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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.discovery.zen;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ClusterStateUpdateTask;
import org.elasticsearch.cluster.NotMasterException;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.cluster.service.MasterService;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.ConnectTransportException;
import org.elasticsearch.transport.TransportChannel;
import org.elasticsearch.transport.TransportException;
import org.elasticsearch.transport.TransportRequest;
import org.elasticsearch.transport.TransportRequestHandler;
import org.elasticsearch.transport.TransportRequestOptions;
import org.elasticsearch.transport.TransportResponse;
import org.elasticsearch.transport.TransportResponseHandler;
import org.elasticsearch.transport.TransportService;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A fault detection that pings the master periodically to see if its alive.
*/
public class MasterFaultDetection extends FaultDetection {
private static final Logger logger = LogManager.getLogger(MasterFaultDetection.class);
public static final String MASTER_PING_ACTION_NAME = "internal:discovery/zen/fd/master_ping";
public interface Listener {
/** called when pinging the master failed, like a timeout, transport disconnects etc */
void onMasterFailure(DiscoveryNode masterNode, Throwable cause, String reason);
}
private final MasterService masterService;
private final java.util.function.Supplier clusterStateSupplier;
private final CopyOnWriteArrayList listeners = new CopyOnWriteArrayList<>();
private volatile MasterPinger masterPinger;
private final Object masterNodeMutex = new Object();
private volatile DiscoveryNode masterNode;
private volatile int retryCount;
private final AtomicBoolean notifiedMasterFailure = new AtomicBoolean();
public MasterFaultDetection(Settings settings, ThreadPool threadPool, TransportService transportService,
java.util.function.Supplier clusterStateSupplier, MasterService masterService,
ClusterName clusterName) {
super(settings, threadPool, transportService, clusterName);
this.clusterStateSupplier = clusterStateSupplier;
this.masterService = masterService;
logger.debug("[master] uses ping_interval [{}], ping_timeout [{}], ping_retries [{}]", pingInterval, pingRetryTimeout,
pingRetryCount);
transportService.registerRequestHandler(
MASTER_PING_ACTION_NAME, ThreadPool.Names.SAME, false, false, MasterPingRequest::new, new MasterPingRequestHandler());
}
public DiscoveryNode masterNode() {
return this.masterNode;
}
public void addListener(Listener listener) {
listeners.add(listener);
}
public void removeListener(Listener listener) {
listeners.remove(listener);
}
public void restart(DiscoveryNode masterNode, String reason) {
synchronized (masterNodeMutex) {
if (logger.isDebugEnabled()) {
logger.debug("[master] restarting fault detection against master [{}], reason [{}]", masterNode, reason);
}
innerStop();
innerStart(masterNode);
}
}
private void innerStart(final DiscoveryNode masterNode) {
this.masterNode = masterNode;
this.retryCount = 0;
this.notifiedMasterFailure.set(false);
if (masterPinger != null) {
masterPinger.stop();
}
this.masterPinger = new MasterPinger();
// we start pinging slightly later to allow the chosen master to complete it's own master election
threadPool.schedule(masterPinger, pingInterval, ThreadPool.Names.SAME);
}
public void stop(String reason) {
synchronized (masterNodeMutex) {
if (masterNode != null) {
if (logger.isDebugEnabled()) {
logger.debug("[master] stopping fault detection against master [{}], reason [{}]", masterNode, reason);
}
}
innerStop();
}
}
private void innerStop() {
// also will stop the next ping schedule
this.retryCount = 0;
if (masterPinger != null) {
masterPinger.stop();
masterPinger = null;
}
this.masterNode = null;
}
@Override
public void close() {
super.close();
stop("closing");
this.listeners.clear();
}
@Override
protected void handleTransportDisconnect(DiscoveryNode node) {
synchronized (masterNodeMutex) {
if (!node.equals(this.masterNode)) {
return;
}
if (connectOnNetworkDisconnect) {
try {
transportService.connectToNode(node);
// if all is well, make sure we restart the pinger
if (masterPinger != null) {
masterPinger.stop();
}
this.masterPinger = new MasterPinger();
// we use schedule with a 0 time value to run the pinger on the pool as it will run on later
threadPool.schedule(masterPinger, TimeValue.timeValueMillis(0), ThreadPool.Names.SAME);
} catch (Exception e) {
logger.trace("[master] [{}] transport disconnected (with verified connect)", masterNode);
notifyMasterFailure(masterNode, null, "transport disconnected (with verified connect)");
}
} else {
logger.trace("[master] [{}] transport disconnected", node);
notifyMasterFailure(node, null, "transport disconnected");
}
}
}
private void notifyMasterFailure(final DiscoveryNode masterNode, final Throwable cause, final String reason) {
if (notifiedMasterFailure.compareAndSet(false, true)) {
try {
threadPool.generic().execute(() -> {
for (Listener listener : listeners) {
listener.onMasterFailure(masterNode, cause, reason);
}
});
} catch (EsRejectedExecutionException e) {
logger.error("master failure notification was rejected, it's highly likely the node is shutting down", e);
}
stop("master failure, " + reason);
}
}
private class MasterPinger implements Runnable {
private volatile boolean running = true;
public void stop() {
this.running = false;
}
@Override
public void run() {
if (!running) {
// return and don't spawn...
