Merge pull request #956 from NASA-AMMOS/contrib-sampl-res-update

contrib/src/main/java/gov/nasa/jpl/aerie/contrib/models/SampledResource.java

@@ -1,35 +1,67 @@
 package gov.nasa.jpl.aerie.contrib.models;
 
 import gov.nasa.jpl.aerie.merlin.framework.resources.discrete.DiscreteResource;
+import gov.nasa.jpl.aerie.merlin.protocol.types.Duration;
 
 import java.util.Objects;
 import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import static gov.nasa.jpl.aerie.merlin.framework.ModelActions.*;
-import static gov.nasa.jpl.aerie.merlin.protocol.types.Duration.SECOND;
 
+/**
+ * Simple resource that samples arbitrarily many existing resources/values at a specified period (default period is once
+ * per second).
+ */
 public class SampledResource<T> implements DiscreteResource<T> {
   private final Register<T> result;
   private final Supplier<T> sampler;
+  private final Register<Double> period = Register.forImmutable(1.0);
 
+  /**
+   * Constructor that does not require caller to specify a period and therefore assumes a sample
+   * period of 1 sample per second.
+   */
   public SampledResource(final Supplier<T> sampler, final UnaryOperator<T> duplicator) {
     this.result = Register.create(sampler.get(), duplicator);
     this.sampler = Objects.requireNonNull(sampler);
+    spawn(this::takeSamples);
+  }
 
+  /**
+   * Constructor that requires caller to specify an initial sample period
+   */
+  public SampledResource(final Supplier<T> sampler, final UnaryOperator<T> duplicator, final double period) {
+    this.result = Register.create(sampler.get(), duplicator);
+    this.sampler = Objects.requireNonNull(sampler);
+    this.period.set(period);
     spawn(this::takeSamples);
   }
 
+  /**
+   * Method that samples the supplied resource at the current specified period
+   */
   private void takeSamples() {
     while (true) {
       var sample = sampler.get();
       if (!result.get().equals(sample)) {
         result.set(sample);
       }
-      delay(1, SECOND);
+      delay( Duration.roundNearest(period.get(), Duration.SECONDS) );
     }
   }
 
+  /**
+   * Get current sample period (seconds per sample)
+   */
+  public double getPeriod() { return period.get(); }
+
+  /**
+   * Method to adjust the specified period of sampling. Note if takeSamples() is currently waiting, the
+   * new period will not take effect until after the current wait cycle.
+   */
+  public void setPeriod(final double newPeriod ) { period.set( newPeriod ); }
+
   @Override
   public T getDynamics() {
     return this.result.getDynamics();