Clean up time code in tendermint-machine

substrate/tendermint/machine/src/time.rs

@@ -0,0 +1,43 @@
+use core::ops::Add;
+use std::time::{UNIX_EPOCH, SystemTime, Instant, Duration};
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub(crate) struct CanonicalInstant {
+  /// Time since the epoch.
+  time: u64,
+  /// An Instant synchronized with the above time.
+  instant: Instant,
+}
+
+pub(crate) fn sys_time(time: u64) -> SystemTime {
+  UNIX_EPOCH + Duration::from_secs(time)
+}
+
+impl CanonicalInstant {
+  pub(crate) fn new(time: u64) -> CanonicalInstant {
+    // This is imprecise yet should be precise enough, as it'll resolve within a few ms
+    let instant_now = Instant::now();
+    let sys_now = SystemTime::now();
+
+    // If the time is in the future, this will be off by that much time
+    let elapsed = sys_now.duration_since(sys_time(time)).unwrap_or(Duration::ZERO);
+    let synced_instant = instant_now - elapsed;
+
+    CanonicalInstant { time, instant: synced_instant }
+  }
+
+  pub(crate) fn canonical(&self) -> u64 {
+    self.time
+  }
+
+  pub(crate) fn instant(&self) -> Instant {
+    self.instant
+  }
+}
+
+impl Add<Duration> for CanonicalInstant {
+  type Output = CanonicalInstant;
+  fn add(self, duration: Duration) -> CanonicalInstant {
+    CanonicalInstant { time: self.time + duration.as_secs(), instant: self.instant + duration }
+  }
+}