com.netflix.control.IController Maven / Gradle / Ivy
/*
* Copyright 2019 Netflix, Inc.
*
* 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.netflix.control;
import rx.Observable;
import rx.Subscriber;
/**
* The Feedback Principle: Constantly compare the actual output to the
* setpoint; then apply a corrective action in the proper direction and
* approximately of the correct size.
*
* Iteratively applying changes in the correct direction allows this
* system to converge onto the correct value over time.
*
*/
public abstract class IController implements Observable.Operator {
private final IController parent = this;
/**
* Implementation method for Controller components. Surrounding RxJava machinery will call this method.
*
* @param value Input from previous stage of control loop processing.
* @return Output intended for next stage of control loop processing.
*/
protected abstract Double processStep(Double value);
@Override
public Subscriber call(final Subscriber s) {
return new Subscriber(s) {
@Override
public void onCompleted() {
if (!s.isUnsubscribed()) {
s.onCompleted();
}
}
@Override
public void onError(Throwable t) {
if (!s.isUnsubscribed()) {
s.onError(t);
}
}
@Override
public void onNext(Double error) {
Double controlAction = parent.processStep(error);
if (!s.isUnsubscribed()) {
s.onNext(controlAction);
}
}
};
}
}