[finagle-stats] Do not allocate a new IndexedSeq on every metric lookup

Differential Revision: https://phabricator.twitter.biz/D1121923
twitter · Jan 25, 2024 · 82e0bdb · 82e0bdb
1 parent 644094e
commit 82e0bdb
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/util-stats/src/main/scala/com/twitter/finagle/stats/MetricBuilder.scala b/util-stats/src/main/scala/com/twitter/finagle/stats/MetricBuilder.scala
@@ -78,6 +78,8 @@ object MetricBuilder {
 
   val NoDescription: String = "No description provided"
 
+  private[this] val EmptyPercentiles = IndexedSeq.empty
+
   /**
    * Construct a MethodBuilder.
    *
@@ -105,7 +107,8 @@ object MetricBuilder {
     relativeName: Seq[String] = Seq.empty,
     processPath: Option[String] = None,
     histogramFormat: HistogramFormat = HistogramFormat.Default,
-    percentiles: IndexedSeq[Double] = IndexedSeq.empty,
+    percentiles: IndexedSeq[Double] =
+      EmptyPercentiles, // IndexedSeq.empty creates a new collection on every call
     isStandard: Boolean = false,
     metricType: MetricType,
   ): MetricBuilder = {