make sync_to_async threadsafe
diff --git a/system/include/emscripten/thread_utils.h b/system/include/emscripten/thread_utils.h
index 81826d4..279f928 100644
--- a/system/include/emscripten/thread_utils.h
+++ b/system/include/emscripten/thread_utils.h
@@ -98,6 +98,10 @@
//
// In the async case, you would call resume() at some later time.
//
+ // It is safe to call this method from multiple threads, as it locks itself.
+ // That is, you can create an instance of this and call it from multiple
+ // threads freely.
+ //
void invoke(std::function<void(Callback)> newWork);
//==============================================================================
@@ -112,6 +116,7 @@
bool finishedWork;
bool quit = false;
std::unique_ptr<std::function<void()>> resume;
+ std::mutex invokeMutex;
// The child will be asynchronous, and therefore we cannot rely on RAII to
// unlock for us, we must do it manually.
@@ -175,6 +180,10 @@
};
void sync_to_async::invoke(std::function<void(Callback)> newWork) {
+ // Use the invokeMutex to prevent more than one invoke being in flight at a
+ // time, so that this is usable from multiple threads safely.
+ std::lock_guard<std::mutex> invokeLock(invokeMutex);
+
// Send the work over.
{
std::lock_guard<std::mutex> lock(mutex);
