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Lua 与 Redis

2016-10-07 14:11 218 查看

http://blog.csdn.net/zjf280441589/article/details/52716720

Lua 与 Redis

从 2.6版本起, Redis 开始支持 Lua 脚本让开发者自己扩展 Redis …

案例-实现访问频率限制: 实现访问者 $ip 在一定的时间 $time 内只能访问 $limit 次.

非脚本实现

<code class="hljs applescript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">private <span class="hljs-type" style="box-sizing: border-box;">boolean</span> accessLimit(String ip, int limit, int <span class="hljs-property" style="box-sizing: border-box;">time</span>, Jedis jedis) {
<span class="hljs-type" style="box-sizing: border-box;">boolean</span> <span class="hljs-constant" style="box-sizing: border-box;">result</span> = <span class="hljs-constant" style="box-sizing: border-box;">true</span>;

String key = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"rate.limit:"</span> + ip;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (jedis.exists(key)) {
long afterValue = jedis.incr(key);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (afterValue > limit) {
<span class="hljs-constant" style="box-sizing: border-box;">result</span> = <span class="hljs-constant" style="box-sizing: border-box;">false</span>;
}
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
Transaction <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">transaction</span> = jedis.multi();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">transaction</span>.incr(key);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">transaction</span>.expire(key, <span class="hljs-property" style="box-sizing: border-box;">time</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">transaction</span>.exec();
}
<span class="hljs-command" style="box-sizing: border-box;">    return</span> <span class="hljs-constant" style="box-sizing: border-box;">result</span>;
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul>

以上代码有两点缺陷

可能会出现竞态条件: 解决方法是用

WATCH

监控

rate.limit:$IP

的变动,
但较为麻烦;
以上代码在不使用

pipeline

的情况下最多需要向Redis请求5条指令, 传输过多.

Lua脚本实现

Redis 允许将 Lua 脚本传到 Redis 服务器中执行, 脚本内可以调用大部分 Redis 命令, 且 Redis 保证脚本的原子性:

首先需要准备Lua代码: script.lua

<code class="hljs livecodeserver has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Created by IntelliJ IDEA.</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- User: jifang</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Date: 16/8/24</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Time: 下午6:11</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--</span>

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">local</span> key = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"rate.limit:"</span> .. KEYS[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">local</span> limit = tonumber(ARGV[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>])
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">local</span> expire_time = ARGV[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>]

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">local</span> is_exists = redis.call(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"EXISTS"</span>, key)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> is_exists == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> redis.call(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"INCR"</span>, key) > limit <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-constant" style="box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
<span class="hljs-constant" style="box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
redis.call(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SET"</span>, key, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)
redis.call(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"EXPIRE"</span>, key, expire_time)
<span class="hljs-constant" style="box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li></ul>

Java

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">accessLimit</span>(String ip, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> limit, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> timeout, Jedis connection) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> IOException {
List<String> keys = Collections.singletonList(ip);
List<String> argv = Arrays.asList(String.valueOf(limit), String.valueOf(timeout));

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> == (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span>) connection.eval(loadScriptString(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"script.lua"</span>), keys, argv);
}

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 加载Lua代码</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String <span class="hljs-title" style="box-sizing: border-box;">loadScriptString</span>(String fileName) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> IOException {
Reader reader = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> InputStreamReader(Client.class.getClassLoader().getResourceAsStream(fileName));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> CharStreams.toString(reader);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

Lua 嵌入 Redis 优势:

减少网络开销: 不使用 Lua 的代码需要向 Redis 发送多次请求, 而脚本只需一次即可, 减少网络传输;
原子操作: Redis 将整个脚本作为一个原子执行, 无需担心并发, 也就无需事务;
复用: 脚本会永久保存 Redis 中, 其他客户端可继续使用.

Lua模型

Lua是一种便于嵌入应用程序的脚本语言, 具备了作为通用脚本语言的所有功能. 其高速虚拟机实现非常有名(Lua的垃圾回收很有讲究- 增量垃圾回收 ), 在很多虚拟机系性能评分中都取得了优异的成绩. Home lua.org.

