From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-02-11 09:51:48
Douglas Gregor wrote:
> Background: Signals performance is sub-par, and much of the problem
> can be traced back to support for named slot groups. I'm trying to
> determine the best way to proceed.
Are you sure that this is the case?
Last time I looked, alternatives beat Boost.Signals because they don't
handle the corner cases of slot disconnection during signal invocation.
Example:
R operator()(void) const
{
typename list::iterator i = list_.begin();
while (i != list_.end())
{
if (i->function_)
{
(i++)->function_();
}
else
{
i = list_.erase(i);
}
}
}
(from Jody Hagins's implementation)
AFAICS this doesn't work if (i++)->function_() disconnects *(i+1).
To handle disconnection correctly, one needs to invoke a temporary list<>. I
haven't looked at what boost::signal does, but this may account for the
dynamic allocations that have been reported.
Of course named slot groups may introduce additional overhead, I don't know.