Prevent recursive VCA assignments

The GUI so far only prevents direct connections  VCA 1 > VCA 2 > VCA 1,
but does not recurse  VCA 1 > VCA 2 > VCA 3 > VCA 1

4 files changed, 47 insertions, 3 deletions

diff --git a/libs/ardour/ardour/slavable.h b/libs/ardour/ardour/slavable.h
index 6e584b2128..91c96edb1e 100644
--- a/libs/ardour/ardour/slavable.h
+++ b/libs/ardour/ardour/slavable.h
@@ -51,7 +51,7 @@ public:
 	XMLNode& get_state () const;
 	int set_state (XMLNode const&, int);
 
-	void assign (boost::shared_ptr<VCA>);
+	virtual void assign (boost::shared_ptr<VCA>);
 	void unassign (boost::shared_ptr<VCA>);
 
 	PBD::Signal2<void,boost::shared_ptr<VCA>,bool> AssignmentChange;
@@ -63,6 +63,11 @@ public:
 	/* signal sent VCAManager once assignment is possible */
 	static PBD::Signal1<void,VCAManager*> Assign;
 
+	std::vector<boost::shared_ptr<VCA> > masters (VCAManager*) const;
+
+	/** recursively test for master assignment to given VCA */
+	bool assigned_to (VCAManager*, boost::shared_ptr<VCA>) const;
+
 protected:
 	virtual SlavableControlList slavables () const = 0;
 
diff --git a/libs/ardour/ardour/vca.h b/libs/ardour/ardour/vca.h
index 49bb575e1d..f5f15d5e33 100644
--- a/libs/ardour/ardour/vca.h
+++ b/libs/ardour/ardour/vca.h
@@ -64,8 +64,10 @@ class LIBARDOUR_API VCA : public Stripable,
 
 	/* Slavable API */
 
-        bool slaved_to (boost::shared_ptr<VCA>) const;
-        bool slaved () const;
+	void assign (boost::shared_ptr<VCA>);
+
+	bool slaved_to (boost::shared_ptr<VCA>) const;
+	bool slaved () const;
 
 	/* Soloable API */
 
diff --git a/libs/ardour/slavable.cc b/libs/ardour/slavable.cc
index 7d8109eac6..155fd4f736 100644
--- a/libs/ardour/slavable.cc
+++ b/libs/ardour/slavable.cc
@@ -60,6 +60,32 @@ Slavable::get_state () const
 	return *node;
 }
 
+std::vector<boost::shared_ptr<VCA> >
+Slavable::masters (VCAManager* manager) const
+{
+	std::vector<boost::shared_ptr<VCA> > rv;
+	Glib::Threads::RWLock::ReaderLock lm (master_lock);
+	for (std::set<uint32_t>::const_iterator i = _masters.begin(); i != _masters.end(); ++i) {
+		rv.push_back (manager->vca_by_number (*i));
+	}
+	return rv;
+}
+
+bool
+Slavable::assigned_to (VCAManager* manager, boost::shared_ptr<VCA> mst) const
+{
+	if (mst.get () == this) {
+		return true;
+	}
+	std::vector<boost::shared_ptr<VCA> > ml = mst->masters (manager);
+	for (std::vector<boost::shared_ptr<VCA> >::const_iterator i = ml.begin (); i != ml.end(); ++i) {
+		if (assigned_to (manager, *i)) {
+			return true;
+		}
+	}
+	return false;
+}
+
 int
 Slavable::set_state (XMLNode const& node, int version)
 {
diff --git a/libs/ardour/vca.cc b/libs/ardour/vca.cc
index 7be103e9e4..b7b95d1271 100644
--- a/libs/ardour/vca.cc
+++ b/libs/ardour/vca.cc
@@ -208,6 +208,17 @@ VCA::slaved_to (boost::shared_ptr<VCA> vca) const
 	return _gain_control->slaved_to (vca->gain_control());
 }
 
+void
+VCA::assign (boost::shared_ptr<VCA> v)
+{
+	/* prevent recursive assignments */
+	if (assigned_to (_session.vca_manager_ptr (), v)) {
+		warning << _("Master assignment inored to prevent recursion") << endmsg;
+		return;
+	}
+	Slavable::assign (v);
+}
+
 SlavableControlList
 VCA::slavables () const
 {