_ Git - rust-lightning/blob - lightning/src/util/time.rs

   1 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   2 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   3 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   4 // You may not use this file except in accordance with one or both of these
   5 // licenses.
   6
   7 //! [`Time`] trait and different implementations. Currently, it's mainly used in tests so we can
   8 //! manually advance time.
   9 //! Other crates may symlink this file to use it while [`Time`] trait is sealed here.
  10
  11 use core::ops::Sub;
  12 use core::time::Duration;
  13
  14 /// A measurement of time.
  15 pub trait Time: Copy + Sub<Duration, Output = Self> where Self: Sized {
  16         /// Returns an instance corresponding to the current moment.
  17         fn now() -> Self;
  18
  19         /// Returns the amount of time elapsed since `self` was created.
  20         fn elapsed(&self) -> Duration;
  21
  22         /// Returns the amount of time passed between `earlier` and `self`.
  23         fn duration_since(&self, earlier: Self) -> Duration;
  24
  25         /// Returns the amount of time passed since the beginning of [`Time`].
  26         ///
  27         /// Used during (de-)serialization.
  28         fn duration_since_epoch() -> Duration;
  29 }
  30
  31 /// A state in which time has no meaning.
  32 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  33 pub struct Eternity;
  34
  35 impl Time for Eternity {
  36         fn now() -> Self {
  37                 Self
  38         }
  39
  40         fn duration_since(&self, _earlier: Self) -> Duration {
  41                 Duration::from_secs(0)
  42         }
  43
  44         fn duration_since_epoch() -> Duration {
  45                 Duration::from_secs(0)
  46         }
  47
  48         fn elapsed(&self) -> Duration {
  49                 Duration::from_secs(0)
  50         }
  51 }
  52
  53 impl Sub<Duration> for Eternity {
  54         type Output = Self;
  55
  56         fn sub(self, _other: Duration) -> Self {
  57                 self
  58         }
  59 }
  60
  61 #[cfg(not(feature = "no-std"))]
  62 impl Time for std::time::Instant {
  63         fn now() -> Self {
  64                 std::time::Instant::now()
  65         }
  66
  67         fn duration_since(&self, earlier: Self) -> Duration {
  68                 self.duration_since(earlier)
  69         }
  70
  71         fn duration_since_epoch() -> Duration {
  72                 use std::time::SystemTime;
  73                 SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
  74         }
  75         fn elapsed(&self) -> Duration {
  76                 std::time::Instant::elapsed(self)
  77         }
  78 }
  79
  80 #[cfg(test)]
  81 pub mod tests {
  82         use super::{Time, Eternity};
  83
  84         use core::time::Duration;
  85         use core::ops::Sub;
  86         use core::cell::Cell;
  87
  88         /// Time that can be advanced manually in tests.
  89         #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  90         pub struct SinceEpoch(Duration);
  91
  92         impl SinceEpoch {
  93                 thread_local! {
  94                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
  95                 }
  96
  97                 pub fn advance(duration: Duration) {
  98                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
  99                 }
 100         }
 101
 102         impl Time for SinceEpoch {
 103                 fn now() -> Self {
 104                         Self(Self::duration_since_epoch())
 105                 }
 106
 107                 fn duration_since(&self, earlier: Self) -> Duration {
 108                         self.0 - earlier.0
 109                 }
 110
 111                 fn duration_since_epoch() -> Duration {
 112                         Self::ELAPSED.with(|elapsed| elapsed.get())
 113                 }
 114
 115                 fn elapsed(&self) -> Duration {
 116                         Self::duration_since_epoch() - self.0
 117                 }
 118         }
 119
 120         impl Sub<Duration> for SinceEpoch {
 121                 type Output = Self;
 122
 123                 fn sub(self, other: Duration) -> Self {
 124                         Self(self.0 - other)
 125                 }
 126         }
 127
 128         #[test]
 129         fn time_passes_when_advanced() {
 130                 let now = SinceEpoch::now();
 131                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 132
 133                 SinceEpoch::advance(Duration::from_secs(1));
 134                 SinceEpoch::advance(Duration::from_secs(1));
 135
 136                 let elapsed = now.elapsed();
 137                 let later = SinceEpoch::now();
 138
 139                 assert_eq!(elapsed, Duration::from_secs(2));
 140                 assert_eq!(later - elapsed, now);
 141         }
 142
 143         #[test]
 144         fn time_never_passes_in_an_eternity() {
 145                 let now = Eternity::now();
 146                 let elapsed = now.elapsed();
 147                 let later = Eternity::now();
 148
 149                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 150                 assert_eq!(later - elapsed, now);
 151         }
 152 }