文盘 Rust -- tonic-Rust grpc 初体验 | 京东云技术团队
作者：京东科技开发者
- 2023-09-18 北京
本文字数：6871 字
阅读完需：约 23 分钟
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
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Cargo.toml 如下
[package]name = "tonic_sample"version = "0.1.0"edition = "2021"
[[bin]] # Bin to run the gRPC servername = "stream-server"path = "src/stream_server.rs"
[[bin]] # Bin to run the gRPC clientname = "stream-client"path = "src/stream_client.rs"
[dependencies]tokio.workspace = truetonic = "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"
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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) {}}
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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(())}
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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); } }
err = match err.source() { Some(err) => err, None => return None, }; }}
#[derive(Debug)]pub struct EchoServer {}
#[tonic::async_trait]impl pb::echo_server::Echo for EchoServer { async fn unary_echo(&self, req: Request<EchoRequest>) -> EchoResult<EchoResponse> { let req_str = req.into_inner().message;
let response = EchoResponse { message: req_str }; Ok(Response::new(response)) }
type ServerStreamingEchoStream = ResponseStream;
async fn server_streaming_echo( &self, req: Request<EchoRequest>, ) -> EchoResult<Self::ServerStreamingEchoStream> { println!("EchoServer::server_streaming_echo"); println!("\tclient connected from: {:?}", req.remote_addr());
// creating infinite stream with requested message let repeat = std::iter::repeat(EchoResponse { message: req.into_inner().message, }); let mut stream = Box::pin(tokio_stream::iter(repeat).throttle(Duration::from_millis(200)));
let (tx, rx) = mpsc::channel(128); tokio::spawn(async move { while let Some(item) = stream.next().await { match tx.send(Result::<_, Status>::Ok(item)).await { Ok(_) => { // item (server response) was queued to be send to client } Err(_item) => { // output_stream was build from rx and both are dropped break; } } } println!("\tclient disconnected"); });
let output_stream = ReceiverStream::new(rx); Ok(Response::new( Box::pin(output_stream) as Self::ServerStreamingEchoStream )) }
async fn client_streaming_echo( &self, _: Request<Streaming<EchoRequest>>, ) -> EchoResult<EchoResponse> { Err(Status::unimplemented("not implemented")) }
type BidirectionalStreamingEchoStream = ResponseStream;
async fn bidirectional_streaming_echo( &self, req: Request<Streaming<EchoRequest>>, ) -> EchoResult<Self::BidirectionalStreamingEchoStream> { println!("EchoServer::bidirectional_streaming_echo");
let mut in_stream = req.into_inner(); let (tx, rx) = mpsc::channel(128);
tokio::spawn(async move { while let Some(result) = in_stream.next().await { match result { Ok(v) => tx .send(Ok(EchoResponse { message: v.message })) .await .expect("working rx"), Err(err) => { if let Some(io_err) = match_for_io_error(&err) { if io_err.kind() == ErrorKind::BrokenPipe { eprintln!("\tclient disconnected: broken pipe"); break; } }
match tx.send(Err(err)).await { Ok(_) => (), Err(_err) => break, // response was droped } } } } println!("\tstream ended"); });
// echo just write the same data that was received let out_stream = ReceiverStream::new(rx);
Ok(Response::new( Box::pin(out_stream) as Self::BidirectionalStreamingEchoStream )) }}
#[tokio::main]async fn main() -> Result<(), Box<dyn std::error::Error>> { // 基础server let server = EchoServer {}; Server::builder() .add_service(pb::echo_server::EchoServer::new(server)) .serve("0.0.0.0:50051".to_socket_addrs().unwrap().next().unwrap()) .await .unwrap(); Ok(())}
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server 端的代码还是比较清晰的，首先通过 tonic::include_proto! 宏引入 grpc 定义，参数是 proto 文件中定义的 package 。我们重点说说 server_streaming_echo function 。这个 function 的处理流程明白了，其他的流式处理大同小异。首先 通过 std::iter::repeat function 定义一个迭代器；然后构建 tokio_stream 在本示例中 每 200 毫秒产生一个 repeat；最后构建一个 channel ，tx 用来发送从 stream 中获取的内容太，rx 封装到 response 中返回。 最后 main 函数 拉起服务。
client 代码如下
pub mod pb { tonic::include_proto!("stream");}
use std::time::Duration;use tokio_stream::{Stream, StreamExt};use tonic::transport::Channel;
use pb::{echo_client::EchoClient, EchoRequest};
fn echo_requests_iter() -> impl Stream<Item = EchoRequest> { tokio_stream::iter(1..usize::MAX).map(|i| EchoRequest { message: format!("msg {:02}", i), })}
async fn unary_echo(client: &mut EchoClient<Channel>, num: usize) { for i in 0..num { let req = tonic::Request::new(EchoRequest { message: "msg".to_string() + &i.to_string(), }); let resp = client.unary_echo(req).await.unwrap(); println!("resp:{}", resp.into_inner().message); }}
async fn streaming_echo(client: &mut EchoClient<Channel>, num: usize) { let stream = client .server_streaming_echo(EchoRequest { message: "foo".into(), }) .await .unwrap() .into_inner();
