cpp11nullptr/lsignal

C++ signal and slot system

lsignal's Issues

Library is not thread-safe: deadlock can happen

Here library calls foreign callbacks under mutex lock here:

template<typename R, typename... Args>
	R signal<R(Args...)>::operator() (Args... args)
	{
		std::lock_guard<std::mutex> locker(_mutex);
		// ...

Imagine that one thread connects to "signal1" own function "slot1" which fires "signal2". First, it locks "signal1" mutex, then attempts to lock "signal2" mutex.

Another thread connects to "signal2" own function "slot2" which fires "signal1". First, it locks "signal2" mutex, then attempts to lock "signal1" mutex.

In some cases, threads will enter into deadlock: thread1 always waits "signal2" mutex, while thread2 always waits "signal1" mutex.

problems testing lsignal

Some found issues during testing:

1. Calling a signal with no connections does not work.

2. Setting one owner to several signals does not work. Only one signal (the last one) gets notified about owner getting destructed the other signals crashes when trying to call functions in destructed object.

3. When connecting signal1 to signal2, if signal2 gets destructed signal1 is informed but if signal1 gets destructed first, signal2 crashes in destructor when trying to remove itself from already destructed signal1.

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