1 files changed, 102 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/metric/instrument/InstrumentFactory.scala b/kamon-core/src/main/scala/kamon/metric/instrument/InstrumentFactory.scala
new file mode 100644
index 00000000..820c05b5
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/instrument/InstrumentFactory.scala
@@ -0,0 +1,102 @@
+package kamon
+package metric
+package instrument
+
+import java.time.Duration
+
+import com.typesafe.config.Config
+import kamon.metric.instrument.InstrumentFactory.CustomInstrumentSettings
+
+
+private[kamon] class InstrumentFactory private (
+    defaultHistogramDynamicRange: DynamicRange,
+    defaultMMCounterDynamicRange: DynamicRange,
+    defaultMMCounterSampleRate: Duration,
+    customSettings: Map[(String, String), CustomInstrumentSettings]) {
+
+  def buildHistogram(entity: Entity, name: String, dynamicRange: DynamicRange = defaultHistogramDynamicRange): Histogram =
+    Histogram(entity, name, instrumentDynamicRange(entity, name, dynamicRange))
+
+  def buildMinMaxCounter(entity: Entity, name: String, dynamicRange: DynamicRange = defaultMMCounterDynamicRange,
+      sampleInterval: Duration = defaultMMCounterSampleRate): MinMaxCounter =
+    MinMaxCounter(
+      entity,
+      name,
+      instrumentDynamicRange(entity, name, dynamicRange),
+      instrumentSampleInterval(entity, name, sampleInterval)
+    )
+
+  def buildGauge(entity: Entity, name: String): Gauge =
+    Gauge(entity, name)
+
+  def buildCounter(entity: Entity, name: String): Counter =
+    Counter(entity, name)
+
+
+  private def instrumentDynamicRange(entity: Entity, instrumentName: String, dynamicRange: DynamicRange): DynamicRange =
+    customSettings.get((entity.category, instrumentName)).fold(dynamicRange) { cs =>
+      overrideDynamicRange(dynamicRange, cs)
+    }
+
+  private def instrumentSampleInterval(entity: Entity, instrumentName: String, sampleInterval: Duration): Duration =
+    customSettings.get((entity.category, instrumentName)).fold(sampleInterval) { cs =>
+      cs.sampleInterval.getOrElse(sampleInterval)
+    }
+
+  private def overrideDynamicRange(defaultDynamicRange: DynamicRange, customSettings: CustomInstrumentSettings): DynamicRange =
+    DynamicRange(
+      customSettings.lowestDiscernibleValue.getOrElse(defaultDynamicRange.lowestDiscernibleValue),
+      customSettings.highestTrackableValue.getOrElse(defaultDynamicRange.highestTrackableValue),
+      customSettings.significantValueDigits.getOrElse(defaultDynamicRange.significantValueDigits)
+    )
+}
+
+object InstrumentFactory {
+
+  def apply(config: Config): InstrumentFactory = {
+    val histogramDynamicRange = readDynamicRange(config.getConfig("default-settings.histogram"))
+    val mmCounterDynamicRange = readDynamicRange(config.getConfig("default-settings.min-max-counter"))
+    val mmCounterSampleInterval = config.getDuration("default-settings.min-max-counter.sample-interval")
+
+    val customSettings = config.getConfig("custom-settings")
+      .configurations
+      .filter(nonEmptyCategories)
+      .flatMap(buildCustomInstrumentSettings)
+
+    new InstrumentFactory(histogramDynamicRange, mmCounterDynamicRange, mmCounterSampleInterval, customSettings)
+  }
+
+  private def nonEmptyCategories(entry: (String, Config)): Boolean = entry match {
+    case (_, config) => config.firstLevelKeys.nonEmpty
+  }
+
+  private def buildCustomInstrumentSettings(entry: (String, Config)): Map[(String, String), CustomInstrumentSettings] = {
+    val (category, categoryConfig) = entry
+    categoryConfig.configurations.map {
+      case (instrumentName, instrumentConfig) => (category, instrumentName) -> readCustomSettings(instrumentConfig)
+    }
+  }
+
+  private def readDynamicRange(config: Config): DynamicRange =
+    DynamicRange(
+      lowestDiscernibleValue = config.getLong("lowest-discernible-value"),
+      highestTrackableValue = config.getLong("highest-trackable-value"),
+      significantValueDigits = config.getInt("significant-value-digits")
+    )
+
+
+  private case class CustomInstrumentSettings(
+    lowestDiscernibleValue: Option[Long],
+    highestTrackableValue: Option[Long],
+    significantValueDigits: Option[Int],
+    sampleInterval: Option[Duration]
+  )
+
+  private def readCustomSettings(config: Config): CustomInstrumentSettings =
+    CustomInstrumentSettings(
+      if (config.hasPath("lowest-discernible-value")) Some(config.getLong("lowest-discernible-value")) else None,
+      if (config.hasPath("highest-trackable-value")) Some(config.getLong("highest-trackable-value")) else None,
+      if (config.hasPath("significant-value-digits")) Some(config.getInt("significant-value-digits")) else None,
+      if (config.hasPath("sample-interval")) Some(config.getDuration("sample-interval")) else None
+    )
+}
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