pygotham_asyncio_full_app.py

pygotham_asyncio_full_app.py

import asyncio


def set_current_context(ctx, loop=None):
    # retrieves the current Task
    loop = loop or asyncio.get_event_loop()
    task = asyncio.Task.current_task(loop=loop)
    # attach the Context to the task!
    setattr(task, '__current_ctx', ctx)


def get_current_context(loop=None):
    # retrieves the current Task
    loop = loop or asyncio.get_event_loop()
    task = asyncio.Task.current_task(loop=loop)
    # get the Context
    ctx = getattr(task, '__current_ctx', None)
    return ctx


async def handle_request(reader, writer):
    """Web handler examples"""
    # set the current context
    ctx = {}
    set_current_context(ctx)

    # read and store the whole request in the context
    data = await reader.read(100)
    ctx['data'] = data.decode()
    result = await retrieve_user_data()
    writer.write(result.encode())
    writer.close()


async def retrieve_user_data():
    # do a long call
    await asyncio.sleep(2)
    ctx = get_current_context()
    return ctx['data']


if __name__ == '__main__':
    # initialize the server
    loop = asyncio.get_event_loop()
    coro = asyncio.start_server(handle_request, '127.0.0.1', 8000, loop=loop)
    server = loop.run_until_complete(coro)

    # Serve requests until Ctrl+C is pressed
    print('Serving on {}'.format(server.sockets[0].getsockname()))
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass

    # Close the server
    server.close()
    loop.run_until_complete(server.wait_closed())
    loop.close()

Requirements

• Python 3.5+

Launch the application

Be sure that you're running python3, then:

$ python pygotham_asyncio_full_app.py
# Serving on ('127.0.0.1', 8000)
# (it waits for a request)

In another shell, launch multiple concurrent calls:

for i in $(eval echo "{1..10}"); do (curl "http://localhost:8000/?id=$i" &) ; done

The expected output should be:

GET /?id=1 HTTP/1.1
Host: localhost:8000
User-Agent: curl/7.54.0
Accept: */*

GET /?id=2 HTTP/1.1
Host: localhost:8000
User-Agent: curl/7.54.0
Accept: */*

# ...