Re: [Boost-users] [signals] thread_safe_signals feature-complete

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-02-19 18:11:37

Gottlob Frege wrote:

> - one of the original reasons (in my head at least) for blocking on
> disconnect() is so that you can disconnect() in your destructor (and
> thus avoid having a dead object being called).

But then you need to deal with the possibility that a call can already be in 
progress at the time your destructor is invoked. (If you can guarantee that 
this cannot happen, it seems to me that you can also guarantee that a call 
isn't started after the disconnect.) So let's assume that you lock the 
object mutex. There's still the nasty scenario where:

~X locks the object mutex
X::f is called by the signal and blocks on the object mutex
~X disconnects and destroys *this, including the object mutex
X::f crashes and burns

I can't think of a way to avoid the above that doesn't also solve the "call 
after disconnect" problem.