// stream is infinite - take just 5 elements and then disconnect let mut stream = stream.take(num); while let Some(item) = stream.next().await { println!("\treceived: {}", item.unwrap().message); } // stream is droped here and the disconnect info is send to server}
async fn bidirectional_streaming_echo(client: &mut EchoClient<Channel>, num: usize) { let in_stream = echo_requests_iter().take(num);
let response = client .bidirectional_streaming_echo(in_stream) .await .unwrap();
let mut resp_stream = response.into_inner();
while let Some(received) = resp_stream.next().await { let received = received.unwrap(); println!("\treceived message: `{}`", received.message); }}
async fn bidirectional_streaming_echo_throttle(client: &mut EchoClient<Channel>, dur: Duration) { let in_stream = echo_requests_iter().throttle(dur);
let response = client .bidirectional_streaming_echo(in_stream) .await .unwrap();
let mut resp_stream = response.into_inner();
while let Some(received) = resp_stream.next().await { let received = received.unwrap(); println!("\treceived message: `{}`", received.message); }}
#[tokio::main]async fn main() -> Result<(), Box<dyn std::error::Error>> { let mut client = EchoClient::connect("http://127.0.0.1:50051").await.unwrap(); println!("Unary echo:"); unary_echo(&mut client, 10).await; tokio::time::sleep(Duration::from_secs(1)).await;
println!("Streaming echo:"); streaming_echo(&mut client, 5).await; tokio::time::sleep(Duration::from_secs(1)).await; //do not mess server println functions
// Echo stream that sends 17 requests then graceful end that connection println!("\r\nBidirectional stream echo:"); bidirectional_streaming_echo(&mut client, 17).await;
// Echo stream that sends up to `usize::MAX` requests. One request each 2s. // Exiting client with CTRL+C demonstrate how to distinguish broken pipe from // graceful client disconnection (above example) on the server side. println!("\r\nBidirectional stream echo (kill client with CTLR+C):"); bidirectional_streaming_echo_throttle(&mut client, Duration::from_secs(2)).await;
Ok(())}
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测试一下,分别运行 server 和 client
cargo run --bin stream-servercargo run --bin stream-client
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在开发中，我们通常不会再 client 和 server 都开发好的情况下才开始测试。通常在开发 server 端的时候采用 grpcurl 工具进行测试工作
grpcurl -import-path ./proto -proto echo.proto listgrpcurl -import-path ./proto -proto echo.proto describe stream.Echogrpcurl -plaintext -import-path ./proto -proto echo.proto -d '{"message":"1234"}' 127.0.0.1:50051 stream.Echo/UnaryEcho
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此时，如果我们不指定 -import-path 参数，执行如下命令
grpcurl -plaintext 127.0.0.1:50051 list
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会出现如下报错信息
Failed to list services: server does not support the reflection API
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让服务端程序支持 reflection API
use std::{env, path::PathBuf};
fn main() -> Result<(), Box<dyn std::error::Error>> { let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap()); tonic_build::configure() .file_descriptor_set_path(out_dir.join("stream_descriptor.bin")) .compile(&["proto/echo.proto"], &["proto"]) .unwrap(); Ok(())}
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file_descriptor_set_path 生成一个文件，其中包含为协议缓冲模块编码的 prost_types::FileDescriptorSet 文件。这是实现 gRPC 服务器反射所必需的。
接下来改造一下 stream-server.rs，涉及两处更改。
新增 STREAM_DESCRIPTOR_SET 常量
pub mod pb { tonic::include_proto!("stream"); pub const STREAM_DESCRIPTOR_SET: &[u8] = tonic::include_file_descriptor_set!("stream_descriptor");}
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修改 main 函数
#[tokio::main]async fn main() -> Result<(), Box<dyn std::error::Error>> { // 基础server // let server = EchoServer {}; // Server::builder() // .add_service(pb::echo_server::EchoServer::new(server)) // .serve("0.0.0.0:50051".to_socket_addrs().unwrap().next().unwrap()) // .await // .unwrap();
// tonic_reflection let service = tonic_reflection::server::Builder::configure() .register_encoded_file_descriptor_set(pb::STREAM_DESCRIPTOR_SET) .with_service_name("stream.Echo") .build() .unwrap();
let addr = "0.0.0.0:50051".parse().unwrap();
let server = EchoServer {};
Server::builder() .add_service(service) .add_service(pb::echo_server::EchoServer::new(server)) .serve(addr) .await?; Ok(())}
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register_encoded_file_descriptor_set 将包含编码的 prost_types::FileDescriptorSet 的 byte slice 注册到 gRPC Reflection 服务生成器注册。
再次测试
grpcurl -plaintext 127.0.0.1:50051 listgrpcurl -plaintext 127.0.0.1:50051 describe stream.Echo
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返回正确结果。
作者：京东科技 贾世闻
来源：京东云开发者社区 转载请注明来源
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发布于: 2023-09-18阅读数: 2
版权声明: 本文为 InfoQ 作者【京东科技开发者】的原创文章。
原文链接:【http://xie.infoq.cn/article/2dfdd928f4c23bcfc6d916ebc】。文章转载请联系作者。
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