第 8 章：对象 ================= 字符串对象 -------------- ``int`` 编码的字符串对象 .. graphviz:: 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 | ... "]; node [shape = plaintext]; number [label = "10086"] redisObject:ptr -> number; } ---- ``raw`` 编码的字符串对象。 .. graphviz:: 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 | ... "]; sdshdr [label = " sdshdr | free \n 0 | len \n 37 | 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。 .. graphviz:: 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 | ... } } | { sdshdr | { free \n 0 | len \n 5 | { buf | { 'h' | 'e' | 'l' | 'l' | 'o' | '\\0'}} }} " ]; embstr:ptr -> embstr:buf; } 列表对象 ------------ ``ziplist`` 编码的列表对象。 .. graphviz:: 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 | ... "]; ziplist [label = " { zlbytes | zltail | zllen | 1 | \"three\" | 5 | zlend } "]; redisObject:ptr -> ziplist; } ---- ``linkedlist`` 编码的列表对象。 .. graphviz:: 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 | ... "]; 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。 .. graphviz:: 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 | ... "]; ziplist [label = " 压缩列表 ", width = 4.0]; redisObject:ptr -> ziplist; } .. graphviz:: 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 | \"name\" | \"Tom\" | \"age\" | 25 | \"career\" | \"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。 .. graphviz:: 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 | ... "]; dict [label = " dict | StringObject \n \"age\" | StringObject \n \"career\" | 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。 .. graphviz:: 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 | ... "]; intset [label = " intset | encoding \n INTSET_ENC_INT16 | length \n 3 | contents "]; contents [label = " { 1 | 3 | 5 } "]; redisObject:ptr -> intset:head; intset:contents -> contents; } ---- ``hashtable`` 编码的集合对象。 .. graphviz:: 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 | ... "]; dict [label = " dict | StringObject \n \"cherry\" | StringObject \n \"apple\" | 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。 .. graphviz:: 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 | ... "]; ziplist [label = "压缩列表", width = 4.0]; redisObject:ptr -> ziplist; } .. graphviz:: 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\" | 5.0 | \"cherry\" | 6.0 | \"apple\" | 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。 .. graphviz:: 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 | ... "]; zset [label = " zset | dict | zsl "]; node [shape = plaintext]; dict [label = "..."]; zsl [label = "..."]; redisObject:ptr -> zset:head; zset:dict -> dict; zset:zsl -> zsl; } .. graphviz:: digraph { rankdir = LR; // node [shape = record]; zset [label = " zset | dict | zsl "]; dict [label = " dict | ... | ht[0] | ... "]; ht0 [label = " dictht | ... | table | ... "]; table [label = " StringObject \n \"banana\" | StringObject \n \"apple\" | 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 | tail | level \n 5 | length \n 3 "]; subgraph cluster_nodes { style = invisible; header [label = " L32 | ... | L5 | L4 | L3 | L2 | L1 "]; bw_null [label = "NULL", shape = plaintext]; level_null [label = "NULL", shape = plaintext]; A [label = " L4 | L3 | L2 | L1 | BW | 5.0 | StringObject \n \"banana\" "]; B [label = " L2 | L1 | BW | 6.0 | StringObject \n \"cherry\" "]; C [label = " L5 | L4 | L3 | L2 | L1 | 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。 .. graphviz:: 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 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。 .. graphviz:: 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 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。 .. graphviz:: 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 = " redisObject | type \n REDIS_STRING | encoding \n REDIS_ENCODING_INT | 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; }