+extern uint64_t now_global;
+extern struct timeval tv_now_global;
+
+static const uint64_t *const now = &now_global;
+static const struct timeval *const tv_now = &tv_now_global;
+
+/* "now" is current program time, in milliseconds. It is derived
+ from tv_now. Both are provided by the event loop. */
+