Re: [Boost-users] Signals2 benchmark

Subject: Re: [Boost-users] Signals2 benchmark
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2015-02-06 15:34:15

On Fri, Feb 6, 2015 at 2:23 PM, Niall Douglas <s_sourceforge_at_[hidden]> wrote:
> On 6 Feb 2015 at 13:41, Gottlob Frege wrote:
>
>> > The easiest solution would be to store the slot as a shared_ptr, and
>> > make a copy of it (pin it) each time you call the slot.
>>
>> So
>>
>> Thread 1: call signal,... copy slot shared_ptr,...
>> Thread 2: disconnect, clean up resources, set global ptrUsedBySlot =
>> null (since it is no longer used, right?)
>> Thread 1: call slot
>> Thread 1: crash on null ptrUsedBySlot
>
> shared_ptr provides some atomic_exchange overloads. You could
> atomically swap a slot being deleted with an empty but valid slot
> type which calls nothing.
>

That would work to track the "winner".  But if the disconnect thread
comes in second, it still needs to wait for the slot thread to finish.
So you still need a waitable synchronization object of some kind.