refactor(gamma): big decimal

Author: cong-or

Cargo.lock

@@ -68,6 +68,16 @@ fn main() -> Result<(), Box<dyn Error>> {
     info!("Audit Tool.");
     info!("Starting Offline Tally");
 
+    if let Some(gamma) = args.gamma {
+        const GAMMA: &str = "QUADRATIC_VOTING_GAMMA";
+        std::env::set_var(GAMMA, gamma);
+    }
+
+    if let Some(precision) = args.precision {
+        const PRECISION: &str = "QUADRATIC_VOTING_PRECISION";
+        std::env::set_var(PRECISION, precision);
+    }
+
     // Load and replay fund fragments from storage
     let storage_path = PathBuf::from(args.fragments);
 
@@ -102,16 +112,6 @@ fn main() -> Result<(), Box<dyn Error>> {
     // use tally tool to validate decrypted results
     let shares_and_results = extract_decryption_shares_and_results(all_fragments);
 
-    if let Some(gamma) = args.gamma {
-        const GAMMA: &str = "QUADRATIC_VOTING_GAMMA";
-        std::env::set_var(GAMMA, gamma);
-    }
-
-    if let Some(precision) = args.precision {
-        const PRECISION: &str = "QUADRATIC_VOTING_PRECISION";
-        std::env::set_var(PRECISION, precision);
-    }
-
     // Compare decrypted tallies with official results if provided
     if let Some(official_results) = args.official_results {
         // official catalyst results in json format

src/audit/src/offline/bin/main.rs

@@ -178,10 +178,15 @@ impl TallyResult {
 
             // Apply quadratic scaling if gamma value specified in env var. Else gamma is 1 and has no effect.
             let gamma = env::var(GAMMA).unwrap_or(1.to_string());
+
             let precision =
                 i64::from_str(&env::var(PRECISION).unwrap_or(1.to_string())).unwrap_or(1);
 
-            let gamma = BigDecimal::from_str(&gamma).unwrap_or(BigDecimal::from(1));
+            let mut gamma = BigDecimal::from_str(&gamma).unwrap_or(BigDecimal::from(1));
+            // Gamma must be between 0 and 1, anything else is treated as bad input; defaulting gamma to 1.
+            if gamma < BigDecimal::from(0) || gamma > BigDecimal::from(1) {
+                gamma = BigDecimal::from(1);
+            }
             let stake = BigDecimal::from(weight.0);
 
             let weight = (gamma * stake)

src/chain-libs/chain-impl-mockchain/src/vote/tally.rs

@@ -15,7 +15,7 @@ cryptoxide = "^0.4.2"
 const_format = "0.2"
 base64 = "0.21.0"
 bigdecimal = "0.4.7"
-
+tracing = "0.1.41"
 
 
 [dev-dependencies]

src/chain-libs/chain-vote/Cargo.toml

@@ -2,6 +2,7 @@ use std::num::NonZeroI64;
 use std::num::NonZeroU64;
 
 use std::str::FromStr;
+use tracing::info;
 
 use crate::GroupElement;
 use crate::{
@@ -172,7 +173,11 @@ impl EncryptedTally {
         let gamma = env::var(GAMMA).unwrap_or(1.to_string());
         let precision = i64::from_str(&env::var(PRECISION).unwrap_or(1.to_string())).unwrap_or(1);
 
-        let gamma = BigDecimal::from_str(&gamma).unwrap_or(BigDecimal::from(1));
+        let mut gamma = BigDecimal::from_str(&gamma).unwrap_or(BigDecimal::from(1));
+        // Gamma must be between 0 and 1, anything else is treated as bad input; defaulting gamma to 1.
+        if gamma < BigDecimal::from(0) || gamma > BigDecimal::from(1) {
+            gamma = BigDecimal::from(1);
+        }
         let stake = BigDecimal::from(weight);
 
         let weight = (gamma * stake).round(precision).to_u64().unwrap_or(weight);