Use async logging while streaming only

The benefits of reliable output outweigh performance concerns during non-streaming activities.

app/main.cpp

@@ -60,9 +60,16 @@
 // Log to console for debug Mac builds
 #endif
 
+// StreamUtils::setAsyncLogging() exposes control of this to the Session
+// class to enable async logging once the stream has started.
+//
+// FIXME: Clean this up
+QAtomicInt g_AsyncLoggingEnabled;
+
 static QElapsedTimer s_LoggerTime;
 static QTextStream s_LoggerStream(stderr);
 static QThreadPool s_LoggerThread;
+static QMutex s_SyncLoggerMutex;
 static bool s_SuppressVerboseOutput;
 static QRegularExpression k_RikeyRegex("&rikey=\\w+");
 static QRegularExpression k_RikeyIdRegex("&rikeyid=[\\d-]+");
@@ -127,8 +134,16 @@ void logToLoggerStream(QString& message)
     }
 #endif
 
+    if (g_AsyncLoggingEnabled) {
         // Queue the log message to be written asynchronously
         s_LoggerThread.start(new LoggerTask(message));
+    }
+    else {
+        // QTextStream is not thread-safe, so we must lock
+        QMutexLocker locker(&s_SyncLoggerMutex);
+        s_LoggerStream << message;
+        s_LoggerStream.flush();
+    }
 }
 
 void sdlLogToDiskHandler(void*, int category, SDL_LogPriority priority, const char* message)
@@ -298,6 +313,11 @@ LONG WINAPI UnhandledExceptionHandler(struct _EXCEPTION_POINTERS *ExceptionInfo)
         qCritical() << "Unhandled exception! Failed to open dump file:" << qDmpFileName << "with error" << GetLastError();
     }
 
+    // Sleep for a moment to allow the logging thread to finish up before crashing
+    if (g_AsyncLoggingEnabled) {
+        Sleep(500);
+    }
+
     // Let the program crash and WER collect a dump
     return EXCEPTION_CONTINUE_SEARCH;
 }
@@ -826,6 +846,9 @@ int main(int argc, char *argv[])
     av_log_set_callback(av_log_default_callback);
 #endif
 
+    // We should not be in async logging mode anymore
+    Q_ASSERT(g_AsyncLoggingEnabled == 0);
+
     // Wait for pending log messages to be printed
     s_LoggerThread.waitForDone();
 

app/streaming/session.cpp

@@ -2014,6 +2014,9 @@ void Session::execInternal()
     // Toggle the stats overlay if requested by the user
     m_OverlayManager.setOverlayState(Overlay::OverlayDebug, m_Preferences->showPerformanceOverlay);
 
+    // Switch to async logging mode when we enter the SDL loop
+    StreamUtils::enterAsyncLoggingMode();
+
     // Hijack this thread to be the SDL main thread. We have to do this
     // because we want to suspend all Qt processing until the stream is over.
     SDL_Event event;
@@ -2363,6 +2366,9 @@ void Session::execInternal()
     }
 
 DispatchDeferredCleanup:
+    // Switch back to synchronous logging mode
+    StreamUtils::exitAsyncLoggingMode();
+
     // Uncapture the mouse and hide the window immediately,
     // so we can return to the Qt GUI ASAP.
     m_InputHandler->setCaptureActive(false);

app/streaming/streamutils.cpp

@@ -417,3 +417,15 @@ int StreamUtils::getDrmFd(bool preferRenderNode)
 
     return -1;
 }
+
+extern QAtomicInt g_AsyncLoggingEnabled;
+
+void StreamUtils::enterAsyncLoggingMode()
+{
+    g_AsyncLoggingEnabled.ref();
+}
+
+void StreamUtils::exitAsyncLoggingMode()
+{
+    g_AsyncLoggingEnabled.deref();
+}

app/streaming/streamutils.h

@@ -31,4 +31,10 @@ public:
 
     static
     int getDrmFd(bool preferRenderNode);
+
+    static
+    void enterAsyncLoggingMode();
+
+    static
+    void exitAsyncLoggingMode();
 };