以嵌入式为方针设计的Lua, 在默认状态下简洁得吓人. 除了基本的数据类型外, 其他一概没有. 标注库也就 Coroutine、String、Table、Math、I/O、OS, 再加上Modules包加载而已.
参考: Lua 5.1 Reference Manual - Standard Libraries(中文版:
Lua 5.1 参考手册).

注: 本文仅介绍 Lua 与众不同的设计模型(对比 Java/C/C++、JavaScript、Python 与 Go),
语言细节可参考文内和附录推荐的文章以及Lua之父Roberto Ierusalimschy的<Programming in Lua>(中文版: <LUA程序设计(第2版)>)

Base

1. 数据类型

作为通用脚本语言, Lua的数据类型如下:

数值型:

全部为浮点数型, 没有整型;

只有

nil

和

false

作为布尔值的

false

,
数字

和空串（

‘’

‘\0’

）都是

true

;
字符串
用户自定义类型
函数(function)
表(table)

变量如果没有特殊说明为全局变量(那怕是语句块 or 函数内), 局部变量前需加

local

关键字.

2. 关键字

3. 操作符

Tips:

数学操作符的操作数如果是字符串会自动转换成数字;
连接

..

自动将数值转换成字符串;
比较操作符的结果一定是布尔类型, 且会严格判断数据类型(

'1' != 1

);

函数(function)

在 Lua 中, 函数是和字符串、数值和表并列的基本数据结构, 属于第一类对象( first-class-object /一等公民),
可以和数值等其他类型一样赋给变量、作为参数传递, 以及作为返回值接收(闭包):

使用方式类似JavaScript:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 全局函数: 求阶乘</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">fact</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(n)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> n == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> n * fact(n - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 1. 赋给变量</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> func = fact
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"func type: "</span> .. <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">type</span>(func), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"fact type: "</span> .. <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">type</span>(fact), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"result: "</span> .. func(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>))

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 2. 闭包</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">new_counter</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> value = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
value = value + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> value
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> counter = new_counter()
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(counter(), counter(), counter())

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 3. 返回值类似Go/Python</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> random_func = <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(param)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'a'</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ƒ∂π"</span>, param
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> var1, var2, var3, var4, var5 = random_func(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"no param is nil"</span>)
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(var1, var2, var3, var4, var5)

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 4. 变数形参</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">square</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(...)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> argv = { ... }
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, #argv <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
argv[i] = argv[i] * argv[i]
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">table</span>.<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">unpack</span>(argv)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(square(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>))</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li></ul>

表(table)

Lua最具特色的数据类型就是表(Table), 可以实现数组、

Hash

、对象所有功能的万能数据类型:

<code class="hljs php has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">-- <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span>
local <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span> = { <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> }
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">print</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span>[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>], <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#array)</span>

-- hash
local hash = { x = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, y = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, z = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> }
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">print</span>(hash.x, hash[<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'y'</span>], hash[<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"z"</span>], <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#hash)</span>

-- <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span> & hash
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span>[<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'x'</span>] = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">print</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">array</span>.x, <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#array)</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

Tips:

数组索引从

开始;
获取数组长度操作符

其’长度’只包括以(正)整数为索引的数组元素.
Lua用表管理全局变量, 将其放入一个叫

_G

的table内:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- pairs会遍历所有值不为nil的索引, 与此类似的ipairs只会从索引1开始递遍历到最后一个值不为nil的整数索引.</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> k, v <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">pairs</span>(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">_G</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(k, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" -> "</span>, v, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" type: "</span> .. <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">type</span>(v))
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

用

Hash

实现对象的还有JavaScript, 将数组和

Hash

合二为一的还有PHP.

