Fix possible deadlock in debug logs.

Telegram/SourceFiles/core/launcher.cpp

@@ -420,7 +420,6 @@ void Launcher::prepareSettings() {
 
 void Launcher::initQtMessageLogging() {
 	static QtMessageHandler OriginalMessageHandler = nullptr;
-	static bool WritingQtMessage = false;
 	OriginalMessageHandler = qInstallMessageHandler([](
 			QtMsgType type,
 			const QMessageLogContext &context,
@@ -429,10 +428,9 @@ void Launcher::initQtMessageLogging() {
 			OriginalMessageHandler(type, context, msg);
 		}
 		if (Logs::DebugEnabled() || !Logs::started()) {
-			if (!WritingQtMessage) {
-				WritingQtMessage = true;
+			if (!Logs::WritingEntry()) {
+				// Sometimes Qt logs something inside our own logging.
 				LOG((msg));
-				WritingQtMessage = false;
 			}
 		}
 	});

Telegram/SourceFiles/logs.cpp

@@ -14,6 +14,17 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 namespace {
 
 std::atomic<int> ThreadCounter/* = 0*/;
+thread_local bool WritingEntryFlag/* = false*/;
+
+class WritingEntryScope final {
+public:
+	WritingEntryScope() {
+		WritingEntryFlag = true;
+	}
+	~WritingEntryScope() {
+		WritingEntryFlag = false;
+	}
+};
 
 } // namespace
 
@@ -73,6 +84,8 @@ public:
 
 	void closeMain() {
 		QMutexLocker lock(_logsMutex(LogDataMain));
+		WritingEntryScope scope;
+
 		const auto file = files[LogDataMain].get();
 		if (file && file->isOpen()) {
 			file->close();
@@ -98,6 +111,8 @@ public:
 
 	void write(LogDataType type, const QString &msg) {
 		QMutexLocker lock(_logsMutex(type));
+		WritingEntryScope scope;
+
 		if (type != LogDataMain) {
 			reopenDebug();
 		}
@@ -323,6 +338,10 @@ bool DebugEnabled() {
 #endif
 }
 
+bool WritingEntry() {
+	return WritingEntryFlag;
+}
+
 void start(not_null<Core::Launcher*> launcher) {
 	Assert(LogsData == nullptr);
 

Telegram/SourceFiles/logs.h

@@ -19,6 +19,7 @@ namespace Logs {
 
 void SetDebugEnabled(bool enabled);
 bool DebugEnabled();
+[[nodiscard]] bool WritingEntry();
 
 void start(not_null<Core::Launcher*> launcher);
 bool started();