[SPARK-13166][SQL] Remove DataStreamReader/Writer

sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala

@@ -1682,22 +1682,14 @@ class DataFrame private[sql](
 
   /**
    * :: Experimental ::
-   * Interface for saving the content of the [[DataFrame]] out into external storage.
+   * Interface for saving the content of the [[DataFrame]] out into external storage or streams.
    *
    * @group output
    * @since 1.4.0
    */
   @Experimental
   def write: DataFrameWriter = new DataFrameWriter(this)
 
-  /**
-   * :: Experimental ::
-   * Interface for starting a streaming query that will continually output results to the specified
-   * external sink as new data arrives.
-   */
-  @Experimental
-  def streamTo: DataStreamWriter = new DataStreamWriter(this)
-
   /**
    * Returns the content of the [[DataFrame]] as a RDD of JSON strings.
    * @group rdd

sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala

@@ -29,17 +29,17 @@ import org.apache.spark.annotation.Experimental
 import org.apache.spark.api.java.JavaRDD
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.catalyst.{CatalystQl}
 import org.apache.spark.sql.execution.datasources.{LogicalRelation, ResolvedDataSource}
 import org.apache.spark.sql.execution.datasources.jdbc.{JDBCPartition, JDBCPartitioningInfo, JDBCRelation}
 import org.apache.spark.sql.execution.datasources.json.JSONRelation
 import org.apache.spark.sql.execution.datasources.parquet.ParquetRelation
+import org.apache.spark.sql.execution.streaming.StreamingRelation
 import org.apache.spark.sql.types.StructType
 
 /**
  * :: Experimental ::
  * Interface used to load a [[DataFrame]] from external storage systems (e.g. file systems,
- * key-value stores, etc). Use [[SQLContext.read]] to access this.
+ * key-value stores, etc) or data streams. Use [[SQLContext.read]] to access this.
  *
  * @since 1.4.0
  */
@@ -136,6 +136,30 @@ class DataFrameReader private[sql](sqlContext: SQLContext) extends Logging {
     option("paths", paths.map(StringUtils.escapeString(_, '\\', ',')).mkString(",")).load()
   }
 
+  /**
+   * Loads input data stream in as a [[DataFrame]], for data streams that don't require a path
+   * (e.g. external key-value stores).
+   *
+   * @since 2.0.0
+   */
+  def stream(): DataFrame = {
+    val resolved = ResolvedDataSource.createSource(
+      sqlContext,
+      userSpecifiedSchema = userSpecifiedSchema,
+      providerName = source,
+      options = extraOptions.toMap)
+    DataFrame(sqlContext, StreamingRelation(resolved))
+  }
+
+  /**
+   * Loads input in as a [[DataFrame]], for data streams that read from some path.
+   *
+   * @since 2.0.0
+   */
+  def stream(path: String): DataFrame = {
+    option("path", path).stream()
+  }
+
   /**
    * Construct a [[DataFrame]] representing the database table accessible via JDBC URL
    * url named table and connection properties.
@@ -165,7 +189,6 @@ class DataFrameReader private[sql](sqlContext: SQLContext) extends Logging {
    * @param connectionProperties JDBC database connection arguments, a list of arbitrary string
    *                             tag/value. Normally at least a "user" and "password" property
    *                             should be included.
-   *
    * @since 1.4.0
    */
   def jdbc(

sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala

@@ -22,17 +22,18 @@ import java.util.Properties
 import scala.collection.JavaConverters._
 
 import org.apache.spark.annotation.Experimental
-import org.apache.spark.sql.catalyst.{CatalystQl, TableIdentifier}
+import org.apache.spark.sql.catalyst.TableIdentifier
 import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
 import org.apache.spark.sql.catalyst.plans.logical.{InsertIntoTable, Project}
 import org.apache.spark.sql.execution.datasources.{BucketSpec, CreateTableUsingAsSelect, ResolvedDataSource}
 import org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils
+import org.apache.spark.sql.execution.streaming.StreamExecution
 import org.apache.spark.sql.sources.HadoopFsRelation
 
 /**
  * :: Experimental ::
  * Interface used to write a [[DataFrame]] to external storage systems (e.g. file systems,
- * key-value stores, etc). Use [[DataFrame.write]] to access this.
+ * key-value stores, etc) or data streams. Use [[DataFrame.write]] to access this.
  *
  * @since 1.4.0
  */
@@ -183,6 +184,34 @@ final class DataFrameWriter private[sql](df: DataFrame) {
       df)
   }
 
+  /**
+   * Starts the execution of the streaming query, which will continually output results to the given
+   * path as new data arrives. The returned [[ContinuousQuery]] object can be used to interact with
+   * the stream.
+   *
+   * @since 2.0.0
+   */
+  def stream(path: String): ContinuousQuery = {
+    option("path", path).stream()
+  }
+
+  /**
+   * Starts the execution of the streaming query, which will continually output results to the given
+   * path as new data arrives. The returned [[ContinuousQuery]] object can be used to interact with
+   * the stream.
+   *
+   * @since 2.0.0
+   */
+  def stream(): ContinuousQuery = {
+    val sink = ResolvedDataSource.createSink(
+      df.sqlContext,
+      source,
+      extraOptions.toMap,
+      normalizedParCols.getOrElse(Nil))
+
+    new StreamExecution(df.sqlContext, df.logicalPlan, sink)
+  }
+
   /**
    * Inserts the content of the [[DataFrame]] to the specified table. It requires that
    * the schema of the [[DataFrame]] is the same as the schema of the table.
@@ -255,7 +284,7 @@ final class DataFrameWriter private[sql](df: DataFrame) {
 
   /**
    * The given column name may not be equal to any of the existing column names if we were in
-   * case-insensitive context.  Normalize the given column name to the real one so that we don't
+   * case-insensitive context. Normalize the given column name to the real one so that we don't
    * need to care about case sensitivity afterwards.
    */
   private def normalize(columnName: String, columnType: String): String = {
@@ -339,7 +368,6 @@ final class DataFrameWriter private[sql](df: DataFrame) {
    * @param connectionProperties JDBC database connection arguments, a list of arbitrary string
    *                             tag/value. Normally at least a "user" and "password" property
    *                             should be included.
-   *
    * @since 1.4.0
    */
   def jdbc(url: String, table: String, connectionProperties: Properties): Unit = {