use super::{Duration, Instant, SystemTime, UNIX_EPOCH}; use core::fmt::Debug; #[cfg(not(target_arch = "wasm32"))] use test::{black_box, Bencher}; macro_rules! assert_almost_eq { ($a:expr, $b:expr) => {{ let (a, b) = ($a, $b); if a != b { let (a, b) = if a > b { (a, b) } else { (b, a) }; assert!(a - Duration::from_micros(1) <= b, "{:?} is not almost equal to {:?}", a, b); } }}; } #[test] fn instant_monotonic() { let a = Instant::now(); loop { let b = Instant::now(); assert!(b >= a); if b > a { break; } } } #[test] #[cfg(not(target_arch = "wasm32"))] fn instant_monotonic_concurrent() -> crate::thread::Result<()> { let threads: Vec<_> = (0..8) .map(|_| { crate::thread::spawn(|| { let mut old = Instant::now(); let count = if cfg!(miri) { 1_000 } else { 5_000_000 }; for _ in 0..count { let new = Instant::now(); assert!(new >= old); old = new; } }) }) .collect(); for t in threads { t.join()?; } Ok(()) } #[test] fn instant_elapsed() { let a = Instant::now(); let _ = a.elapsed(); } #[test] fn instant_math() { let a = Instant::now(); let b = Instant::now(); println!("a: {a:?}"); println!("b: {b:?}"); let dur = b.duration_since(a); println!("dur: {dur:?}"); assert_almost_eq!(b - dur, a); assert_almost_eq!(a + dur, b); let second = Duration::SECOND; assert_almost_eq!(a - second + second, a); assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a); // checked_add_duration will not panic on overflow let mut maybe_t = Some(Instant::now()); let max_duration = Duration::from_secs(u64::MAX); // in case `Instant` can store `>= now + max_duration`. for _ in 0..2 { maybe_t = maybe_t.and_then(|t| t.checked_add(max_duration)); } assert_eq!(maybe_t, None); // checked_add_duration calculates the right time and will work for another year let year = Duration::from_secs(60 * 60 * 24 * 365); assert_eq!(a + year, a.checked_add(year).unwrap()); } #[test] fn instant_math_is_associative() { let now = Instant::now(); let offset = Duration::from_millis(5); // Changing the order of instant math shouldn't change the results, // especially when the expression reduces to X + identity. assert_eq!((now + offset) - now, (now - now) + offset); // On any platform, `Instant` should have the same resolution as `Duration` (e.g. 1 nanosecond) // or better. Otherwise, math will be non-associative (see #91417). let now = Instant::now(); let provided_offset = Duration::from_nanos(1); let later = now + provided_offset; let measured_offset = later - now; assert_eq!(measured_offset, provided_offset); } #[test] fn instant_duration_since_saturates() { let a = Instant::now(); assert_eq!((a - Duration::SECOND).duration_since(a), Duration::ZERO); } #[test] fn instant_checked_duration_since_nopanic() { let now = Instant::now(); let earlier = now - Duration::SECOND; let later = now + Duration::SECOND; assert_eq!(earlier.checked_duration_since(now), None); assert_eq!(later.checked_duration_since(now), Some(Duration::SECOND)); assert_eq!(now.checked_duration_since(now), Some(Duration::ZERO)); } #[test] fn instant_saturating_duration_since_nopanic() { let a = Instant::now(); #[allow(deprecated, deprecated_in_future)] let ret = (a - Duration::SECOND).saturating_duration_since(a); assert_eq!(ret, Duration::ZERO); } #[test] fn system_time_math() { let a = SystemTime::now(); let b = SystemTime::now(); match b.duration_since(a) { Ok(Duration::ZERO) => { assert_almost_eq!(a, b); } Ok(dur) => { assert!(b > a); assert_almost_eq!(b - dur, a); assert_almost_eq!(a + dur, b); } Err(dur) => { let dur = dur.duration(); assert!(a > b); assert_almost_eq!(b + dur, a); assert_almost_eq!(a - dur, b); } } let second = Duration::SECOND; assert_almost_eq!(a.duration_since(a - second).unwrap(), second); assert_almost_eq!(a.duration_since(a + second).unwrap_err().duration(), second); assert_almost_eq!