Merge pull request #1315 from sdroege/0.15-backports

[0.15] Don't require `Send` closures for GIO-style async functions
gtk-rs · Jan 28, 2022 · 78e3d3c · 78e3d3c
2 parents ee37253 + e181b33
commit 78e3d3c
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Showing 3 changed files with 34 additions and 10 deletions.
diff --git a/src/analysis/bounds.rs b/src/analysis/bounds.rs
@@ -133,10 +133,8 @@ impl Bounds {
                         }
                         let parameters = format_out_parameters(&out_parameters);
                         let error_type = find_error_type(env, function);
-                        type_string = format!(
-                            "FnOnce(Result<{}, {}>) + Send + 'static",
-                            parameters, error_type
-                        );
+                        type_string =
+                            format!("FnOnce(Result<{}, {}>) + 'static", parameters, error_type);
                         let bound_name = *self.unused.front().unwrap();
                         callback_info = Some(CallbackInfo {
                             callback_type: type_string.clone(),

diff --git a/src/codegen/function_body_chunk.rs b/src/codegen/function_body_chunk.rs
@@ -716,12 +716,30 @@ impl Builder {
         chunks: &mut Vec<Chunk>,
         trampoline: &AsyncTrampoline,
     ) {
+        chunks.push(Chunk::Custom(String::from(
+            r###"
+                let main_context = glib::MainContext::ref_thread_default();
+                let is_main_context_owner = main_context.is_owner();
+                let has_acquired_main_context = (!is_main_context_owner)
+                    .then(|| main_context.acquire().ok())
+                    .flatten();
+                assert!(
+                    is_main_context_owner || has_acquired_main_context.is_some(),
+                    "Async operations only allowed if the thread is owning the MainContext"
+                );
+        "###,
+        )));
+
         chunks.push(Chunk::Let {
             name: "user_data".to_string(),
             is_mut: false,
-            value: Box::new(Chunk::Custom("Box_::new(callback)".into())),
+            value: Box::new(Chunk::Custom(format!(
+                "Box_::new({}::new(callback))",
+                use_glib_type(env, "thread_guard::ThreadGuard")
+            ))),
             type_: Some(Box::new(Chunk::Custom(format!(
-                "Box_<{}>",
+                "Box_<{}<{}>>",
+                use_glib_type(env, "thread_guard::ThreadGuard"),
                 trampoline.bound_name
             )))),
         });
@@ -874,7 +892,17 @@ impl Builder {
             is_mut: false,
             value: Box::new(Chunk::Custom("Box_::from_raw(user_data as *mut _)".into())),
             type_: Some(Box::new(Chunk::Custom(format!(
-                "Box_<{}>",
+                "Box_<{}<{}>>",
+                use_glib_type(env, "thread_guard::ThreadGuard"),
+                trampoline.bound_name
+            )))),
+        });
+        body.push(Chunk::Let {
+            name: "callback".to_string(),
+            is_mut: false,
+            value: Box::new(Chunk::Custom("callback.into_inner()".into())),
+            type_: Some(Box::new(Chunk::Custom(format!(
+                "{}",
                 trampoline.bound_name
             )))),
         });

diff --git a/src/codegen/signal.rs b/src/codegen/signal.rs
@@ -160,9 +160,7 @@ fn function_type_string(
     analysis: &analysis::signals::Info,
     closure: bool,
 ) -> Option<String> {
-    if analysis.trampoline.is_err() {
-        return None;
-    }
+    analysis.trampoline.as_ref().ok()?;
 
     let trampoline = analysis.trampoline.as_ref().unwrap_or_else(|_| {
         panic!(