/*
* 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.cassandra.gms;
import java.io.*;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.TimeUnit;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.io.FSWriteError;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.utils.BoundedStatsDeque;
import org.apache.cassandra.utils.FBUtilities;
/**
* This FailureDetector is an implementation of the paper titled
* "The Phi Accrual Failure Detector" by Hayashibara.
* Check the paper and the <i>IFailureDetector</i> interface for details.
*/
public class FailureDetector implements IFailureDetector, FailureDetectorMBean
{
private static final Logger logger = LoggerFactory.getLogger(FailureDetector.class);
public static final String MBEAN_NAME = "org.apache.cassandra.net:type=FailureDetector";
private static final int SAMPLE_SIZE = 1000;
protected static final long INITIAL_VALUE_NANOS = TimeUnit.NANOSECONDS.convert(getInitialValue(), TimeUnit.MILLISECONDS);
public static final IFailureDetector instance = new FailureDetector();
// this is useless except to provide backwards compatibility in phi_convict_threshold,
// because everyone seems pretty accustomed to the default of 8, and users who have
// already tuned their phi_convict_threshold for their own environments won't need to
// change.
private final double PHI_FACTOR = 1.0 / Math.log(10.0); // 0.434...
private final Map<InetAddress, ArrivalWindow> arrivalSamples = new Hashtable<InetAddress, ArrivalWindow>();
private final List<IFailureDetectionEventListener> fdEvntListeners = new CopyOnWriteArrayList<IFailureDetectionEventListener>();
public FailureDetector()
{
// Register this instance with JMX
try
{
MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
mbs.registerMBean(this, new ObjectName(MBEAN_NAME));
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}
private static long getInitialValue()
{
String newvalue = System.getProperty("cassandra.fd_initial_value_ms");
if (newvalue == null)
{
return Gossiper.intervalInMillis * 2;
}
else
{
logger.info("Overriding FD INITIAL_VALUE to {}ms", newvalue);
return Integer.parseInt(newvalue);
}
}
public String getAllEndpointStates()
{
StringBuilder sb = new StringBuilder();
for (Map.Entry<InetAddress, EndpointState> entry : Gossiper.instance.endpointStateMap.entrySet())
{
sb.append(entry.getKey()).append("\n");
appendEndpointState(sb, entry.getValue());
}
return sb.toString();
}
public Map<String, String> getSimpleStates()
{
Map<String, String> nodesStatus = new HashMap<String, String>(Gossiper.instance.endpointStateMap.size());
for (Map.Entry<InetAddress, EndpointState> entry : Gossiper.instance.endpointStateMap.entrySet())
{
if (entry.getValue().isAlive())
nodesStatus.put(entry.getKey().toString(), "UP");
else
nodesStatus.put(entry.getKey().toString(), "DOWN");
}
return nodesStatus;
}
public int getDownEndpointCount()
{
int count = 0;
for (Map.Entry<InetAddress, EndpointState> entry : Gossiper.instance.endpointStateMap.entrySet())
{
if (!entry.getValue().isAlive())
count++;
}
return count;
}
public int getUpEndpointCount()
{
int count = 0;
for (Map.Entry<InetAddress, EndpointState> entry : Gossiper.instance.endpointStateMap.entrySet())
{
if (entry.getValue().isAlive())
count++;
}
return count;
}
public String getEndpointState(String address) throws UnknownHostException
{
StringBuilder sb = new StringBuilder();
EndpointState endpointState = Gossiper.instance.getEndpointStateForEndpoint(InetAddress.getByName(address));
appendEndpointState(sb, endpointState);
return sb.toString();
}
private void appendEndpointState(StringBuilder sb, EndpointState endpointState)
{
sb.append(" generation:").append(endpointState.getHeartBeatState().getGeneration()).append("\n");
sb.append(" heartbeat:").append(endpointState.getHeartBeatState().getHeartBeatVersion()).append("\n");
for (Map.Entry<ApplicationState, VersionedValue> state : endpointState.applicationState.entrySet())
{
if (state.getKey() == ApplicationState.TOKENS)
continue;
sb.append(" ").append(state.getKey()).append(":").append(state.getValue().value).append("\n");
}
}
/**
* Dump the inter arrival times for examination if necessary.
*/
public void dumpInterArrivalTimes()
{
File file = FileUtils.createTempFile("failuredetector-", ".dat");
OutputStream os = null;
try
{
os = new BufferedOutputStream(new FileOutputStream(file, true));
os.write(toString().getBytes());
}
catch (IOException e)
{
throw new FSWriteError(e, file);
}
finally
{
FileUtils.closeQuietly(os);
}
}
public void setPhiConvictThreshold(double phi)
{
DatabaseDescriptor.setPhiConvictThreshold(phi);
}
public double getPhiConvictThreshold()
{
return DatabaseDescriptor.getPhiConvictThreshold();
}
public boolean isAlive(InetAddress ep)
{
if (ep.equals(FBUtilities.getBroadcastAddress()))
return true;
EndpointState epState = Gossiper.instance.getEndpointStateForEndpoint(ep);
// we could assert not-null, but having isAlive fail screws a node over so badly that
// it's worth being defensive here so minor bugs don't cause disproportionate
// badness. (See CASSANDRA-1463 for an example).
