深入 Redis 数据结构和底层原理

127.0.0.1:6379> set str helloOK127.0.0.1:6379> get str"hello"

typedef char *sds;
/* Sdshdr5从未被使用过，我们只是直接访问标记字节，在这里是为了记录类型5 SDS字符串的布局。*/struct __attribute__ ((__packed__)) sdshdr5 {    unsigned char flags; /* 3LSB的类型，5MSB的字符串长度   */    char buf[];};struct __attribute__ ((__packed__)) sdshdr8 {    uint8_t len;     uint8_t alloc; /* 排除头和空结束符 */    unsigned char flags;     char buf[];};struct __attribute__ ((__packed__)) sdshdr16 {    uint16_t len;     uint16_t alloc;     unsigned char flags;     char buf[];};struct __attribute__ ((__packed__)) sdshdr32 {    uint32_t len;     uint32_t alloc;     unsigned char flags;     char buf[];};struct __attribute__ ((__packed__)) sdshdr64 {    uint64_t len;    uint64_t alloc;    unsigned char flags;     char buf[];};

127.0.0.1:6379> lpush items a b c(integer) 3127.0.0.1:6379> lrange items 1 101) "b"2) "a"127.0.0.1:6379> lrange items 0 101) "c"2) "b"3) "a"127.0.0.1:6379> lpush items d(integer) 4127.0.0.1:6379> lrange items 0 101) "d"2) "c"3) "b"4) "a"127.0.0.1:6379> lpop items"d"127.0.0.1:6379> lrange items 0 101) "c"2) "b"3) "a"

typedef struct listNode {    struct listNode *prev; //头指针    struct listNode *next; //尾指针    void *value; //节点的值} listNode;
typedef struct listIter {    listNode *next;     int direction;} listIter;
typedef struct list {    listNode *head;    listNode *tail;    void *(*dup)(void *ptr);    void (*free)(void *ptr);    int (*match)(void *ptr, void *key);    unsigned long len;} list;

127.0.0.1:6379> sadd set_items a b c c d d(integer) 4127.0.0.1:6379> smembers set_items1) "c"2) "b"3) "d"4) "a"127.0.0.1:6379> sadd set_items e(integer) 1127.0.0.1:6379> smembers set_items1) "d"2) "a"3) "e"4) "b"5) "c"127.0.0.1:6379>

typedef struct intset {    uint32_t encoding;    uint32_t length;    int8_t contents[];} intset;

127.0.0.1:6379> zadd zset_items 1 a 2 c 3 b(integer) 3127.0.0.1:6379> zrange zset_items 0 101) "a"2) "c"3) "b"127.0.0.1:6379> add 2 d(error) ERR unknown command 'add'127.0.0.1:6379> zadd zset_items 2 d(integer) 1127.0.0.1:6379> zrange zset_items 0 101) "a"2) "c"3) "d"4) "b"

/* ZSET使用特殊版本的跳表 */typedef struct zskiplistNode {    sds ele;    double score;     struct zskiplistNode *backward;    struct zskiplistLevel { // 跳表的层数        struct zskiplistNode *forward;        unsigned long span;    } level[];} zskiplistNode;
typedef struct zskiplist {    struct zskiplistNode *header, *tail; //头指针和尾指针    unsigned long length;    int level;} zskiplist;
typedef struct zset {    dict *dict; //哈希表    zskiplist *zsl; //跳表} zset;

127.0.0.1:6379> hmset map name zs age 12OK127.0.0.1:6379> hgetall map1) "name"2) "zs"3) "age"4) "12"127.0.0.1:6379> hget map name"zs"127.0.0.1:6379> hmset map school zzOK127.0.0.1:6379> hgetall map1) "name"2) "zs"3) "age"4) "12"5) "school"6) "zz"127.0.0.1:6379> hdel map age(integer) 1127.0.0.1:6379> hgetall map1) "name"2) "zs"3) "school"4) "zz"127.0.0.1:6379>

typedef struct dictEntry {    void *key;    union {        void *val;        uint64_t u64;        int64_t s64;        double d;    } v;    struct dictEntry *next;} dictEntry;
typedef struct dictType {    uint64_t (*hashFunction)(const void *key);    void *(*keyDup)(void *privdata, const void *key);    void *(*valDup)(void *privdata, const void *obj);    int (*keyCompare)(void *privdata, const void *key1, const void *key2);    void (*keyDestructor)(void *privdata, void *key);    void (*valDestructor)(void *privdata, void *obj);} dictType;
/* 这是哈希表结构。 当我们实现增量重哈希时，每个字典都有两个这样的表，从旧表到新表。 */typedef struct dictht {    dictEntry **table;    unsigned long size;    unsigned long sizemask;    unsigned long used;} dictht;
typedef struct dict {    dictType *type;    void *privdata;    dictht ht[2];    long rehashidx;     unsigned long iterators; /* 当前运行的迭代器数量 */} dict;