1 files changed, 16 insertions, 3 deletions
diff --git a/kamon-core/src/main/scala/kamon/metrics/package.scala b/kamon-core/src/main/scala/kamon/metrics/package.scala
index f89d84a3..640157a9 100644
--- a/kamon-core/src/main/scala/kamon/metrics/package.scala
+++ b/kamon-core/src/main/scala/kamon/metrics/package.scala
@@ -16,11 +16,24 @@
 
 package kamon
 
+import scala.annotation.tailrec
+import com.typesafe.config.Config
+
 package object metrics {
 
-  def combineMaps[K, V](left: Map[K, V], right: Map[K, V])(valueMerger: (V, V) ⇒ V): Map[K, V] = {
-    (left ++ right) map {
-      case (key, rightValue) ⇒ key -> left.get(key).map(leftValue ⇒ valueMerger(leftValue, rightValue)).getOrElse(rightValue)
+  case class HdrPrecisionConfig(highestTrackableValue: Long, significantValueDigits: Int)
+
+  def extractPrecisionConfig(config: Config): HdrPrecisionConfig =
+    HdrPrecisionConfig(config.getLong("highest-trackable-value"), config.getInt("significant-value-digits"))
+
+  @tailrec def combineMaps[K, V](left: Map[K, V], right: Map[K, V])(valueMerger: (V, V) ⇒ V): Map[K, V] = {
+    if (right.isEmpty)
+      left
+    else {
+      val (key, rightValue) = right.head
+      val value = left.get(key).map(valueMerger(_, rightValue)).getOrElse(rightValue)
+
+      combineMaps(left.updated(key, value), right.tail)(valueMerger)
     }
   }
 }