From 5961d4b408615d99af16e90b7314b775750e2ccf Mon Sep 17 00:00:00 2001
From: Edoardo Luppi <lp.edoardo@gmail.com>
Date: Wed, 31 Jan 2024 23:31:33 +0100
Subject: [PATCH] refactor: drop the slowest run

---
 .../benchmarks/ManualMySQLBenchmarks.kt        | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/antlr-kotlin-benchmarks/src/commonTest/kotlin/org/antlr/v4/kotlinruntime/benchmarks/ManualMySQLBenchmarks.kt b/antlr-kotlin-benchmarks/src/commonTest/kotlin/org/antlr/v4/kotlinruntime/benchmarks/ManualMySQLBenchmarks.kt
index 9c693d69..a47b8be1 100644
--- a/antlr-kotlin-benchmarks/src/commonTest/kotlin/org/antlr/v4/kotlinruntime/benchmarks/ManualMySQLBenchmarks.kt
+++ b/antlr-kotlin-benchmarks/src/commonTest/kotlin/org/antlr/v4/kotlinruntime/benchmarks/ManualMySQLBenchmarks.kt
@@ -54,6 +54,10 @@ class ManualMySQLBenchmarks {
   }
 
   private fun averageTimeMs(title: String, times: Int, action: () -> Duration): Double {
+    require(times > 3) {
+      "At least 4 iterations are required"
+    }
+
     val durations = ArrayList<Duration>(times)
     println("\nBenchmark: $title")
 
@@ -68,12 +72,18 @@ class ManualMySQLBenchmarks {
   }
 
   private fun averageMs(durations: List<Duration>): Double {
-    if (durations.isEmpty()) {
-      return 0.0
+    require(durations.size > 3) {
+      "At least 4 durations are required"
     }
 
-    val sum = durations.fold(Duration.ZERO) { acc, duration -> acc + duration }
-    val duration = sum / durations.size
+    // Sort and drop the slowest run
+    val durationsMinusSlowest = durations.asSequence()
+      .sortedDescending()
+      .drop(1)
+      .toList()
+
+    val sum = durationsMinusSlowest.fold(Duration.ZERO) { acc, duration -> acc + duration }
+    val duration = sum / durationsMinusSlowest.size
     return milliseconds(duration)
   }