第 8 章：对象

字符串对象

int 编码的字符串对象

digraph { label = "\n 图 8-1 int 编码的字符串对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_STRING | encoding \n REDIS_ENCODING_INT | <ptr> ptr | ... "]; node [shape = plaintext]; number [label = "10086"] redisObject:ptr -> number; }

raw 编码的字符串对象。

digraph { label = "\n 图 8-2 raw 编码的字符串对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_STRING | encoding \n REDIS_ENCODING_RAW | <ptr> ptr | ... "]; sdshdr [label = " <head> sdshdr | free \n 0 | len \n 37 | <buf> buf"]; buf [label = " { 'L' | 'o' | 'n' | 'g' | ... | 'k' | 'i' | 'n' | 'g' | ' ' | '.' | '.' | '.' | '\\0' } " ]; // redisObject:ptr -> sdshdr:head; sdshdr:buf -> buf; }

embstr 编码的字符串对象。

digraph { label = "\n 图 8-4 embstr 编码的字符串对象"; node [shape = record]; embstr [ label = " { redisObject | { type \n REDIS_STRING | encoding \n REDIS_ENCODING_EMBSTR | <ptr> ptr | ... } } | { sdshdr | { free \n 0 | len \n 5 | { buf | { <buf> 'h' | 'e' | 'l' | 'l' | 'o' | '\\0'}} }} " ]; embstr:ptr -> embstr:buf; }

列表对象

ziplist 编码的列表对象。

digraph { label = "\n 图 8-5 ziplist 编码的 numbers 列表对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_LIST | encoding \n REDIS_ENCODING_ZIPLIST | <ptr> ptr | ... "]; ziplist [label = " { zlbytes | zltail | zllen | 1 | \"three\" | 5 | zlend } "]; redisObject:ptr -> ziplist; }

linkedlist 编码的列表对象。

digraph { label = "\n 图 8-6 linkedlist 编码的 numbers 列表对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_LIST | encoding \n REDIS_ENCODING_LINKEDLIST | <ptr> ptr | ... "]; subgraph cluster_linked_list { label = "链表"; style = dashed; node1 [label = "StringObject \n 1 "]; node2 [label = "StringObject \n \"three\""]; node3 [label = "StringObject \n 5 "]; node1 -> node2 -> node3; } redisObject:ptr -> node1; }

哈希对象

ziplist 编码的哈希对象。

digraph { label = "\n 图 8-9 ziplist 编码的 profile 哈希对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_HASH | encoding \n REDIS_ENCODING_ZIPLIST | <ptr> ptr | ... "]; ziplist [label = " 压缩列表 ", width = 4.0]; redisObject:ptr -> ziplist; }

digraph { label = "\n 图 8-10 profile 哈希对象的压缩列表底层实现"; // node [shape = record]; ziplist [label = " zlbytes | zltail | zllen | <key1> \"name\" | <value1> \"Tom\" | <key2> \"age\" | <value2> 25 | <key3> \"career\" | <value3> \"Programmer\" | zlend "]; node [shape = plaintext]; edge [style = dashed]; kv1 [label = "第一个添加的键值对"]; kv1 -> ziplist:key1 [label = "键"]; kv1 -> ziplist:value1 [label = "值"]; kv2 [label = "第二个添加的键值对"]; kv2 -> ziplist:key2; kv2 -> ziplist:value2; kvN [label = "最新添加的键值对"]; kvN -> ziplist:key3; kvN -> ziplist:value3; }

hashtable 编码的哈希对象。

digraph { label = "\n 图 8-11 hashtable 编码的 profile 哈希对象"; rankdir = LR; // node [shape = record]; redisObject [label = " redisObject | type \n REDIS_HASH | encoding \n REDIS_ENCODING_HT | <ptr> ptr | ... "]; dict [label = " <head> dict | <key1> StringObject \n \"age\" | <key2> StringObject \n \"career\" | <key3> StringObject \n \"name\" ", width = 1.5]; age_value [label = "StringObject \n 25"]; career_value [label = "StringObject \n \"Programmer\""]; name_value [label = "StringObject \n \"Tom\""]; // redisObject:ptr -> dict:head; dict:key1 -> age_value; dict:key2 -> career_value; dict:key3 -> name_value; }

