+ core: introduce the new kamon.metrics.default-collection-context-buffer-size setting

5 files changed, 23 insertions, 12 deletions

diff --git a/kamon-core/src/main/resources/reference.conf b/kamon-core/src/main/resources/reference.conf
index b7f5c70e..3c8f3686 100644
--- a/kamon-core/src/main/resources/reference.conf
+++ b/kamon-core/src/main/resources/reference.conf
@@ -16,6 +16,16 @@ kamon {
     gauge-recording-interval = 100 milliseconds
 
 
+    # Default size for the LongBuffer that gets allocated for metrics collection and merge. The
+    # value should correspond to the highest number of different buckets with values that might
+    # exist in a single histogram during a metrics collection. The default value of 33792 is a
+    # very conservative value and its equal to the total number of buckets required to cover values
+    # from 1 nanosecond to 1 hour with 0.1% precision (3 significant value digits). That means
+    # that would need to have at least one measurement on every bucket of a single histogram to
+    # fully utilize this buffer, which is *really* unlikely to ever happen. Since the buffer should
+    # be allocated once and reused it shouldn't impose a memory footprint issue.
+    default-collection-context-buffer-size = 33792
+
     dispatchers {
 
       # Dispatcher for periodical gauge value recordings.
diff --git a/kamon-core/src/main/scala/kamon/metric/EntityMetrics.scala b/kamon-core/src/main/scala/kamon/metric/EntityMetrics.scala
index 325dd216..3761f5a5 100644
--- a/kamon-core/src/main/scala/kamon/metric/EntityMetrics.scala
+++ b/kamon-core/src/main/scala/kamon/metric/EntityMetrics.scala
@@ -38,8 +38,8 @@ trait CollectionContext {
 }
 
 object CollectionContext {
-  def default: CollectionContext = new CollectionContext {
-    val buffer: LongBuffer = LongBuffer.allocate(10000)
+  def apply(longBufferSize: Int): CollectionContext = new CollectionContext {
+    val buffer: LongBuffer = LongBuffer.allocate(longBufferSize)
   }
 }
 
diff --git a/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala b/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
index 1025f0de..8c6d0359 100644
--- a/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
+++ b/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
@@ -57,14 +57,6 @@ class MetricsExtension(system: ExtendedActorSystem) extends Kamon.Extension {
     subscriptions.tell(Subscribe(category, selection, permanently), receiver)
   }
 
-  def collect: Map[MetricGroupIdentity, MetricGroupSnapshot] = {
-    // TODO: Improve the way in which we are getting the context.
-    val context = new CollectionContext {
-      val buffer: LongBuffer = LongBuffer.allocate(50000)
-    }
-    (for ((identity, recorder) ← storage) yield (identity, recorder.collect(context))).toMap
-  }
-
   def scheduleGaugeRecorder(body: ⇒ Unit): Cancellable = {
     import scala.concurrent.duration._
 
@@ -98,6 +90,9 @@ class MetricsExtension(system: ExtendedActorSystem) extends Kamon.Extension {
 
     allFilters.toMap
   }
+
+  def buildDefaultCollectionContext: CollectionContext =
+    CollectionContext(metricsExtConfig.getInt("default-collection-context-buffer-size"))
 }
 
 object Metrics extends ExtensionId[MetricsExtension] with ExtensionIdProvider {
diff --git a/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala b/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala
index a9f4c721..eb2168ad 100644
--- a/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala
+++ b/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala
@@ -30,6 +30,7 @@ class Subscriptions extends Actor {
   val config = context.system.settings.config
   val tickInterval = Duration(config.getDuration("kamon.metrics.tick-interval", TimeUnit.NANOSECONDS), TimeUnit.NANOSECONDS)
   val flushMetricsSchedule = context.system.scheduler.schedule(tickInterval, tickInterval, self, FlushMetrics)(context.dispatcher)
+  val collectionContext = Kamon(Metrics).buildDefaultCollectionContext
 
   var lastTick: Long = System.currentTimeMillis()
   var subscribedPermanently: Map[MetricGroupFilter, List[ActorRef]] = Map.empty
@@ -55,7 +56,7 @@ class Subscriptions extends Actor {
 
   def flush(): Unit = {
     val currentTick = System.currentTimeMillis()
-    val snapshots = Kamon(Metrics).collect
+    val snapshots = collectAll()
 
     dispatchSelectedMetrics(lastTick, currentTick, subscribedPermanently, snapshots)
     dispatchSelectedMetrics(lastTick, currentTick, subscribedForOneShot, snapshots)
@@ -64,6 +65,9 @@ class Subscriptions extends Actor {
     subscribedForOneShot = Map.empty
   }
 
+  def collectAll(): Map[MetricGroupIdentity, MetricGroupSnapshot] =
+    (for ((identity, recorder) ← Kamon(Metrics).storage) yield (identity, recorder.collect(collectionContext))).toMap
+
   def dispatchSelectedMetrics(lastTick: Long, currentTick: Long, subscriptions: Map[MetricGroupFilter, List[ActorRef]],
     snapshots: Map[MetricGroupIdentity, MetricGroupSnapshot]): Unit = {
 
@@ -90,7 +94,7 @@ object Subscriptions {
 
 class TickMetricSnapshotBuffer(flushInterval: FiniteDuration, receiver: ActorRef) extends Actor {
   val flushSchedule = context.system.scheduler.schedule(flushInterval, flushInterval, self, FlushBuffer)(context.dispatcher)
-  val collectionContext = CollectionContext.default
+  val collectionContext = Kamon(Metrics)(context.system).buildDefaultCollectionContext
 
   def receive = empty
 
diff --git a/kamon-core/src/main/scala/kamon/metric/instrument/Histogram.scala b/kamon-core/src/main/scala/kamon/metric/instrument/Histogram.scala
index 9ae077f4..8c81e717 100644
--- a/kamon-core/src/main/scala/kamon/metric/instrument/Histogram.scala
+++ b/kamon-core/src/main/scala/kamon/metric/instrument/Histogram.scala
@@ -103,6 +103,8 @@ class HdrHistogram(lowestTrackableValue: Long, highestTrackableValue: Long, sign
     new CompactHdrSnapshot(scale, nrOfMeasurements, measurementsArray, unitMagnitude(), subBucketHalfCount(), subBucketHalfCountMagnitude())
   }
 
+  def getCounts = countsArray().length()
+
   def cleanup: Unit = {}
 
   private def writeSnapshotTo(buffer: LongBuffer): Long = {