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_sampleCargo.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/462if 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 messagelet 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 droppedbreak;}}}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 receivedlet 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serverlet 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(())
}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 disconnectlet 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 connectionprintln!("\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(())
}测试一下,分别运行 server 和 client
cargo run --bin stream-server
cargo run --bin stream-client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 list
grpcurl -import-path ./proto -proto echo.proto describe stream.Echo
grpcurl -plaintext -import-path ./proto -proto echo.proto -d '{"message":"1234"}' 127.0.0.1:50051 stream.Echo/UnaryEcho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会出现如下报错信息
Failed to list services: server does not support the reflection API让服务端程序支持 reflection API
首先改造build.rs
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(())
}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");
}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(())
}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 list
grpcurl -plaintext 127.0.0.1:50051 describe stream.Echo返回正确结果。
以上完整代码地址
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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