Make ObjectiveCoefficients Rc to remove need for deep copy

Author: alexdewar

src/fixture.rs

@@ -386,11 +386,11 @@ pub fn appraisal_output(asset: Asset, time_slice: TimeSliceID) -> AppraisalOutpu
     AppraisalOutput {
         asset: AssetRef::from(asset),
         capacity: AssetCapacity::Continuous(Capacity(42.0)),
-        coefficients: ObjectiveCoefficients {
+        coefficients: Rc::new(ObjectiveCoefficients {
             capacity_coefficient: MoneyPerCapacity(2.14),
             activity_coefficients,
             unmet_demand_coefficient: MoneyPerFlow(10000.0),
-        },
+        }),
         activity,
         unmet_demand,
         metric: Box::new(LCOXMetric::new(MoneyPerActivity(4.14))),

src/simulation/investment/appraisal.rs

@@ -14,6 +14,7 @@ use indexmap::IndexMap;
 use serde::Serialize;
 use std::any::Any;
 use std::cmp::Ordering;
+use std::rc::Rc;
 
 pub mod coefficients;
 mod constraints;
@@ -60,7 +61,7 @@ pub struct AppraisalOutput {
     /// The comparison metric to compare investment decisions
     pub metric: Box<dyn MetricTrait>,
     /// Capacity and activity coefficients used in the appraisal
-    pub coefficients: ObjectiveCoefficients,
+    pub coefficients: Rc<ObjectiveCoefficients>,
 }
 
 impl AppraisalOutput {
@@ -223,7 +224,7 @@ fn calculate_lcox(
     asset: &AssetRef,
     max_capacity: Option<AssetCapacity>,
     commodity: &Commodity,
-    coefficients: &ObjectiveCoefficients,
+    coefficients: &Rc<ObjectiveCoefficients>,
     demand: &DemandMap,
 ) -> Result<AppraisalOutput> {
     let results = perform_optimisation(
@@ -263,7 +264,7 @@ fn calculate_npv(
     asset: &AssetRef,
     max_capacity: Option<AssetCapacity>,
     commodity: &Commodity,
-    coefficients: &ObjectiveCoefficients,
+    coefficients: &Rc<ObjectiveCoefficients>,
     demand: &DemandMap,
 ) -> Result<AppraisalOutput> {
     let results = perform_optimisation(
@@ -311,7 +312,7 @@ pub fn appraise_investment(
     max_capacity: Option<AssetCapacity>,
     commodity: &Commodity,
     objective_type: &ObjectiveType,
-    coefficients: &ObjectiveCoefficients,
+    coefficients: &Rc<ObjectiveCoefficients>,
     demand: &DemandMap,
 ) -> Result<AppraisalOutput> {
     let appraisal_method = match objective_type {
@@ -526,6 +527,14 @@ mod tests {
         assert!(compare_asset_fallback(&asset2, &asset3).is_gt());
     }
 
+    fn objective_coeffs() -> Rc<ObjectiveCoefficients> {
+        Rc::new(ObjectiveCoefficients {
+            capacity_coefficient: MoneyPerCapacity(0.0),
+            activity_coefficients: IndexMap::new(),
+            unmet_demand_coefficient: MoneyPerFlow(0.0),
+        })
+    }
+
     /// Creates appraisal from corresponding assets and metrics
     ///
     /// # Panics
@@ -547,11 +556,7 @@ mod tests {
             .map(|(asset, metric)| AppraisalOutput {
                 asset: AssetRef::from(asset),
                 capacity: AssetCapacity::Continuous(Capacity(10.0)),
-                coefficients: ObjectiveCoefficients {
-                    capacity_coefficient: MoneyPerCapacity(0.0),
-                    activity_coefficients: IndexMap::new(),
-                    unmet_demand_coefficient: MoneyPerFlow(0.0),
-                },
+                coefficients: objective_coeffs(),
                 activity: IndexMap::new(),
                 unmet_demand: IndexMap::new(),
                 metric,
@@ -876,11 +881,7 @@ mod tests {
             .map(|metric| AppraisalOutput {
                 asset: AssetRef::from(asset.clone()),
                 capacity: AssetCapacity::Continuous(Capacity(0.0)),
-                coefficients: ObjectiveCoefficients {
-                    capacity_coefficient: MoneyPerCapacity(0.0),
-                    activity_coefficients: IndexMap::new(),
-                    unmet_demand_coefficient: MoneyPerFlow(0.0),
-                },
+                coefficients: objective_coeffs(),
                 activity: IndexMap::new(),
                 unmet_demand: IndexMap::new(),
                 metric,

src/simulation/investment/appraisal/coefficients.rs

@@ -8,6 +8,7 @@ use crate::time_slice::{TimeSliceID, TimeSliceInfo};
 use crate::units::{MoneyPerActivity, MoneyPerCapacity, MoneyPerFlow};
 use indexmap::IndexMap;
 use std::collections::HashMap;
+use std::rc::Rc;
 
 /// Map storing cost coefficients for an asset.
 ///
@@ -31,7 +32,7 @@ pub fn calculate_coefficients_for_assets(
     assets: &[AssetRef],
     prices: &CommodityPrices,
     year: u32,
-) -> HashMap<AssetRef, ObjectiveCoefficients> {
+) -> HashMap<AssetRef, Rc<ObjectiveCoefficients>> {
     assets
         .iter()
         .map(|asset| {
@@ -47,7 +48,7 @@ pub fn calculate_coefficients_for_assets(
                     calculate_coefficients_for_npv(asset, &model.time_slice_info, prices, year)
                 }
             };
-            (asset.clone(), coefficient)
+            (asset.clone(), Rc::new(coefficient))
         })
         .collect()
 }