From 20578b535e31fac21d8099c2ba01f5c4d9739b23 Mon Sep 17 00:00:00 2001
From: asahi <mikiyashiki@outlook.com>
Date: Fri, 5 Sep 2025 17:22:26 +0800
Subject: [PATCH] =?UTF-8?q?doc:=20=E9=98=85=E8=AF=BBredis=20list=E6=96=87?=
 =?UTF-8?q?=E6=A1=A3?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 中间件/redis/redis.md | 111 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)

diff --git a/中间件/redis/redis.md b/中间件/redis/redis.md
index dbe2d91..fb80f7d 100644
--- a/中间件/redis/redis.md
+++ b/中间件/redis/redis.md
@@ -40,6 +40,16 @@
       - [json object操作](#json-object操作)
       - [format output](#format-output)
       - [Limitation](#limitation)
+    - [Redis lists](#redis-lists)
+      - [Blocking commands](#blocking-commands)
+      - [Queue(first in, first out)](#queuefirst-in-first-out)
+      - [Stack(first in, last out)](#stackfirst-in-last-out)
+      - [check length of list](#check-length-of-list)
+      - [Atomically pop one element from one list and push to another](#atomically-pop-one-element-from-one-list-and-push-to-another)
+      - [trim the list](#trim-the-list)
+      - [Redis List Impl](#redis-list-impl)
+      - [`LPUSH, RPUSH`](#lpush-rpush)
+      - [`LRANGE`](#lrange)
 
 
 # redis
@@ -589,3 +599,104 @@ $ redis-cli --raw
 #### Limitation
 传递给command的json值最大深度只能为128，如果嵌套深度大于128，那么command将返回错误。
 
+### Redis lists
+Redis lists为string values的链表，redis list通常用于如下场景：
+- 实现stack和queue
+- 用于backgroup worker system的队列管理
+
+#### Blocking commands
+redis lists中支持阻塞命令
+- `BLPOP`: 从`head of a list`移除并且返回一个element，如果list为空，该command会阻塞，直至list被填充元素或发生超时
+- `BLMOVE`: 从source list中pop一个element，并且将其push到target list中。如果source list为空，那么command将会被阻塞，直到source list中出现new element
+
+> 在上述文档描述中，`阻塞`实际指的是针对客户端的阻塞。该`Blocking Command`命令的调用会实际的阻塞客户端，直到redis server返回结果。
+>
+> 但是，`server并不会被blocking command所阻塞`。redis server为单线程模型，当用户发送blocking command给server，并且该command无法立即被执行而导致客户端阻塞时，`server会挂起该客户端的连接`，并且转而处理其他请求，直至该客户端的阻塞命令满足执行条件时，才会将挂起的连接唤醒重新执行。
+>
+> 故而，`Blocking Command`并不会对server造成阻塞，而是会阻塞客户端的调用。
+
+#### Queue(first in, first out)
+依次调用`LPUSH`后再依次调用`RPOP`，可模拟队列行为，元素的弹出顺序和元素的添加顺序相同：
+```redis-cli
+> LPUSH bikes:repairs bike:1
+(integer) 1
+> LPUSH bikes:repairs bike:2
+(integer) 2
+> RPOP bikes:repairs
+"bike:1"
+> RPOP bikes:repairs
+"bike:2"
+```
+#### Stack(first in, last out)
+依次调用`LPUSH`后再依次调用`LPOP`，可模拟栈的行为，元素的移除顺序和添加顺序相反：
+```redis-cli
+> LPUSH bikes:repairs bike:1
+(integer) 1
+> LPUSH bikes:repairs bike:2
+(integer) 2
+> LPOP bikes:repairs
+"bike:2"
+> LPOP bikes:repairs
+"bike:1"
+```
+#### check length of list
+可通过`LLEN`命令来检查list的长度
+```redis-cli
+> LLEN bikes:repairs
+(integer) 0
+```
+#### Atomically pop one element from one list and push to another 
+通过`lmove`命令能够实现原子的`从srclist移除并添加到dstlist`的操作
+```redis-cli
+> LPUSH bikes:repairs bike:1
+(integer) 1
+> LPUSH bikes:repairs bike:2
+(integer) 2
+> LMOVE bikes:repairs bikes:finished LEFT LEFT
+"bike:2"
+> LRANGE bikes:repairs 0 -1
+1) "bike:1"
+> LRANGE bikes:finished 0 -1
+1) "bike:2"
+```
+#### trim the list
+可以通过`LTRIM`命令来完成对list的裁剪操作：
+```redis-cli
+> LPUSH bikes:repairs bike:1
+(integer) 1
+> LPUSH bikes:repairs bike:2
+(integer) 2
+> LMOVE bikes:repairs bikes:finished LEFT LEFT
+"bike:2"
+> LRANGE bikes:repairs 0 -1
+1) "bike:1"
+> LRANGE bikes:finished 0 -1
+1) "bike:2"
+```
+#### Redis List Impl
+redis lists是通过Linked List来实现的，其元素的添加操作并开销永远是常量的，并不会和Array一样因扩容而可能导致内存的复制。
+
+#### `LPUSH, RPUSH`
+`LPUSH`会将元素添加到list的最左端（头部），而`RPUSH`则会将新元素添加奥list的最右端（尾部）。
+
+LPUSH和RPUSH接收的参数都是可变的，在单次调用中可以向list中添加多个元素。
+
+例如，向空list中调用`lpush 1 2 3`时，其等价于`lpush 1; lpush 2; lpush3`，即调用后list中元素为`3,2,1`
+
+#### `LRANGE`
+`LRANGE`命令能够从list中解析范围内的数据，其接收两个indexes，为range中开始和结束元素的位置。index可以是负的，负数代表从尾端开始计数：
+- `-1`代表最后的元素
+- `-2`代表倒数第二个元素
+
+```redis-cli
+> RPUSH bikes:repairs bike:1
+(integer) 1
+> RPUSH bikes:repairs bike:2
+(integer) 2
+> LPUSH bikes:repairs bike:important_bike
+(integer) 3
+> LRANGE bikes:repairs 0 -1
+1) "bike:important_bike"
+2) "bike:1"
+3) "bike:2"
+```