why is there a tokio::time::Instant ?

[barkanido]

What is the justification and motivation for introducing tokio::time::Instant?
Is it maybe to better support no_std environments?

[Darksonn]

It is because when you enable the test-util feature, it is possible to pause time, which can be very useful in tests.

[barkanido]

so, internally, Tokio has to use the tokio::time wrapper instead of std::time?
In other words, in order to pause time in tests for code that I write using Tokio, I need to use tokio::time instead?

[Darksonn]

Yes, if you want to use that feature, you should be using Tokio's Instant. Tokio cannot override the std Instant, and the std Instant will give the real time even if you have paused it with tokio::time::pause.

Of course, you can always convert between the std and Tokio Instant types via the from_std and into_std methods on the Tokio Instant.