httpx tqdm example

example.py

"""
Run as below:

    ❯ pip install pex
    ❯ pex httpx tqdm -- ./example.py
"""
import asyncio, tqdm, httpx

async def get_chunks_with_progress(response: httpx.Response):
    total = int(response.headers["Content-Length"])
    num_bytes_downloaded = response.num_bytes_downloaded
    with tqdm.tqdm(total=total, unit_scale=True, unit_divisor=1024, unit='B') as progress:
        async for chunk in response.aiter_bytes():
            yield chunk
            progress.update(response.num_bytes_downloaded - num_bytes_downloaded)
            num_bytes_downloaded = response.num_bytes_downloaded

async def a_download():
    url = "https://archive.org/download/stackexchange/beer.stackexchange.com.7z"
    async with httpx.AsyncClient() as client:
        async with client.stream("GET", url) as response:
            with open('/tmp/dump.7z', 'wb') as fp:
                async for chunk in get_chunks_with_progress(response):
                    fp.write(chunk)

asyncio.run(a_download())

"""
Some relevant links:
    pex: https://github.com/pantsbuild/pex
    tqdm: https://github.com/tqdm/tqdm
    httpx: https://www.python-httpx.org/
    httpx doc for the example: https://www.python-httpx.org/advanced/#monitoring-download-progress
    Why we can't just use `progress.update(len(chunk))`? 
        Answer: Compression
        Explanation: https://github.com/encode/httpx/pull/1565#issuecomment-817098129
"""