Use exponential moving average to adjust solution signature threshold.

tig-protocol/src/add_block.rs

@@ -1,10 +1,7 @@
 use crate::context::*;
 use logging_timer::time;
 use rand::{prelude::SliceRandom, rngs::StdRng, SeedableRng};
-use std::{
-    collections::{HashMap, HashSet},
-    ops::Mul,
-};
+use std::collections::{HashMap, HashSet};
 use tig_structs::{config::*, core::*};
 use tig_utils::*;
 
@@ -455,21 +452,8 @@ async fn update_solution_signature_thresholds<T: Context>(ctx: &mut T, block: &B
     }
 
     for challenge_id in block.data().active_challenge_ids.iter() {
-        let num_new_solutions = *num_new_solutions_by_challenge
-            .get(challenge_id)
-            .unwrap_or(&0) as f64;
-        let equilibrium_rate = config.qualifiers.total_qualifiers_threshold as f64
-            / config.benchmark_submissions.lifespan_period as f64;
-        let percentage_error = 1f64
-            - num_new_solutions
-                / (config.solution_signature.equilibrium_rate_multiplier * equilibrium_rate);
         let max_threshold = u32::MAX as f64;
-        let percent_delta = (percentage_error * config.solution_signature.percent_error_multiplier)
-            .abs()
-            .clamp(0f64, config.solution_signature.max_percent_delta)
-            .mul(if percentage_error < 0f64 { -1f64 } else { 1f64 });
-
-        let prev_solution_signature_threshold =
+        let current_threshold =
             match get_challenge_by_id(ctx, challenge_id, Some(&block.details.prev_block_id))
                 .await
                 .unwrap_or_else(|e| panic!("get_challenge_by_id error: {:?}", e))
@@ -478,14 +462,30 @@ async fn update_solution_signature_thresholds<T: Context>(ctx: &mut T, block: &B
                 Some(data) => *data.solution_signature_threshold() as f64,
                 None => max_threshold,
             };
+        let current_probability = current_threshold / max_threshold;
+        let current_rate = *num_new_solutions_by_challenge
+            .get(challenge_id)
+            .unwrap_or(&0) as f64;
+
+        let equilibrium_rate = config.qualifiers.total_qualifiers_threshold as f64
+            / config.benchmark_submissions.lifespan_period as f64;
+        let target_rate = config.solution_signature.equilibrium_rate_multiplier * equilibrium_rate;
+        let target_probability = if current_rate == 0.0 {
+            1.0
+        } else {
+            (current_probability * target_rate / current_rate).clamp(0.0, 1.0)
+        };
+        let target_threshold = (target_probability * max_threshold).clamp(0.0, max_threshold);
+
+        let threshold_decay = config.solution_signature.threshold_decay.unwrap_or(0.99);
         let mut block_data = get_challenge_by_id(ctx, challenge_id, Some(&block.id))
             .await
             .unwrap_or_else(|e| panic!("get_challenge_by_id error: {:?}", e))
             .block_data()
             .clone();
         block_data.solution_signature_threshold = Some(
-            (prev_solution_signature_threshold + percent_delta * max_threshold)
-                .clamp(0f64, max_threshold) as u32,
+            (current_threshold * threshold_decay + target_threshold * (1.0 - threshold_decay))
+                .clamp(0.0, max_threshold) as u32,
         );
 
         ctx.update_challenge_block_data(challenge_id, &block.id, &block_data)

tig-structs/src/config.rs

@@ -42,7 +42,7 @@ serializable_struct_with_getters! {
 }
 serializable_struct_with_getters! {
     SolutionSignatureConfig {
-        max_percent_delta: f64,
+        threshold_decay: Option<f64>,
         equilibrium_rate_multiplier: f64,
         percent_error_multiplier: f64,
     }