+/*
+ Copyright (C) 2015 Carl Hetherington <cth@carlh.net>
+
+ 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 DCPOMATIC_SIGNALLER_H
+#define DCPOMATIC_SIGNALLER_H
+
+#include "ui_signaller.h"
+#include <boost/thread/mutex.hpp>
+#include <boost/signals2.hpp>
+
+class WrapperBase
+{
+public:
+ WrapperBase ()
+ : _valid (true)
+ , _finished (false)
+ {}
+
+ virtual ~WrapperBase () {}
+
+ /* Can be called from any thread */
+ void invalidate ()
+ {
+ boost::mutex::scoped_lock lm (_mutex);
+ _valid = false;
+ }
+
+ bool finished () const {
+ boost::mutex::scoped_lock lm (_mutex);
+ return _finished;
+ }
+
+protected:
+ /* Protect _valid and _finished */
+ mutable boost::mutex _mutex;
+ bool _valid;
+ bool _finished;
+};
+
+/** Helper class to manage lifetime of signals, specifically to address
+ * the problem where an object containing a signal is deleted before
+ * its signal is emitted.
+ */
+template <class T>
+class Wrapper : public WrapperBase
+{
+public:
+ Wrapper (T signal)
+ : _signal (signal)
+ {
+
+ }
+
+ /* Called by the UI thread only */
+ void signal ()
+ {
+ boost::mutex::scoped_lock lm (_mutex);
+ if (_valid) {
+ _signal ();
+ }
+ _finished = true;
+ }
+
+private:
+ T _signal;
+};
+
+/** Parent for any class which needs to raise cross-thread signals (from non-UI
+ * to UI). Subclasses should call, e.g. emit (boost::bind (boost::ref (MySignal), foo, bar));
+ */
+class Signaller
+{
+public:
+ /* Can be called from any thread */
+ virtual ~Signaller () {
+ boost::mutex::scoped_lock lm (_mutex);
+ for (std::list<WrapperBase*>::iterator i = _wrappers.begin(); i != _wrappers.end(); ++i) {
+ (*i)->invalidate ();
+ }
+ }
+
+ /* Can be called from any thread */
+ template <class T>
+ void emit (T signal)
+ {
+ Wrapper<T>* w = new Wrapper<T> (signal);
+ if (ui_signaller) {
+ ui_signaller->emit (boost::bind (&Wrapper<T>::signal, w));
+ }
+
+ boost::mutex::scoped_lock lm (_mutex);
+
+ /* Clean up finished Wrappers */
+ std::list<WrapperBase*>::iterator i = _wrappers.begin ();
+ while (i != _wrappers.end ()) {
+ std::list<WrapperBase*>::iterator tmp = i;
+ ++tmp;
+ if ((*i)->finished ()) {
+ delete *i;
+ _wrappers.erase (i);
+ }
+ i = tmp;
+ }
+
+ /* Add the new one */
+ _wrappers.push_back (w);
+ }
+
+private:
+ /* Protect _wrappers */
+ boost::mutex _mutex;
+ std::list<WrapperBase*> _wrappers;
+};
+
+#endif