Created new SortedGrouping to move the group order from the Grouping

stratosphere-java/src/main/java/eu/stratosphere/api/java/operators/Grouping.java

@@ -14,8 +14,6 @@
  **********************************************************************************************************************/
 package eu.stratosphere.api.java.operators;
 
-import java.util.Arrays;
-
 import eu.stratosphere.api.common.InvalidProgramException;
 import eu.stratosphere.api.common.operators.Order;
 import eu.stratosphere.api.java.DataSet;
@@ -38,12 +36,9 @@ import eu.stratosphere.api.java.functions.ReduceFunction;
  */
 public class Grouping<T> {
 	
-	private final DataSet<T> dataSet;
-	
-	private final Keys<T> keys;
+	protected final DataSet<T> dataSet;
 	
-	private int[] groupSortKeyPositions = null;
-	private Order[] groupSortOrders = null;
+	protected final Keys<T> keys;
 
 	public Grouping(DataSet<T> set, Keys<T> keys) {
 		if (set == null || keys == null) {
@@ -67,14 +62,6 @@ public class Grouping<T> {
 		return this.keys;
 	}
 	
-	protected int[] getGroupSortKeyPositions() {
-		return this.groupSortKeyPositions;
-	}
-	
-	protected Order[] getGroupSortOrders() {
-		return this.groupSortOrders;
-	}
-	
 	// --------------------------------------------------------------------------------------------
 	//  Operations / Transformations
 	// --------------------------------------------------------------------------------------------
@@ -96,9 +83,6 @@ public class Grouping<T> {
 	 * @see DataSet
 	 */
 	public AggregateOperator<T> aggregate(Aggregations agg, int field) {
-		if(this.groupSortKeyPositions != null) {
-			throw new UnsupportedOperationException("Sorted groups not supported for Aggregation operation at the moment.");
-		}
 		return new AggregateOperator<T>(this, agg, field);
 	}
 	
@@ -116,9 +100,6 @@ public class Grouping<T> {
 	 * @see DataSet
 	 */
 	public ReduceOperator<T> reduce(ReduceFunction<T> reducer) {
-		if(this.groupSortKeyPositions != null) {
-			throw new UnsupportedOperationException("Sorted groups not supported for Aggregation operation at the moment.");
-		}
 		return new ReduceOperator<T>(this, reducer);
 	}
 	
@@ -150,14 +131,16 @@ public class Grouping<T> {
 	 * 
 	 * @param field The Tuple field on which the group is sorted.
 	 * @param order The Order in which the specified Tuple field is sorted.
-	 * @return A Grouping with specified order of group element.
+	 * @return A SortedGrouping with specified order of group element.
 	 * 
 	 * @see Tuple
 	 * @see Order
 	 */
-	public Grouping<T> sortGroup(int field, Order order) {
+	public SortedGrouping<T> sortGroup(int field, Order order) {
 		
 		int pos;
+		int[] groupSortKeyPositions;
+		Order[] groupSortOrders ;
 		
 		if (!dataSet.getType().isTupleType()) {
 			throw new InvalidProgramException("Specifying order keys via field positions is only valid for tuple data types");
@@ -166,20 +149,13 @@ public class Grouping<T> {
 			throw new IllegalArgumentException("Order key out of tuple bounds.");
 		}
 		
-		if(this.groupSortKeyPositions == null) {
-			this.groupSortKeyPositions = new int[1];
-			this.groupSortOrders = new Order[1];
-			pos = 0;
-		} else {
-			int newLength = this.groupSortKeyPositions.length + 1;
-			this.groupSortKeyPositions = Arrays.copyOf(this.groupSortKeyPositions, newLength);
-			this.groupSortOrders = Arrays.copyOf(this.groupSortOrders, newLength);
-			pos = newLength - 1;
-		}
+		groupSortKeyPositions = new int[1];
+		groupSortOrders = new Order[1];
+		pos = 0;
 		
-		this.groupSortKeyPositions[pos] = field;
-		this.groupSortOrders[pos] = order;
-		return this;
+		groupSortKeyPositions[pos] = field;
+		groupSortOrders[pos] = order;
+		return new SortedGrouping<T>(this.dataSet, this.keys, groupSortKeyPositions, groupSortOrders);
 	}
 	
 //	public <K extends Comparable<K>> Grouping<T> sortGroup(KeySelector<T, K> keyExtractor, Order order) {

stratosphere-java/src/main/java/eu/stratosphere/api/java/operators/ReduceGroupOperator.java

@@ -148,10 +148,11 @@ public class ReduceGroupOperator<IN, OUT> extends SingleInputUdfOperator<IN, OUT
 			po.setDegreeOfParallelism(this.getParallelism());
 			
