From 8fe69a9224071efea10e8fa6c1c76c807f6925e3 Mon Sep 17 00:00:00 2001
From: Theo Butler <theodusbutler@gmail.com>
Date: Wed, 29 Nov 2023 09:21:09 -0500
Subject: [PATCH] fix(budget): reduce windup

---
 graph-gateway/src/budgets.rs | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/graph-gateway/src/budgets.rs b/graph-gateway/src/budgets.rs
index e0a52a9b9..bf21d2af0 100644
--- a/graph-gateway/src/budgets.rs
+++ b/graph-gateway/src/budgets.rs
@@ -97,13 +97,11 @@ struct Controller {
 
 impl Controller {
     fn new(target_query_fees: USD) -> Self {
-        let mut error_history = FastDecayBuffer::default();
-        *error_history.current_mut() = target_query_fees.0.into();
         Self {
             target_query_fees,
             recent_fees: USD(UDecimal18::from(0)),
             recent_query_count: 0,
-            error_history,
+            error_history: FastDecayBuffer::default(),
         }
     }
 
@@ -123,12 +121,12 @@ impl Controller {
         self.recent_query_count = 0;
         self.error_history.decay();
         let error = f64::from(self.target_query_fees.0) - process_variable;
-        *self.error_history.current_mut() = error;
+        *self.error_history.current_mut() += error;
 
         let i: f64 = self.error_history.frames().iter().sum();
-        let k_i = 1.2;
-        let correction = UDecimal18::try_from(i * k_i).unwrap_or_default();
-        self.target_query_fees.0 + correction
+        let k_i = 30e3;
+        self.target_query_fees.0
+            * (UDecimal18::from(1) + UDecimal18::try_from(i * k_i).unwrap_or_default())
     }
 }
 
@@ -147,7 +145,7 @@ mod tests {
         ) {
             let setpoint: f64 = controller.target_query_fees.0.into();
             let mut process_variable = 0.0;
-            for i in 0..20 {
+            for i in 0..60 {
                 let control_variable: f64 = controller.control_variable().into();
                 process_variable = control_variable * process_variable_multiplier;
                 println!(
@@ -159,19 +157,20 @@ mod tests {
             assert_within(process_variable, setpoint, tolerance);
         }
 
+        let tolerance = 1.0e-6;
         for setpoint in [10e-6, 20e-6, 50e-6] {
             let setpoint = USD(UDecimal18::try_from(setpoint).unwrap());
             let mut controller = Controller::new(setpoint);
-            test_controller(&mut controller, 0.2, 1e-6);
+            test_controller(&mut controller, 0.2, tolerance);
             let mut controller = Controller::new(setpoint);
-            test_controller(&mut controller, 0.6, 1e-6);
+            test_controller(&mut controller, 0.6, tolerance);
             let mut controller = Controller::new(setpoint);
-            test_controller(&mut controller, 0.8, 1e-6);
+            test_controller(&mut controller, 0.8, tolerance);
 
             let mut controller = Controller::new(setpoint);
-            test_controller(&mut controller, 0.2, 1e-6);
-            test_controller(&mut controller, 0.6, 1e-6);
-            test_controller(&mut controller, 0.7, 1e-6);
+            test_controller(&mut controller, 0.2, tolerance);
+            test_controller(&mut controller, 0.6, tolerance);
+            test_controller(&mut controller, 0.7, tolerance);
         }
     }
 }