Adding MetricDefinition Key Generator (#78)

src/main/scala/com/expedia/www/haystack/commons/util/MetricDefinitionKeyGenerator.scala

@@ -0,0 +1,19 @@
+package com.expedia.www.haystack.commons.util
+
+import com.expedia.metrics.{MetricDefinition, TagCollection}
+
+import scala.collection.JavaConverters._
+import scala.collection.immutable.ListMap
+
+object MetricDefinitionKeyGenerator {
+
+  def generateKey(metricDefinition: MetricDefinition): String = {
+    List(s"key=${metricDefinition.getKey}", getTagsAsString(metricDefinition.getTags),
+      getTagsAsString(metricDefinition.getMeta)).filter(!_.isEmpty).mkString(",")
+  }
+
+  def getTagsAsString(tags: TagCollection): String = {
+    ListMap(tags.getKv.asScala.toSeq.sortBy(_._1): _*).map(tag => s"${tag._1}=${tag._2}").mkString(",")
+  }
+
+}

src/test/scala/com/expedia/www/haystack/commons/util/MetricDefinitionKeyGeneratorSpec.scala

@@ -0,0 +1,37 @@
+package com.expedia.www.haystack.commons.util
+
+import java.util
+
+import com.expedia.metrics.{MetricDefinition, TagCollection}
+import com.expedia.www.haystack.commons.entities.TagKeys.PRODUCT_KEY
+import com.expedia.www.haystack.commons.unit.UnitTestSpec
+
+class MetricDefinitionKeyGeneratorSpec extends UnitTestSpec {
+  "Metric Definition Key Generator" should {
+    "generate a unique key based on key and tags in MetricDefinition" in {
+      Given("a Metric Definition")
+      val metricDefinition = getMetricDefinition
+
+      When("MetricDefinitionKeyGenerator is called")
+      val key = MetricDefinitionKeyGenerator.generateKey(metricDefinition)
+
+      Then("a unique key is generated")
+      key should equal("key=duration,mtype=gauge,op=some-op,product=haystack,svc=some-svc,unit=short")
+    }
+  }
+
+  private def getMetricDefinition: MetricDefinition = {
+    val metricTags = new util.LinkedHashMap[String, String] {
+      put("svc", "some-svc")
+      put("op", "some-op")
+    }
+    val tags = new util.LinkedHashMap[String, String] {
+      putAll(metricTags)
+      put(MetricDefinition.MTYPE, "gauge")
+      put(MetricDefinition.UNIT, "short")
+      put(PRODUCT_KEY, "haystack")
+    }
+    val tc = new TagCollection(tags)
+    new MetricDefinition("duration", tc, TagCollection.EMPTY)
+  }
+}