1 files changed, 86 insertions, 0 deletions
diff --git a/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala b/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala
new file mode 100644
index 0000000000..26983138ff
--- /dev/null
+++ b/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala
@@ -0,0 +1,86 @@
+/*
+ * 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.util
+
+import scala.collection.mutable.Set
+import scala.collection.JavaConversions
+import java.util.concurrent.ConcurrentHashMap
+
+
+class TimeStampedHashSet[A] extends Set[A] {
+  val internalMap = new ConcurrentHashMap[A, Long]()
+
+  def contains(key: A): Boolean = {
+    internalMap.contains(key)
+  }
+
+  def iterator: Iterator[A] = {
+    val jIterator = internalMap.entrySet().iterator()
+    JavaConversions.asScalaIterator(jIterator).map(_.getKey)
+  }
+
+  override def + (elem: A): Set[A] = {
+    val newSet = new TimeStampedHashSet[A]
+    newSet ++= this
+    newSet += elem
+    newSet
+  }
+
+  override def - (elem: A): Set[A] = {
+    val newSet = new TimeStampedHashSet[A]
+    newSet ++= this
+    newSet -= elem
+    newSet
+  }
+
+  override def += (key: A): this.type = {
+    internalMap.put(key, currentTime)
+    this
+  }
+
+  override def -= (key: A): this.type = {
+    internalMap.remove(key)
+    this
+  }
+
+  override def empty: Set[A] = new TimeStampedHashSet[A]()
+
+  override def size(): Int = internalMap.size()
+
+  override def foreach[U](f: (A) => U): Unit = {
+    val iterator = internalMap.entrySet().iterator()
+    while(iterator.hasNext) {
+      f(iterator.next.getKey)
+    }
+  }
+
+  /**
+   * Removes old values that have timestamp earlier than `threshTime`
+   */
+  def clearOldValues(threshTime: Long) {
+    val iterator = internalMap.entrySet().iterator()
+    while(iterator.hasNext) {
+      val entry = iterator.next()
+      if (entry.getValue < threshTime) {
+        iterator.remove()
+      }
+    }
+  }
+
+  private def currentTime: Long = System.currentTimeMillis()
+}