Fix race causing MIDI tracer to stop working when master record state is changed.

git-svn-id: svn://localhost/ardour2/branches/3.0@7320 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 7 insertions, 1 deletions

diff --git a/gtk2_ardour/midi_tracer.h b/gtk2_ardour/midi_tracer.h
index 47f1738243..fb5943370d 100644
--- a/gtk2_ardour/midi_tracer.h
+++ b/gtk2_ardour/midi_tracer.h
@@ -36,7 +36,13 @@ class MidiTracer : public ArdourDialog
 	bool autoscroll;
 	bool show_hex;
 	bool collect;
-	volatile bool update_queued;
+	
+	/** Incremented when an update is requested, decremented when one is handled; hence
+	 *  equal to 0 when an update is not queued.  May temporarily be negative if a
+	 *  update is handled before it was noted that it had just been queued.
+	 */
+	volatile gint _update_queued;
+	 
 	RingBuffer<char *> fifo;
 	Pool buffer_pool;
 	static const size_t buffer_size = 256;