文盘Rust -- tonic-Rust grpc初体验 | 京东云技术团队

gRPC 是开发中常用的开源高性能远程过程调用（RPC）框架，tonic 是基于 HTTP/2 的 gRPC 实现，专注于高性能、互操作性和灵活性。该库的创建是为了对 async/await 提供一流的支持，并充当用 Rust 编写的生产系统的核心构建块。今天我们聊聊通过使用tonic 调用grpc的的具体过程。

工程规划

rpc程序一般包含server端和client端，为了方便我们把两个程序打包到一个工程里面 新建tonic_sample工程

cargo new tonic_sample

Cargo.toml 如下

[package]
name = "tonic_sample"
version = "0.1.0"
edition = "2021"

[[bin]] # Bin to run the gRPC server
name = "stream-server"
path = "src/stream_server.rs"

[[bin]] # Bin to run the gRPC client
name = "stream-client"
path = "src/stream_client.rs"


[dependencies]
tokio.workspace = true
tonic = "0.9"
tonic-reflection = "0.9.2"
prost = "0.11"
tokio-stream = "0.1"
async-stream = "0.2"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
rand = "0.7"
h2 = { version = "0.3" }
anyhow = "1.0.75"
futures-util = "0.3.28"

[build-dependencies]
tonic-build = "0.9"

tonic 的示例代码还是比较齐全的，本次我们参考 tonic 的 streaming example。

首先编写 proto 文件，用来描述报文。 proto/echo.proto

syntax = "proto3";

package stream;

// EchoRequest is the request for echo.
message EchoRequest { string message = 1; }

// EchoResponse is the response for echo.
message EchoResponse { string message = 1; }

// Echo is the echo service.
service Echo {
  // UnaryEcho is unary echo.
  rpc UnaryEcho(EchoRequest) returns (EchoResponse) {}
  // ServerStreamingEcho is server side streaming.
  rpc ServerStreamingEcho(EchoRequest) returns (stream EchoResponse) {}
  // ClientStreamingEcho is client side streaming.
  rpc ClientStreamingEcho(stream EchoRequest) returns (EchoResponse) {}
  // BidirectionalStreamingEcho is bidi streaming.
  rpc BidirectionalStreamingEcho(stream EchoRequest)
      returns (stream EchoResponse) {}
}

文件并不复杂，只有两个 message 一个请求一个返回，之所以选择这个示例是因为该示例包含了rpc中的流式处理，包扩了server 流、client 流以及双向流的操作。 编辑build.rs 文件

use std::{
   
   env, path::PathBuf};

fn main() -> Result<(), Box<dyn std::error::Error>> {
   
   
    tonic_build::compile_protos("proto/echo.proto")?;
    Ok(())
}

该文件用来通过 tonic-build 生成 grpc 的 rust 基础代码

完成上述工作后就可以构建 server 和 client 代码了

stream_server.rs

pub mod pb {
   
   
    tonic::include_proto!("stream");
}

use anyhow::Result;
use futures_util::FutureExt;
use pb::{
   
   EchoRequest, EchoResponse};
use std::{
   
   
    error::Error,
    io::ErrorKind,
    net::{
   
   SocketAddr, ToSocketAddrs},
    pin::Pin,
    thread,
    time::Duration,
};
use tokio::{
   
   
    net::TcpListener,
    sync::{
   
   
        mpsc,
        oneshot::{
   
   self, Receiver, Sender},
        Mutex,
    },
    task::{
   
   self, JoinHandle},
};
use tokio_stream::{
   
   
    wrappers::{
   
   ReceiverStream, TcpListenerStream},
    Stream, StreamExt,
};
use tonic::{
   
   transport::Server, Request, Response, Status, Streaming};
type EchoResult<T> = Result<Response<T>, Status>;
type ResponseStream = Pin<Box<dyn Stream<Item = Result<EchoResponse, Status>> + Send>>;

fn match_for_io_error(err_status: &Status) -> Option<&std::io::Error> {
   
   
    let mut err: &(dyn Error + 'static) = err_status;

    loop {
   
   
        if let Some(io_err) = err.downcast_ref::<std::io::Error>() {
   
   
            return Some(io_err);
        }

        // h2::Error do not expose std::io::Error with `source()`
        // https://github.com/hyperium/h2/pull/462
        if let Some(h2_err) = err.downcast_ref::<h2::Error>() {
   
   
            if let Some(io_err) = h2_err.get_io() {
   
   
                return Some(io_err);
            }
        }