Added additional sbt settings for controlling JMH.

Signed-off-by: Simeon H.K. fitch <fitch@astraea.io>

bench/build.sbt

@@ -8,16 +8,44 @@ enablePlugins(JmhPlugin)
 val jmhOutputFormat = settingKey[String]("Output format: {text|csv|scsv|json|latex}")
 jmhOutputFormat := "csv"
 
+val jmhOutputDir = settingKey[File]("Directory for writing JMH results")
+jmhOutputDir := target.value
+
 val jmhFileRegex = settingKey[Regex]("Filename regular expression for selecting files to benchmark")
 jmhFileRegex := ".*Bench.*".r
 
+val jmhThreads = settingKey[Int]("Number of worker threads")
+jmhThreads := 1
+
+val jmhFork = settingKey[Int]("How many times to fork a single benchmark")
+jmhFork := 1
+
+val jmhIterations = settingKey[Int]("Number of measurement iterations to do")
+jmhIterations := 10
+
+val jmhWarmupIterations = settingKey[Int]("Number of warmup iterations to do.")
+jmhWarmupIterations := math.max(jmhIterations.value/2, 5)
+
+val jmhTimeUnit = settingKey[String]("Benchmark results unit: {m|s|ms|us|ns}.")
+jmhTimeUnit := "ms"
+
+
 val jmhRun = Def.taskDyn {
   val rf = jmhOutputFormat.value
   def timestamp = new SimpleDateFormat("yyyyMMdd").format(new Date())
+  val dir = jmhOutputDir.value
+  IO.createDirectory(dir)
+
   val rff = target.value / s"jmh-results-$timestamp.${jmhOutputFormat.value}"
   val pat = jmhFileRegex.value.toString
 
-  val args = s" -rf $rf -rff $rff $pat"
+  val t = jmhThreads.value
+  val f = jmhFork.value
+  val i = jmhIterations.value
+  val wi = jmhWarmupIterations.value
+  val tu = jmhTimeUnit.value
+
+  val args = s" -t $t -f $f -i $i -wi $wi -tu $tu -rf $rf -rff $rff $pat"
   (run in Jmh).toTask(args)
 }
 

bench/src/main/scala/geotrellis/spark/io/index/MergeQueueBench.scala

@@ -1,18 +1,22 @@
 package geotrellis.spark.io.index
 
-
-import java.util.concurrent.TimeUnit
 import org.openjdk.jmh.annotations._
 
 @BenchmarkMode(Array(Mode.AverageTime))
-@OutputTimeUnit(TimeUnit.MICROSECONDS)
-@Warmup(iterations = 5)
-@Measurement(iterations = 10)
-@Fork(1)
-@Threads(1)
 @State(Scope.Thread)
 class MergeQueueBench {
-  val queue = new MergeQueue()
+
+  var queue: MergeQueue = _
+
+  @Setup
+  def setup() = {
+    queue = new MergeQueue()
+  }
+
+  @TearDown
+  def tearDown() = {
+    queue = null
+  }
 
   @Benchmark
   def mergeOrderedDense  = {