Move durationBetween into Duration

Author: David Legg

contrib/src/main/java/gov/nasa/jpl/aerie/contrib/streamline/modeling/clocks/InstantClock.java

@@ -4,7 +4,6 @@
 import gov.nasa.jpl.aerie.merlin.protocol.types.Duration;
 
 import java.time.Instant;
-import java.time.temporal.ChronoUnit;
 
 import static gov.nasa.jpl.aerie.merlin.protocol.types.Duration.addToInstant;
 
@@ -17,10 +16,4 @@ public record InstantClock(Instant extract) implements Dynamics<Instant, Instant
     public InstantClock step(Duration t) {
         return new InstantClock(addToInstant(extract, t));
     }
-
-    // TODO - this method belongs somewhere else...
-    //  Making it package-private at least lets us move it later without dependency issues outside the library.
-    static Duration durationBetween(Instant start, Instant end) {
-        return Duration.of(ChronoUnit.MICROS.between(start, end), Duration.MICROSECONDS);
-    }
 }

contrib/src/main/java/gov/nasa/jpl/aerie/contrib/streamline/modeling/clocks/InstantClockResources.java

@@ -34,7 +34,7 @@ public static Resource<InstantClock> addToInstant(Resource<Discrete<Instant>> ze
     }
 
     public static Resource<Clock> relativeTo(Resource<InstantClock> clock, Resource<Discrete<Instant>> zeroTime) {
-        return name(ResourceMonad.map(clock, zeroTime, (c, t) -> new Clock(InstantClock.durationBetween(t.extract(), c.extract()))),
+        return name(ResourceMonad.map(clock, zeroTime, (c, t) -> new Clock(Duration.between(t.extract(), c.extract()))),
                 "%s relative to %s", clock, zeroTime);
     }
 

contrib/src/main/java/gov/nasa/jpl/aerie/contrib/streamline/modeling/clocks/VariableInstantClockResources.java

@@ -8,15 +8,14 @@
 
 import static gov.nasa.jpl.aerie.contrib.streamline.core.monads.ResourceMonad.map;
 import static gov.nasa.jpl.aerie.contrib.streamline.debugging.Naming.name;
-import static gov.nasa.jpl.aerie.contrib.streamline.modeling.clocks.InstantClock.durationBetween;
 import static gov.nasa.jpl.aerie.contrib.streamline.modeling.discrete.DiscreteResources.constant;
 
 public final class VariableInstantClockResources {
     private VariableInstantClockResources() {}
 
     public static Resource<VariableClock> relativeTo(Resource<VariableInstantClock> clock, Resource<Discrete<Instant>> zeroTime) {
         return name(map(clock, zeroTime, (c, t) ->
-                        new VariableClock(durationBetween(c.extract(), t.extract()), c.multiplier())),
+                        new VariableClock(Duration.between(c.extract(), t.extract()), c.multiplier())),
                 "%s relative to %s", clock, zeroTime);
     }
 
@@ -37,6 +36,6 @@ public static Resource<Discrete<Boolean>> greaterThanOrEquals(Resource<VariableI
     }
 
     public static Resource<VariableClock> between(Resource<VariableInstantClock> start, Resource<VariableInstantClock> end) {
-        return map(start, end, (s, e) -> new VariableClock(durationBetween(s.extract(), e.extract()), e.multiplier() - s.multiplier()));
+        return map(start, end, (s, e) -> new VariableClock(Duration.between(s.extract(), e.extract()), e.multiplier() - s.multiplier()));
     }
 }

merlin-sdk/src/main/java/gov/nasa/jpl/aerie/merlin/protocol/types/Duration.java

@@ -1,5 +1,6 @@
 package gov.nasa.jpl.aerie.merlin.protocol.types;
 
+import java.time.Instant;
 import java.time.temporal.ChronoUnit;
 import java.util.Collections;
 import java.util.List;
@@ -455,6 +456,11 @@ public static java.time.Instant addToInstant(final java.time.Instant instant, fi
         .plusNanos(1000 * duration.remainderOf(Duration.MILLISECONDS).dividedBy(Duration.MICROSECONDS));
   }
 
+  /** Compute the duration between two {@link Instant}s. */
+  public static Duration between(Instant start, Instant end) {
+    return Duration.of(ChronoUnit.MICROS.between(start, end), Duration.MICROSECONDS);
+  }
+
   /** @see Duration#add(Duration, Duration) */
   public Duration plus(final Duration other) throws ArithmeticException {
     return Duration.add(this, other);