feat: Replace deprecated time crate with std::time

[danielmellado]

The v0.2 time crate is deprecated and time::precise_time_ns() has been removed in newer versions. This causes build failures with modern Rust toolchains.

This replaces that function with std::time::Instant, which provides cross-platform monotonic time functionality using only the standard library. The bpf_time_getns() helper now returns elapsed nanoseconds since the first call, and the documentation has been updated to reflect this behavior.

The uptime.rs example has been replaced with a new date.rs example. This new example defines a helper that returns the current Unix timestamp and prints the current date and time.

Signed-off-by: Daniel Mellado dmellado@fedoraproject.org

[qmonnet]

Thanks for the PR.

The reason we used this crate is that libc and clock_gettime() caused issues on some platforms, see #19.

Do you know if there's another alternative? Does the API from the current time crate version offers a way to reproduce the timestamp generated in the helper?

[danielmellado]

Hey, thanks for the quick response. Tbh I've been really surprised about the windows in appveyor, but it did really pick up the cross-platform issue. I'll update this xD

[danielmellado]

Hi, @qmonnet, I took a look and saw no direct way to do this in time v0.3. I assume this should also work in cross-platforms. It now uses std::time::Instant to capture a reference time on the first call and returns elapsed nanoseconds from that point. TL;DR time intervals should be the same, which should work the same for eBPF programs since they typically just measure elapsed time between events anyway. Let me know ;)

[qmonnet]

Why not, we can do this I suppose.

Could you please also do the following?:

• Update the time crate dependency version in the Cargo.toml

• Update the comment for the bpf_time_getns helper, it's not from boot time (it hasn't been since we switched to time anyway 🤦)

• Rename (including in Cargo.toml) and change the uptime example (examples/uptime.rs). One suggestion, if you feel like: instead of reusing the existing bpf_time_getns helper, we could use re-implement a separate helper in that file, that returns the current time, and print it (and rename the example to date). If you don't want to spend too much time on this one I can understand, I can follow up with it. Note: running the JIT for the examples currently doesn't work on my setup, I had to change it to use the interpreter instead.

[danielmellado]

Hi @qmonnet, yeah, JIT also crashed for me. I kept it as it was later but I'm wondering if it'd make sense to just change it. Thanks!

[qmonnet]

Thanks for the update. I'll try to take a look in the next few days, sorry for the delay.

[danielmellado]

@qmonnet could you PTAL? Thanks!

[qmonnet]

Apologies for the delay - Looks OK, let's go for it, thank you!

[qmonnet]

FYI I just tagged and published v0.4.0, which includes your changes.

[danielmellado]

FYI I just tagged and published v0.4.0, which includes your changes.

Awesome, thanks! I was about to ask for that ;)