+int consumer_close_metadata(struct consumer_socket *socket,
+ uint64_t metadata_key);
+int consumer_setup_metadata(struct consumer_socket *socket,
+ uint64_t metadata_key);
+int consumer_push_metadata(struct consumer_socket *socket,
+ uint64_t metadata_key, char *metadata_str, size_t len,
+ size_t target_offset);
+int consumer_flush_channel(struct consumer_socket *socket, uint64_t key);