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Camel EtcD v3 component based on jetcd
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/*
* 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.camel.component.etcd3.policy;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import io.etcd.jetcd.ByteSequence;
import io.etcd.jetcd.Client;
import io.etcd.jetcd.KV;
import io.etcd.jetcd.Lease;
import io.etcd.jetcd.Txn;
import io.etcd.jetcd.common.exception.ErrorCode;
import io.etcd.jetcd.common.exception.EtcdException;
import io.etcd.jetcd.kv.TxnResponse;
import io.etcd.jetcd.lease.LeaseKeepAliveResponse;
import io.etcd.jetcd.op.Cmp;
import io.etcd.jetcd.op.CmpTarget;
import io.etcd.jetcd.op.Op;
import io.etcd.jetcd.options.PutOption;
import org.apache.camel.CamelContext;
import org.apache.camel.CamelContextAware;
import org.apache.camel.Route;
import org.apache.camel.api.management.ManagedAttribute;
import org.apache.camel.api.management.ManagedResource;
import org.apache.camel.component.etcd3.Etcd3Configuration;
import org.apache.camel.support.RoutePolicySupport;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.apache.camel.component.etcd3.Etcd3Constants.ETCD_DEFAULT_ENDPOINTS;
/**
* An implementation of a route policy based on etcd.
*/
@ManagedResource(description = "Route policy using Etcd as clustered lock")
public class Etcd3RoutePolicy extends RoutePolicySupport implements CamelContextAware {
/**
* The logger
*/
private static final Logger LOGGER = LoggerFactory.getLogger(Etcd3RoutePolicy.class);
/**
* The flag indicating whether the current node is a leader.
*/
private final AtomicBoolean leader = new AtomicBoolean();
/**
* The routes that have been suspended.
*/
private final Set suspendedRoutes = new HashSet<>();
/**
* The time to live in seconds of a key-value pair inserted into etcd. Default value is {@code 60}.
*/
private int ttl = 60;
/**
* The timeout in seconds of all requests. Default value is {@code 10}.
*/
private int timeout = 10;
/**
* The route to which the policy is applied.
*/
private volatile Route route;
/**
* The etcd service name.
*/
private String serviceName;
/**
* The etcd service path.
*/
private String servicePath;
/**
* The camel context associated to the policy.
*/
private CamelContext camelContext;
/**
* The etcd endpoints.
*/
private String[] endpoints;
/**
* The scheduler used to evaluate regularly the leadership.
*/
private volatile ScheduledExecutorService executorService;
/**
* The flag indicating whether the consumer should be stopped.
*/
private final AtomicBoolean shouldStopConsumer = new AtomicBoolean(true);
/**
* The id of the current lease. Only set if the current node is the leader.
*/
private final AtomicLong leaseId = new AtomicLong();
/**
* The client to access to etcd.
*/
private final AtomicReference client = new AtomicReference<>();
/**
* The client to access to the key-value pairs stored into etcd.
*/
private final AtomicReference kv = new AtomicReference<>();
/**
* The client to access to the leases stored into etcd.
*/
private final AtomicReference lease = new AtomicReference<>();
/**
* The flag indicating whether the client has been created by the policy or outside the policy.
*/
private final boolean managedClient;
public Etcd3RoutePolicy() {
this(ETCD_DEFAULT_ENDPOINTS);
}
public Etcd3RoutePolicy(Etcd3Configuration configuration) {
this(configuration.createClient(), true);
}
public Etcd3RoutePolicy(Client client) {
this(client, false);
}
private Etcd3RoutePolicy(Client client, boolean managedClient) {
this.client.set(ObjectHelper.notNull(client, "client"));
this.managedClient = managedClient;
}
public Etcd3RoutePolicy(String... endpoints) {
this.endpoints = endpoints;
this.managedClient = true;
}
@Override
public void onInit(Route route) {
super.onInit(route);
this.route = route;
if (executorService == null) {
executorService = ObjectHelper.notNull(camelContext, "camelContext", this)
.getExecutorServiceManager().newSingleThreadScheduledExecutor(this,
"Etcd3RoutePolicy[" + route.getRouteId() + "]");
}
}
@Override
public void onStart(Route route) {
if (!leader.get() && shouldStopConsumer.get()) {
stopConsumer(route);
}
}
@Override
public void onStop(Route route) {
lock.lock();
try {
suspendedRoutes.remove(route);
} finally {
lock.unlock();
}
}
@Override
public void onSuspend(Route route) {
lock.lock();
try {
suspendedRoutes.remove(route);
} finally {
lock.unlock();
}
}
@Override
protected void doStart() throws Exception {
Client c = client.get();
if (c == null) {
c = Client.builder().endpoints(ObjectHelper.notNull(endpoints, "endpoints")).build();
this.client.set(c);
}
lease.set(c.getLeaseClient());
kv.set(c.getKVClient());
evaluateLeadershipAndSchedule();
super.doStart();
}
@Override
protected void doStop() throws Exception {
if (executorService != null) {
camelContext.getExecutorServiceManager().shutdownNow(executorService);
executorService = null;
}
try {
Client c = client.get();
if (managedClient && c != null) {
c.close();
}
} finally {
super.doStop();
}
}
// *************************************************************************
//
// *************************************************************************
@Override
public CamelContext getCamelContext() {
return camelContext;
}
@Override
public void setCamelContext(CamelContext camelContext) {
this.camelContext = camelContext;
}
/**
* Sets the latest leadership state of the current node and potentially triggers actions if the state has changed.
