oh i see. I did the same thing myself instead of using track_foreign. In my case the signal is a private member of a class so it's not directly accessible at the site which wants to register a callback. Instead the class with the signal has function exposed so i wonder if using track would be possible. I did something like this: boost::signals2::connection ClassWithSignal::registerListener(const std::function< void() > &refListener) { return m_signal.connect(refListener); } void SomeListenerClass::funct() { std::weak_ptr< SomeListenerClass > weakSelf = shared_from_this(); classWithSignal->registerListener( [weakSelf]{auto self = weakSelf.lock(); if(self) { self->myCallback(); }} ); } i did a few alpha test cases and seemed to pass thread safety issues. I guess this should work. I did not read into track() too much because i thought the registerListener(..) definition above does not permit it, but i don't know if that's true. BR// On Tue, Oct 22, 2013 at 12:07 AM, Scott Mueller [via Boost] < ml-node+s2283326n4653459h27@n4.nabble.com> wrote:
On Saturday, October 19, 2013 2:47 PM, ustulation wrote:
I've the following:
<1> a single instance of io_service object with a program life-time and several threads calling it's run() method. io_service::work is given to it so >that it never terminates (unless we stop it).
<2> class A which has boost::signals2::signal connecting functions for callback. * async operations (eg., async_read_until, async_write etc)
<3> class B which is derived from std::shared_from_this ; * has a composition of class A as std::unique_ptr which is instantiated in B's constructor ; <c> has functions/listeners which are registered with signals of class A (eg., signals2::connection connectionObj = uniqPtrA->someSig.connect([=]{shared_from_this_ptrB->listenerFuncOfB();} uniqPtrA->);
<4> Another thread outside the thread-pool of <1> above which instantiates (and manages) class B: auto ptrB = std::make_shared(); //and further operations.
The problem is when I need to destroy ptrB I can't. For instance, i call some method of class B on ptrB to clear all connections it has with class A and allow ptrB to go out of scope, but class B destructor is never called:
{//local scope auto ptrB = std::make_shared(); ptrB->connectListenersToA(); /* eg auto self = shared_from_this(); connectionObj = uniqPtrA->someSig.connect([=]{self ->listenerFuncOfB();}); referring to <3> above */ //... do some operations ptrB->disconnectListenersWithA(); //eg connectionObj.disconnect(); referring to <3> above }//Scope ends I want ptrB to destroy the underlying pointer.
The ptrB destructor is never called because signals2::connection::disconnect does not seem to wipe out the given slot so the shared_ptr reference of B remains with the signal in class A as anonymous functor (due to lambda in <3> above) containing it does not get destroyed.
How do I achieve this?
Have you tried to use track_foreign so that boost uses the weak reference of your shared_ptr as an analogue for your connection object? You can even do this with std::shared_ptr, instead of boost::shared_ptr<>, since the traits specializations are in place (with a properly configured environment). Then your connect call looks like this: //ptrB->connectListenersToA(); // would do something like this uniqPtrA->someSig.connect(&B::listenerFuncOfB, this).track_foreign(shared_from_this());
If you do all of this, then you can just cut your shared_ptrs free and they'll get destroyed. Signals2 will store a weak_ptr instead, and get rid of that some time afterward.
Best regards,
M. Scott Mueller _______________________________________________ Boost-users mailing list [hidden email] http://user/SendEmail.jtp?type=node&node=4653459&i=0 http://lists.boost.org/mailman/listinfo.cgi/boost-users
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