Tokio Brodcast Channel Receiver not receiving - rust

Question

I currently am attempting to write a server and client using Tokio and the broadcast channel. I have a loop that essentially listens for connections and, after reading the TcpStream, I send through the channel.
Here is the code that I have attempted:
What I end up getting is a print each time I connect to the server and bytes are read.. , but I never get a 'Received'
use dbjade::serverops::ServerOp;
use tokio::io::{BufReader};
use tokio::net::TcpStream;
use tokio::{net::TcpListener, io::AsyncReadExt};
use tokio::sync::broadcast;
const ADDR: &str = "localhost:7676"; // Your own address : TODO change to be configured
const CHANNEL_NUM: usize = 100;
use std::io;
use std::net::{SocketAddr};
use bincode;
#[tokio::main]
async fn main() {
// Create listener instance that bounds to certain address
let listener = TcpListener::bind(ADDR).await.map_err(|err| panic!("Failed to bind: {err}")).unwrap();
let (tx, mut rx) = broadcast::channel::<(ServerOp, SocketAddr)>(CHANNEL_NUM);
loop {
if let Ok((mut socket, addr)) = listener.accept().await {
let tx = tx.clone();
let mut rx = tx.subscribe();
println!("Receieved stream from: {}", addr);
let mut buf = vec![0, 255];
tokio::select! {
result = socket.read(&mut buf) => {
match result {
Ok(res) => println!("Bytes Read: {res}"),
Err(_) => println!(""),
}
tx.send((ServerOp::Dummy, addr)).unwrap();
}
result = rx.recv() =>{
let (msg, addr) = result.unwrap();
println!("Receieved: {msg}");
}
}
}
}
}

Answer 1

The main problem in your code are these lines
let tx = tx.clone();
let mut rx = tx.subscribe();
You are redefining tx and rx. and you do it in the loop, so next iteration there is never same tx and rx so they can not be connected between iterations. And so when you do rx.recv() it is not the rx that you expect that is on the other end of the channel. The rx that you define in the beginning is unused. Variable shadowing is a common problem in Rust. The general way to solve it is to read all warnings of the compiler and resolve all "unused" variables, imports, etc. I would argue that turning these warnings into errors by default won't harm either. So that's what I did: I removed all unused stuff and connected the correct channel ends. I also removed dbjade as I've no idea where to get it and for the sake of the example replaced it with "Dummy" string.
use tokio::{net::TcpListener, io::AsyncReadExt};
use tokio::sync::broadcast;
const ADDR: &str = "localhost:7676"; // Your own address : TODO change to be configured
const CHANNEL_NUM: usize = 100;
use std::net::{SocketAddr};
#[tokio::main]
async fn main() {
// Create listener instance that bounds to certain address
let listener = TcpListener::bind(ADDR).await.map_err(|err| panic!("Failed to bind: {err}")).unwrap();
let (tx, mut rx) = broadcast::channel::<(String, SocketAddr)>(CHANNEL_NUM);
loop {
if let Ok((mut socket, addr)) = listener.accept().await {
println!("Receieved stream from: {}", addr);
let mut buf = vec![0, 255];
tokio::select! {
result = socket.read(&mut buf) => {
match result {
Ok(res) => println!("Bytes Read: {res}"),
Err(_) => println!("Err"),
}
tx.send(("Dummy".to_string(), addr)).unwrap();
}
result = rx.recv() =>{
let (msg, _) = result.unwrap();
println!("Receieved: {msg}");
}
}
}
}
}