| /* |
| * 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.gossip.accrual; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.commons.math.MathException; |
| import org.apache.commons.math.distribution.ExponentialDistributionImpl; |
| import org.apache.commons.math.stat.descriptive.DescriptiveStatistics; |
| import org.apache.gossip.LocalGossipMember; |
| import org.apache.log4j.Logger; |
| |
| public class FailureDetector { |
| |
| private static final Logger LOGGER = Logger.getLogger(FailureDetector.class); |
| private final DescriptiveStatistics descriptiveStatistics; |
| private final long minimumSamples; |
| private volatile long latestHeartbeatMs = -1; |
| private final LocalGossipMember parent; |
| |
| public FailureDetector(LocalGossipMember parent, long minimumSamples, int windowSize){ |
| this.parent = parent; |
| descriptiveStatistics = new DescriptiveStatistics(windowSize); |
| this.minimumSamples = minimumSamples; |
| } |
| |
| /** |
| * Updates the statistics based on the delta between the last |
| * heartbeat and supplied time |
| * @param now the time of the heartbeat in milliseconds |
| */ |
| public void recordHeartbeat(long now){ |
| if (now < latestHeartbeatMs) |
| return; |
| synchronized (descriptiveStatistics) { |
| if (latestHeartbeatMs != -1){ |
| descriptiveStatistics.addValue(now - latestHeartbeatMs); |
| } else { |
| latestHeartbeatMs = now; |
| } |
| } |
| } |
| |
| public Double computePhiMeasure(long now) { |
| if (latestHeartbeatMs == -1 || descriptiveStatistics.getN() < minimumSamples) { |
| LOGGER.debug( |
| String.format( "%s latests %s samples %s minumumSamples %s", parent.getId(), latestHeartbeatMs, descriptiveStatistics.getN(), minimumSamples)); |
| return null; |
| } |
| synchronized (descriptiveStatistics) { |
| long delta = now - latestHeartbeatMs; |
| try { |
| //double probability = 1.0d - new NormalDistributionImpl(descriptiveStatistics.getMean(), descriptiveStatistics.getVariance()).cumulativeProbability(delta); |
| double probability = 1.0d - new ExponentialDistributionImpl(descriptiveStatistics.getMean()).cumulativeProbability(delta); |
| //LOGGER.warn (parent.getId() + " worked "+ -1.0d * Math.log10(probability)); |
| return -1.0d * Math.log10(probability); |
| } catch (MathException | IllegalArgumentException e) { |
| //LOGGER.warn(parent.getId() + " Exception while computing phi", e); |
| //LOGGER.warn(descriptiveStatistics); |
| //LOGGER.warn(descriptiveStatistics.getMean()); |
| List<Double> x = new ArrayList<>(); |
| for (double z : descriptiveStatistics.getValues()){ |
| x.add(z); |
| } |
| //LOGGER.warn(x); |
| //LOGGER.warn(parent.getId() + " " + descriptiveStatistics); |
| throw new IllegalArgumentException(e); |
| } |
| } |
| } |
| } |