Add missing file.

Author: JoshRosen

core/src/main/scala/org/apache/spark/api/java/JavaSparkStatusAPI.scala

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+/*
+ * 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.api.java
+
+import org.apache.spark.{SparkStageInfo, SparkJobInfo, SparkContext}
+
+/**
+ * Low-level status reporting APIs for monitoring job and stage progress.
+ *
+ * These APIs intentionally provide very weak consistency semantics; consumers of these APIs should
+ * be prepared to handle empty / missing information.  For example, a job's stage ids may be known
+ * but the status API may not have any information about the details of those stages, so
+ * `getStageInfo` could potentially return `null` for a valid stage id.
+ *
+ * To limit memory usage, these APIs only provide information on recent jobs / stages.  These APIs
+ * will provide information for the last `spark.ui.retainedStages` stages and
+ * `spark.ui.retainedJobs` jobs.
+ */
+class JavaSparkStatusAPI private (sc: SparkContext) {
+
+  /**
+   * Return a list of all known jobs in a particular job group.  If `jobGroup` is `null`, then
+   * returns all known jobs that are not associated with a job group.
+   *
+   * The returned list may contain running, failed, and completed jobs, and may vary across
+   * invocations of this method.  This method does not guarantee the order of the elements in
+   * its result.
+   */
+  def getJobIdsForGroup(jobGroup: String): Array[Int] = sc.statusAPI.getJobIdsForGroup(jobGroup)
+
+  /**
+   * Returns an array containing the ids of all active stages.
+   *
+   * This method does not guarantee the order of the elements in its result.
+   */
+  def getActiveStageIds(): Array[Int] = sc.statusAPI.getActiveStageIds()
+
+  /**
+   * Returns an array containing the ids of all active jobs.
+   *
+   * This method does not guarantee the order of the elements in its result.
+   */
+  def getActiveJobIds(): Array[Int] = sc.statusAPI.getActiveJobIds()
+
+  /**
+   * Returns job information, or `null` if the job info could not be found or was garbage collected.
+   */
+  def getJobInfo(jobId: Int): SparkJobInfo = sc.statusAPI.getJobInfo(jobId).orNull
+
+  /**
+   * Returns stage information, or `null` if the stage info could not be found or was
+   * garbage collected.
+   */
+  def getStageInfo(stageId: Int): SparkStageInfo = sc.statusAPI.getStageInfo(stageId).orNull
+}
+
+private[spark] object JavaSparkStatusAPI {
+  def apply(sc: SparkContext): JavaSparkStatusAPI = {
+    new JavaSparkStatusAPI(sc)
+  }
+}