From 3bc7f863ca3434aeda872a862229b8d14e6eef62 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Fri, 2 Oct 2015 19:22:16 -0400
Subject: explicitly drop control surface protocols before disconnecting from
 engine.

This is not bomb/thread proof yet, because it still requires at least one process callback to function
---
 libs/ardour/ardour/control_protocol_manager.h |  5 ++--
 libs/ardour/control_protocol_manager.cc       | 43 ++++++++++++++++-----------
 libs/ardour/session.cc                        |  6 ++++
 3 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/libs/ardour/ardour/control_protocol_manager.h b/libs/ardour/ardour/control_protocol_manager.h
index 0c8c9014f0..8d196b36d7 100644
--- a/libs/ardour/ardour/control_protocol_manager.h
+++ b/libs/ardour/ardour/control_protocol_manager.h
@@ -64,8 +64,9 @@ class LIBARDOUR_API ControlProtocolManager : public PBD::Stateful, public ARDOUR
 	void foreach_known_protocol (boost::function<void(const ControlProtocolInfo*)>);
 	void load_mandatory_protocols ();
 	void midi_connectivity_established ();
-
-        int activate (ControlProtocolInfo&);
+	void drop_protocols ();
+	
+	int activate (ControlProtocolInfo&);
         int deactivate (ControlProtocolInfo&);
 	
 	std::list<ControlProtocolInfo*> control_protocol_info;
diff --git a/libs/ardour/control_protocol_manager.cc b/libs/ardour/control_protocol_manager.cc
index fdac48e731..376152c139 100644
--- a/libs/ardour/control_protocol_manager.cc
+++ b/libs/ardour/control_protocol_manager.cc
@@ -126,26 +126,35 @@ void
 ControlProtocolManager::session_going_away()
 {
 	SessionHandlePtr::session_going_away ();
+	/* Session::destroy() will explicitly call drop_protocols() so we don't
+	 * have to worry about that here.
+	 */
+}
 
-	{
-		Glib::Threads::Mutex::Lock lm (protocols_lock);
-
-		for (list<ControlProtocol*>::iterator p = control_protocols.begin(); p != control_protocols.end(); ++p) {
-			delete *p;
-		}
-
-		control_protocols.clear ();
-
-		for (list<ControlProtocolInfo*>::iterator p = control_protocol_info.begin(); p != control_protocol_info.end(); ++p) {
-			// mark existing protocols as requested
-			// otherwise the ControlProtocol instances are not recreated in set_session
-			if ((*p)->protocol) {
-				(*p)->requested = true;
-				(*p)->protocol = 0;
-			}
+void
+ControlProtocolManager::drop_protocols ()
+{
+	/* called explicitly by Session::destroy() so that we can clean up
+	 * before the process cycle stops and ports vanish.
+	 */
+	
+	Glib::Threads::Mutex::Lock lm (protocols_lock);
+	
+	for (list<ControlProtocol*>::iterator p = control_protocols.begin(); p != control_protocols.end(); ++p) {
+		delete *p;
+	}
+	
+	control_protocols.clear ();
+	
+	for (list<ControlProtocolInfo*>::iterator p = control_protocol_info.begin(); p != control_protocol_info.end(); ++p) {
+		// mark existing protocols as requested
+		// otherwise the ControlProtocol instances are not recreated in set_session
+		if ((*p)->protocol) {
+			(*p)->requested = true;
+			(*p)->protocol = 0;
 		}
 	}
-}
+}	
 
 ControlProtocol*
 ControlProtocolManager::instantiate (ControlProtocolInfo& cpi)
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 496afad83b..b0aee20ce3 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -551,6 +551,12 @@ Session::destroy ()
 
 	drop_connections ();
 
+	/* shutdown control surface protocols while we still have ports
+	   and the engine to move data to any devices.
+	*/
+	
+	ControlProtocolManager::instance().drop_protocols ();
+	
 	_engine.remove_session ();
 
 #ifdef USE_TRACKS_CODE_FEATURES
-- 
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