| /** |
| * 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.stream; |
| |
| import com.datatorrent.api.Context.OperatorContext; |
| import com.datatorrent.api.DefaultInputPort; |
| import com.datatorrent.api.DefaultOutputPort; |
| import com.datatorrent.api.Operator; |
| import com.datatorrent.api.Operator.Unifier; |
| |
| /** |
| * An implementation of Operator and Unifier that counts the number of tuples delivered to it in each window and emits the count. |
| * <p> |
| * This is a pass through operator<br> |
| * <br> |
| * <b>StateFull : Yes</b>, tuples are counted over application window. <br> |
| * <b>Partitions : Yes</b>, count is unified at output port. <br> |
| * <b>Ports</b>:<br> |
| * <b>input</b>: expects Object<br> |
| * <b>output</b>: emits Integer<br> |
| * <br> |
| * @displayName Counter |
| * @category Stream Manipulators |
| * @tags integer, object, count |
| * @since 0.3.3 |
| */ |
| public class Counter implements Operator, Unifier<Integer> |
| { |
| /** |
| * Input port that takes objects to be counted in each window. |
| */ |
| public final transient DefaultInputPort<Object> input = new DefaultInputPort<Object>() |
| { |
| @Override |
| public void process(Object tuple) |
| { |
| Counter.this.count++; |
| } |
| |
| }; |
| |
| /** |
| * Output port that takes emits count in each window. |
| */ |
| public final transient DefaultOutputPort<Integer> output = new DefaultOutputPort<Integer>() |
| { |
| @Override |
| public Unifier<Integer> getUnifier() |
| { |
| return Counter.this; |
| } |
| |
| }; |
| |
| @Override |
| public void beginWindow(long windowId) |
| { |
| count = 0; |
| } |
| |
| @Override |
| public void process(Integer tuple) |
| { |
| count += tuple; |
| } |
| |
| @Override |
| public void endWindow() |
| { |
| output.emit(count); |
| } |
| |
| @Override |
| public void setup(OperatorContext context) |
| { |
| } |
| |
| @Override |
| public void teardown() |
| { |
| } |
| |
| private transient int count; |
| } |