集合对象

intset 编码的集合对象。

digraph { label = "\n 图 8-12 intset 编码的 numbers 集合对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_SET | encoding \n REDIS_ENCODING_INTSET | <ptr> ptr | ... "]; intset [label = " <head> intset | encoding \n INTSET_ENC_INT16 | length \n 3 | <contents> contents "]; contents [label = " { 1 | 3 | 5 } "]; redisObject:ptr -> intset:head; intset:contents -> contents; }

hashtable 编码的集合对象。

digraph { label = "\n 图 8-13 hashtable 编码的 fruits 集合对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_SET | encoding \n REDIS_ENCODING_HT | <ptr> ptr | ... "]; dict [label = " <head> dict | <cherry> StringObject \n \"cherry\" | <apple> StringObject \n \"apple\" | <banana> StringObject \n \"banana\" ", width = 1.5]; redisObject:ptr -> dict:head; node [shape = plaintext, label = "NULL"]; dict:apple -> nullX; dict:banana -> nullY; dict:cherry -> nullZ; }

有序集合对象

ziplist 编码的有序集合对象。

digraph { label = "\n 图 8-14 ziplist 编码的有序集合对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_ZSET | encoding \n REDIS_ENCODING_ZIPLIST | <ptr> ptr | ... "]; ziplist [label = "压缩列表", width = 4.0]; redisObject:ptr -> ziplist; }

digraph { label = "\n 图 8-15 有序集合元素在压缩列表中按分值从小到大排列"; // node [shape = record]; ziplist [label = " zlbytes | zltail | zllen | <banana> \"banana\" | <banana_price> 5.0 | <cherry> \"cherry\" | <cherry_price> 6.0 | <apple> \"apple\" | <apple_price> 8.5 | zlend "]; node [shape = plaintext]; banana [label = "分值最少的元素"]; cherry [label = "分值排第二的元素"]; apple [label = "分值最大的元素"]; // banana -> ziplist:banana [label = "成员"]; banana -> ziplist:banana_price [label = "分值"]; cherry -> ziplist:cherry; cherry -> ziplist:cherry_price; apple -> ziplist:apple; apple -> ziplist:apple_price; }

skiplist 编码的有序集合对象。

digraph { label = "\n 图 8-16 skiplist 编码的有序集合对象"; rankdir = LR; node [shape = record]; redisObject [label = " redisObject | type \n REDIS_ZSET | encoding \n REDIS_ENCODING_SKIPLIST | <ptr> ptr | ... "]; zset [label = " <head> zset | <dict> dict | <zsl> zsl "]; node [shape = plaintext]; dict [label = "..."]; zsl [label = "..."]; redisObject:ptr -> zset:head; zset:dict -> dict; zset:zsl -> zsl; }

