1 files changed, 27 insertions, 4 deletions
diff --git a/kamon-core/src/main/scala/kamon/metric/instrument/Counter.scala b/kamon-core/src/main/scala/kamon/metric/instrument/Counter.scala
index 4a9edd77..10b9c3a6 100644
--- a/kamon-core/src/main/scala/kamon/metric/instrument/Counter.scala
+++ b/kamon-core/src/main/scala/kamon/metric/instrument/Counter.scala
@@ -1,11 +1,34 @@
-package kamon.metric.instrument
+package kamon
+package metric
+package instrument
 
-import kamon.metric.Entity
+import java.util.concurrent.atomic.LongAdder
+
+import com.typesafe.scalalogging.StrictLogging
+import kamon.util.MeasurementUnit
 
 trait Counter {
+  def measurementUnit: MeasurementUnit
+
   def increment(): Unit
+  def increment(times: Long): Unit
 }
 
-object Counter {
-  def apply(entity: Entity, name: String): Counter = ???
+class LongAdderCounter(entity: Entity, name: String, val measurementUnit: MeasurementUnit)
+    extends Counter with SingleValueSnapshotInstrument with StrictLogging {
+
+  private val adder = new LongAdder()
+
+  def increment(): Unit =
+    adder.increment()
+
+  def increment(times: Long): Unit = {
+    if (times >= 0)
+      adder.add(times)
+    else
+      logger.warn(s"Ignored attempt to decrement counter [$name] on entity [$entity]")
+  }
+
+  def snapshot(): SingleValueSnapshot =
+    SingleValueSnapshot(name, measurementUnit, adder.sumThenReset())
 }