创建zset

c
robj *createZsetObject(void) {
    zset *zs = zmalloc(sizeof(*zs));
    robj *o;

    zs->dict = dictCreate(&zsetDictType);
    zs->zsl = zslCreate();
    o = createObject(OBJ_ZSET,zs);
    o->encoding = OBJ_ENCODING_SKIPLIST;
    return o;
}




struct redisObject {
    unsigned type:4;      // 对象类型，占用4位，用于标识不同类型的对象
    unsigned encoding:4;  // 对象编码方式，占用4位，用于表示对象数据的存储方式
    unsigned lru:LRU_BITS; /* LRU time (relative to global lru_clock) or
                            * LFU data (least significant 8 bits frequency
                            * and most significant 16 bits access time). */
    int refcount;         // 引用计数，用于记录对象的被引用次数
    void *ptr;            // 指向实际存储对象数据的指针
};

插入

c
int zsetAdd(robj *zobj, double score, sds ele, int in_flags, int *out_flags, double *newscore) {
    /* Turn options into simple to check vars. */
    int incr = (in_flags & ZADD_IN_INCR) != 0;
    int nx = (in_flags & ZADD_IN_NX) != 0;
    int xx = (in_flags & ZADD_IN_XX) != 0;
    int gt = (in_flags & ZADD_IN_GT) != 0;
    int lt = (in_flags & ZADD_IN_LT) != 0;
    *out_flags = 0; /* We'll return our response flags. */
    double curscore;

    /* NaN as input is an error regardless of all the other parameters. */
    if (isnan(score)) {
        *out_flags = ZADD_OUT_NAN;
        return 0;
    }

    /* Update the sorted set according to its encoding. */
    if (zobj->encoding == OBJ_ENCODING_LISTPACK) {
        unsigned char *eptr;

        if ((eptr = zzlFind(zobj->ptr,ele,&curscore)) != NULL) {
            /* NX? Return, same element already exists. */
            if (nx) {
                *out_flags |= ZADD_OUT_NOP;
                return 1;
            }

            /* Prepare the score for the increment if needed. */
            if (incr) {
                score += curscore;
                if (isnan(score)) {
                    *out_flags |= ZADD_OUT_NAN;
                    return 0;
                }
            }

            /* GT/LT? Only update if score is greater/less than current. */
            if ((lt && score >= curscore) || (gt && score <= curscore)) {
                *out_flags |= ZADD_OUT_NOP;
                return 1;
            }

            if (newscore) *newscore = score;

            /* Remove and re-insert when score changed. */
            if (score != curscore) {
                zobj->ptr = zzlDelete(zobj->ptr,eptr);
                zobj->ptr = zzlInsert(zobj->ptr,ele,score);
                *out_flags |= ZADD_OUT_UPDATED;
            }
            return 1;
        } else if (!xx) {
            /* check if the element is too large or the list
             * becomes too long *before* executing zzlInsert. */
            if (zzlLength(zobj->ptr)+1 > server.zset_max_listpack_entries ||
                sdslen(ele) > server.zset_max_listpack_value ||
                !lpSafeToAdd(zobj->ptr, sdslen(ele)))
            {
                zsetConvertAndExpand(zobj, OBJ_ENCODING_SKIPLIST, zsetLength(zobj) + 1);
            } else {
                zobj->ptr = zzlInsert(zobj->ptr,ele,score);
                if (newscore) *newscore = score;
                *out_flags |= ZADD_OUT_ADDED;
                return 1;
            }
        } else {
            *out_flags |= ZADD_OUT_NOP;
            return 1;
        }
    }

    /* Note that the above block handling listpack would have either returned or
     * converted the key to skiplist. */
    if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
        zset *zs = zobj->ptr;
        zskiplistNode *znode;
        dictEntry *de;

        de = dictFind(zs->dict,ele);
        if (de != NULL) {
            /* NX? Return, same element already exists. */
            if (nx) {
                *out_flags |= ZADD_OUT_NOP;
                return 1;
            }

            curscore = *(double*)dictGetVal(de);

            /* Prepare the score for the increment if needed. */
            if (incr) {
                score += curscore;
                if (isnan(score)) {
                    *out_flags |= ZADD_OUT_NAN;
                    return 0;
                }
            }

            /* GT/LT? Only update if score is greater/less than current. */
            if ((lt && score >= curscore) || (gt && score <= curscore)) {
                *out_flags |= ZADD_OUT_NOP;
                return 1;
            }

            if (newscore) *newscore = score;

            /* Remove and re-insert when score changes. */
            if (score != curscore) {
                znode = zslUpdateScore(zs->zsl,curscore,ele,score);
                /* Note that we did not removed the original element from
                 * the hash table representing the sorted set, so we just
                 * update the score. */
                dictSetVal(zs->dict, de, &znode->score); /* Update score ptr. */
                *out_flags |= ZADD_OUT_UPDATED;
            }
            return 1;
        } else if (!xx) {
            ele = sdsdup(ele);
            znode = zslInsert(zs->zsl,score,ele);
            serverAssert(dictAdd(zs->dict,ele,&znode->score) == DICT_OK);
            *out_flags |= ZADD_OUT_ADDED;
            if (newscore) *newscore = score;
            return 1;
        } else {
            *out_flags |= ZADD_OUT_NOP;
            return 1;
        }
    } else {
        serverPanic("Unknown sorted set encoding");
    }
    return 0; /* Never reached. */
}

删除

c
int zsetDel(robj *zobj, sds ele) {
    if (zobj->encoding == OBJ_ENCODING_LISTPACK) {
        // 如果编码方式为列表包（Listpack）
        unsigned char *eptr;

        // 在列表包中查找指定元素
        if ((eptr = zzlFind(zobj->ptr,ele,NULL)) != NULL) {
            // 如果找到元素，则从列表包中删除它
            zobj->ptr = zzlDelete(zobj->ptr,eptr);
            return 1;
        }
    } else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
        // 如果编码方式为跳跃表（Skip List）
        zset *zs = zobj->ptr;
        if (zsetRemoveFromSkiplist(zs, ele)) {
            // 如果从跳跃表中成功删除元素
            if (htNeedsResize(zs->dict)) dictResize(zs->dict);
            return 1;
        }
    } else {
        // 如果编码方式未知，则触发服务器崩溃
        serverPanic("Unknown sorted set encoding");
    }
    return 0; // 没有找到指定元素
}



static int zsetRemoveFromSkiplist(zset *zs, sds ele) {
    dictEntry *de;
    double score;

    de = dictUnlink(zs->dict,ele);
    if (de != NULL) {
        /* Get the score in order to delete from the skiplist later. */
        score = *(double*)dictGetVal(de);

        /* Delete from the hash table and later from the skiplist.
         * Note that the order is important: deleting from the skiplist
         * actually releases the SDS string representing the element,
         * which is shared between the skiplist and the hash table, so
         * we need to delete from the skiplist as the final step. */
        dictFreeUnlinkedEntry(zs->dict,de);

        /* Delete from skiplist. */
        int retval = zslDelete(zs->zsl,score,ele,NULL);
        serverAssert(retval);

        return 1;
    }

    return 0;
}