com.datatorrent.lib.math.ChangeAlert Maven / Gradle / Ivy
/**
* 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.math;
import javax.validation.constraints.Min;
import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.lib.util.BaseNumberValueOperator;
import com.datatorrent.lib.util.KeyValPair;
/**
* Compares consecutive input data values, emits <value,percent change value> pair on alert output port, if percent change exceeds certain thresh hold value.
*
* Operator is StateFull since current value is stored for comparison in next window.
* This operator can not be partitioned, partitioning will result in inconsistent base value
* across replicated copies.
*
*
* Ports:
* data: expects KeyValPair<K,V extends Number>
* alert: emits KeyValPair<K,KeyValPair<V,Double>>(1)
*
* Properties:
* threshold: The threshold of change between consecutive tuples of the
* same key that triggers an alert tuple
* inverse: if set to true the key in the filter will block tuple
* filterBy: List of keys to filter on
*
* Specific compile time checks: None
* Specific run time checks: None
*
* @displayName Change Alert
* @category Rules and Alerts
* @tags change, key value, numeric, percentage
* @since 0.3.3
*/
public class ChangeAlert extends BaseNumberValueOperator
{
/**
* Input port that takes in a number.
*/
public final transient DefaultInputPort data = new DefaultInputPort()
{
/**
* Process each key, compute change or percent, and emit it. If we get 0 as
* tuple next will be skipped.
*/
@Override
public void process(V tuple)
{
double tval = tuple.doubleValue();
if (baseValue == 0) { // Avoid divide by zero, Emit an error tuple?
baseValue = tval;
return;
}
double change = tval - baseValue;
double percent = (change / baseValue) * 100;
if (percent < 0.0) {
percent = 0.0 - percent;
}
if (percent > percentThreshold) {
KeyValPair kv = new KeyValPair(cloneKey(tuple),
percent);
alert.emit(kv);
}
baseValue = tval;
}
};
/**
* Output port which emits a key value pair.
*/
public final transient DefaultOutputPort> alert = new DefaultOutputPort>();
/**
* baseValue is a state full field. It is retained across windows
*/
private double baseValue = 0;
@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;
}
}