fix: make timestamps strictly increasing

[Stebalien]

On Linux, this is almost always the case. Windows, however, doesn't have nanosecond accuracy.

We make the timestamp sequence numbers strictly increasing by returning the last timestamp + 1 where necessary.

[marten-seemann]

1. I searched all locally checked out code and all of GitHub, and it looks like TimestampSeq isn't used anywhere. Would removing it be an option?
2. I find the three atomic operations really hard to reason about. A mutex would be a lot simpler.

[Stebalien]

I searched all locally checked out code and all of GitHub, and it looks like TimestampSeq isn't used anywhere. Would removing it be an option?

It's used by the NewPeerRecord constructor (here).

I find the three atomic operations really hard to reason about. A mutex would be a lot simpler.

Hm. Yeah, that's probably fine. This is definitely not a hotspot.

[marten-seemann]

It's used by the NewPeerRecord constructor (here).

I meant outside of the repo. There's no real reason to export it. But I'm ok with not changing that (in this PR at least).

[marten-seemann]

That's a lot easier to read, thanks!

[Stebalien]

I meant outside of the repo. There's no real reason to export it. But I'm ok with not changing that (in this PR at least).

Ah. I see... Yeah, probably. But no energy.