(a - second + second, a); assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a); let one_second_from_epoch = UNIX_EPOCH + Duration::SECOND; let one_second_from_epoch2 = UNIX_EPOCH + Duration::from_millis(500) + Duration::from_millis(500); assert_eq!(one_second_from_epoch, one_second_from_epoch2); // checked_add_duration will not panic on overflow let mut maybe_t = Some(SystemTime::UNIX_EPOCH); let max_duration = Duration::from_secs(u64::MAX); // in case `SystemTime` can store `>= UNIX_EPOCH + max_duration`. for _ in 0..2 { maybe_t = maybe_t.and_then(|t| t.checked_add(max_duration)); } assert_eq!(maybe_t, None); // checked_add_duration calculates the right time and will work for another year let year = Duration::from_secs(60 * 60 * 24 * 365); assert_eq!(a + year, a.checked_add(year).unwrap()); } #[test] fn system_time_elapsed() { let a = SystemTime::now(); drop(a.elapsed()); } #[test] fn since_epoch() { let ts = SystemTime::now(); let a = ts.duration_since(UNIX_EPOCH + Duration::SECOND).unwrap(); let b = ts.duration_since(UNIX_EPOCH).unwrap(); assert!(b > a); assert_eq!(b - a, Duration::SECOND); let thirty_years = Duration::SECOND * 60 * 60 * 24 * 365 * 30; // Right now for CI this test is run in an emulator, and apparently the // aarch64 emulator's sense of time is that we're still living in the // 70s. This is also true for riscv (also qemu) // // Otherwise let's assume that we're all running computers later than // 2000. if !cfg!(target_arch = "aarch64") && !cfg!(target_arch = "riscv64") { assert!(a > thirty_years); } // let's assume that we're all running computers earlier than 2090. // Should give us ~70 years to fix this! let hundred_twenty_years = thirty_years * 4; assert!(a < hundred_twenty_years); } #[test] fn big_math() { // Check that the same result occurs when adding/subtracting each duration one at a time as when // adding/subtracting them all at once. #[track_caller] fn check(start: Option, op: impl Fn(&T, Duration) -> Option) { const DURATIONS: [Duration; 2] = [Duration::from_secs(i64::MAX as _), Duration::from_secs(50)]; if let Some(start) = start { assert_eq!( op(&start, DURATIONS.into_iter().sum()), DURATIONS.into_iter().try_fold(start, |t, d| op(&t, d)) ) } } check(SystemTime::UNIX_EPOCH.checked_sub(Duration::from_secs(100)), SystemTime::checked_add); check(SystemTime::UNIX_EPOCH.checked_add(Duration::from_secs(100)), SystemTime::checked_sub); let instant = Instant::now(); check(instant.checked_sub(Duration::from_secs(100)), Instant::checked_add); check(instant.checked_sub(Duration::from_secs(i64::MAX as _)), Instant::checked_add); check(instant.checked_add(Duration::from_secs(100)), Instant::checked_sub); check(instant.checked_add(Duration::from_secs(i64::MAX as _)), Instant::checked_sub); } macro_rules! bench_instant_threaded { ($bench_name:ident, $thread_count:expr) => { #[bench] #[cfg(not(target_arch = "wasm32"))] fn $bench_name(b: &mut Bencher) -> crate::thread::Result<()> { use crate::sync::atomic::{AtomicBool, Ordering}; use crate::sync::Arc; let running = Arc::new(AtomicBool::new(true)); let threads: Vec<_> = (0..$thread_count) .map(|_| { let flag = Arc::clone(&running); crate::thread::spawn(move || { while flag.load(Ordering::Relaxed) { black_box(Instant::now()); } }) }) .collect(); b.iter(|| { let a = Instant::now(); let b = Instant::now(); assert!(b >= a); }); running.store(false, Ordering::Relaxed); for t in threads { t.join()?; } Ok(()) } }; } bench_instant_threaded!(instant_contention_01_threads, 0); bench_instant_threaded!(instant_contention_02_threads, 1); bench_instant_threaded!(instant_contention_04_threads, 3); bench_instant_threaded!(instant_contention_08_threads, 7); bench_instant_threaded!(instant_contention_16_threads, 15);