clock: time extent, maker, and associated traits

`TimeExtent` is a simple structure that contains base increment (duration), and amount (a multiplier for the base the base increment). The resulting product of the base and the multiplier is the total duration of the time extent.

`TimeExtentClock` is a helper that generates time extents based upon the increment length and the time of the clock, this clock is specialised according to the `test` predicate with the `DefaultClockExtentMaker` type.

src/protocol/clock.rs → src/protocol/clock/mod.rs

@@ -1,5 +1,5 @@
 use std::num::IntErrorKind;
-pub use std::time::Duration;
+use std::time::Duration;
 
 pub type DurationSinceUnixEpoch = Duration;
 
@@ -240,9 +240,11 @@ mod stopped_clock {
 
             #[test]
             fn it_should_get_app_start_time() {
-                const TIME_AT_WRITING_THIS_TEST: Duration = Duration::new(1662983731, 000022312);
+                const TIME_AT_WRITING_THIS_TEST: Duration = Duration::new(1662983731, 22312);
                 assert!(get_app_start_time() > TIME_AT_WRITING_THIS_TEST);
             }
         }
     }
 }
+
+pub mod timeextent;

src/protocol/clock/timeextent.rs

@@ -0,0 +1,185 @@
+use std::num::{IntErrorKind, TryFromIntError};
+use std::time::Duration;
+
+use super::{ClockType, StoppedClock, TimeNow, WorkingClock};
+
+pub trait Extent: Sized + Default {
+    type Base;
+    type Multiplier;
+    type Product;
+
+    fn new(unit: &Self::Base, count: &Self::Multiplier) -> Self;
+
+    fn add(&self, add: Self::Multiplier) -> Result<Self, IntErrorKind>;
+    fn sub(&self, sub: Self::Multiplier) -> Result<Self, IntErrorKind>;
+
+    fn total(&self) -> Result<Option<Self::Product>, TryFromIntError>;
+    fn total_next(&self) -> Result<Option<Self::Product>, TryFromIntError>;
+}
+
+pub type TimeExtentBase = Duration;
+pub type TimeExtentMultiplier = u64;
+pub type TimeExtentProduct = TimeExtentBase;
+
+#[derive(Debug, Default, Hash, PartialEq, Eq)]
+pub struct TimeExtent {
+    pub increment: TimeExtentBase,
+    pub amount: TimeExtentMultiplier,
+}
+
+impl TimeExtent {
+    pub const fn from_sec(seconds: u64, amount: &TimeExtentMultiplier) -> Self {
+        Self {
+            increment: TimeExtentBase::from_secs(seconds),
+            amount: *amount,
+        }
+    }
+}
+
+impl Extent for TimeExtent {
+    type Base = TimeExtentBase;
+    type Multiplier = TimeExtentMultiplier;
+    type Product = TimeExtentProduct;
+
+    fn new(increment: &Self::Base, amount: &Self::Multiplier) -> Self {
+        Self {
+            increment: *increment,
+            amount: *amount,
+        }
+    }
+
+    fn add(&self, add: Self::Multiplier) -> Result<Self, IntErrorKind> {
+        match self.amount.checked_add(add) {
+            None => Err(IntErrorKind::PosOverflow),
+            Some(amount) => Ok(Self {
+                increment: self.increment,
+                amount,
+            }),
+        }
+    }
+
+    fn sub(&self, sub: Self::Multiplier) -> Result<Self, IntErrorKind> {
+        match self.amount.checked_sub(sub) {
+            None => Err(IntErrorKind::NegOverflow),
+            Some(amount) => Ok(Self {
+                increment: self.increment,
+                amount,
+            }),
+        }
+    }
+
+    fn total(&self) -> Result<Option<Self::Product>, TryFromIntError> {
+        match u32::try_from(self.amount) {
+            Err(error) => Err(error),
+            Ok(amount) => Ok(self.increment.checked_mul(amount)),
+        }
+    }
+
+    fn total_next(&self) -> Result<Option<Self::Product>, TryFromIntError> {
+        match u32::try_from(self.amount) {
+            Err(e) => Err(e),
