本系列是關(guān)于用Rust構(gòu)建一個(gè)KV Server的系列文章，內(nèi)容包括用tokio做底層異步網(wǎng)絡(luò)通訊、使用toml文件做配置、protobuf做傳輸協(xié)議、內(nèi)存/RockDB做數(shù)據(jù)存儲(chǔ)、事件通知、優(yōu)雅關(guān)機(jī)、并發(fā)連接限制及測(cè)量監(jiān)控等。

讓我們先使用tokio實(shí)現(xiàn)一個(gè)簡(jiǎn)單的Client & Server通訊模型，然后在此基礎(chǔ)上逐步實(shí)現(xiàn)上面提及的各項(xiàng)內(nèi)容。

創(chuàng)建一個(gè)新項(xiàng)目：

cargo new --lib kvserver_rust

在Cargo.toml文件中加入tokio依賴(lài)：

[dependencies]tokio = { version = "1.19", features = ["full"] }

Server

在src目錄下創(chuàng)建bin文件夾，然后創(chuàng)建kv_server.rs文件：

use anyhow::Result;use tokio::{    io::{AsyncReadExt, AsyncWriteExt},    net::TcpListener,};
#[tokio::main]async fn main() -> Result<(), Box> {    let addr = "127.0.0.1:19999";    let listener = TcpListener::bind(addr).await?;    println!("Listening on {addr} ......");
    loop {        let (mut stream, addr) = listener.accept().await?;        println!("Client: {:?} connected", addr);
        tokio::spawn(async move {            let mut buf = vec![0u8; 1024];
            loop {                let n = stream.read(&mut buf).await.expect("從Socket讀取數(shù)據(jù)失敗！");
                if n == 0 {                    return;                }
                stream                    .write_all(&buf[0..n])                    .await                    .expect("向Socket寫(xiě)入數(shù)據(jù)失敗！");            }        });    }}

在"127.0.0.1:19999"地址監(jiān)聽(tīng)客戶(hù)端的連接，收到客戶(hù)端發(fā)來(lái)的信息后再返回給客戶(hù)端。

Client

在src/bin目錄下創(chuàng)建kv_client.rs文件：

use anyhow::Result;use tokio::{    io::{AsyncReadExt, AsyncWriteExt},    net::TcpStream,};
#[tokio::main]async fn main() -> Result<(), Box> {    let addr = "127.0.0.1:19999";    let mut stream = TcpStream::connect(addr).await?;
    let n = stream.write(b"Hello, world!").await?;    println!("Send info successed！n = {n}");
    let mut buf = vec![0u8; 1024];    let n = stream.read(&mut buf).await.expect("從Socket讀取數(shù)據(jù)失敗！");    println!("Receive info：{}, n = {n}", String::from_utf8(buf).unwrap());
    Ok(())}

連接server端"127.0.0.1:19999"這個(gè)地址，向Server端發(fā)送"Hello, world!"消息，然后再接收Server端返回的消息。

打開(kāi)兩個(gè)終端，分別執(zhí)行：

cargo run --bin kv_servercargo run --bin kv_client

執(zhí)行結(jié)果

kv_server：

Listening on 127.0.0.1:19999 ......Client: 127.0.0.1:51724 connected

kv_client：

Send info successed！n = 13Receive info：Hello, world!, n = 13

配置文件

使用 toml 做配置文件，serde 來(lái)處理配置的序列化和反序列化。在項(xiàng)目根目錄下新建conf目錄，并在下面新建server.conf文件：

[listen_address]addr = '127.0.0.1:19999'

和client.conf文件：

[connect_address]server_addr = '127.0.0.1:19999'

新建src/config.rs文件：

use std::{error::Error, fs};
use serde::{Deserialize, Serialize};
// Server端配置#[derive(Debug, Serialize, Deserialize)]pub struct ServerConfig {    pub listen_address: ListenAddress,}
// 監(jiān)聽(tīng)地址#[derive(Debug, Serialize, Deserialize)]pub struct ListenAddress {    pub addr: String,}
// Client端配置#[derive(Debug, Serialize, Deserialize)]pub struct ClientConfig {    pub connect_address: ConnectAddress,}
// 連接地址#[derive(Debug, Serialize, Deserialize)]pub struct ConnectAddress {    pub server_addr: String,}
impl ServerConfig {    // 加載Server端配置文件    pub fn load(path: &str) -> Result> {        let config = fs::read_to_string(path)?;        let server_conf: Self = toml::from_str(&config)?;        Ok(server_conf)    }}
impl ClientConfig {    // 加載Client端配置文件    pub fn load(path: &str) -> Result> {        let config = fs::read_to_string(path)?;        let client_conf: Self = toml::from_str(&config)?;        Ok(client_conf)    }}

然后在lib.rs中加入：

mod config;pub use config::*;

修改src/bin/kv_server.rs代碼：

#[tokio::main]async fn main() -> Result<(), Box> {    let server_conf = ServerConfig::load("conf/server.conf")?;    let listen_addr = server_conf.listen_address.addr;
    let listener = TcpListener::bind(&listen_addr).await?;    println!("Listening on {} ......", listen_addr);    ......}

修改src/bin/kv_client.rs代碼：

#[tokio::main]async fn main() -> Result<(), Box> {    let client_conf = ClientConfig::load("conf/client.conf")?;    let connect_addr = client_conf.connect_address.server_addr;
    let mut stream = TcpStream::connect(&connect_addr).await?;    ......}

運(yùn)行kv_sever和kv_client后，執(zhí)行結(jié)果與上面一致。