1 files changed, 27 insertions, 0 deletions
diff --git a/core/src/main/scala/org/apache/spark/partial/ApproximateEvaluator.scala b/core/src/main/scala/org/apache/spark/partial/ApproximateEvaluator.scala
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+++ b/core/src/main/scala/org/apache/spark/partial/ApproximateEvaluator.scala
@@ -0,0 +1,27 @@
+/*
+ * 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.partial
+
+/**
+ * An object that computes a function incrementally by merging in results of type U from multiple
+ * tasks. Allows partial evaluation at any point by calling currentResult().
+ */
+private[spark] trait ApproximateEvaluator[U, R] {
+  def merge(outputId: Int, taskResult: U): Unit
+  def currentResult(): R
+}