+            Ok(amount) => match amount.checked_add(1) {
+                None => Ok(None),
+                Some(amount) => match self.increment.checked_mul(amount) {
+                    None => Ok(None),
+                    Some(extent) => Ok(Some(extent)),
+                },
+            },
+        }
+    }
+}
+
+pub trait MakeTimeExtent<Clock>: Sized
+where
+    Clock: TimeNow,
+{
+    fn now(increment: &TimeExtentBase) -> Option<Result<TimeExtent, TryFromIntError>> {
+        Clock::now()
+            .as_nanos()
+            .checked_div((*increment).as_nanos())
+            .map(|amount| match TimeExtentMultiplier::try_from(amount) {
+                Err(error) => Err(error),
+                Ok(amount) => Ok(TimeExtent::new(increment, &amount)),
+            })
+    }
+
+    fn now_add(increment: &TimeExtentBase, add_time: &Duration) -> Option<Result<TimeExtent, TryFromIntError>> {
+        match Clock::add(add_time) {
+            None => None,
+            Some(time) => {
+                time.as_nanos()
+                    .checked_div(increment.as_nanos())
+                    .map(|amount| match TimeExtentMultiplier::try_from(amount) {
+                        Err(error) => Err(error),
+                        Ok(amount) => Ok(TimeExtent::new(increment, &amount)),
+                    })
+            }
+        }
+    }
+    fn now_sub(increment: &TimeExtentBase, sub_time: &Duration) -> Option<Result<TimeExtent, TryFromIntError>> {
+        match Clock::sub(sub_time) {
+            None => None,
+            Some(time) => {
+                time.as_nanos()
+                    .checked_div(increment.as_nanos())
+                    .map(|amount| match TimeExtentMultiplier::try_from(amount) {
+                        Err(error) => Err(error),
+                        Ok(amount) => Ok(TimeExtent::new(increment, &amount)),
+                    })
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct TimeExtentClock<const T: usize> {}
+
+pub type WorkingClockExtentMaker = TimeExtentClock<{ ClockType::WorkingClock as usize }>;
+pub type StoppedClockExtentMaker = TimeExtentClock<{ ClockType::StoppedClock as usize }>;
+
+impl MakeTimeExtent<WorkingClock> for WorkingClockExtentMaker {}
+impl MakeTimeExtent<StoppedClock> for StoppedClockExtentMaker {}
+
+#[cfg(not(test))]
+pub type DefaultClockExtentMaker = WorkingClockExtentMaker;
+
+#[cfg(test)]
+pub type DefaultClockExtentMaker = StoppedClockExtentMaker;
+
+#[cfg(test)]
+mod test {
+
+    use std::time::Duration;
+
+    use crate::protocol::clock::timeextent::{DefaultClockExtentMaker, Extent, MakeTimeExtent, TimeExtent};
+    use crate::protocol::clock::{DefaultClock, DurationSinceUnixEpoch, StoppedTime};
+
+    #[test]
+    fn it_should_get_the_total_duration() {
+        assert_eq!(TimeExtent::default().total().unwrap().unwrap(), Duration::ZERO);
+
+        assert_eq!(
+            TimeExtent::from_sec(12, &12).total().unwrap().unwrap(),
+            Duration::from_secs(144)
+        );
+        assert_eq!(
+            TimeExtent::from_sec(12, &12).total_next().unwrap().unwrap(),
+            Duration::from_secs(156)
+        );
+    }
+
+    #[test]
+    fn it_should_make_the_current_extent() {
+        assert_eq!(
+            DefaultClockExtentMaker::now(&Duration::from_secs(2)).unwrap().unwrap(),
+            TimeExtent::from_sec(2, &0)
+        );
+
+        DefaultClock::local_set(&DurationSinceUnixEpoch::from_secs(12387687123));
+
+        assert_eq!(
+            DefaultClockExtentMaker::now(&Duration::from_secs(2)).unwrap().unwrap(),
+            TimeExtent::from_sec(2, &6193843561)
+        );
+    }
+}