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/*
* =========================================================================================
* Copyright © 2013 the kamon project <http://kamon.io/>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
* =========================================================================================
*/
package kamon.metric.instrument
import java.nio.LongBuffer
import com.typesafe.config.ConfigFactory
import kamon.metric.CollectionContext
import org.scalatest.{ Matchers, WordSpec }
import scala.util.Random
class HistogramSpec extends WordSpec with Matchers {
val histogramConfig = ConfigFactory.parseString(
"""
|
|highest-trackable-value = 100000
|significant-value-digits = 2
|
""".stripMargin)
"a Histogram" should {
"allow record values within the configured range" in new HistogramFixture {
histogram.record(1000)
histogram.record(5000, count = 100)
histogram.record(10000)
}
"fail when recording values higher than the highest trackable value" in new HistogramFixture {
intercept[IndexOutOfBoundsException] {
histogram.record(1000000)
}
}
"reset all recorded levels to zero after a snapshot collection" in new HistogramFixture {
histogram.record(100)
histogram.record(200)
histogram.record(300)
takeSnapshot().numberOfMeasurements should be(3)
takeSnapshot().numberOfMeasurements should be(0)
}
"produce a snapshot" which {
"supports min, max and numberOfMeasurements operations" in new HistogramFixture {
histogram.record(100)
histogram.record(200, count = 200)
histogram.record(300)
histogram.record(900)
val snapshot = takeSnapshot()
snapshot.min should equal(100L +- 1L)
snapshot.max should equal(900L +- 9L)
snapshot.numberOfMeasurements should be(203)
}
"can be merged with another snapshot" in new MultipleHistogramFixture {
val random = new Random(System.nanoTime())
for (repetitions ← 1 to 1000) {
// Put some values on A and Control
for (_ ← 1 to 1000) {
val newRecording = random.nextInt(100000)
controlHistogram.record(newRecording)
histogramA.record(newRecording)
}
// Put some values on B and Control
for (_ ← 1 to 2000) {
val newRecording = random.nextInt(100000)
controlHistogram.record(newRecording)
histogramB.record(newRecording)
}
val controlSnapshot = takeSnapshotFrom(controlHistogram)
val histogramASnapshot = takeSnapshotFrom(histogramA)
val histogramBSnapshot = takeSnapshotFrom(histogramB)
assertEquals(controlSnapshot, histogramASnapshot.merge(histogramBSnapshot, collectionContext))
assertEquals(controlSnapshot, histogramBSnapshot.merge(histogramASnapshot, collectionContext))
}
}
}
}
trait HistogramFixture {
val collectionContext = new CollectionContext {
val buffer: LongBuffer = LongBuffer.allocate(10000)
}
val histogram = Histogram.fromConfig(histogramConfig)
def takeSnapshot(): Histogram.Snapshot = histogram.collect(collectionContext)
}
trait MultipleHistogramFixture {
val collectionContext = new CollectionContext {
val buffer: LongBuffer = LongBuffer.allocate(10000)
}
val controlHistogram = Histogram.fromConfig(histogramConfig)
val histogramA = Histogram.fromConfig(histogramConfig)
val histogramB = Histogram.fromConfig(histogramConfig)
def takeSnapshotFrom(histogram: Histogram): Histogram.Snapshot = histogram.collect(collectionContext)
def assertEquals(left: Histogram.Snapshot, right: Histogram.Snapshot): Unit = {
left.numberOfMeasurements should equal(right.numberOfMeasurements)
left.min should equal(right.min)
left.max should equal(right.max)
left.recordsIterator.toStream should contain theSameElementsAs (right.recordsIterator.toStream)
}
}
}
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