redis源码(5):跳跃表

typedef struct  {
    sds ele;
    double score;
    struct  *backward;
    struct zskiplistLevel {
        struct  *forward;
        unsigned long span;
    } level[];
} zskiplistNode;

typedef struct zskiplist {
    struct  *header, *tail;
    unsigned long length;
    int level;
} zskiplist;