GSOC Project discussion : Async sftp implementation

[Eshan Kelkar <eshankelkar@xxxxxxxxxxxxx>]

Hi, I am Eshan Kelkar and would like to create the async sftp for libssh as
the GSOC project. I have gone through liburing to understand what async i/o
is and how it is implemented using io_uring. So in this async sftp
implementation I believe we can place calls to the liburing api functions
from inside of the async sftp api functions so that things occur
asynchronously.

Another approach that comes to my mind is that on a call to async sftp api
function a seperate thread gets created which does the waiting and all and
on completion places a call to the callback function notifying that the
operation has occurred. The second approach is async conceptually as the
user of api can continue his job after the call as the waiting occurs on
the separate thread but this approach seems a bit "naive" as for each api
call a new thread gets created which is resource expensive.

Kindly comment on these two approaches and suggest any other approach which
you have in mind to implement the async sftp api, those suggestions will
help me prepare better before sending in the proposal.