digraph { rankdir = LR; // node [shape = record]; zset [label = " <head> zset | <dict> dict | <zsl> zsl "]; dict [label = " <head> dict | ... | <ht0> ht[0] | ... "]; ht0 [label = " <head> dictht | ... | <table> table | ... "]; table [label = " <banana> StringObject \n \"banana\" | <apple> StringObject \n \"apple\" | <cherry> StringObject \n \"cherry\" "]; node [shape = plaintext]; apple_price [label = "8.5"]; banana_price [label = "5.0"]; cherry_price [label = "6.0"]; // zset:dict -> dict:head; dict:ht0 -> ht0:head; ht0:table -> table:head; table:apple -> apple_price; table:banana -> banana_price; table:cherry -> cherry_price; // node [shape = record, width = "0.5"]; // l [label = " <header> header | <tail> tail | level \n 5 | length \n 3 "]; subgraph cluster_nodes { style = invisible; header [label = " <l32> L32 | ... | <l5> L5 | <l4> L4 | <l3> L3 | <l2> L2 | <l1> L1 "]; bw_null [label = "NULL", shape = plaintext]; level_null [label = "NULL", shape = plaintext]; A [label = " <l4> L4 | <l3> L3 | <l2> L2 | <l1> L1 | <backward> BW | 5.0 | StringObject \n \"banana\" "]; B [label = " <l2> L2 | <l1> L1 | <backward> BW | 6.0 | StringObject \n \"cherry\" "]; C [label = " <l5> L5 | <l4> L4 | <l3> L3 | <l2> L2 | <l1> L1 | <backward> BW | 8.5 | StringObject \n \"apple\" "]; } subgraph cluster_nulls { style = invisible; n1 [label = "NULL", shape = plaintext]; n2 [label = "NULL", shape = plaintext]; n3 [label = "NULL", shape = plaintext]; n4 [label = "NULL", shape = plaintext]; n5 [label = "NULL", shape = plaintext]; } // l:header -> header; l:tail -> C; header:l32 -> level_null; header:l5 -> C:l5; header:l4 -> A:l4; header:l3 -> A:l3; header:l2 -> A:l2; header:l1 -> A:l1; A:l4 -> C:l4; A:l3 -> C:l3; A:l2 -> B:l2; A:l1 -> B:l1; B:l2 -> C:l2; B:l1 -> C:l1; C:l5 -> n5; C:l4 -> n4; C:l3 -> n3; C:l2 -> n2; C:l1 -> n1; bw_null -> A:backward -> B:backward -> C:backward [dir = back]; zset:zsl -> l:header; // HACK: 放在开头的话 NULL 指针的长度会有异样 label = "\n 图 8-17 有序集合元素同时被保存在字典和跳跃表中"; }

类型检查与命令多态

LLEN 命令执行时的类型检查过程。

digraph { label = "\n 图 8-18 LLEN 命令执行时的类型检查过程"; // call_command [label = "客户端发送 LLEN <key> 命令", shape = box]; check_type [label = "服务器检查 \n 键 key 的值对象\n是否列表对象", shape = diamond]; execute_command [label = "对键 key 执行 LLEN 命令", shape = box]; type_error [label = "返回一个类型错误", shape = box]; // call_command -> check_type; check_type -> execute_command [label = "是"]; check_type -> type_error [label = "否"]; }

LLEN 命令的多态行为。

digraph { label = "\n 图 8-19 LLEN 命令的执行过程"; // node [shape = box]; call_command [label = "客户端发送 LLEN <key> 命令"]; check_type [label = "服务器检查 \n 键 key 的值对象\n是否列表对象", shape = diamond]; //execute_command [label = "对键 key 执行 LLEN 命令"]; select_encoding [label = "对象的编码是 \n ziplist 还是 linkedlist ？", shape = diamond]; ziplist [label = "调用 ziplistLen 函数 \n 返回压缩列表的长度"]; linkedlist [label = "调用 listLength 函数 \n 返回双端链表的长度"]; type_error [label = "返回一个类型错误"]; // call_command -> check_type; //check_type -> execute_command [label = "是"]; check_type -> type_error [label = "否"]; //execute_command -> select_encoding; check_type -> select_encoding [label = "是"]; select_encoding -> ziplist [label = "ziplist \n 编码"]; select_encoding -> linkedlist [label = "linkedlist \n 编码"]; }

对象共享

对象共享的示例。

digraph { label = "\n 图 8-23 引用数为 3 的共享对象"; rankdir = LR; server [label = "服务器程序", shape = box, width = 1.5]; key_a [label = "键 A", shape = box, width = 1.5]; key_b [label = "键 B", shape = box, width = 1.5]; redisObject [label = " <head> redisObject | type \n REDIS_STRING | encoding \n REDIS_ENCODING_INT | <ptr> ptr | refcount \n 3 | ... ", shape = record]; node [shape = plaintext]; number [label = "100"] redisObject:ptr -> number; key_a -> redisObject:head; key_b -> redisObject:head; server -> redisObject:head; }