return;
}
final DiscoveryNode masterToPing = masterNode;
if (masterToPing == null) {
// master is null, should not happen, but we are still running, so reschedule
threadPool.schedule(MasterPinger.this, pingInterval, ThreadPool.Names.SAME);
return;
}
final MasterPingRequest request = new MasterPingRequest(
clusterStateSupplier.get().nodes().getLocalNode(), masterToPing, clusterName);
final TransportRequestOptions options = TransportRequestOptions.builder().withType(TransportRequestOptions.Type.PING)
.withTimeout(pingRetryTimeout).build();
transportService.sendRequest(masterToPing, MASTER_PING_ACTION_NAME, request, options,
new TransportResponseHandler() {
@Override
public MasterPingResponseResponse read(StreamInput in) throws IOException {
return new MasterPingResponseResponse(in);
}
@Override
public void handleResponse(MasterPingResponseResponse response) {
if (!running) {
return;
}
// reset the counter, we got a good result
MasterFaultDetection.this.retryCount = 0;
// check if the master node did not get switched on us..., if it did, we simply return with no reschedule
if (masterToPing.equals(MasterFaultDetection.this.masterNode())) {
// we don't stop on disconnection from master, we keep pinging it
threadPool.schedule(MasterPinger.this, pingInterval, ThreadPool.Names.SAME);
}
}
@Override
public void handleException(TransportException exp) {
if (!running) {
return;
}
synchronized (masterNodeMutex) {
// check if the master node did not get switched on us...
if (masterToPing.equals(MasterFaultDetection.this.masterNode())) {
if (exp instanceof ConnectTransportException || exp.getCause() instanceof ConnectTransportException) {
handleTransportDisconnect(masterToPing);
return;
} else if (exp.getCause() instanceof NotMasterException) {
logger.debug("[master] pinging a master {} that is no longer a master", masterNode);
notifyMasterFailure(masterToPing, exp, "no longer master");
return;
} else if (exp.getCause() instanceof ThisIsNotTheMasterYouAreLookingForException) {
logger.debug("[master] pinging a master {} that is not the master", masterNode);
notifyMasterFailure(masterToPing, exp,"not master");
return;
} else if (exp.getCause() instanceof NodeDoesNotExistOnMasterException) {
logger.debug("[master] pinging a master {} but we do not exists on it, act as if its master failure"
, masterNode);
notifyMasterFailure(masterToPing, exp,"do not exists on master, act as master failure");
return;
}
int retryCount = ++MasterFaultDetection.this.retryCount;
logger.trace(() -> new ParameterizedMessage(
"[master] failed to ping [{}], retry [{}] out of [{}]",
masterNode, retryCount, pingRetryCount), exp);
if (retryCount >= pingRetryCount) {
logger.debug("[master] failed to ping [{}], tried [{}] times, each with maximum [{}] timeout",
masterNode, pingRetryCount, pingRetryTimeout);
// not good, failure
notifyMasterFailure(masterToPing, null, "failed to ping, tried [" + pingRetryCount
+ "] times, each with maximum [" + pingRetryTimeout + "] timeout");
} else {
// resend the request, not reschedule, rely on send timeout
transportService.sendRequest(masterToPing, MASTER_PING_ACTION_NAME, request, options, this);
}
}
}
}
@Override
public String executor() {
return ThreadPool.Names.SAME;
}
}
);
}
}
/** Thrown when a ping reaches the wrong node */
public static class ThisIsNotTheMasterYouAreLookingForException extends IllegalStateException {
public ThisIsNotTheMasterYouAreLookingForException(String msg) {
super(msg);
}
public ThisIsNotTheMasterYouAreLookingForException() {
}
@Override
public Throwable fillInStackTrace() {
return null;
}
}
static class NodeDoesNotExistOnMasterException extends IllegalStateException {
@Override
public Throwable fillInStackTrace() {
return null;
}
}
private class MasterPingRequestHandler implements TransportRequestHandler {
