! all: improve the metric recorders infrastructure

1 files changed, 47 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/metric/EntitySnapshot.scala b/kamon-core/src/main/scala/kamon/metric/EntitySnapshot.scala
new file mode 100644
index 00000000..17c8f4c5
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/EntitySnapshot.scala
@@ -0,0 +1,47 @@
+package kamon.metric
+
+import kamon.metric.instrument.{ Counter, Histogram, CollectionContext, InstrumentSnapshot }
+import kamon.util.MapMerge
+import scala.reflect.ClassTag
+
+trait EntitySnapshot {
+  def metrics: Map[MetricKey, InstrumentSnapshot]
+  def merge(that: EntitySnapshot, collectionContext: CollectionContext): EntitySnapshot
+
+  def histogram(name: String): Option[Histogram.Snapshot] =
+    find[HistogramKey, Histogram.Snapshot](name)
+
+  def minMaxCounter(name: String): Option[Histogram.Snapshot] =
+    find[MinMaxCounterKey, Histogram.Snapshot](name)
+
+  def gauge(name: String): Option[Histogram.Snapshot] =
+    find[GaugeKey, Histogram.Snapshot](name)
+
+  def counter(name: String): Option[Counter.Snapshot] =
+    find[CounterKey, Counter.Snapshot](name)
+
+  def histograms: Map[HistogramKey, Histogram.Snapshot] =
+    filterByType[HistogramKey, Histogram.Snapshot]
+
+  def minMaxCounters: Map[MinMaxCounterKey, Histogram.Snapshot] =
+    filterByType[MinMaxCounterKey, Histogram.Snapshot]
+
+  def gauges: Map[GaugeKey, Histogram.Snapshot] =
+    filterByType[GaugeKey, Histogram.Snapshot]
+
+  def counters: Map[CounterKey, Counter.Snapshot] =
+    filterByType[CounterKey, Counter.Snapshot]
+
+  private def filterByType[K <: MetricKey, V <: InstrumentSnapshot](implicit keyCT: ClassTag[K]): Map[K, V] =
+    metrics.collect { case (k, v) if keyCT.runtimeClass.isInstance(k) ⇒ (k.asInstanceOf[K], v.asInstanceOf[V]) }
+
+  private def find[K <: MetricKey, V <: InstrumentSnapshot](name: String)(implicit keyCT: ClassTag[K]) =
+    metrics.find { case (k, v) ⇒ keyCT.runtimeClass.isInstance(k) && k.name == name } map (_._2.asInstanceOf[V])
+}
+
+class DefaultEntitySnapshot(val metrics: Map[MetricKey, InstrumentSnapshot]) extends EntitySnapshot {
+  import MapMerge.Syntax
+
+  override def merge(that: EntitySnapshot, collectionContext: CollectionContext): EntitySnapshot =
+    new DefaultEntitySnapshot(metrics.merge(that.metrics, (l, r) ⇒ l.merge(r, collectionContext)))
+}
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