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authorKjell Ahlstedt <kjell.ahlstedt@bredband.net>2016-12-11 10:08:57 +0100
committerKjell Ahlstedt <kjell.ahlstedt@bredband.net>2016-12-11 10:08:57 +0100
commit404a79cb246c723fc64e6a0f9316afbbcf7c7844 (patch)
tree07bfd79384e023479466bb133ca1a012bcda4915 /sigc++
parentabf29c46861da4c81237644342e3399312f96eae (diff)
downloadsigc++-404a79cb246c723fc64e6a0f9316afbbcf7c7844.tar.gz
signal_impl: Use std::weak_ptr<signal_impl> in connected slots
A signal_impl object shall not store std::shared_ptr to itself via connected slots. It results in memory leaks. Use std::weak_ptr in the self_and_iter struct. Bug 775871
Diffstat (limited to 'sigc++')
-rw-r--r--sigc++/signal_base.cc24
1 files changed, 18 insertions, 6 deletions
diff --git a/sigc++/signal_base.cc b/sigc++/signal_base.cc
index a3dabdc..2038568 100644
--- a/sigc++/signal_base.cc
+++ b/sigc++/signal_base.cc
@@ -28,10 +28,11 @@ namespace internal
// when the slot is disconnected. Bug 167714.
struct self_and_iter : public notifiable
{
- const std::shared_ptr<signal_impl> self_;
+ const std::weak_ptr<signal_impl> self_;
const signal_impl::iterator_type iter_;
- self_and_iter(const std::shared_ptr<signal_impl>& self, const signal_impl::iterator_type& iter) : self_(self), iter_(iter) {}
+ self_and_iter(const std::weak_ptr<signal_impl>& self, const signal_impl::iterator_type& iter)
+ : self_(self), iter_(iter) {}
};
signal_impl::signal_impl() : exec_count_(0), deferred_(false)
@@ -64,6 +65,9 @@ signal_impl::clear()
{
// Don't let signal_impl::notify() erase the slots. It would invalidate the
// iterator in the following loop.
+ // Don't call shared_from_this() here. clear() is called from the destructor.
+ // When the destructor is executing, shared_ptr's use_count has reached 0,
+ // and it's no longer possible to get a shared_ptr to this.
const bool saved_deferred = deferred_;
signal_impl_exec_holder exec(this);
@@ -179,14 +183,22 @@ void
signal_impl::notify_self_and_iter_of_invalidated_slot(notifiable* d)
{
std::unique_ptr<self_and_iter> si(static_cast<self_and_iter*>(d));
+ auto self = si->self_.lock();
+ if (!self)
+ {
+ // The signal_impl object is being deleted. The use_count has reached 0.
+ // Nothing to do here. exec_count_ > 0 and clear() will restore deferred_.
+ return;
+ }
- if (si->self_->exec_count_ == 0)
+ if (self->exec_count_ == 0)
{
// The deletion of a slot may cause the deletion of a signal_base,
// a decrementation of si->self_->ref_count_, and the deletion of si->self_.
// In that case, the deletion of si->self_ is deferred to ~signal_impl_holder().
- signal_impl_holder exec(si->self_);
- si->self_->slots_.erase(si->iter_);
+ // https://bugzilla.gnome.org/show_bug.cgi?id=564005#c24
+ signal_impl_holder exec(self);
+ self->slots_.erase(si->iter_);
}
else
{
@@ -194,7 +206,7 @@ signal_impl::notify_self_and_iter_of_invalidated_slot(notifiable* d)
// => sweep() will be called from ~signal_impl_holder() after signal emission.
// This is safer because we don't have to care about our
// iterators in emit(), clear(), and erase().
- si->self_->deferred_ = true;
+ self->deferred_ = true;
}
}