@Override
public void messageReceived(final MasterPingRequest request, final TransportChannel channel, Task task) throws Exception {
final DiscoveryNodes nodes = clusterStateSupplier.get().nodes();
// check if we are really the same master as the one we seemed to be think we are
// this can happen if the master got "kill -9" and then another node started using the same port
if (!request.masterNode.equals(nodes.getLocalNode())) {
throw new ThisIsNotTheMasterYouAreLookingForException();
}
// ping from nodes of version < 1.4.0 will have the clustername set to null
if (request.clusterName != null && !request.clusterName.equals(clusterName)) {
logger.trace("master fault detection ping request is targeted for a different [{}] cluster then us [{}]",
request.clusterName, clusterName);
throw new ThisIsNotTheMasterYouAreLookingForException("master fault detection ping request is targeted for a different ["
+ request.clusterName + "] cluster then us [" + clusterName + "]");
}
// when we are elected as master or when a node joins, we use a cluster state update thread
// to incorporate that information in the cluster state. That cluster state is published
// before we make it available locally. This means that a master ping can come from a node
// that has already processed the new CS but it is not known locally.
// Therefore, if we fail we have to check again under a cluster state thread to make sure
// all processing is finished.
//
if (!nodes.isLocalNodeElectedMaster() || !nodes.nodeExists(request.sourceNode)) {
logger.trace("checking ping from {} under a cluster state thread", request.sourceNode);
masterService.submitStateUpdateTask("master ping (from: " + request.sourceNode + ")", new ClusterStateUpdateTask() {
@Override
public ClusterState execute(ClusterState currentState) throws Exception {
// if we are no longer master, fail...
DiscoveryNodes nodes = currentState.nodes();
if (!nodes.nodeExists(request.sourceNode)) {
throw new NodeDoesNotExistOnMasterException();
}
return currentState;
}
@Override
public void onNoLongerMaster(String source) {
onFailure(source, new NotMasterException("local node is not master"));
}
@Override
public void onFailure(String source, @Nullable Exception e) {
if (e == null) {
e = new ElasticsearchException("unknown error while processing ping");
}
try {
channel.sendResponse(e);
} catch (IOException inner) {
inner.addSuppressed(e);
logger.warn("error while sending ping response", inner);
}
}
@Override
public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
try {
channel.sendResponse(new MasterPingResponseResponse());
} catch (IOException e) {
logger.warn("error while sending ping response", e);
}
}
});
} else {
// send a response, and note if we are connected to the master or not
channel.sendResponse(new MasterPingResponseResponse());
}
}
}
public static class MasterPingRequest extends TransportRequest {
public DiscoveryNode sourceNode;
private DiscoveryNode masterNode;
private ClusterName clusterName;
public MasterPingRequest(StreamInput in) throws IOException {
super(in);
sourceNode = new DiscoveryNode(in);
masterNode = new DiscoveryNode(in);
clusterName = new ClusterName(in);
}
public MasterPingRequest(DiscoveryNode sourceNode, DiscoveryNode masterNode, ClusterName clusterName) {
this.sourceNode = sourceNode;
this.masterNode = masterNode;
this.clusterName = clusterName;
}
@Override
public void writeTo(StreamOutput out) throws IOException {
super.writeTo(out);
sourceNode.writeTo(out);
masterNode.writeTo(out);
clusterName.writeTo(out);
}
}
public static class MasterPingResponseResponse extends TransportResponse {
public MasterPingResponseResponse() {
}
public MasterPingResponseResponse(StreamInput in) throws IOException {
super(in);
}
@Override
public void writeTo(StreamOutput out) throws IOException {}
}
}