Optimize calculation of prioritization fees stats (#301)

* Optimize calculation of prioritization fees stats

* comment on arrays in response

* Fix the calculation of supp

* Fix fmt

---------

Co-authored-by: GroovieGermanikus <groovie@mango.markets>

block_priofees/src/rpc_data.rs

@@ -10,10 +10,15 @@ pub struct TxAggregateStats {
 
 #[derive(Clone, Serialize, Debug)]
 pub struct PrioFeesStats {
+    // the arrays are same size and ordered monotonically
     pub by_tx: Vec<u64>,
     pub by_tx_percentiles: Vec<f32>,
+
+    // the arrays are same size and ordered monotonically
     pub by_cu: Vec<u64>,
     pub by_cu_percentiles: Vec<f32>,
+
+    // per block stats
     pub tx_count: TxAggregateStats,
     pub cu_consumed: TxAggregateStats,
 }

block_priofees/src/stats_calculation.rs

@@ -1,6 +1,5 @@
 use crate::rpc_data::FeePoint;
 use itertools::Itertools;
-use std::collections::HashMap;
 use std::iter::zip;
 
 /// `quantile` function is the same as the median if q=50, the same as the minimum if q=0 and the same as the maximum if q=100.
@@ -39,25 +38,22 @@ pub fn calculate_supp_percentiles(
 
     // get stats by CU
     let cu_sum: u64 = prio_fees_in_block.iter().map(|x| x.1).sum();
-    let mut dist_fee_by_cu: HashMap<i32, u64> = HashMap::new();
-    let mut agg: u64 = 0;
-    let mut p = 0;
+    let mut agg: u64 = prio_fees_in_block[0].1;
+    let mut index = 0;
     let p_step = 5;
-    for (prio, cu) in &prio_fees_in_block {
-        agg += cu;
-        // write p's as long as agg beats the aggregated cu
-        while agg >= (cu_sum as f64 * p as f64 / 100.0) as u64 && p <= 100 {
-            dist_fee_by_cu.insert(p, *prio);
-            assert_ne!(p_step, 0, "zero steps might cause infinite loop");
-            p += p_step;
-        }
-    }
-    let dist_fee_by_cu: Vec<FeePoint> = dist_fee_by_cu
-        .into_iter()
-        .sorted_by_key(|(p, _)| *p)
-        .map(|(p, fees)| FeePoint {
-            percentile: p as u32,
-            fees,
+
+    let dist_fee_by_cu = (0..=100)
+        .step_by(p_step)
+        .map(|p| {
+            if agg < (cu_sum * p) / 100 {
+                index += 1;
+                agg += prio_fees_in_block[index].1;
+            }
+            let (prio, _) = prio_fees_in_block[index];
+            FeePoint {
+                percentile: p as u32,
+                fees: prio,
+            }
         })
         .collect_vec();