feat: provide a mechanism to check if an iroh program is already running

[fabricedesre]

This addresses n0-computer/beetle#211 (and #231)

cc @dignifiedquire : I implemented a non opinionated way to acquire a lock and check its state. The example use in iroh-one works as expected so we can generalize to other binaries if the api is fine.

[dignifiedquire]

General approach looks good to me, just need to make sure the locking works cross platform in some reasonable manners.

[fabricedesre]

General approach looks good to me, just need to make sure the locking works cross platform in some reasonable manners.

Do we care about windows? I tested on Mac & Linux so far.

[fabricedesre]

@dignifiedquire I switched to https://docs.rs/file-guard/0.1.0/file_guard/ that has the benefits of being cross platform, pure Rust, and to work in our case :) (fslock is not a good fit because its locks are per-handle and not per-process )

[dignifiedquire]

@dignifiedquire I switched to https://docs.rs/file-guard/0.1.0/file_guard/ that has the benefits of being cross platform, pure Rust, and to work in our case :) (fslock is not a good fit because its locks are per-handle and not per-process )

Thanks, looks great.

[b5]

We've had a proper review from dig, and I've checked that all comments are addressed. Looks good!