#1838: lb: add getModeledWork method to load models

src/vt/vrt/collection/balance/model/load_model.h

@@ -263,6 +263,22 @@ struct LoadModel
     return {};
   }
 
+ /**
+   * \brief Provide an estimate of the given object's work during a specified
+   * interval
+   *
+   * \param[in] object The object whose work is requested
+   * \param[in] when The interval in which the estimated work is requested
+   *
+   * \return How much work the object is estimated to require
+   *
+   * The `updateLoads` method must have been called before any call to
+   * this.
+   */
+  virtual TimeType getModeledWork(ElementIDStruct object, PhaseOffset when) {
+    return {};
+  }
+
   /**
    * \brief Compute how many phases of past load statistics need to be
    * kept availble for the model to use

src/vt/vrt/collection/balance/model/weighted_communication_volume.cc

@@ -42,7 +42,15 @@
 */
 
 #include "vt/vrt/collection/balance/model/weighted_communication_volume.h"
+#include "vt/vrt/collection/balance/model/composed_model.h"
 
 namespace vt { namespace vrt { namespace collection { namespace balance {
 
+TimeType WeightedCommunicationVolume::getModeledWork(
+    ElementIDStruct object, PhaseOffset when
+) {
+  return alpha_ * ComposedModel::getModeledLoad(object, when) +
+    beta_ * ComposedModel::getModeledComm(object, when) + gamma_;
+}
+
 }}}} // namespace vt::vrt::collection::balance

src/vt/vrt/collection/balance/model/weighted_communication_volume.h

@@ -68,6 +68,8 @@ class WeightedCommunicationVolume : public ComposedModel {
       beta_(beta),
       gamma_(gamma) { }
 
+  TimeType getModeledWork(ElementIDStruct object, PhaseOffset when) override;
+
 private:
   double alpha_;
   double beta_;