Merge pull request #2002 from ealmloff/fix-signal-leak

Fix signals leaking memory

packages/signals/README.md

@@ -36,18 +36,18 @@ use dioxus_signals::*;
 #[component]
 fn App() -> Element {
     // Because signal is never read in this component, this component will not rerun when the signal changes
-    let signal = use_signal(|| 0);
+    let mut signal = use_signal(|| 0);
 
     rsx! {
         button {
             onclick: move |_| {
-                *signal.write() += 1;
+                signal += 1;
             },
             "Increase"
         }
         for id in 0..10 {
             Child {
-                signal: signal,
+                signal,
             }
         }
     }
@@ -58,11 +58,10 @@ struct ChildProps {
     signal: Signal<usize>,
 }
 
-#[component]
+fn Child(props: ChildProps) -> Element {
-fn Child(cx: Scope<ChildProps>) -> Element {
     // This component does read from the signal, so when the signal changes it will rerun
     rsx! {
-        "{cx.props.signal}"
+        "{props.signal}"
     }
 }
 ```
@@ -85,7 +84,7 @@ fn App() -> Element {
 
 #[component]
 fn Child() -> Element {
-    let signal: Signal<i32> = *use_context(cx).unwrap();
+    let signal: Signal<i32> = use_context();
     // This component does read from the signal, so when the signal changes it will rerun
     rsx! {
         "{signal}"
@@ -105,12 +104,12 @@ use dioxus_signals::*;
 
 #[component]
 fn App() -> Element {
-    let signal = use_signal(|| 0);
+    let mut signal = use_signal(|| 0);
-    let doubled = use_memo(|| signal * 2);
+    let doubled = use_memo(move || signal * 2);
 
     rsx! {
         button {
-            onclick: move |_| *signal.write() += 1,
+            onclick: move |_| signal += 1,
             "Increase"
         }
         Child {

packages/signals/src/copy_value.rs

@@ -93,7 +93,7 @@ fn current_owner<S: Storage<T>, T>() -> Owner<S> {
 }
 
 fn owner_in_scope<S: Storage<T>, T>(scope: ScopeId) -> Owner<S> {
-    match consume_context_from_scope(scope) {
+    match scope.has_context() {
         Some(rt) => rt,
         None => {
             let owner = S::owner();

packages/signals/src/signal.rs

@@ -30,17 +30,15 @@ use std::{
 /// }
 ///
 /// #[component]
-/// fn Child(state: Signal<u32>) -> Element {
+/// fn Child(mut state: Signal<u32>) -> Element {
-///     let state = *state;
+///     use_future(move || async move {
-///
-///     use_future( |()| async move {
 ///         // Because the signal is a Copy type, we can use it in an async block without cloning it.
-///         *state.write() += 1;
+///         state += 1;
 ///     });
 ///
 ///     rsx! {
 ///         button {
-///             onclick: move |_| *state.write() += 1,
+///             onclick: move |_| state += 1,
 ///             "{state}"
 ///         }
 ///     }

packages/signals/tests/create.rs

@@ -56,6 +56,11 @@ fn deref_signal() {
 
 #[test]
 fn drop_signals() {
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::atomic::Ordering;
+
+    static SIGNAL_DROP_COUNT: AtomicUsize = AtomicUsize::new(0);
+
     let mut dom = VirtualDom::new(|| {
         let generation = generation();
 
@@ -68,10 +73,18 @@ fn drop_signals() {
     });
 
     fn Child() -> Element {
-        let signal = create_without_cx();
+        struct TracksDrops;
+
+        impl Drop for TracksDrops {
+            fn drop(&mut self) {
+                SIGNAL_DROP_COUNT.fetch_add(1, Ordering::Relaxed);
+            }
+        }
+
+        use_signal(|| TracksDrops);
 
         rsx! {
-            "{signal}"
+            ""
         }
     }
 
@@ -79,7 +92,5 @@ fn drop_signals() {
     dom.mark_dirty(ScopeId::ROOT);
     dom.render_immediate(&mut NoOpMutations);
 
-    fn create_without_cx() -> Signal<String> {
+    assert_eq!(SIGNAL_DROP_COUNT.load(Ordering::Relaxed), 10);
-        Signal::new("hello world".to_string())
-    }
 }