client.rs

pub mod pb {
    tonic::include_proto!("grpc.examples.echo");
}

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 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 dropped here and the disconnect info is sent 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://[::1]:50051").await.unwrap();

    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(())
}