Don't allow process callback to be invoked between Engine and JACK::Client destruction.

Patch submitted by Peter Nelson. Comments added.

Timeline/Engine/Engine.C

@@ -38,6 +38,10 @@ Engine::Engine ( ) : _thread( "RT" )
 
 Engine::~Engine ( )
 {
+    /* We have to deactivate here in order to avoid our process
+       callback is being invoked after we're already destroyed, but
+       before the base class is */
+    deactivate();
 }
 
 

nonlib/JACK/Client.C

@@ -34,10 +34,16 @@ namespace JACK
 
     Client::~Client ( )
     {
-        jack_deactivate( _client );
         jack_client_close( _client );
     }
 
+    /** Tell JACK to calling process callback. This MUST be called in
+     * an inheriting class' destructor */
+    void
+    Client::deactivate ( )
+    {
+        jack_deactivate( _client );
+    }
 
 
 /*******************/

nonlib/JACK/Client.H

@@ -55,6 +55,10 @@ namespace JACK
         Client ( const Client &rhs );
         Client & operator = ( const Client &rhs );
 
+    protected:
+
+        void deactivate ( void );
+
     private:
 
         friend class Port;