 			// set group order
-			if(grouper.getGroupSortKeyPositions() != null) {
+			if(grouper instanceof SortedGrouping) {
+				SortedGrouping<IN> sortedGrouper = (SortedGrouping<IN>) grouper;
 								
-				int[] sortKeyPositions = grouper.getGroupSortKeyPositions();
-				Order[] sortOrders = grouper.getGroupSortOrders();
+				int[] sortKeyPositions = sortedGrouper.getGroupSortKeyPositions();
+				Order[] sortOrders = sortedGrouper.getGroupSortOrders();
 				
 				Ordering o = new Ordering();
 				for(int i=0; i < sortKeyPositions.length; i++) {

stratosphere-java/src/main/java/eu/stratosphere/api/java/operators/SortedGrouping.java

+/***********************************************************************************************************************
+ *
+ * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
+ *
+ * Licensed 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 eu.stratosphere.api.java.operators;
+
+import java.util.Arrays;
+
+import eu.stratosphere.api.common.InvalidProgramException;
+import eu.stratosphere.api.common.operators.Order;
+import eu.stratosphere.api.java.DataSet;
+import eu.stratosphere.api.java.functions.GroupReduceFunction;
+
+/**
+ * SortedGrouping is an intermediate step for a transformation on a grouped and sorted DataSet.<br/>
+ * The following transformation can be applied on sorted groups:
+ * <ul>
+ * 	<li>{@link Grouping#reduce(ReduceFunction)},</li>
+ * </ul>
+ * 
+ * @param <T> The type of the elements of the sorted and grouped DataSet.
+ */
+public class SortedGrouping<T> extends Grouping<T> {
+	
+	private int[] groupSortKeyPositions;
+	private Order[] groupSortOrders ;
+	
+	public SortedGrouping(DataSet<T> set, Keys<T> keys, int[] groupSortKeyPositions, Order[] groupSortOrders) {
+		super(set, keys);
+		
+		if (groupSortKeyPositions == null || groupSortKeyPositions.length == 0 || groupSortOrders == null || groupSortOrders.length == 0) {
+			throw new InvalidProgramException("Key positions and sort orders must be specified in order to create a SortedGrouping.");
+		}
+		
+		this.groupSortKeyPositions = groupSortKeyPositions;
+		this.groupSortOrders = groupSortOrders;
+	}
+	
+	protected int[] getGroupSortKeyPositions() {
+		return this.groupSortKeyPositions;
+	}
+	
+	protected Order[] getGroupSortOrders() {
+		return this.groupSortOrders;
+	}
+
+	/**
+	 * Applies a GroupReduce transformation on a grouped and sorted {@link DataSet}.<br/>
+	 * The transformation calls a {@link GroupReduceFunction} for each group of the DataSet.
+	 * A GroupReduceFunction can iterate over all elements of a group and emit any
+	 *   number of output elements including none.
+	 * 
+	 * @param reducer The GroupReduceFunction that is applied on each group of the DataSet.
+	 * @return A GroupReduceOperator that represents the reduced DataSet.
+	 * 
+	 * @see GroupReduceFunction
+	 * @see GroupReduceOperator
+	 * @see DataSet
+	 */
+	public <R> ReduceGroupOperator<T, R> reduceGroup(GroupReduceFunction<T, R> reducer) {
+		return new ReduceGroupOperator<T, R>(this, reducer);
+	}
+	
+	// --------------------------------------------------------------------------------------------
+	//  Group Operations
+	// --------------------------------------------------------------------------------------------
+	
+	/**
+	 * Sorts {@link Tuple} elements within a group on the specified field in the specified {@link Order}.</br>
+	 * <b>Note: Only groups of Tuple elements can be sorted.</b><br/>
+	 * Groups can be sorted by multiple fields by chaining {@link #sortGroup(int, Order)} calls.
+	 * 
+	 * @param field The Tuple field on which the group is sorted.
+	 * @param order The Order in which the specified Tuple field is sorted.
+	 * @return A SortedGrouping with specified order of group element.
+	 * 
+	 * @see Tuple
+	 * @see Order
+	 */
+	public SortedGrouping<T> sortGroup(int field, Order order) {
+		
+		int pos;
+		
+		if (!dataSet.getType().isTupleType()) {
+			throw new InvalidProgramException("Specifying order keys via field positions is only valid for tuple data types");
+		}
+		if (field >= dataSet.getType().getArity()) {
+			throw new IllegalArgumentException("Order key out of tuple bounds.");
+		}
+		
+		int newLength = this.groupSortKeyPositions.length + 1;
+		this.groupSortKeyPositions = Arrays.copyOf(this.groupSortKeyPositions, newLength);
+		this.groupSortOrders = Arrays.copyOf(this.groupSortOrders, newLength);
+		pos = newLength - 1;
+		
+		this.groupSortKeyPositions[pos] = field;
+		this.groupSortOrders[pos] = order;
+		return this;
+	}
+}