pub unsafe extern "C" fn rocksdb_write_buffer_manager_mutable_memtable_memory_usage(
wbm: *mut rocksdb_write_buffer_manager_t
) -> usize
pub unsafe extern "C" fn rocksdb_write_buffer_manager_mutable_memtable_memory_usage(
wbm: *mut rocksdb_write_buffer_manager_t
) -> usize