polars_utils/
tick_counter.rs

1/// **Unsynchronized** tick counter.
2///
3/// This is intended to be used to *roughly* organize events across threads in
4/// their received order but without any actual guarantees around monotonicity
5/// or synchronization, for maximum speed.
6///
7/// This does not guarantee monotonicity or any particular (fixed) time unit.
8/// If correctness matters use Instant::now().
9#[inline]
10pub fn tick_counter() -> u64 {
11    cfg_select! {
12        target_arch = "x86_64" => unsafe { core::arch::x86_64::_rdtsc() },
13
14        target_arch = "aarch64" => {
15            let cnt: u64;
16            unsafe {
17                core::arch::asm!(
18                    "mrs {cnt}, cntvct_el0",
19                    cnt = out(reg) cnt,
20                    options(nomem, nostack, preserves_flags),
21                );
22            }
23            cnt
24        },
25
26        _ => {
27            use std::sync::LazyLock;
28            use std::time::Instant;
29
30            static REFERENCE_INSTANT: LazyLock<Instant> = LazyLock::new(Instant::now);
31            REFERENCE_INSTANT.elapsed().as_nanos() as u64
32        },
33    }
34}
polars_utils/tick_counter.rs

polars_utils/
tick_counter.rs
