fix: max message size not included in tornado settings.

[ikwilnaarhuisman]

The max message size used to be implicitly used by the tornado settings, but this was broken in commit 949d7c3.

Because what used to happen is that the tornado.web.Application could implicitly find the attribute about the max_message_size, but because this was moved to a dictionary it can no longer. Causing Tornado to automatically disconnect when it receives a message exceeding 10 megabytes.

@YannickdeHoop

[bjsowa]

It would be helpful to add a test to rosbridge_server which tests this behavior so this does not happen in the future. Could you write one?

[ikwilnaarhuisman]

I had a look at implementing a unit test where you could assert the max_message_size with the tornado max_message_size, but because tornado doesn't expose its parameters at runtime. I can't access it. I'm not sure how to unit test it without adding extra functionality.

[ikwilnaarhuisman]

Please note that when tornado receives messages bigger than the max_message_size the connection is terminated. Making this is a very annoying issue.

https://github.com/tornadoweb/tornado/blob/3dfc965b2828fb2e48b700b1436dfbd16224a05d/tornado/websocket.py#L323

[YannickdeHoop]

@bjsowa Do you have any suggestions with regard to testing?

[bjsowa]

@bjsowa Do you have any suggestions with regard to testing?

If we want to define a certain behavior, IMO we should write an integration test which asserts this behavior, for example, by sending large messages to the server and testing how different values for max_message_size affect it.

[bjsowa]

The test got stuck so I cancelled the workflow

[ikwilnaarhuisman]

They run locally (on jazzy) without a problem.

Other than mypy, whatever happens there.

[ikwilnaarhuisman]

@bjsowa I removed some floating debug code. Be sure to quit the workflow if required