library/src/main/java/com/datatorrent/lib/math/ChangeAlertKeyVal.java

/*
 * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved.
 *
 * 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 com.datatorrent.lib.math;

import java.util.HashMap;

import javax.validation.constraints.Min;

import org.apache.commons.lang.mutable.MutableDouble;

import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.lib.util.BaseNumberKeyValueOperator;
import com.datatorrent.lib.util.KeyValPair;

/**
 * Operator compares consecutive values arriving at input port mapped by keys, emits <key,percent change> pair on output alert port if percent change exceeds percentage threshold set in operator.
 * <p>
 * StateFull : Yes, current key/value is stored in operator for comparison in
 * next successive windows. <br>
 * Partition(s): No, base comparison value will be inconsistent across
 * instantiated copies. <br>
 * <br>
 * <b>Ports</b>:<br>
 * <b>data</b>: expects KeyValPair&lt;K,V extends Number&gt;<br>
 * <b>alert</b>: emits KeyValPair&lt;K,KeyValPair&lt;V,Double&gt;&gt;(1)<br>
 * <br>
 * <b>Properties</b>:<br>
 * <b>threshold</b>: The threshold of change between consecutive tuples of the
 * same key that triggers an alert tuple<br>
 * <b>inverse</b>: if set to true the key in the filter will block tuple<br>
 * <b>filterBy</b>: List of keys to filter on<br>
 * @displayName Change Alert Key Value
 * @category Math
 * @tags change, key value, numeric, percentage
 * @since 0.3.3
 */
public class ChangeAlertKeyVal<K, V extends Number> extends
		BaseNumberKeyValueOperator<K, V>
{
	/**
	 * Base map is a StateFull field. It is retained across windows
	 */
	private HashMap<K, MutableDouble> basemap = new HashMap<K, MutableDouble>();

	/**
	 * Input data port that takes a key value pair.
	 */
	public final transient DefaultInputPort<KeyValPair<K, V>> data = new DefaultInputPort<KeyValPair<K, V>>()
	{
		/**
		 * Process each key, compute change or percent, and emit it.
		 */
		@Override
		public void process(KeyValPair<K, V> tuple)
		{
			K key = tuple.getKey();
			double tval = tuple.getValue().doubleValue();
			MutableDouble val = basemap.get(key);
			if (!doprocessKey(key)) {
				return;
			}
			if (val == null) { // Only process keys that are in the basemap
				val = new MutableDouble(tval);
				basemap.put(cloneKey(key), val);
				return;
			}
			double change = tval - val.doubleValue();
			double percent = (change / val.doubleValue()) * 100;
			if (percent < 0.0) {
				percent = 0.0 - percent;
			}
			if (percent > percentThreshold) {
				KeyValPair<V, Double> dmap = new KeyValPair<V, Double>(
						cloneValue(tuple.getValue()), percent);
				KeyValPair<K, KeyValPair<V, Double>> otuple = new KeyValPair<K, KeyValPair<V, Double>>(
						cloneKey(key), dmap);
				alert.emit(otuple);
			}
			val.setValue(tval);
		}
	};
	
	/**
	 * Key,Percent Change output port.
	 */
	public final transient DefaultOutputPort<KeyValPair<K, KeyValPair<V, Double>>> alert = new DefaultOutputPort<KeyValPair<K, KeyValPair<V, Double>>>();

	/**
	 * Alert thresh hold percentage set by application.
	 */
	@Min(1)
	private double percentThreshold = 0.0;

	/**
	 * getter function for threshold value
	 * 
	 * @return threshold value
	 */
	@Min(1)
	public double getPercentThreshold()
	{
		return percentThreshold;
	}

	/**
	 * setter function for threshold value
	 */
	public void setPercentThreshold(double d)
	{
		percentThreshold = d;
	}
}