop
+        let desktop = self.desktop.upgrade().ok_or(QueryError::Finished)?;
+        desktop
             .webview
             .evaluate_script(&script)
             .map_err(|e| QueryError::Send(e.to_string()))?;