step 6

apps/LoopThroughWithOpenGLCompositing/runtime/persistence/PersistenceWriter.cpp

@@ -72,6 +72,12 @@ bool PersistenceWriter::EnqueueSnapshot(const PersistenceSnapshot& snapshot, std
 }
 
 void PersistenceWriter::StopAndFlush()
+{
+	std::string error;
+	StopAndFlush((std::chrono::milliseconds::max)(), error);
+}
+
+bool PersistenceWriter::StopAndFlush(std::chrono::milliseconds timeout, std::string& error)
 {
 	{
 		std::lock_guard<std::mutex> lock(mMutex);
@@ -83,8 +89,28 @@ void PersistenceWriter::StopAndFlush()
 	}
 	mCondition.notify_all();
 
+	std::unique_lock<std::mutex> lock(mMutex);
+	if (mWorkerRunning)
+	{
+		if (timeout == (std::chrono::milliseconds::max)())
+		{
+			mCondition.wait(lock, [this]() { return !mWorkerRunning; });
+		}
+		else
+		{
+			const auto deadline = std::chrono::steady_clock::now() + timeout;
+			if (!mCondition.wait_until(lock, deadline, [this]() { return !mWorkerRunning; }))
+			{
+				error = "Timed out while flushing persistence writer.";
+				return false;
+			}
+		}
+	}
+	lock.unlock();
+
 	if (mWorker.joinable())
 		mWorker.join();
+	return true;
 }
 
 PersistenceWriterMetrics PersistenceWriter::GetMetrics() const
@@ -221,6 +247,7 @@ void PersistenceWriter::WorkerMain()
 				if (mStopping)
 				{
 					mWorkerRunning = false;
+					mCondition.notify_all();
 					return;
 				}
 

apps/LoopThroughWithOpenGLCompositing/runtime/persistence/PersistenceWriter.h

@@ -45,6 +45,7 @@ public:
 	void SetResultCallback(ResultCallback callback);
 	bool WriteSnapshot(const PersistenceSnapshot& snapshot, std::string& error);
 	bool EnqueueSnapshot(const PersistenceSnapshot& snapshot, std::string& error);
+	bool StopAndFlush(std::chrono::milliseconds timeout, std::string& error);
 	void StopAndFlush();
 	PersistenceWriterMetrics GetMetrics() const;
 

apps/LoopThroughWithOpenGLCompositing/runtime/store/RuntimeStore.cpp

@@ -156,6 +156,21 @@ bool RuntimeStore::RequestPersistence(const PersistenceRequest& request, std::st
 	return false;
 }
 
+bool RuntimeStore::FlushPersistenceForShutdown(std::chrono::milliseconds timeout, std::string& error)
+{
+	if (mPersistenceWriter.StopAndFlush(timeout, error))
+		return true;
+
+	mHealthTelemetry.RecordPersistenceWriteResult(
+		false,
+		PersistenceTargetKindName(PersistenceTargetKind::RuntimeState),
+		std::string(),
+		"shutdown-flush",
+		error,
+		true);
+	return false;
+}
+
 PersistenceSnapshot RuntimeStore::BuildRuntimeStatePersistenceSnapshotLocked(const PersistenceRequest& request) const
 {
 	PersistenceSnapshot snapshot;

apps/LoopThroughWithOpenGLCompositing/runtime/store/RuntimeStore.h

@@ -33,6 +33,7 @@ public:
 	std::string BuildPersistentStateJson() const;
 	PersistenceSnapshot BuildRuntimeStatePersistenceSnapshot(const PersistenceRequest& request) const;
 	bool RequestPersistence(const PersistenceRequest& request, std::string& error);
+	bool FlushPersistenceForShutdown(std::chrono::milliseconds timeout, std::string& error);
 	bool PollStoredFileChanges(bool& registryChanged, bool& reloadRequested, std::string& error);
 
 	bool CreateStoredLayer(const std::string& shaderId, std::string& error);