Code shared from the Rust Playground

playground.rs

use async_compression::tokio::bufread::GzipDecoder;
use futures::join;
use tokio::fs::File;
use tokio::io::{AsyncBufRead, AsyncBufReadExt, BufReader};

async fn count_lines<R>(mut reader: R) -> usize
where
    R: AsyncBufRead + Send + Unpin,
{
    let mut line = String::new();
    let mut num_lines = 0;
    while reader.read_line(&mut line).await.unwrap() > 0 {
        num_lines += 1;
        line.clear();
    }
    return num_lines;
}

#[tokio::main]
async fn main() {
    // Read file lines
    let unzipped_handle = tokio::spawn(async move {
        let file = File::open("unzipped_file").await;
        let reader = BufReader::new(file.unwrap());
        count_lines(reader).await
    });

    // Read gzipped lines
    let gzipped_handle = tokio::spawn(async move {
        let file = File::open("gzipped_file").await;
        let reader = BufReader::new(GzipDecoder::new(BufReader::new(file.unwrap())));
        count_lines(reader).await
    });

    // Compare lines
    let (unzipped_result, gzipped_result) = join!(unzipped_handle, gzipped_handle);
    assert_eq!(413484, unzipped_result.unwrap());
    assert_eq!(65654, gzipped_result.unwrap());
}