元表

Every value in Lua can have a metatable/元表. This metatable is an ordinary Lua table that defines the behavior of the original value under certain special operations. You can change several aspects of
the behavior of operations over a value by setting specific fields in its metatable. For instance, when a non-numeric value is the operand of an addition, Lua checks for a function in the field“__add” of the
value’s metatable. If it finds one, Lua calls this function to perform the addition.

The key for each event in a metatable is a string with the event name prefixed by two underscores

__

; the corresponding values
are called metamethods. In the previous example, the key is “__add” and the metamethod is the function that performs the addition.

metatable中的键名称为事件/event, 值称为元方法/metamethod, 我们可通过

getmetatable()

来获取任一值的metatable,
也可通过

setmetatable()

来替换table的metatable. Lua 事件一览表:

对于这些操作, Lua 都将其关联到 metatable 的事件Key, 当 Lua 需要对一个值发起这些操作时, 首先会去检查其metatable中是否有对应的事件Key, 如果有则调用之以控制Lua解释器作出响应.

MetaMethods

MetaMethods主要用作一些类似C++中的运算符重载操作, 如重载

运算符:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> frac_a = { numerator = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, denominator = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> }
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> frac_b = { numerator = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>, denominator = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span> }

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> operator = {
__add = <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(f1, f2)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> ret = {}
ret.numerator = f1.numerator * f2.denominator + f1.denominator * f2.numerator
ret.denominator = f1.denominator * f2.denominator
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> ret
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>,

__tostring = <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(self)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"{ "</span> .. self.numerator .. <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" ,"</span> .. self.denominator .. <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" }"</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
}

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(frac_a, operator)
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(frac_b, operator)

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> frac_res = frac_a + frac_b
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(frac_res, operator) <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 使tostring()方法生效</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">tostring</span>(frac_res))</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>

关于更多Lua事件处理可参考文档: Metamethods.

MetaTables 与面向对象

Lua本来就不是设计为一种面向对象语言, 因此其面向对象功能需要通过元表(metatable)这种非常怪异的方式实现, Lua并不直接支持面向对象语言中常见的类、对象和方法: 其

对象

和

类

通过

表

实现,
而

方法

是通过

函数

来实现.

上面的Event一览表内我们看到有

__index

这个事件重载,这个东西主要是重载了

find
key

操作, 该操作可以让Lua变得有点面向对象的感觉(类似JavaScript中的prototype). 通过Lua代码模拟:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">gettable_event</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(t, key)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> h
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">type</span>(t) == <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"table"</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> value = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">rawget</span>(t, key)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> value ~= <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nil</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> value
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

h = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">getmetatable</span>(t).__index
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> h == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nil</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nil</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
h = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">getmetatable</span>(t).__index
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> h == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nil</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">error</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"error"</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">type</span>(h) == <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"function"</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- call the handler</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> (h(t, key))
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- or repeat opration on it</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> h[key]
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 测试</span>
obj = { <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> }
op = {
x = <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"xx"</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
}

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(obj, { __index = op[<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'x'</span>] })
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(gettable_event(obj, x))</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul>

对于任何事件, Lua的处理都可以归结为以下逻辑:

如果存在规定的操作则执行它;
否则从元表中取出各事件对应的

__

开头的元素, 如果该元素为函数, 则调用;
如果该元素不为函数, 则用该元素代替

table

来执行事件所对应的处理逻辑.

这里的代码仅作模拟, 实际的行为已经嵌入Lua解释器, 执行效率要远高于这些模拟代码.

