Fix hang on closing the dialogue in some circumstances. Further fix for #3560.

git-svn-id: svn://localhost/ardour2/branches/3.0@8071 d708f5d6-7413-0410-9779-e7cbd77b26cf

gtk2_ardour/strip_silence_dialog.cc

@@ -52,6 +52,7 @@ StripSilenceDialog::StripSilenceDialog (Session* s, list<boost::shared_ptr<ARDOU
         , _wave_width (640)
         , _wave_height (64)
 	, _peaks_ready_connection (0)
+	, _destroying (false)
 {
         set_session (s);
 
@@ -151,13 +152,15 @@ StripSilenceDialog::StripSilenceDialog (Session* s, list<boost::shared_ptr<ARDOU
 
 StripSilenceDialog::~StripSilenceDialog ()
 {
+	_destroying = true;
+	
 	/* Terminate our thread */
 	
 	_lock.lock ();
 	_interthread_info.cancel = true;
 	_thread_should_finish = true;
 	_lock.unlock ();
-	
+
 	_run_cond.signal ();
 	pthread_join (_thread, 0);
 	
@@ -408,6 +411,15 @@ StripSilenceDialog::detection_thread_work ()
 void
 StripSilenceDialog::restart_thread ()
 {
+	if (_destroying) {
+		/* I don't know how this happens, but it seems to be possible for this
+		   method to be called after our destructor has finished executing.
+		   If this happens, bad things follow; _lock cannot be locked and
+		   Ardour hangs.  So if we are destroying, just bail early.
+		*/
+		return;
+	}
+	
 	/* Cancel any current run */
 	_interthread_info.cancel = true;
 

gtk2_ardour/strip_silence_dialog.h

@@ -91,6 +91,8 @@ private:
 
 	PBD::ScopedConnection* _peaks_ready_connection;
 
+	bool _destroying;
+
 	pthread_t _thread; ///< thread to compute silence in the background
 	static void * _detection_thread_work (void *);
 	void * detection_thread_work ();