Clean-up the TaskContext API.

core/src/main/java/org/apache/spark/TaskContext.java

@@ -18,57 +18,56 @@
 package org.apache.spark;
 
 import java.io.Serializable;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
 
 import scala.Function0;
 import scala.Function1;
 import scala.Unit;
-import scala.collection.JavaConversions;
 
 import org.apache.spark.annotation.DeveloperApi;
 import org.apache.spark.executor.TaskMetrics;
 import org.apache.spark.util.TaskCompletionListener;
-import org.apache.spark.util.TaskCompletionListenerException;
 
 /**
-* :: DeveloperApi ::
-* Contextual information about a task which can be read or mutated during execution.
-*/
-@DeveloperApi
+ * Contextual information about a task which can be read or mutated during
+ * execution. To access the TaskContext for a running task use
+ * TaskContext.get().
+ */
 public abstract class TaskContext implements Serializable {
+  /**
+   * Return the currently active TaskContext. This can be called inside of
+   * user functions to access contextual information about running tasks.
+   */
+  public static TaskContext get() {
+    return taskContext.get();
+  }
 
   private static ThreadLocal<TaskContext> taskContext =
     new ThreadLocal<TaskContext>();
 
-  /**
-   * :: Internal API ::
-   * This is spark internal API, not intended to be called from user programs.
-   */
   static void setTaskContext(TaskContext tc) {
     taskContext.set(tc);
   }
 
-  public static TaskContext get() {
-    return taskContext.get();
-  }
-
-  /** :: Internal API ::  */
   static void unset() {
     taskContext.remove();
   }
 
   /**
-   * Checks whether the task has completed.
+   * Whether the task has completed.
    */
   public abstract boolean isCompleted();
 
   /**
-   * Checks whether the task has been killed.
+   * Whether the task has been killed.
    */
   public abstract boolean isInterrupted();
 
+  @Deprecated
+  /** Deprecated: use isRunningLocally() */
+  public abstract boolean runningLocally();
+
+  public abstract boolean isRunningLocally();
+
   /**
    * Add a (Java friendly) listener to be executed on task completion.
    * This will be called in all situation - success, failure, or cancellation.
@@ -103,12 +102,7 @@ static void unset() {
 
   public abstract long attemptId();
 
-  @Deprecated
-  /** Deprecated: use isRunningLocally() */
-  public abstract boolean runningLocally();
-
-  public abstract boolean isRunningLocally();
-
-  /** ::Internal API:: */
+  /** ::DeveloperApi:: */
+  @DeveloperApi
   public abstract TaskMetrics taskMetrics();
 }

core/src/main/scala/org/apache/spark/TaskContextHelper.scala

@@ -17,6 +17,9 @@
 
 package org.apache.spark
 
+/**
+ * This class exists to restrict the visibility of TaskContext setters.
+ */
 private [spark] object TaskContextHelper {
 
   def setTaskContext(tc: TaskContext): Unit = TaskContext.setTaskContext(tc)

core/src/main/scala/org/apache/spark/TaskContextImpl.scala

@@ -27,7 +27,7 @@ private[spark] class TaskContextImpl(val stageId: Int,
     val attemptId: Long,
     val runningLocally: Boolean = false,
     val taskMetrics: TaskMetrics = TaskMetrics.empty)
-  extends TaskContext(stageId, partitionId, attemptId, runningLocally, taskMetrics)
+  extends TaskContext
   with Logging {
 
   // List of callback functions to execute when the task completes.

core/src/main/scala/org/apache/spark/scheduler/Task.scala

@@ -70,7 +70,7 @@ private[spark] abstract class Task[T](val stageId: Int, var partitionId: Int) ex
   var metrics: Option[TaskMetrics] = None
 
   // Task context, to be initialized in run().
-  @transient protected var context: TaskContext = _
+  @transient protected var context: TaskContextImpl = _
 
   // The actual Thread on which the task is running, if any. Initialized in run().
   @volatile @transient private var taskThread: Thread = _

project/MimaBuild.scala

@@ -39,8 +39,8 @@ object MimaBuild {
       ProblemFilters.exclude[MissingFieldProblem](fullName),
       ProblemFilters.exclude[IncompatibleResultTypeProblem](fullName),
       ProblemFilters.exclude[IncompatibleMethTypeProblem](fullName),
-      ProblemFilters.exclude[IncompatibleFieldTypeProblem](fullName),
-      ProblemFilters.exclude[AbstractClassProblem](fullName)
+      ProblemFilters.exclude[IncompatibleFieldTypeProblem](fullName)
+//      ProblemFilters.exclude[AbstractClassProblem](fullName)
     )
 
   // Exclude a single class and its corresponding object

project/MimaExcludes.scala

@@ -50,7 +50,11 @@ object MimaExcludes {
               "org.apache.spark.mllib.stat.MultivariateStatisticalSummary.normL2"),
             // MapStatus should be private[spark]
             ProblemFilters.exclude[IncompatibleTemplateDefProblem](
-              "org.apache.spark.scheduler.MapStatus")
+              "org.apache.spark.scheduler.MapStatus"),
+            // TaskContext was promoted to Abstract class
+            ProblemFilters.exclude[AbstractClassProblem](
+              "org.apache.spark.TaskContext")
+
           )
 
         case v if v.startsWith("1.1") =>