You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: io.rs
    path of file: ./repos/azuredatastudio/cli/src/util
    
    the code of the file until where you have to start completion: /*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
use std::{
	fs::File,
	io::{self, BufRead, Seek},
	task::Poll,
	time::Duration,
};

use tokio::{
	io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt},
	sync::mpsc,
	time::sleep,
};

use super::ring_buffer::RingBuffer;

pub trait ReportCopyProgress {
	fn report_progress(&mut self, bytes_so_far: u64, total_bytes: u64);
}

/// Type that doesn't emit anything for download progress.
pub struct SilentCopyProgress();

impl ReportCopyProgress for SilentCopyProgress {
	fn report_progress(&mut self, _bytes_so_far: u64, _total_bytes: u64) {}
}

/// Copies from the reader to the writer, reporting progres
    
	async fn test_tailf_with_data() {
		let dir = tempfile::tempdir().unwrap();
		let file_path = dir.path().join("tmp");

		let mut read_file = OpenOptions::new()
			.write(true)
			.read(true)
			.create(true)
			.open(&file_path)
			.unwrap();
		let mut rng = rand::thread_rng();

		let mut written = vec![];
		let base_line = "Elit ipsum cillum ex cillum. Adipisicing consequat cupidatat do proident ut in sunt Lorem ipsum tempor. Eiusmod ipsum Lorem labore exercitation sunt pariatur excepteur fugiat cillum velit cillum enim. Nisi Lorem cupidatat ad enim velit officia eiusmod esse tempor aliquip. Deserunt pariatur tempor in duis culpa esse sit nulla irure ullamco ipsum voluptate non laboris. Occaecat officia nulla officia mollit do aliquip reprehenderit ad incididunt.";
		for i in 0..100 {
			let line = format!("{}: {}", i, &base_line[..rng.gen_range(0..base_line.len())]);
			writeln!(&mut read_file, "{}", line).unwrap();
			written.push(line);
		}
		write!(&mut read_file, "partial line").unwrap();
		read_file.seek(io::SeekFrom::Start(0)).unwrap();

		let last_n = 32;
		let mut rx = tailf(read_file, last_n);
		for i in 0..last_n {
			let recv = rx.try_recv().unwrap();
			if let TailEvent::Line(l) = recv {
				let mut expected = written[written.len() - last_n + i].to_string();
				expected.push('\n');
				assert_eq!(expected, l);
			} else {
				unreachable!("expect a line event, got {:?}", recv)
			}
		}

		assert!(rx.try_recv().is_err());

		let mut append_file = OpenOptions::new()
			.write(true)
			.append(true)
			.open(&file_path)
			.unwrap();
		writeln!(append_file, " is now complete").unwrap();

		let recv = rx.recv().await;
		if let Some(TailEvent::Line(l)) = recv {
			assert_eq!("partial line is now complete\n".to_string(), l);
		} else {
			unreachable!("expect a line event, got {:?}", recv)
		}
	}