Viability of a getrandom feature?

[silverstillisntgold]

Hello, awesome library! Was combing through it's internals and noticed you currently use thread-local/atomic pointer addresses for seeding the RandomState/SeedableRandomState types. What are your thoughts on providing a getrandom feature to toggle delegating that to the OS-provided RNG?

Most pressing issue I can see this raising is how to deal with the error handling, but it looks like the tracking issue for something like this being introduced in std is trending towards just panicking on failure. This is also the approach go settled on a while back.

It may be worth it to investigate how the API could be altered to allow for a seeding process that might fail, since that should make it easier to move to whatever failing RNG API core will eventually provide (assuming that's something you plan to do).

[orlp]

I think this is worthwhile, it would also solve problems such as the one raised in #31.

An optional feature to swap out the initial random generation by a getrandom call seems fine to me.

[silverstillisntgold]

I'm down to work on a PR for it, what are your thoughts on how a potential error should be handled?

[orlp]

I'm not exactly sure, how do others handle it?

[silverstillisntgold]

The go solution would be to just unwrap the error, with the reasoning being that the OS RNG returning an error isn't something userspace can normally recover from. The discussion for how this should be implemented in rust is long ongoing but seems to be trending in that same direction.

An approach I'm a fan of is to provide a pair of initializer functions, one which is prefixed with try_* and returns the associated error, and another which just calls the try_* initializer and unwraps the error internally. So people working on systems with OS RNGs that suck have the option to try and work around that. But this approach might require refactoring the current trait APIs.

The easiest way to go about it would be to just unwrap the error with a useful message, and only allow the getrandom feature to be enabled when std is enabled.