# 安裝centos-release-scl
% yum -y install centos-release-scl
# 安裝devtoolset GGC9
% yum -y install devtoolset-9-gcc devtoolset-9-gcc-c++ devtoolset-9-binutils
# 激活對應的devtoolset
% echo “source /opt/rh/devtoolset-9/enable” >> /etc/profile
# 查看版本
% gcc -v

% wget http://download.redis.io/releases/redis-6.2.6.tar.gz
% tar -zxvf redis-6.2.6.tar.gz -C  /home/jay/redis/redis-6.2.6/ && rm -rf redis-6.2.6.tar.gz
% cd  /home/jay/redis/redis-6.2.6/
% make
% make install
# 啟動Redis
% cd src
% ./redis-server
# 驗證
% cd src
% ./redis-cli

//server.h
typedef struct redisDb {
    dict *dict;                 /* The keyspace for this DB */
    dict *expires;              /* Timeout of keys with a timeout set */
    dict *blocking_keys;        /* Keys with clients waiting for data (BLPOP)*/
    dict *ready_keys;           /* Blocked keys that received a PUSH */
    dict *watched_keys;         /* WATCHED keys for MULTI/EXEC CAS */
    int id;                     /* Database ID */
    long long avg_ttl;          /* Average TTL, just for stats */
    unsigned long expires_cursor; /* Cursor of the active expire cycle. */
    list *defrag_later;         /* List of key names to attempt to defrag one by one, gradually. */
} redisDb;

int dictRehash(dict *d, int n) {
    int empty_visits = n*10; /* Max number of empty buckets to visit. */
    if (!dictIsRehashing(d)) return 0;
    while(n-- && d->ht[0].used != 0) {
        dictEntry *de, *nextde;
        /* Note that rehashidx can't overflow as we are sure there are more
         * elements because ht[0].used != 0 */
        assert(d->ht[0].size > (unsigned long)d->rehashidx);
        while(d->ht[0].table[d->rehashidx] == NULL) {
            d->rehashidx++;
            if (--empty_visits == 0) return 1;
        }
      /*在HASH桶中找到非空的索引后，開始鏈表的數據移動工作*/
        de = d->ht[0].table[d->rehashidx];
        /* Move all the keys in this bucket from the old to the new hash HT */
        while(de) {
            uint64_t h;
            nextde = de->next;
            /* 在新的hash表中找到對應鍵值的索引 */
            h = dictHashKey(d, de->key) & d->ht[1].sizemask;
            /* 把要增加的數據放在新的hash表對應索引鏈表的開始 */
            de->next = d->ht[1].table[h];
            d->ht[1].table[h] = de;
            /* 更新計數器 */
            d->ht[0].used--;
            d->ht[1].used++;
             /* 鏈表中的下一個Node */
            de = nextde;
        }
         /* 因數據已完成移動，因此清空老的hash表對應的桶 */
        d->ht[0].table[d->rehashidx] = NULL;
         /* 指向下一個桶 */
        d->rehashidx++;
    }
/* 如果已經rehashed了所有的表，釋放HT[0]的表空間，將HT[1]設置為當前的表，重置HT[1] */
    if (d->ht[0].used == 0) {
        zfree(d->ht[0].table);
        d->ht[0] = d->ht[1];
        _dictReset(&d->ht[1]);
        d->rehashidx = -1;
        return 0;
    }
    /* More to rehash... */
    return 1;
}

//SDS.H
struct __attribute__ ((__packed__)) sdshdr8 {
    uint8_t len; /* used */
    uint8_t alloc; /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};
struct __attribute__ ((__packed__)) sdshdr16 {
    uint16_t len; /* used */
    uint16_t alloc; /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};

//object.c
robj *createQuicklistObject(void) {
    quicklist *l = quicklistCreate();
    robj *o = createObject(OBJ_LIST,l);
    o->encoding = OBJ_ENCODING_QUICKLIST;
    return o;
}
robj *createZiplistObject(void) {
    unsigned char *zl = ziplistNew();
    robj *o = createObject(OBJ_LIST,zl);
    o->encoding = OBJ_ENCODING_ZIPLIST;
    return o;
}
robj *createSetObject(void) {
    dict *d = dictCreate(&setDictType,NULL);
    robj *o = createObject(OBJ_SET,d);
    o->encoding = OBJ_ENCODING_HT;
    return o;
}
robj *createIntsetObject(void) {
    intset *is = intsetNew();
    robj *o = createObject(OBJ_SET,is);
    o->encoding = OBJ_ENCODING_INTSET;
    return o;
}
robj *createHashObject(void) {
    unsigned char *zl = ziplistNew();
    robj *o = createObject(OBJ_HASH, zl);
    o->encoding = OBJ_ENCODING_ZIPLIST;
    return o;
}