From be4d09cc4bd27a911ec8f8e772c349f0929fd1b2 Mon Sep 17 00:00:00 2001
From: Brandon Vrooman <brandon.vrooman@gmail.com>
Date: Sun, 19 Nov 2023 22:09:03 -0500
Subject: [PATCH] Use linear regression when quadratic

---
 benches/src/collect/costs.rs | 99 ++++++++++++++++++++++++------------
 1 file changed, 67 insertions(+), 32 deletions(-)

diff --git a/benches/src/collect/costs.rs b/benches/src/collect/costs.rs
index b289e561522..6ed3a03f04b 100644
--- a/benches/src/collect/costs.rs
+++ b/benches/src/collect/costs.rs
@@ -1,5 +1,7 @@
 use crate::{
     estimate_model,
+    regression::linear_regression,
+    LinearCoefficients,
     Model,
 };
 use serde::{
@@ -35,7 +37,6 @@ pub fn dependent_cost(
     points: Vec<(f64, f64)>,
 ) -> anyhow::Result<DependentCost> {
     let model = estimate_model(&points)?;
-
     let cost = match model {
         Model::Zero => {
             // Zero
@@ -63,34 +64,13 @@ pub fn dependent_cost(
             }
         }
         Model::Linear(coefficients) => {
-            match coefficients.slope {
-                slope if slope > 0.0 && slope < 1.0 => {
-                    // Slope is between (0.0, 1.0)
-                    // Light operation
-                    let base = coefficients.intercept;
-                    let base = base.max(0.0);
-                    let base = base.round() as u64;
-                    let inverse_slope = 1.0 / slope;
-                    let units_per_gas = inverse_slope.round() as u64;
-                    DependentCost::LightOperation {
-                        base,
-                        units_per_gas,
-                    }
-                }
-                slope if slope >= 1.0 => {
-                    // Slope is greater than 1.0
-                    // Heavy operation
-                    let base = coefficients.intercept;
-                    let base = base.max(0.0);
-                    let base = base.round() as u64;
-                    let gas_per_unit = slope.round() as u64;
-                    DependentCost::HeavyOperation { base, gas_per_unit }
-                }
-                _ => {
-                    // Slope is negative
+            let cost = coefficients.try_into();
+            match cost {
+                Ok(cost) => cost,
+                Err(DependentCostError::NegativeSlope(slope)) => {
                     let warning = format!("Warning: \
-                        Evaluating the regression on the dataset for `{name}` produced a negative slope. \
-                        This implies a negative cost behavior and is not supported in a dependent context.", name = name);
+                        Evaluating the regression on the dataset for `{name}` produced a negative slope: {slope}. \
+                        This implies a negative cost behavior and is not supported in a dependent context.", slope = slope, name = name);
                     eprintln!("{}", warning);
                     let base = coefficients.intercept;
                     let base = base.round() as u64;
@@ -105,11 +85,24 @@ pub fn dependent_cost(
             // Quadratic
             let warning = format!("Warning: \
             Evaluating the regression on the dataset for `{name}` produced a quadratic function({:?}). \
-            Quadratic behavior is not supported in a dependent context. Points: {points:?}", coefficients, name = name, points = points);
+            Quadratic behavior is not supported in a dependent context. Points: {points:?}. Defaulting to linear model", coefficients, name = name, points = points);
             eprintln!("{}", warning);
-            DependentCost::HeavyOperation {
-                base: 0,
-                gas_per_unit: 0,
+            let coefficients = linear_regression(&points);
+            let cost = coefficients.try_into();
+            match cost {
+                Ok(cost) => cost,
+                Err(DependentCostError::NegativeSlope(slope)) => {
+                    let warning = format!("Warning: \
+                        Evaluating the regression on the dataset for `{name}` produced a negative slope: {slope}. \
+                        This implies a negative cost behavior and is not supported in a dependent context.", slope = slope, name = name);
+                    eprintln!("{}", warning);
+                    let base = coefficients.intercept;
+                    let base = base.round() as u64;
+                    DependentCost::HeavyOperation {
+                        base,
+                        gas_per_unit: 0,
+                    }
+                }
             }
         }
         Model::Other => {
@@ -127,3 +120,45 @@ pub fn dependent_cost(
     };
     Ok(cost)
 }
+
+#[derive(Debug)]
+pub enum DependentCostError {
+    NegativeSlope(f64),
+}
+
+impl TryFrom<LinearCoefficients> for DependentCost {
+    type Error = DependentCostError;
+
+    fn try_from(coefficients: LinearCoefficients) -> Result<Self, Self::Error> {
+        match coefficients.slope {
+            slope if slope > 0.0 && slope < 1.0 => {
+                // Slope is between (0.0, 1.0)
+                // Light operation
+                let base = coefficients.intercept;
+                let base = base.max(0.0);
+                let base = base.round() as u64;
+                let inverse_slope = 1.0 / slope;
+                let units_per_gas = inverse_slope.round() as u64;
+                let cost = DependentCost::LightOperation {
+                    base,
+                    units_per_gas,
+                };
+                Ok(cost)
+            }
+            slope if slope >= 1.0 => {
+                // Slope is greater than 1.0
+                // Heavy operation
+                let base = coefficients.intercept;
+                let base = base.max(0.0);
+                let base = base.round() as u64;
+                let gas_per_unit = slope.round() as u64;
+                let cost = DependentCost::HeavyOperation { base, gas_per_unit };
+                Ok(cost)
+            }
+            slope => {
+                // Slope is negative
+                Err(DependentCostError::NegativeSlope(slope))
+            }
+        }
+    }
+}