if (epState == null)
logger.error("unknown endpoint {}", ep);
return epState != null && epState.isAlive();
}
public void report(InetAddress ep)
{
if (logger.isTraceEnabled())
logger.trace("reporting {}", ep);
long now = System.nanoTime();
ArrivalWindow heartbeatWindow = arrivalSamples.get(ep);
if (heartbeatWindow == null)
{
// avoid adding an empty ArrivalWindow to the Map
heartbeatWindow = new ArrivalWindow(SAMPLE_SIZE);
heartbeatWindow.add(now, ep);
arrivalSamples.put(ep, heartbeatWindow);
}
else
{
heartbeatWindow.add(now, ep);
}
}
public void interpret(InetAddress ep)
{
ArrivalWindow hbWnd = arrivalSamples.get(ep);
if (hbWnd == null)
{
return;
}
long now = System.nanoTime();
double phi = hbWnd.phi(now);
if (logger.isTraceEnabled())
logger.trace("PHI for " + ep + " : " + phi);
if (PHI_FACTOR * phi > getPhiConvictThreshold())
{
logger.trace("notifying listeners that {} is down", ep);
logger.trace("intervals: {} mean: {}", hbWnd, hbWnd.mean());
for (IFailureDetectionEventListener listener : fdEvntListeners)
{
listener.convict(ep, phi);
}
}
}
public void forceConviction(InetAddress ep)
{
logger.debug("Forcing conviction of {}", ep);
for (IFailureDetectionEventListener listener : fdEvntListeners)
{
listener.convict(ep, getPhiConvictThreshold());
}
}
public void remove(InetAddress ep)
{
arrivalSamples.remove(ep);
}
public void registerFailureDetectionEventListener(IFailureDetectionEventListener listener)
{
fdEvntListeners.add(listener);
}
public void unregisterFailureDetectionEventListener(IFailureDetectionEventListener listener)
{
fdEvntListeners.remove(listener);
}
public String toString()
{
StringBuilder sb = new StringBuilder();
Set<InetAddress> eps = arrivalSamples.keySet();
sb.append("-----------------------------------------------------------------------");
for (InetAddress ep : eps)
{
ArrivalWindow hWnd = arrivalSamples.get(ep);
sb.append(ep + " : ");
sb.append(hWnd.toString());
sb.append(System.getProperty("line.separator"));
}
sb.append("-----------------------------------------------------------------------");
return sb.toString();
}
public static void main(String[] args)
{
}
}
class ArrivalWindow
{
private static final Logger logger = LoggerFactory.getLogger(ArrivalWindow.class);
private long tLast = 0L;
private final BoundedStatsDeque arrivalIntervals;
// this is useless except to provide backwards compatibility in phi_convict_threshold,
// because everyone seems pretty accustomed to the default of 8, and users who have
// already tuned their phi_convict_threshold for their own environments won't need to
// change.
private final double PHI_FACTOR = 1.0 / Math.log(10.0);
// in the event of a long partition, never record an interval longer than the rpc timeout,
// since if a host is regularly experiencing connectivity problems lasting this long we'd
// rather mark it down quickly instead of adapting
// this value defaults to the same initial value the FD is seeded with
private final long MAX_INTERVAL_IN_NANO = getMaxInterval();
ArrivalWindow(int size)
{
arrivalIntervals = new BoundedStatsDeque(size);
}
private static long getMaxInterval()
{
String newvalue = System.getProperty("cassandra.fd_max_interval_ms");
if (newvalue == null)
{
return FailureDetector.INITIAL_VALUE_NANOS;
}
else
{
logger.info("Overriding FD MAX_INTERVAL to {}ms", newvalue);
return TimeUnit.NANOSECONDS.convert(Integer.parseInt(newvalue), TimeUnit.MILLISECONDS);
}
}
synchronized void add(long value, InetAddress ep)
{
assert tLast >= 0;
if (tLast > 0L)
{
long interArrivalTime = (value - tLast);
if (interArrivalTime <= MAX_INTERVAL_IN_NANO)
arrivalIntervals.add(interArrivalTime);
else
logger.debug("Ignoring interval time of {} for {}", interArrivalTime, ep);
}
else
{
// We use a very large initial interval since the "right" average depends on the cluster size
// and it's better to err high (false negatives, which will be corrected by waiting a bit longer)
// than low (false positives, which cause "flapping").
arrivalIntervals.add(FailureDetector.INITIAL_VALUE_NANOS);
}
tLast = value;
}
double mean()
{
return arrivalIntervals.mean();
}
// see CASSANDRA-2597 for an explanation of the math at work here.
double phi(long tnow)
{
assert arrivalIntervals.size() > 0 && tLast > 0; // should not be called before any samples arrive
long t = tnow - tLast;
return t / mean();
}
public String toString()
{
return StringUtils.join(arrivalIntervals.iterator(), " ");
}
}