handle deletion of UI objects between the time that a callback is queued with the UI event loop and the execution of the callback (intrusive, big)

git-svn-id: svn://localhost/ardour2/branches/3.0@6807 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 30 insertions, 1 deletions

diff --git a/libs/pbd/pbd/event_loop.h b/libs/pbd/pbd/event_loop.h
index be98fcd852..088b061826 100644
--- a/libs/pbd/pbd/event_loop.h
+++ b/libs/pbd/pbd/event_loop.h
@@ -33,7 +33,34 @@ class EventLoop
 	EventLoop() {}
 	virtual ~EventLoop() {}
 
-	virtual void call_slot (const boost::function<void()>&) = 0;
+	enum RequestType {
+		range_guarantee = ~0
+	};
+
+        struct BaseRequestObject;
+    
+        struct InvalidationRecord {
+            BaseRequestObject* request;
+            PBD::EventLoop* event_loop;
+            const char* file;
+            int line;
+
+            InvalidationRecord() : request (0), event_loop (0) {}
+        };
+
+        static void* invalidate_request (void* data);
+
+	struct BaseRequestObject {
+	    RequestType             type;
+            bool                    valid;
+            InvalidationRecord*     invalidation;
+	    boost::function<void()> the_slot;
+            
+            BaseRequestObject() : valid (true), invalidation (0) {}
+	};
+
+	virtual void call_slot (InvalidationRecord*, const boost::function<void()>&) = 0;
+        virtual Glib::Mutex& slot_invalidation_mutex() = 0;
 
 	static EventLoop* get_event_loop_for_thread();
 	static void set_event_loop_for_thread (EventLoop* ui);
@@ -45,4 +72,6 @@ class EventLoop
 
 }
 
+#define MISSING_INVALIDATOR 0 // used to mark places where we fail to provide an invalidator
+
 #endif /* __pbd_event_loop_h__ */