BRPOPLPUSH

    is the blocking variant of RPOPLPUSH. When source contains elements, this command behaves exactly like RPOPLPUSH. When used inside a MULTI/ block, this command behaves exactly like RPOPLPUSH. When source is empty, Dragonfly will block the connection until another client pushes to it or until timeout is reached. A timeout of zero can be used to block indefinitely.

    Bulk string reply: the element being popped from source and pushed to destination. If timeout is reached, a is returned.

    Please see the pattern description in the documentation.