[core, ios, qt, android] Close race condition in RunLoop (issue #9620)upstream/cloer_9620

Because a message we queue from the foreground may cause the background to complete, exit, and tear down the AsyncTask, we have to block queue processing until we've finished our call to AsyncTask::send().
Broadening the scope of a mutex is scary, but I audited the code of our four implementations of AsyncTask and I don't see any way this could cause a deadlock.

4 files changed, 16 insertions, 8 deletions

diff --git a/platform/android/src/run_loop.cpp b/platform/android/src/run_loop.cpp
index dff7d1d984..1d284a9e72 100644
--- a/platform/android/src/run_loop.cpp
+++ b/platform/android/src/run_loop.cpp
@@ -217,8 +217,10 @@ LOOP_HANDLE RunLoop::getLoopHandle() {
 }
 
 void RunLoop::push(std::shared_ptr<WorkTask> task) {
-    withMutex([&] { queue.push(std::move(task)); });
-    impl->wake();
+    withMutex([&] {
+        queue.push(std::move(task));
+        impl->wake();
+    });
 }
 
 void RunLoop::run() {
diff --git a/platform/darwin/src/run_loop.cpp b/platform/darwin/src/run_loop.cpp
index 2ba8f8415b..d60a88cf52 100644
--- a/platform/darwin/src/run_loop.cpp
+++ b/platform/darwin/src/run_loop.cpp
@@ -30,8 +30,10 @@ RunLoop::~RunLoop() {
 }
 
 void RunLoop::push(std::shared_ptr<WorkTask> task) {
-    withMutex([&] { queue.push(std::move(task)); });
-    impl->async->send();
+    withMutex([&] {
+        queue.push(std::move(task));
+        impl->async->send();
+    });
 }
 
 void RunLoop::run() {
diff --git a/platform/default/run_loop.cpp b/platform/default/run_loop.cpp
index 6375dba78e..5bccd21d56 100644
--- a/platform/default/run_loop.cpp
+++ b/platform/default/run_loop.cpp
@@ -130,8 +130,10 @@ LOOP_HANDLE RunLoop::getLoopHandle() {
 }
 
 void RunLoop::push(std::shared_ptr<WorkTask> task) {
-    withMutex([&] { queue.push(std::move(task)); });
-    impl->async->send();
+    withMutex([&] {
+        queue.push(std::move(task));
+        impl->async->send();
+    });
 }
 
 void RunLoop::run() {
diff --git a/platform/qt/src/run_loop.cpp b/platform/qt/src/run_loop.cpp
index 71ea19032a..af0c50ebb9 100644
--- a/platform/qt/src/run_loop.cpp
+++ b/platform/qt/src/run_loop.cpp
@@ -53,8 +53,10 @@ LOOP_HANDLE RunLoop::getLoopHandle() {
 }
 
 void RunLoop::push(std::shared_ptr<WorkTask> task) {
-    withMutex([&] { queue.push(task); });
-    impl->async->send();
+    withMutex([&] {
+        queue.push(std::move(task));
+        impl->async->send();
+    });
 }
 
 void RunLoop::run() {