环境
- Time 2022-12-11
- WSL-Ubuntu 22.04
- Rust 1.65.0
前言
说明
参考：https://github.com/pingcap/talent-plan
目标
在上一节的基础上，实现 set 和 remove 的返回。
Cargo.toml
[package]
edition = "2021"
name = "kvs"
version = "1.0.0"[dependencies]
clap = {version = "4", features = ["derive"]}
serde = {version = "1", features = ["derive"]}
serde_json = "1"
cmd.rs
#[derive(serde::Serialize, serde::Deserialize)]
pub enum Command<'a> {Set { key: String, value: String },Remove { key: &'a str },
}
set 方法
pub (crate) fn set(&mut self, key: String, value: String) -> Result<Option<String>> {let command = Command::Set {key: key.to_string(),value: value.to_string(),};let json = serde_json::to_string(&command)?;self.writer.write_all(json.as_bytes())?;Ok(self.map.insert(key, value))
}
remove 方法
pub(crate) fn remove(&mut self, key: String) -> Result<Option<String>> {let command = Command::Remove { key: &key };let json = serde_json::to_string(&command)?;self.writer.write_all(json.as_bytes())?;Ok(self.map.remove(&key))
}
运行
使用 cargo build --release 构建后运行。
root@jiangbo12490:~/git/game/target/release# ./kvs set name JiangBo
SET KEY: name, VALUE: None
root@jiangbo12490:~/git/game/target/release# ./kvs set name ZhangSan
SET KEY: name, VALUE: JiangBo
root@jiangbo12490:~/git/game/target/release# ./kvs rm name
REM KEY: name, VALUE: ZhangSan
查看文件
root@jiangbo12490:~/log# cat /root/log/1.log
{"Set":{"key":"name","value":"JiangBo"}}{"Set":{"key":"name","value":"ZhangSan"}}{"Remove":{"key":"name"}}
总结
实现了 set 和 remove 时返回之前已经存在的值。