方法调用的实现

面向对象的基础是创建对象和调用方法. Lua中, 表作为对象使用, 因此创建对象没有问题, 关于调用方法, 如果表元素为函数的话, 则可直接调用:

<code class="hljs haml has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">-<span class="ruby" style="box-sizing: border-box;">- 从obj取键为x的值, 将之视为function进行调用
</span>obj.x(foo)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

不过这种实现方法调用的方式, 从面向对象角度来说还有2个问题:

首先:

obj.x

这种调用方式, 只是将表

obj

的属性

这个函数对象取出而已,
而在大多数面向对象语言中, 方法的实体位于类中, 而非单独的对象中. 在JavaScript等基于原型的语言中, 是以原型对象来代替类进行方法的搜索, 因此每个单独的对象也并不拥有方法实体. 在Lua中, 为了实现基于原型的方法搜索, 需要使用元表的

__index

事件:

如果我们有两个对象

和

,想让

作为

的prototype需要

setmetatable(a,
{__index = b})

, 如下例: 为

obj

设置

__index

加上

proto

模板来创建另一个实例:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">proto = {
x = <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"x"</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> obj = {}
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(obj, { __index = proto })
obj.x()</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

proto

变成了原型对象, 当

obj

中不存在的属性被引用时,
就会去搜索

proto

.

其次: 通过方法搜索得到的函数对象只是单纯的函数, 而无法获得最初调用方法的表(接收器)相关信息. 于是, 过程和数据就发生了分离.JavaScript中, 关于接收器的信息可由关键字

this

获得,
而在Python中通过方法调用形式获得的并非单纯的函数对象, 而是一个“方法对象” –其接收器会在内部作为第一参数附在函数的调用过程中.

而Lua准备了支持方法调用的语法糖:

obj:x()

. 表示

obj.x(obj)

,
也就是: 通过冒号记法调用的函数, 其接收器会被作为第一参数添加进来(

obj

的求值只会进行一次, 即使有副作用也只生效一次).

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 这个语法糖对定义也有效</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">proto:y</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(param)</span></span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(self, param)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

- Tips: 用冒号记法定义的方法, 调用时最好也用冒号记法, 避免参数错乱
obj:y(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"parameter"</span>)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

更多MetaTable介绍可参考文档Metatable与博客metatable和metamethod.

基于原型的编程

Lua虽然能够进行面向对象编程, 但用元表来实现, 仿佛把对象剖开看到五脏六腑一样.

<代码的未来>中松本行弘老师向我们展示了一个基于原型编程的Lua库,
通过该库, 即使没有深入解Lua原始机制, 也可以实现面向对象:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Author: Matz</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Date: 16/9/24</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Time: 下午5:13</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Object为所有对象的上级</span>
Object = {}

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 创建现有对象副本</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Object:clone</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> object = {}

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 复制表元素</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> k, v <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">pairs</span>(self) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
object[k] = v
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 设定元表: 指定向自身`转发`</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(object, { __index = self })

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> object
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 基于类的编程</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Object:new</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(...)</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> object = {}

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 设定元表: 指定向自身`转发`</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setmetatable</span>(object, { __index = self })

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 初始化</span>
object:init(...)

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> object
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 初始化实例</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Object:init</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(...)</span></span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 默认不进行任何操作</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

Class = Object:new()</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li></ul>

另存为prototype.lua, 使用时只需

require()

引入即可:

<code class="hljs lua has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"prototype"</span>)

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- Point类定义</span>
Point = Class:new()
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Point:init</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(x, y)</span></span>
self.x = x
self.y = y
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Point:magnitude</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">math</span>.sqrt(self.x ^ <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + self.y ^ <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 对象定义</span>
point = Point:new(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>)
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(point:magnitude())

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 继承: Point3D定义</span>
Point3D = Point:clone()
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Point3D:init</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(x, y, z)</span></span>
self.x = x
self.y = y
self.z = z
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">Point3D:magnitude</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">math</span>.sqrt(self.x ^ <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + self.y ^ <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + self.z ^ <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>

p3 = Point3D:new(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>)
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(p3:magnitude())

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">-- 创建p3副本</span>
ap3 = p3:clone()
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">print</span>(ap3.x, ap3.y, ap3.z)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul>

Redis - Lua

在传入到Redis的Lua脚本中可使用

redis.call()

redis.pcall()

函数调用Reids命令:

<code class="hljs sql has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">redis.<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"set"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"foo"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"bar"</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">local</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"get"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"foo"</span>)</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

redis.call()

