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，新增 anyhow 依赖，处理代码中的错误。
Cargo.toml
[package]
edition = "2021"
name = "kvs"
version = "1.0.0"[dependencies]
anyhow = "1"
clap = {version = "4", features = ["derive"]}
serde = {version = "1", features = ["derive"]}
serde_json = "1"
main.rs
use clap::{Parser, Subcommand};
use kvs::KvStore;#[derive(Parser)]
#[command(author, version, about, long_about = None)]
struct Cli {#[command(subcommand)]command: Commands,
}#[derive(Subcommand)]
enum Commands {/// 设置值Set {/// 键key: String,/// 值value: String,},/// 获取值Get {/// 键key: String,},/// 删除值Rm {/// 键key: String,},
}fn main() -> anyhow::Result<()> {let cli = Cli::parse();let mut store = KvStore::new()?;match cli.command {Commands::Set { key, value } => {if let Some(value) = store.set(key.to_string(), value)? {println!("SET KEY: {key}, VALUE: {value}");} else {println!("SET KEY: {key}, VALUE: None");}}Commands::Get { key } => {if let Some(value) = store.get(&key)? {println!("GET KEY: {key}, VALUE: {value}");} else {println!("GET KEY: {key}, VALUE: None");}}Commands::Rm { key } => {if let Some(value) = store.remove(key.to_string())? {println!("REM KEY: {key}, VALUE: {value}");} else {println!("REM KEY: {key}, VALUE: None");}}}Ok(())
}
lib.rs
use anyhow::Result;
use log::CommandLog;mod cmd;
mod log;pub struct KvStore {log: CommandLog,
}impl KvStore {pub fn new() -> Result<KvStore> {Ok(Self {log: CommandLog::new()?,})}pub fn get(&mut self, key: &str) -> Result<Option<String>> {self.log.get(key)}pub fn set(&mut self, key: String, value: String) -> Result<Option<String>> {self.log.set(key, value)}pub fn remove(&mut self, key: String) -> Result<Option<String>> {self.log.remove(key)}
}
log.rs
use std::collections::HashMap;
use std::fs::{File, OpenOptions};
use std::io::{BufReader, BufWriter, Write};use anyhow::{Ok, Result};
use serde_json::Deserializer;use crate::cmd::Command;pub(crate) struct CommandLog {writer: BufWriter<File>,map: HashMap<String, String>,
}impl CommandLog {pub(crate) fn new() -> Result<Self> {let path = "/root/log/1.log";let writer = new_writer(path)?;let mut map = HashMap::default();load(path, &mut map)?;Ok(Self { writer, map })}pub(crate) fn get(&mut self, key: &str) -> Result<Option<String>> {Ok(self.map.get(key).map(String::from))}pub(crate) fn set(&mut self, key: String, value: String) -> Result<Option<String>> {let command = Command::Set { key, value };let json = serde_json::to_string(&command)?;self.writer.write_all(json.as_bytes())?;Ok(None)}pub(crate) fn remove(&mut self, key: String) -> Result<Option<String>> {let command = Command::Remove { key };let json = serde_json::to_string(&command)?;self.writer.write_all(json.as_bytes())?;Ok(None)}
}fn new_writer(path: &str) -> Result<BufWriter<File>> {let file = OpenOptions::new().append(true).create(true).open(path)?;Ok(BufWriter::new(file))
}fn load(path: &str, map: &mut HashMap<String, String>) -> Result<()> {let stream = Deserializer::from_reader(new_reader(path)?).into_iter();for cmd in stream {match cmd? {Command::Set { key, value } => map.insert(key, value),Command::Remove { key } => map.remove(&key),};}Ok(())
}fn new_reader(path: &str) -> Result<BufReader<File>> {let file = OpenOptions::new().read(true).open(path)?;Ok(BufReader::new(file))
}
总结
使用 anyhow 来处理程序中遇到的错误。
