6 files changed, 36 insertions, 19 deletions

diff --git a/libs/pbd/pbd/abstract_ui.cc b/libs/pbd/pbd/abstract_ui.cc
index 97f19e1fe5..8e5b9ceb07 100644
--- a/libs/pbd/pbd/abstract_ui.cc
+++ b/libs/pbd/pbd/abstract_ui.cc
@@ -17,7 +17,6 @@ AbstractUI<RequestObject>::AbstractUI (string name, bool with_signal_pipes)
 		throw failed_constructor();
 	}
 
-	PBD::ThreadCreated.connect (mem_fun (*this, &AbstractUI<RequestObject>::register_thread));
 	PBD::ThreadCreatedWithRequestSize.connect (mem_fun (*this, &AbstractUI<RequestObject>::register_thread_with_request_count));
 }
 
diff --git a/libs/pbd/pbd/command.h b/libs/pbd/pbd/command.h
index a66485bc0d..3fac531591 100644
--- a/libs/pbd/pbd/command.h
+++ b/libs/pbd/pbd/command.h
@@ -26,7 +26,7 @@
 class Command : public PBD::StatefulDestructible
 {
 public:
-	virtual ~Command() {}
+	virtual ~Command() { /* NOTE: derived classes must call drop_references() */ }
 
 	virtual void operator() () = 0;
 	
diff --git a/libs/pbd/pbd/memento_command.h b/libs/pbd/pbd/memento_command.h
index fdc7527dc6..660e5875d5 100644
--- a/libs/pbd/pbd/memento_command.h
+++ b/libs/pbd/pbd/memento_command.h
@@ -43,7 +43,7 @@ public:
 		: obj(object), before(before), after(after)
 	{
 		/* catch destruction of the object */
-		new PBD::Shiva<obj_T,MementoCommand<obj_T> > (object, *this);
+		new PBD::PairedShiva<obj_T,MementoCommand<obj_T> > (object, *this);
 	}
 
 	~MementoCommand ()
diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index 9fa6ba4ce4..dd91e0a2b1 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -35,8 +35,11 @@ void pthread_exit_pbd (void* status);
 std::string pthread_name ();
 
 namespace PBD {
-  extern sigc::signal<void,pthread_t,std::string> ThreadCreated;
-  extern sigc::signal<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
+	extern void notify_gui_about_thread_creation (pthread_t, std::string, int requests = 256);
+	extern void notify_gui_about_thread_exit (pthread_t);
+
+	extern sigc::signal<void,pthread_t>             ThreadLeaving;
+	extern sigc::signal<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
 #endif /* __pbd_pthread_utils__ */
diff --git a/libs/pbd/pbd/shiva.h b/libs/pbd/pbd/shiva.h
index 2e53ff65f5..90adad6250 100644
--- a/libs/pbd/pbd/shiva.h
+++ b/libs/pbd/pbd/shiva.h
@@ -27,7 +27,8 @@ namespace PBD {
 /* named after the Hindu god Shiva, The Destroyer */
 
 template<typename ObjectWithGoingAway, typename ObjectToBeDestroyed>
-class Shiva {
+class Shiva : public sigc::trackable 
+{
   public:
 	Shiva (ObjectWithGoingAway& emitter, ObjectToBeDestroyed& receiver) {
 
@@ -58,15 +59,15 @@ class Shiva {
 };
 
 template<typename ObjectWithGoingAway, typename ObjectToBeDestroyed>
-class ProxyShiva {
+class ProxyShiva : public sigc::trackable 
+{
   public:
 	ProxyShiva (ObjectWithGoingAway& emitter, ObjectToBeDestroyed& receiver, void (*callback)(ObjectToBeDestroyed*, ObjectWithGoingAway*)) {
-
+		
 		/* if the emitter goes away, destroy the receiver */
 
 		_callback = callback;
-		_callback_argument1 = &receiver;
-		_callback_argument2 = &emitter;
+		_callback_argument = &emitter;
 
 		_connection = emitter.GoingAway.connect 
 			(sigc::bind (sigc::mem_fun 
@@ -74,19 +75,18 @@ class ProxyShiva {
 				     &receiver));
 	}
 
-	~ProxyShiva() { 
+	~ProxyShiva () {
 		forget ();
 	}
 
   private:
 	sigc::connection _connection;
 	void (*_callback) (ObjectToBeDestroyed*, ObjectWithGoingAway*);
-	ObjectToBeDestroyed* _callback_argument1;
-	ObjectWithGoingAway* _callback_argument2;
+	ObjectWithGoingAway* _callback_argument;
 
 	void destroy (ObjectToBeDestroyed* obj) {
 		/* callback must destroy obj if appropriate, not done here */
-		_callback (obj, _callback_argument2);
+		_callback (obj, _callback_argument);
 		forget ();
 	}
 
@@ -96,7 +96,8 @@ class ProxyShiva {
 };
 
 template<typename ObjectWithGoingAway, typename ObjectToBeDestroyed>
-class PairedShiva {
+class PairedShiva : public sigc::trackable 
+{
   public:
 	PairedShiva (ObjectWithGoingAway& emitter, ObjectToBeDestroyed& receiver) {
 
diff --git a/libs/pbd/pbd/undo.h b/libs/pbd/pbd/undo.h
index 8f1716d09f..cf1f6f3470 100644
--- a/libs/pbd/pbd/undo.h
+++ b/libs/pbd/pbd/undo.h
@@ -27,6 +27,7 @@
 #include <sigc++/bind.h>
 #include <sys/time.h>
 #include <pbd/command.h>
+#include <pbd/shiva.h>
 
 typedef sigc::slot<void> UndoAction;
 
@@ -36,7 +37,6 @@ class UndoTransaction : public Command
 	UndoTransaction ();
 	UndoTransaction (const UndoTransaction&);
 	UndoTransaction& operator= (const UndoTransaction&);
-	~UndoTransaction ();
 
 	void clear ();
 	bool empty() const;
@@ -61,10 +61,17 @@ class UndoTransaction : public Command
 
   private:
 	std::list<Command*>    actions;
+	std::list<PBD::ProxyShiva<Command,UndoTransaction>*> shivas;
 	struct timeval        _timestamp;
 	bool                  _clearing;
 
 	friend void command_death (UndoTransaction*, Command *);
+	
+	friend class UndoHistory;
+
+	~UndoTransaction ();
+	void about_to_explicitly_delete ();
+	
 };
 
 class UndoHistory : public sigc::trackable
@@ -87,17 +94,24 @@ class UndoHistory : public sigc::trackable
 	void clear_undo ();
 	void clear_redo ();
 
+	/* returns all or part of the history.
+	   If depth==0 it returns just the top
+	   node. If depth<0, it returns everything.
+	   If depth>0, it returns state for that
+	   many elements of the history, or 
+	   the full history, whichever is smaller.
+	*/
+
         XMLNode &get_state(int32_t depth = 0);
         void save_state();
 
-	void set_depth (int32_t);
-	int32_t get_depth() const { return _depth; }
+	void set_depth (uint32_t);
 
 	sigc::signal<void> Changed;
 	
   private:
 	bool _clearing;
-	int32_t _depth;
+	uint32_t _depth;
 	std::list<UndoTransaction*> UndoList;
 	std::list<UndoTransaction*> RedoList;