返回值就是Reids命令的执行结果, Redis回复与Lua数据类型的对应关系如下:


Reids返回值类型	Lua数据类型
整数	数值
字符串	字符串
多行字符串	表(数组)
状态回复	表(只有一个 ok 字段存储状态信息)
错误回复	表(只有一个 err 字段存储错误信息)

注: Lua 的

false

会转化为空结果.

redis-cli提供了

EVAL

与

EVALSHA

命令执行Lua脚本:

EVAL

EVAL script numkeys key [key ...] arg [arg ...]

key和arg两类参数用于向脚本传递数据, 他们的值可在脚本中使用

KEYS

和

ARGV

两个table访问:

KEYS

表示要操作的键名,

ARGV

表示非键名参数(并非强制).
EVALSHA

EVALSHA

命令允许通过脚本的SHA1来执行(节省带宽), Redis在执行

EVAL

SCRIPT
LOAD

后会计算脚本SHA1缓存,

EVALSHA

根据SHA1取出缓存脚本执行.

创建Lua环境

为了在 Redis 服务器中执行 Lua 脚本, Redis 内嵌了一个 Lua 环境, 并对该环境进行了一系列修改, 从而确保满足 Redis 的需要. 其创建步骤如下:

创建基础 Lua 环境, 之后所有的修改都基于该环境进行;
载入函数库到 Lua 环境, 使 Lua 脚本可以使用这些函数库进行数据操作: 如基础库(删除了

loadfile()

函数)、Table、String、Math、Debug等标准库, 以及CJSON、 Struct(用于Lua值与C结构体转换)、
cmsgpack等扩展库(Redis 禁用Lua标准库中与文件或系统调用相关函数, 只允许对 Redis 数据处理).
创建全局表

redis

, 其包含了对 Redis 操作的函数, 如

redis.call()

、

redis.pcall()

等;
替换随机函数: 为了确保相同脚本可在不同机器上产生相同结果, Redis 要求所有传入服务器的 Lua 脚本, 以及 Lua 环境中的所有函数, 都必须是无副作用的纯函数, 因此Redis使用自制函数替换了 Math 库中原有的

math.random()

和

math.randomseed()

.
创建辅助排序函数: 对于 Lua 脚本来说, 另一个可能产生数据不一致的地方是那些带有不确定性质的命令(如: 由于

set

集合无序, 因此即使两个集合内元素相同, 其输出结果也并不一样),
这类命令包括SINTER、SUNION、SDIFF、SMEMBERS、HKEYS、HVALS、KEYS 等.

Redis 会创建一个辅助排序函数

__redis__compare_helper

, 当执行完以上命令后, Redis会调用

table.sort()

以

__redis__compare_helper

作为辅助函数对命令返回值排序.
创建错误处理函数: Redis创建一个

__redis__err__handler

错误处理函数, 当调用

redis.pcall()

执行
Redis 命令出错时, 该函数将打印异常详细信息.
Lua全局环境保护: 确保传入脚本内不会将额外的全局变量导入到 Lua 环境内.

小心: Redis 并未禁止用户修改已存在的全局变量.

完成Redis的

lua

属性与Lua环境的关联:

整个 Redis 服务器只需创建一个 Lua 环境.

Lua环境协作组件

Redis创建两个用于与Lua环境协作的组件: 伪客户端- 负责执行 Lua 脚本中的 Redis 命令,

lua_scripts

字典- 保存 Lua
脚本:

伪客户端

执行Reids命令必须有对应的客户端状态, 因此执行 Lua 脚本内的 Redis 命令必须为 Lua 环境专门创建一个伪客户端, 由该客户端处理 Lua 内所有命令:

redis.call()

redis.pcall()

执行一个Redis命令步骤如下:

lua_scripts

字典

字典key为脚本 SHA1 校验和, value为 SHA1 对应脚本内容, 所有被

EVAL

和

SCRIPT
LOAD

载入过的脚本都被记录到

lua_scripts

中, 便于实现

SCRIPT
EXISTS

命令和脚本复制功能.

