readme.md

[Project 3: Synchronous client-server networking][p3]

Task: Create a single-threaded, persistent key/value store server and client with synchronous networking over a custom protocol.

Goals:

• x Create a client-server application
• x Write a custom protocol with std networking APIs
• x Introduce logging to the server
• Implement pluggable backends with traits
• Benchmark the hand-written backend against sled

Topics: std::net, logging, traits, benchmarking.

Introduction

In this project you will create a simple key/value server and client. They will communicate with a custom networking protocol of your design. You will emit logs using standard logging crates, and handle errors correctly across the network boundary. Once you have a working client-server architecture, then you will abstract the storage engine behind traits, and compare the performance of yours to the [sled] engine.

程序运行流程

• client
  • 等待输入
  • 输入一行，创建tcp短链接，发送给服务端
  • 读取返回信息，解析输出到命令行
• server
  • 初始化kv内核
  • 启动服务端，监听新的链接，解析接受数据，转换为消息枚举发给kv内核
  • 等待kv内核结果，返回给客户端

Record

1. 单线程短链接tcp

   Building a Single-Threaded Web Server - The Rust Programming Language (rust-lang.org)

   协议就先简单点好了，直接吧命令发过去，返回也直接返回消息，开头用f: s:标注是否成功

   基本很快就换完了

2. logging

   主要作用是将一些错误调试信息更加结构化输出，便于开发时寻找漏洞，同时可以配置log级别来选择log内容

3. benchmark 对比sled

   benchmark是比较重要但我未曾实践过的环节，只有测验性能才能知道自己代码真正的效率

   对比来看，写操作特别慢，因为这里每次写都要重新打开文件

   破案了，sled 默认500ms fsync,也就是一次set后不代表真正的操作成功了，只是进入了内存，后来测试sled一次set大约12us

4. 可插拔（可替换引擎）

   这里考虑到后面要引入async，但trait不支持零开销async，所以暂时不考虑用trait