From ff9321e971511262ca35640fee27b20c2523521b Mon Sep 17 00:00:00 2001
From: Ilya Fedin <fedin-ilja2010@ya.ru>
Date: Mon, 21 Aug 2023 03:21:30 +0400
Subject: [PATCH] Main thread deadlock detector for debug mode

---
 Telegram/CMakeLists.txt                       |  1 +
 Telegram/SourceFiles/core/deadlock_detector.h | 83 +++++++++++++++++++
 Telegram/SourceFiles/core/sandbox.cpp         | 12 +++
 Telegram/SourceFiles/core/sandbox.h           |  2 +
 4 files changed, 98 insertions(+)
 create mode 100644 Telegram/SourceFiles/core/deadlock_detector.h

diff --git a/Telegram/CMakeLists.txt b/Telegram/CMakeLists.txt
index 6f9dbff7d..d555578f7 100644
--- a/Telegram/CMakeLists.txt
+++ b/Telegram/CMakeLists.txt
@@ -413,6 +413,7 @@ PRIVATE
     core/crash_report_window.h
     core/crash_reports.cpp
     core/crash_reports.h
+    core/deadlock_detector.h
     core/file_utilities.cpp
     core/file_utilities.h
     core/launcher.cpp
diff --git a/Telegram/SourceFiles/core/deadlock_detector.h b/Telegram/SourceFiles/core/deadlock_detector.h
new file mode 100644
index 000000000..fb538cf62
--- /dev/null
+++ b/Telegram/SourceFiles/core/deadlock_detector.h
@@ -0,0 +1,83 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+namespace Core::DeadlockDetector {
+
+class PingPongEvent : public QEvent {
+public:
+	static auto Type() {
+		static const auto Result = QEvent::Type(QEvent::registerEventType());
+		return Result;
+	}
+
+	PingPongEvent(not_null<QObject*> sender)
+	: QEvent(Type())
+	, _sender(sender) {
+	}
+
+	[[nodiscard]] not_null<QObject*> sender() const {
+		return _sender;
+	}
+
+private:
+	not_null<QObject*> _sender;
+
+};
+
+class Pinger : public QObject {
+public:
+	Pinger(not_null<QObject*> receiver)
+	: _receiver(receiver)
+	, _abortTimer([] { Unexpected("Deadlock found!"); }) {
+		const auto callback = [=] {
+			QCoreApplication::postEvent(_receiver, new PingPongEvent(this));
+			_abortTimer.callOnce(30000);
+		};
+		_pingTimer.setCallback(callback);
+		_pingTimer.callEach(60000);
+		callback();
+	}
+
+protected:
+	bool event(QEvent *e) override {
+		if (e->type() == PingPongEvent::Type()
+			&& static_cast<PingPongEvent*>(e)->sender() == _receiver) {
+			_abortTimer.cancel();
+		}
+		return QObject::event(e);
+	}
+
+private:
+	not_null<QObject*> _receiver;
+	base::Timer _pingTimer;
+	base::Timer _abortTimer;
+
+};
+
+class PingThread : public QThread {
+public:
+	PingThread(not_null<QObject*> parent)
+	: QThread(parent) {
+		start();
+	}
+
+	~PingThread() {
+		quit();
+		wait();
+	}
+
+protected:
+	void run() override {
+		Pinger pinger(parent());
+		QThread::run();
+	}
+
+};
+
+} // namespace Core::DeadlockDetector
diff --git a/Telegram/SourceFiles/core/sandbox.cpp b/Telegram/SourceFiles/core/sandbox.cpp
index 1a6c949cf..45d2bef81 100644
--- a/Telegram/SourceFiles/core/sandbox.cpp
+++ b/Telegram/SourceFiles/core/sandbox.cpp
@@ -20,6 +20,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "core/launcher.h"
 #include "core/local_url_handlers.h"
 #include "core/update_checker.h"
+#include "core/deadlock_detector.h"
 #include "base/timer.h"
 #include "base/concurrent_timer.h"
 #include "base/invoke_queued.h"
@@ -198,6 +199,13 @@ void Sandbox::launchApplication() {
 		}
 		setupScreenScale();
 
+#ifndef _DEBUG
+		if (Logs::DebugEnabled()) {
+			using DeadlockDetector::PingThread;
+			_deadlockDetector = std::make_unique<PingThread>(this);
+		}
+#endif // !_DEBUG
+
 		_application = std::make_unique<Application>();
 
 		// Ideally this should go to constructor.
@@ -267,6 +275,10 @@ bool Sandbox::event(QEvent *e) {
 		return false;
 	} else if (e->type() == QEvent::Close) {
 		Quit();
+	} else if (e->type() == DeadlockDetector::PingPongEvent::Type()) {
+		postEvent(
+			static_cast<DeadlockDetector::PingPongEvent*>(e)->sender(),
+			new DeadlockDetector::PingPongEvent(this));
 	}
 	return QApplication::event(e);
 }
diff --git a/Telegram/SourceFiles/core/sandbox.h b/Telegram/SourceFiles/core/sandbox.h
index d8f47cd5a..4c15c2828 100644
--- a/Telegram/SourceFiles/core/sandbox.h
+++ b/Telegram/SourceFiles/core/sandbox.h
@@ -131,6 +131,8 @@ private:
 
 	rpl::event_stream<> _widgetUpdateRequests;
 
+	std::unique_ptr<QThread> _deadlockDetector;
+
 };
 
 } // namespace Core