+ bool _peaks_built;
+ /** This mutex is used to protect both the _peaks_built
+ * variable and also the emission (and handling) of the
+ * PeaksReady signal. Holding the lock when emitting
+ * PeaksReady means that _peaks_built cannot be changed
+ * during the handling of the signal.
+ */
+ mutable Glib::Mutex _peaks_ready_lock;
+