mco_rollback_buf_info

获取实时事务的使用统计信息（复制到缓冲区的总页数和复制的空闲页数）。

    typedef struct mco_rollback_buf_info_t_ {
        uint4 n_pages;      // - total number of pages copied to the buffer
        uint4 n_free_pages; // - number of copied free pages
    } mco_rollback_buf_info_t;

    MCO_RET mco_rollback_buf_info(
    	mco_trans_h trans, 
    	mco_rollback_buf_info_t *rb_info
    );