/*
* 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 org.apache.nifi.cluster.coordination.http.replication;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import org.apache.nifi.cluster.protocol.NodeIdentifier;
public class ResponseUtils {
/**
* Finds the Node Identifier for all nodes that had a 'slow' response time. A 'slow' response time
* is defined as being more than X standard deviations from the mean response time, where X is the
* given Standard Deviation Multiple
*
* @param response the AsyncClusterResponse to base the calculations off of
* @param stdDeviationMultiple the number of standard deviations that a response time must be away from the mean in order
* to be considered 'slow'
*
* @return a Set of all Node Identifiers that took a long time to respond
*/
public static Set<NodeIdentifier> findLongResponseTimes(final AsyncClusterResponse response, final double stdDeviationMultiple) {
final Set<NodeIdentifier> slowResponses = new HashSet<>();
if (response.isOlderThan(1, TimeUnit.SECONDS)) {
// If the response is older than 2 seconds, determines if any node took a long time to respond.
final Set<NodeIdentifier> completedIds = response.getCompletedNodeIdentifiers();
if (completedIds.size() < 2) {
return slowResponses;
}
long requestMillisSum = 0L;
int numNodes = 0;
for (final NodeIdentifier nodeId : completedIds) {
final long requestMillis = response.getNodeResponse(nodeId).getRequestDuration(TimeUnit.NANOSECONDS);
if (requestMillis < 0) {
continue;
}
requestMillisSum += requestMillis;
numNodes++;
}
if (numNodes < 2) {
return slowResponses;
}
final double mean = requestMillisSum / numNodes;
double differenceSquaredSum = 0D;
for (final NodeIdentifier nodeId : completedIds) {
final long requestMillis = response.getNodeResponse(nodeId).getRequestDuration(TimeUnit.NANOSECONDS);
final double differenceSquared = Math.pow(mean - requestMillis, 2);
differenceSquaredSum += differenceSquared;
}
final double meanOfDifferenceSquared = differenceSquaredSum / numNodes;
final double stdDev = Math.pow(meanOfDifferenceSquared, 0.5D);
final double longTimeThreshold = mean + stdDev * stdDeviationMultiple;
for (final NodeIdentifier nodeId : completedIds) {
final long requestMillis = response.getNodeResponse(nodeId).getRequestDuration(TimeUnit.NANOSECONDS);
if (requestMillis > longTimeThreshold) {
slowResponses.add(nodeId);
}
}
}
return slowResponses;
}
}