added files

git-svn-id: svn://localhost/ardour2/branches/3.0@6374 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/pbd/scoped_connections.h

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+/*
+    Copyright (C) 2009 Paul Davis 
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef __pbd_scoped_connections_h__
+#define __pbd_scoped_connections_h__
+
+#include <list>
+#include <glibmm/thread.h>
+#include <boost/signals2.hpp>
+
+#include "pbd/destructible.h"
+
+namespace PBD {
+
+class ScopedConnectionList 
+{
+  public:
+	ScopedConnectionList();
+	~ScopedConnectionList ();
+	
+	void add_connection (const boost::signals2::connection& c);
+	void drop_connections ();
+
+	template<typename S> void scoped_connect (S& sig, const typename S::slot_function_type& sf) {
+		add_connection (sig.connect (sf));
+	}
+
+  private:
+	/* this class is not copyable */
+	ScopedConnectionList(const ScopedConnectionList&) {}
+
+	/* this lock is shared by all instances of a ScopedConnectionList.
+	   We do not want one mutex per list, and since we only need the lock
+	   when adding or dropping connections, which are generally occuring
+	   in object creation and UI operations, the contention on this 
+	   lock is low and not of significant consequence. Even though
+	   boost::signals2 is thread-safe, this additional list of
+	   scoped connections needs to be protected in 2 cases:
+
+	   (1) (unlikely) we make a connection involving a callback on the
+	       same object from 2 threads. (wouldn't that just be appalling 
+	       programming style?)
+	     
+	   (2) where we are dropping connections in one thread and adding
+	       one from another.
+	 */
+
+	static Glib::StaticMutex _lock;
+
+	typedef std::list<boost::signals2::scoped_connection*> ConnectionList;
+	ConnectionList _list;
+};
+
+} /* namespace */
+
+#endif /* __pbd_scoped_connections_h__ */

libs/pbd/scoped_connections.cc

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+/*
+    Copyright (C) 2009 Paul Davis 
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "pbd/scoped_connections.h"
+
+using namespace PBD;
+
+Glib::StaticMutex ScopedConnectionList::_lock = GLIBMM_STATIC_MUTEX_INIT;
+
+ScopedConnectionList::ScopedConnectionList()
+{
+}
+
+ScopedConnectionList::~ScopedConnectionList()
+{
+	drop_connections ();
+}
+
+void
+ScopedConnectionList::add_connection (const boost::signals2::connection& c)
+{
+	Glib::Mutex::Lock lm (_lock);
+	_list.push_back (new boost::signals2::scoped_connection (c));
+}
+
+void
+ScopedConnectionList::drop_connections ()
+{
+	Glib::Mutex::Lock lm (_lock);
+
+	for (ConnectionList::iterator i = _list.begin(); i != _list.end(); ++i) {
+		delete *i;
+	}
+
+	_list.clear ();
+}
+