file_writing.rust

use std::{
    fs,
    io::{self, BufWriter, Write},
    time::Instant,
};

fn main() -> io::Result<()> {
    println!("Hello, world!");

    let file = fs::File::create("output.txt")?;

    let mut logID = 0;
    let mut total_written_bytes = 0;

    let msg = "This is a long line of log text with the id is";
    let mut writer = BufWriter::with_capacity(10_024_000, file);

    let begin = Instant::now();

    loop {
        let written_bytes = writer.write(msg.as_bytes())?;
        total_written_bytes += written_bytes;
        logID += 1;

        if total_written_bytes >= 512_000_000 {
            break;
        }
    }

    writer.flush()?;

    let total_duration = Instant::now().duration_since(begin);
    let total_seconds = total_duration.as_secs_f64();
    let total_megabytes = (total_written_bytes as f64) / 1_024_000.0;
    let megabytes_per_second = total_megabytes / total_seconds;

    println!(
        "Wrote {} mbytes in {} seconds, {} mb/s",
        total_megabytes as i64, total_seconds, megabytes_per_second
    );

    return Ok(());
}