redis-lists

关于 redis lists 类型

https://redis.io/topics/data-types-intro

lists 相关操作命令 : https://redis.io/commands#list

根据文档中的关于 lists 的简介 为 其基于 linked list 数据结构

对于链表(双向链表)数据结构,对于链表的相关操作包含以下特点

• 新增节点时间复杂度为 O(1)
• 对于查询/删除/更新操作其时间复杂度为 O(n) ,对于 删除/更新操作主要是因为查询的时间复杂度,对于实际的删除/更新操作时间复杂度为o(1) , 由于定位指定节点的时间复杂度为 O(n)

redis 相关内存优化配置

https://redis.io/topics/memory-optimization 

 

对于其 lists 底层数据结构优化

相关配置:  https://redis.io/topics/config

redis 6.0 conf : https://raw.githubusercontent.com/redis/redis/6.0/redis.conf

关于 配置 "list-max-ziplist-size -2" 设置每个 element 的大小自适应设置限制数据量,其通过对数据进行特殊编码进行节省空间;

关于配置 "list-compress-depth 0"  设置是否使用 数据压缩

关于 ziplist 源码 :https://github.com/redis/redis/blob/unstable/src/ziplist.c

重点在于其开头注释

 根据其注释可以看到其实际是一个特殊的双向链表,但其进行了相关的压缩操作,并通过记录每个节点的信息实现快速查找

其 结构特点为 "<zlbytes> <zltail> <zllen> <entry> <entry> ... <entry> <zlend>"

/* We use this function to receive information about a ziplist entry.
 * Note that this is not how the data is actually encoded, is just what we
 * get filled by a function in order to operate more easily. */
typedef struct zlentry {
    unsigned int prevrawlensize; /* Bytes used to encode the previous entry len*/
    unsigned int prevrawlen;     /* Previous entry len. */
    unsigned int lensize;        /* Bytes used to encode this entry type/len.
                                    For example strings have a 1, 2 or 5 bytes
                                    header. Integers always use a single byte.*/
    unsigned int len;            /* Bytes used to represent the actual entry.
                                    For strings this is just the string length
                                    while for integers it is 1, 2, 3, 4, 8 or
                                    0 (for 4 bit immediate) depending on the
                                    number range. */
    unsigned int headersize;     /* prevrawlensize + lensize. */
    unsigned char encoding;      /* Set to ZIP_STR_* or ZIP_INT_* depending on
                                    the entry encoding. However for 4 bits
                                    immediate integers this can assume a range
                                    of values and must be range-checked. */
    unsigned char *p;            /* Pointer to the very start of the entry, that
                                    is, this points to prev-entry-len field. */
} zlentry;

关于 entry 的定义

 

关于quicklist

https://github.com/redis/redis/blob/unstable/src/quicklist.c

A doubly linked list of ziplists