Reload TLS certificate files when they change

[fmoor]

fixes #4277

[elprans]

Is there an asyncio-compatible watching library we can use instead of spawning threads?

[1st1]

Is there an asyncio-compatible watching library we can use instead of spawning threads?

No popular and trusted one afaik. Maybe we spawn a thread and just check mtime in a loop every 5 seconds?

[elprans]

Is there an asyncio-compatible watching library we can use instead of spawning threads?

No popular and trusted one afaik. Maybe we spawn a thread and just check mtime in a loop every 5 seconds?

Threads mean GIL. If it can't be in the event loop, then a monitoring subprocess sending SIGHUP to the main process seems better to me.

[1st1]

Threads mean GIL. If it can't be in the event loop, then a monitoring subprocess sending SIGHUP to the main process seems better to me.

That's too complicated.

@fantix how about we add a hidden API to uvloop to expose libuv watchers? That should be easy.

[fmoor]

There is https://github.com/samuelcolvin/watchfiles which is mostly an interface to https://github.com/notify-rs/notify but its not 1.0 yet.

[1st1]

There is https://github.com/samuelcolvin/watchfiles which is mostly an interface to https://github.com/notify-rs/notify but its not 1.0 yet.

It also uses threads for its async API.

[fantix]

@fantix how about we add a hidden API to uvloop to expose libuv watchers? That should be easy.

I'm looking into this now - we can start with tweaking MagicStack/uvloop#474, the basic API should be pretty straightforward.

Even though we don't need the recursive watching in this PR, it'll be needed by the edgedb-python codegen --watch mode. However, libuv doesn't support recursive watching out of the box on Linux, and libuv is likely NOT going to add support for that. So IMO we should at least make the hidden uvloop API friendly-enough for implementing recursive watching, given aside of whether we want to support Linux recursive watching directly in uvloop. I'll try something on top of @jensbjorgensen's implementation, and start a new thread in the uvloop repo for further discussion.

Oh, edgedb-python doesn't depend on uvloop, and --watch mode will probably be just an extra feature that doesn't necessarily require uvloop for watching changes recursively. So it'll be easy then, literally quoting Yury's "we add a hidden API to uvloop to (simply) expose libuv watchers".

[1st1]

@fantix can you pick this one up given that we have the necessary new API in uvloop?

[elprans]

Closing in favor of the merged #4297.