EVAL命令原理

EVAL

命令执行分为以下三个步骤:

定义Lua函数:

在 Lua 环境内定义 Lua函数 : 名为

f_

前缀+脚本 SHA1 校验和, 体为脚本内容本身. 优势:

执行脚本步骤简单, 调用函数即可;
函数的局部性可保持 Lua 环境清洁, 减少垃圾回收工作量, 且避免使用全局变量;
只要记住 SHA1 校验和, 即可在不知脚本内容的情况下, 直接调用 Lua 函数执行脚本(

EVALSHA

命令实现).

将脚本保存到

lua_scripts

字典;

执行脚本函数:

执行刚刚在定义的函数, 间接执行 Lua 脚本, 其准备和执行过程如下:

1). 将

EVAL

传入的键名和参数分别保存到

KEYS

和

ARGV

,
然后将这两个数组作为全局变量传入到Lua环境;

2). 为Lua环境装载超时处理

hook

(

handler

),
可在脚本出现运行超时时让通过

SCRIPT KILL

停止脚本, 或

SHUTDOWN

关闭Redis;

3). 执行脚本函数;

4). 移除超时

hook

;

5). 将执行结果保存到客户端输出缓冲区, 等待将结果返回客户端;

6). 对Lua环境执行垃圾回收.

对于会产生随机结果但无法排序的命令(如只产生一个元素, 如 SPOP、SRANDMEMBER、RANDOMKEY、TIME),
Redis在这类命令执行后将脚本状态置为

lua_random_dirty

, 此后只允许脚本调用只读命令, 不允许修改数据库值.

实践

使用Lua脚本重新构建带有过期时间的分布式锁.

案例来源: <Redis实战> 第6、11章, 构建步骤:

锁申请

首先尝试加锁:

成功则为锁设定过期时间; 返回;
失败检测锁是否添加了过期时间;

wait.

锁释放

检查当前线程是否真的持有了该锁:

持有: 则释放; 返回成功;
失败: 返回失败.

非Lua实现

<code class="hljs javascript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> acquireLockWithTimeOut(Jedis connection, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> lockName, long acquireTimeOut, int lockTimeOut) {
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> identifier = UUID.randomUUID().toString();
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> key = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"lock:"</span> + lockName;

long acquireTimeEnd = System.currentTimeMillis() + acquireTimeOut;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (System.currentTimeMillis() < acquireTimeEnd) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 获取锁并设置过期时间</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (connection.setnx(key, identifier) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
connection.expire(key, lockTimeOut);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> identifier;
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 检查过期时间, 并在必要时对其更新</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (connection.ttl(key) == -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>) {
connection.expire(key, lockTimeOut);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
Thread.sleep(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (InterruptedException ignored) {
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>;
}

boolean releaseLock(Jedis connection, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> lockName, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> identifier) {
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> key = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"lock:"</span> + lockName;

connection.watch(key);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 确保当前线程还持有锁</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (identifier.equals(connection.get(key))) {
Transaction transaction = connection.multi();
transaction.del(key);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> transaction.exec().isEmpty();
}
connection.unwatch();

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">false</span>;
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul>

Lua脚本实现

Lua脚本: acquire

<code class="hljs vbnet has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">local <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span> = KEYS[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]
local identifier = ARGV[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]
local lockTimeOut = ARGV[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>]

-- 锁定成功
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SETNX"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>, identifier) == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"EXPIRE"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>, lockTimeOut)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">elseif</span> redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"TTL"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>) == -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"EXPIRE"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>, lockTimeOut)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

Lua脚本: release

<code class="hljs vbnet has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">local <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span> = KEYS[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]
local identifier = ARGV[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"GET"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>) == identifier <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">then</span>
redis.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"DEL"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">end</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

