How to use async with file IO in Rust

Use the tokio crate with fs module to perform non-blocking file operations by marking your function as async and awaiting the result. Add tokio to your Cargo.toml dependencies and import the fs module to read or write files without blocking the thread.

use tokio::fs::File;
use tokio::io::AsyncReadExt;

async fn read_file(path: &str) -> Result<String, std::io::Error> {
    let mut file = File::open(path).await?;
    let mut contents = String::new();
    file.read_to_string(&mut contents).await?;
    Ok(contents)
}

Async file IO lets your program read or write files without freezing while waiting for the disk. Think of it like ordering food at a restaurant; you can chat with friends while waiting for the kitchen to finish, rather than standing at the counter staring at the door. You use this when your app needs to handle many files or other tasks at the same time.