1 files changed, 70 insertions, 0 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/ml/tree/impl/TimeTracker.scala b/mllib/src/main/scala/org/apache/spark/ml/tree/impl/TimeTracker.scala
new file mode 100644
index 0000000000..4cc250aa46
--- /dev/null
+++ b/mllib/src/main/scala/org/apache/spark/ml/tree/impl/TimeTracker.scala
@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.spark.ml.tree.impl
+
+import scala.collection.mutable.{HashMap => MutableHashMap}
+
+/**
+ * Time tracker implementation which holds labeled timers.
+ */
+private[spark] class TimeTracker extends Serializable {
+
+  private val starts: MutableHashMap[String, Long] = new MutableHashMap[String, Long]()
+
+  private val totals: MutableHashMap[String, Long] = new MutableHashMap[String, Long]()
+
+  /**
+   * Starts a new timer, or re-starts a stopped timer.
+   */
+  def start(timerLabel: String): Unit = {
+    val currentTime = System.nanoTime()
+    if (starts.contains(timerLabel)) {
+      throw new RuntimeException(s"TimeTracker.start(timerLabel) called again on" +
+        s" timerLabel = $timerLabel before that timer was stopped.")
+    }
+    starts(timerLabel) = currentTime
+  }
+
+  /**
+   * Stops a timer and returns the elapsed time in seconds.
+   */
+  def stop(timerLabel: String): Double = {
+    val currentTime = System.nanoTime()
+    if (!starts.contains(timerLabel)) {
+      throw new RuntimeException(s"TimeTracker.stop(timerLabel) called on" +
+        s" timerLabel = $timerLabel, but that timer was not started.")
+    }
+    val elapsed = currentTime - starts(timerLabel)
+    starts.remove(timerLabel)
+    if (totals.contains(timerLabel)) {
+      totals(timerLabel) += elapsed
+    } else {
+      totals(timerLabel) = elapsed
+    }
+    elapsed / 1e9
+  }
+
+  /**
+   * Print all timing results in seconds.
+   */
+  override def toString: String = {
+    totals.map { case (label, elapsed) =>
+        s"  $label: ${elapsed / 1e9}"
+      }.mkString("\n")
+  }
+}