Pre工具: 脚本执行器

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @author</span> jifang
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @since</span> 16/8/25 下午3:35.
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ScriptCaller</span> {</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> ConcurrentMap<String, String> SHA_CACHE = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ConcurrentHashMap<>();

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String script;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-title" style="box-sizing: border-box;">ScriptCaller</span>(String script) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.script = script;
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> ScriptCaller <span class="hljs-title" style="box-sizing: border-box;">getInstance</span>(String script) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ScriptCaller(script);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Object <span class="hljs-title" style="box-sizing: border-box;">call</span>(Jedis connection, List<String> keys, List<String> argv, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> forceEval) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!forceEval) {
String sha = SHA_CACHE.get(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.script);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (Strings.isNullOrEmpty(sha)) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// load 脚本得到 sha1 缓存</span>
sha = connection.scriptLoad(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.script);
SHA_CACHE.put(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.script, sha);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> connection.evalsha(sha, keys, argv);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> connection.eval(script, keys, argv);
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li></ul>

Client

<code class="hljs vbscript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> Client {

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> ScriptCaller acquireCaller = ScriptCaller.getInstance(
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"local key = KEYS[1]\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"local identifier = ARGV[1]\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"local lockTimeOut = ARGV[2]\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"if redis.call(\"</span>SETNX\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key, identifier) == 1 then\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"    redis.call(\"</span>EXPIRE\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key, lockTimeOut)\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"    return 1\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"elseif redis.call(\"</span>TTL\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key) == -1 then\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"    redis.call(\"</span>EXPIRE\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key, lockTimeOut)\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"end\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"return 0"</span>
);

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> ScriptCaller releaseCaller = ScriptCaller.getInstance(
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"local key = KEYS[1]\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"local identifier = ARGV[1]\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"if redis.call(\"</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">GET</span>\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key) == identifier then\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"    redis.call(\"</span>DEL\<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", key)\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"    return 1\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"end\n"</span> +
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"return 0"</span>
);

@Test
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> void client() {
Jedis jedis = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Jedis(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"127.0.0.1"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9736</span>);
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> identifier = acquireLockWithTimeOut(jedis, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ret1"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">200</span> * <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1000</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">300</span>);
System.out.println(releaseLock(jedis, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ret1"</span>, identifier));
}

<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> acquireLockWithTimeOut(Jedis connection, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> lockName, long acquireTimeOut, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">int</span> lockTimeOut) {
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> identifier = UUID.randomUUID().toString();

List<<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>> keys = Collections.singletonList(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"lock:"</span> + lockName);
List<<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>> argv = Arrays.asList(identifier,
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>.valueOf(lockTimeOut));

long acquireTimeEnd = System.currentTimeMillis() + acquireTimeOut;
boolean acquired = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">false</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (!acquired && (System.currentTimeMillis() < acquireTimeEnd)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> == (long) acquireCaller.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(connection, keys, argv, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">false</span>)) {
acquired = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">true</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
try {
Thread.sleep(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);
} catch (InterruptedException ignored) {
}
}
}

return acquired ? identifier : <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>;
}

boolean releaseLock(Jedis connection, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> lockName, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> identifier) {
List<<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>> keys = Collections.singletonList(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"lock:"</span> + lockName);
List<<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>> argv = Collections.singletonList(identifier);
return <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> == (long) releaseCaller.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(connection, keys, argv, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">true</span>);
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li></ul>

参考 & 推荐代码的未来 Redis入门指南 Redis实战 Redis设计与实现云风的Blog: Lua与虚拟机 Lua简明教程- CoolShell Lua-newbie Lua-Users redis.io

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章节导航

Lua 与 Redis

Lua 与 Redis

Lua模型

Base

1. 数据类型

2. 关键字

3. 操作符

函数(function)

表(table)

元表

MetaMethods

MetaTables 与 面向对象

方法调用的实现

基于原型的编程

Redis - Lua

创建Lua环境

Lua环境协作组件

EVAL命令原理

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