Block until all the elements in this queue are removed.
Declared in <bdlcc_singleproducerqueueimpl.h>
int
waitUntilEmpty() const;
Return 0 on success, and a non-zero value otherwise. Specifically, return e_DISABLED if !isEmpty() && isPopFrontDisabled(). A blocked thread waiting for the queue to empty will return e_DISABLED if disablePopFront is invoked.
0 on success, and a non-zero value otherwise