八、Redis列表简单实现队列

在Redis中，List类型是按照插入顺序排列的字符串链表。与数据结构中的普通链表一样，可以在头部和尾部新增元素。新增时，如是key不存在，则创建。若列表中的元素被移除完毕，那么key也将被移除。因此使用List来实现队列是最合适的。

下面简单用Redis中的List来实现一个队列，并支持阻塞式读取。

先进先出。从左向右插入，从右先左弹出

<span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(103, 110, 149)"># 入栈</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> lpush book_list a b c d</span><br></br><span style="box-sizing: border-box;padding-right: 0.1px">(integer) <span style="box-sizing: border-box;color: rgb(255, 83, 112)">4</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> lrange book_list <span style="box-sizing: border-box;color: rgb(255, 83, 112)">0</span> <span style="box-sizing: border-box;color: rgb(199, 146, 234)">-1</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">1</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"d"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">2</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"c"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">3</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"b"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">4</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"a"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(103, 110, 149)"># 出栈</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> rpop book_list</span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(195, 232, 141)">"a"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> rpop book_list</span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(195, 232, 141)">"b"</span></span>

图示

1）执行入栈操作之后的数据结构如下图（满足先进先出队列模式）

2）第一次执行rpop之后的数据结构

从右向左插入，从左右弹出

<span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> rpush book_list2 a b c d</span><br></br><span style="box-sizing: border-box;padding-right: 0.1px">(integer) <span style="box-sizing: border-box;color: rgb(255, 83, 112)">4</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> lrange book_list2 <span style="box-sizing: border-box;color: rgb(255, 83, 112)">0</span> <span style="box-sizing: border-box;color: rgb(199, 146, 234)">-1</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">1</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"a"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">2</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"b"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">3</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"c"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">4</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"d"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> lpop book_list2</span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(195, 232, 141)">"a"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">127</span>.0.0.1:6379> lrange book_list2 <span style="box-sizing: border-box;color: rgb(255, 83, 112)">0</span> <span style="box-sizing: border-box;color: rgb(199, 146, 234)">-1</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">1</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"b"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">2</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"c"</span></span><br></br><span style="box-sizing: border-box;padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(255, 83, 112)">3</span>) <span style="box-sizing: border-box;color: rgb(195, 232, 141)">"d"</span></span>

1）执行rpush之后的数据结构

2）执行lpop之后的数据格式

我是夕阳何处寻，期待和优秀的你一起同行!

小白

2020年09月01日