concurrency.py

import asyncio

import aiohttp


### Concurrency .. Simple Definition: using  threads to execute tasks. Simple Analogy: Imagine how frustrating it'd be or how long it'd take 
# if there was only 1 platform
# at Woolwich Arsenal station and you are travelling to London Bridge. So you have to wait for the train to arrive from London Bridge 
# and for people to disembark from the train before you get a chance to begin your journey to London Bridge. Or even simpler imagine Ade's Cash
# and Carry with only 1 till open and you are doing Christmas shopping.. Happens sometimes :) Python provides a construct called async/await.
# If a task is gonna a while then we need to "async" it. If we don't know that a function call will be immediate we need to "await" it.
# To use it just put it async before the word "def" and  when I call my method call it with await before method name


async def get_html(session, url):
    async with session.get(url, ssl=False) as res:
        return await res.text()


async def main():
    async with aiohttp.ClientSession() as session:
        html = await get_html(session, 'http://datascience.com')
        print(html[: 1000])  # first 1000 characters


loop = asyncio.get_event_loop()
loop.run_until_complete(main())