Acurl

It is an asynchronous wrapper around libcurl which is built to interface with the Uvloop python library.

Using Acurl In Mite

The gateway into Acurl is through the CurlWrapper (discussed in Architectural Notes) and requires an event loop being passed to its constructor. Below is the mite implementation of acurl:

class SessionPool:
    ...
    def __init__(self):
        import acurl
        self._wrapper = acurl.CurlWrapper(asyncio.get_event_loop_policy().get_event_loop())
        ...

Architectural Notes

Acurl uses a single loop maintained within python using UVloop.

Acurl surfaces the CurlWrapper interface which takes the asyncio event loop as an argument. The wrapper deals directly with the curl_multi interface from libcurl, defining 2 functions (curl_perform_write and curl_perform_read) for checking both read and write availability of file descriptors.

There are 2 notable functions within the core Acurl implementation, notably handle_socket and start_timer:

• handle_socket is passed as a callback function to the curl_multi interface and upon calls to the curl_multi_socket_action function, will receive updates regarding the socket status. We then handle those statuses by either adding or removing the aforementioned readers or writers.
• start_timer is another callback function that is passed to the curl_multi interface and is used as a way to handle timeouts and retries within curl. Upon a timeout, the timeout callback will be called and the transfer can be retried.