| /** |
| * 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 com.datatorrent.lib.algo; |
| |
| import java.util.HashMap; |
| |
| import com.datatorrent.api.DefaultInputPort; |
| import com.datatorrent.api.DefaultOutputPort; |
| import com.datatorrent.api.Operator.Unifier; |
| import com.datatorrent.api.annotation.OperatorAnnotation; |
| |
| import com.datatorrent.lib.util.BaseKeyOperator; |
| |
| /** |
| * This operator computes and emits distinct tuples of type K (i.e drops duplicates) at end of window. |
| * <p> |
| * Computes and emits distinct tuples of type K (i.e drops duplicates) at end of window |
| * </p> |
| * <p> |
| * <br> |
| * This module is same as a "FirstOf" metric on any key, val pair |
| * Even though this module produces continuous tuples, at end of window all data is flushed. Thus the data set is windowed |
| * and no history is kept of previous windows<br> |
| * <br> |
| * <b>StateFull : Yes, </b> tuple are compare across application window(s). <br> |
| * <b>Partitions : Yes, </b> distinct output is unified by same operator. <br> |
| * <br> |
| * <b>Ports</b><br> |
| * <b>data</b>: Input data port expects K<br> |
| * <b>distinct</b>: Output data port, emits K<br> |
| * <br> |
| * <b>Properties</b>: None<br> |
| * <br> |
| * </p> |
| * |
| * @displayName Emit Distinct |
| * @category Rules and Alerts |
| * @tags filter, unique |
| * |
| * @since 0.3.3 |
| */ |
| |
| @OperatorAnnotation(partitionable = true) |
| public class Distinct<K> extends BaseKeyOperator<K> implements Unifier<K> |
| { |
| /** |
| * Distinct key map. |
| */ |
| protected HashMap<K, Object> map = new HashMap<K, Object>(); |
| |
| /** |
| * The input port on which tuples are received. |
| */ |
| public final transient DefaultInputPort<K> data = new DefaultInputPort<K>() |
| { |
| /** |
| * Process HashMap<K,V> tuple on input port data, and emits if match not found. Updates the cache |
| * with new key,val pair |
| */ |
| @Override |
| public void process(K tuple) |
| { |
| Distinct.this.process(tuple); |
| } |
| }; |
| |
| /** |
| * The output port on which distinct values are emitted. |
| */ |
| public final transient DefaultOutputPort<K> distinct = new DefaultOutputPort<K>() |
| { |
| @Override |
| public Unifier<K> getUnifier() |
| { |
| return new Distinct<K>(); |
| } |
| }; |
| |
| /** |
| * Clears the cache/hash |
| */ |
| @Override |
| public void endWindow() |
| { |
| map.clear(); |
| } |
| |
| @Override |
| public void process(K tuple) |
| { |
| if (!map.containsKey(tuple)) { |
| distinct.emit(cloneKey(tuple)); |
| map.put(cloneKey(tuple), null); |
| } |
| } |
| } |