EQ2EMu/EQ2/source/depends/boost_1_72_0/libs/signals2/test/deadlock_regression_test.cpp

// Signals2 library
//
// Regression test based on bug report from Arian Alin Radu.
// The problem was that tracked objects could be released 
// while holding the signal mutex during signal invocation.  
// This could result in a recursive
// lock attempt if the tracked object manipulates the signal
// in its destructor.

// Copyright Frank Mori Hess 2019
// Use, modification and
// distribution is subject to the Boost Software License, Version
// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

// For more information, see http://www.boost.org

#define BOOST_TEST_MODULE signals2 deadlock regression test
#include <boost/test/included/unit_test.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
#include <boost/signals2/signal.hpp>
#include <boost/signals2/signal_type.hpp>

namespace bs2 = boost::signals2;


// dummy mutex that detects attempts to recursively lock
class test_mutex
{
public:
	test_mutex(): m_locked(false) {}
	void lock()
	{
		BOOST_CHECK(m_locked == false);
		m_locked = true;
	}
	bool try_lock()
	{
		if(m_locked) return false;
		lock();
		return true;
	}
	void unlock()
	{
		m_locked = false;
	}
private:
	bool m_locked;
};

using namespace bs2::keywords;
typedef bs2::signal_type<void(), mutex_type<test_mutex> >::type Signal;

class SelfReference: private boost::noncopyable
{
public:
	boost::shared_ptr<SelfReference> m_self;
	boost::shared_ptr<Signal> m_signal;

	boost::signals2::connection m_conReleaseSelf;
	boost::signals2::connection m_conDoNothing;

	SelfReference()
	{
		m_signal = boost::make_shared<Signal>();
	}

	~SelfReference()
	{
		// the first slot (ReleaseSelf) has been called; now the trackable object (this)
		// was released, while the second slot is locked
		BOOST_CHECK(!m_conReleaseSelf.connected());
		// the second slot is locked, and we enter a recursive (pthread: dead) lock
		BOOST_CHECK(m_conDoNothing.connected());
		m_conReleaseSelf.disconnect();
		m_conDoNothing.disconnect();
		// enter recursive (pthread: dead) lock again:
		BOOST_CHECK(m_signal->empty());
	}

	void ReleaseSelf()
	{
		m_self.reset();
	}

	static void DoNothing()
	{
	}

	static void Run()
	{
		boost::shared_ptr<Signal> signal;
		{
			boost::shared_ptr<SelfReference> obj = boost::make_shared<SelfReference>();
			obj->m_self = obj;
			signal = obj->m_signal;

			obj->m_conReleaseSelf = signal->connect(Signal::slot_type(&SelfReference::ReleaseSelf, obj.get()).track(obj));
			obj->m_conDoNothing = signal->connect(Signal::slot_type(&SelfReference::DoNothing));
		}
		(*signal)();
	}
};

BOOST_AUTO_TEST_CASE(test_main)
{
	SelfReference::Run();
}