fix(android): Speed up async dev assets loading

.changes/early-mutex-release.md

@@ -0,0 +1,5 @@
+---
+"wry": minor
+---
+
+On Android, release REQUEST_HANDLER mutex sooner by cloning the underlying Send + Sync handler.

src/android/binding.rs

@@ -99,7 +99,13 @@ fn handle_request(
   let webview_id = env.get_string(&webview_id)?;
   let webview_id = webview_id.to_str().ok().unwrap_or_default();
 
-  if let Some(handler) = REQUEST_HANDLER.lock().unwrap().get(webview_id) {
+  let handler = REQUEST_HANDLER
+    .lock()
+    .unwrap()
+    .get(webview_id)
+    .map(|handler| handler.handler.clone());
+
+  if let Some(handler) = handler {
     #[cfg(feature = "tracing")]
     let span =
       tracing::info_span!(parent: None, "wry::custom_protocol::handle", uri = tracing::field::Empty).entered();
@@ -162,7 +168,7 @@ fn handle_request(
     let response = {
       #[cfg(feature = "tracing")]
       let _span = tracing::info_span!("wry::custom_protocol::call_handler").entered();
-      (handler.handler)(
+      handler(
         webview_id,
         final_request,
         is_document_start_script_enabled != 0,

src/android/mod.rs

@@ -21,7 +21,7 @@ use raw_window_handle::HasWindowHandle;
 use std::{
   borrow::Cow,
   collections::HashMap,
-  sync::{mpsc::channel, Mutex},
+  sync::{mpsc::channel, Arc, Mutex},
   time::Duration,
 };
 
@@ -70,7 +70,7 @@ macro_rules! define_static_handlers {
 
 define_static_handlers! {
   IPC = UnsafeIpc { handler: Box<dyn Fn(Request<String>)> };
-  REQUEST_HANDLER = UnsafeRequestHandler { handler:  Box<dyn Fn(&str, Request<Vec<u8>>, bool) -> Option<HttpResponse<Cow<'static, [u8]>>>> };
+  REQUEST_HANDLER = UnsafeRequestHandler { handler: Arc<dyn Fn(&str, Request<Vec<u8>>, bool) -> Option<HttpResponse<Cow<'static, [u8]>>> + Send + Sync> };
   TITLE_CHANGE_HANDLER = UnsafeTitleHandler { handler: Box<dyn Fn(String)> };
   URL_LOADING_OVERRIDE = UnsafeUrlLoadingOverride { handler: Box<dyn Fn(String) -> bool> };
   ON_LOAD_HANDLER = UnsafeOnPageLoadHandler { handler: Box<dyn Fn(PageLoadEvent, String)> };
@@ -247,7 +247,7 @@ impl InnerWebView {
       .unwrap()
       .insert(
         id.clone(),
-        UnsafeRequestHandler::new(Box::new(
+        UnsafeRequestHandler::new(Arc::new(
           move |webview_id: &str, mut request, is_document_start_script_enabled| {
             let uri = request.uri().to_string();
             if let Some((custom_protocol, custom_protocol_handler)) =

src/lib.rs

@@ -644,7 +644,7 @@ struct WebViewAttributes<'a> {
   ///   locate your files in those directories. For more information, see [Loading in-app content](https://developer.android.com/guide/webapps/load-local-content) page.
   /// - iOS: To get the path of your assets, you can call [`CFBundle::resources_path`](https://docs.rs/core-foundation/latest/core_foundation/bundle/struct.CFBundle.html#method.resources_path). So url like `wry://assets/index.html` could get the html file in assets directory.
   pub custom_protocols:
-    HashMap<String, Box<dyn Fn(WebViewId, Request<Vec<u8>>, RequestAsyncResponder)>>,
+    HashMap<String, Box<dyn Fn(WebViewId, Request<Vec<u8>>, RequestAsyncResponder) + Send + Sync>>,
 
   /// The IPC handler to receive the message from Javascript on webview
   /// using `window.ipc.postMessage("insert_message_here")` to host Rust code.
@@ -1037,7 +1037,7 @@ impl<'a> WebViewBuilder<'a> {
   #[cfg(feature = "protocol")]
   pub fn with_custom_protocol<F>(mut self, name: String, handler: F) -> Self
   where
-    F: Fn(WebViewId, Request<Vec<u8>>) -> Response<Cow<'static, [u8]>> + 'static,
+    F: Fn(WebViewId, Request<Vec<u8>>) -> Response<Cow<'static, [u8]>> + Send + Sync + 'static,
   {
     #[cfg(any(
       target_os = "linux",
@@ -1102,7 +1102,7 @@ impl<'a> WebViewBuilder<'a> {
   #[cfg(feature = "protocol")]
   pub fn with_asynchronous_custom_protocol<F>(mut self, name: String, handler: F) -> Self
   where
-    F: Fn(WebViewId, Request<Vec<u8>>, RequestAsyncResponder) + 'static,
+    F: Fn(WebViewId, Request<Vec<u8>>, RequestAsyncResponder) + Send + Sync + 'static,
   {
     #[cfg(any(
       target_os = "linux",

src/wkwebview/mod.rs

@@ -109,7 +109,8 @@ static COUNTER: Counter = Counter::new();
 static WEBVIEW_STATE: Lazy<RwLock<HashMap<String, WebViewState>>> = Lazy::new(Default::default);
 
 struct WebViewState {
-  pub protocol_ptrs: Vec<Rc<dyn Fn(crate::WebViewId, Request<Vec<u8>>, RequestAsyncResponder)>>,
+  pub protocol_ptrs:
+    Vec<Rc<dyn Fn(crate::WebViewId, Request<Vec<u8>>, RequestAsyncResponder) + Send + Sync>>,
 }
 
 unsafe impl Send for WebViewState {}