The WSGI container is a good option to wrap a multi-modal webapp
(Flask + websocket routes), but it's constrained to a single-process
approach and queued/pre-buffered requests. That makes performance poor
when handling requests that may take a few seconds to complete.
The Tensorflow module may take a few seconds to load the first time and
slow down the first scan of the plugins.
All the Tensorflow imports should therefore be placed close to where
they are used instead of being defined at the top of the module.
Defined a `platypush.backend.http.ws` package with all the routes, a
base `WSRoute` class that all the websocket routes can extend, and a
logic in the HTTP backend to automatically scan the package to register
exposed websocket routes.
It was just too painful to find a combination of versions of gunicorn,
gevent, eventlet, pyuwsgi etc. that could work on all of my systems.
On the other hand, Tornado works out of the box with no headaches.
Also in this commit:
- Updated a bunch of outdated/required integration dependencies.
- Black'd and LINTed a couple of old plugins.
The eventlet API has way too many dependency issues with gunicorn.
Still TODO: Fix or at least mitigate the WSGI workers timeout issue when
they handle websocket connections.
The websocket service is no longer provided by a different service,
controlled by a different thread running on another port.
Instead, it's now exposed directly over Flask routes, using
WSGI+eventlet+simple_websocket.
Also, the SSL context options have been removed from `backend.http`, for
sake of simplicity. If you want to enable SSL, you can serve Platypush
through a reverse proxy like nginx.
Instead of iterating over each of the entities in a grouping to find out
which groups should be displayed based on the selector's policy, the
selector can directly keep its `selectedGroups` attribute in sync with
the index.
`delete` will actually remove the record from the database (same as
`unset`'s new behaviour), while `unset` will set it to null without
deleting it (same as the `unset`'s previous behaviour).
Added `waitress` dependency. For performance and security reasons, it's
better to always run the Flask application inside of a uWSGI server.
`waitress` also makes things easier by avoiding to ask the user to
manually provide the external executable arguments, as it was the case
with `uwsgi` and `gunicorn`.