*
* @param isLeader {@code true} if the current node is the leader, {@code false} otherwise.
*/
protected void setLeader(boolean isLeader) {
if (isLeader) {
if (leader.compareAndSet(false, true)) {
LOGGER.info("Leadership taken (path={}, name={})", servicePath, serviceName);
startAllStoppedConsumers();
}
} else if (leader.compareAndSet(true, false)) {
LOGGER.info("Leadership lost (path={}, name={})", servicePath, serviceName);
}
}
/**
* Stops the consumer of the given route.
*
* @param route the route for which the consumer should be stopped.
*/
private void stopConsumer(Route route) {
lock.lock();
try {
if (!suspendedRoutes.contains(route)) {
LOGGER.debug("Stopping consumer for {} ({})", route.getId(), route.getConsumer());
stopConsumer(route.getConsumer());
suspendedRoutes.add(route);
}
} catch (Exception e) {
handleException(e);
} finally {
lock.unlock();
}
}
/**
* Start all the consumers that have been stopped.
*/
private void startAllStoppedConsumers() {
lock.lock();
try {
for (Route suspendedRoute : suspendedRoutes) {
LOGGER.debug("Starting consumer for {} ({})", suspendedRoute.getId(), suspendedRoute.getConsumer());
startConsumer(suspendedRoute.getConsumer());
}
suspendedRoutes.clear();
} catch (Exception e) {
handleException(e);
} finally {
lock.unlock();
}
}
// *************************************************************************
// Getter/Setters
// *************************************************************************
public Client getClient() {
return client.get();
}
@ManagedAttribute(description = "The route id")
public String getRouteId() {
if (route != null) {
return route.getId();
}
return null;
}
@ManagedAttribute(description = "The consumer endpoint", mask = true)
public String getEndpointUrl() {
if (route != null && route.getConsumer() != null && route.getConsumer().getEndpoint() != null) {
return route.getConsumer().getEndpoint().toString();
}
return null;
}
public String getServiceName() {
return serviceName;
}
@ManagedAttribute(description = "The etcd service name")
public void setServiceName(String serviceName) {
this.serviceName = serviceName;
}
@ManagedAttribute(description = "The etcd service path")
public String getServicePath() {
return servicePath;
}
public void setServicePath(String servicePath) {
this.servicePath = servicePath;
}
@ManagedAttribute(description = "The time to live (seconds)")
public int getTtl() {
return ttl;
}
public void setTtl(int ttl) {
this.ttl = ttl;
}
@ManagedAttribute(description = "The request timeout (seconds)")
public int getTimeout() {
return timeout;
}
public void setTimeout(int timeout) {
this.timeout = timeout;
}
@ManagedAttribute(description = "Whether to stop consumer when starting up and failed to become master")
public boolean isShouldStopConsumer() {
return shouldStopConsumer.get();
}
public void setShouldStopConsumer(boolean shouldStopConsumer) {
this.shouldStopConsumer.set(shouldStopConsumer);
}
@ManagedAttribute(description = "Is this route the master or a slave")
public boolean isLeader() {
return leader.get();
}
@ManagedAttribute(description = "Etcd endpoints")
public String getEndpoints() {
return endpoints == null ? "" : String.join(",", endpoints);
}
public void setEndpoints(String[] endpoints) {
this.endpoints = endpoints;
}
public void setEndpoints(String endpoints) {
this.endpoints = endpoints.split(",");
}
long getLeaseId() {
return leaseId.get();
}
/**
* Evaluates the leadership and schedule the next evaluation.
*/
private void evaluateLeadershipAndSchedule() {
evaluateLeadership();
executorService.schedule(this::evaluateLeadershipAndSchedule, Math.max(2 * ttl / 3, 1), TimeUnit.SECONDS);
}
/**
* In case the current node is the leader, it tries to renew the lease if it failed or the current node is a not
* leader, it tries to take the leadership.
*/
private void evaluateLeadership() {
if (isLeader() && renewLease()) {
// The lease could be renewed successfully, so the status of the node did not change
return;
}
setLeader(tryTakeLeadership());
}
/**
* Renew the lease using a KeepAlive request to avoid losing the leadership.
*
* @return {@code true} if the lease could be renewed within the timeout, {@code false} otherwise.
*/
private boolean renewLease() {
long id = leaseId.get();
if (id == 0) {
return false;
}
try {
LeaseKeepAliveResponse keepAliveResponse = lease.get().keepAliveOnce(id).get(timeout, TimeUnit.SECONDS);
LOGGER.debug("New TTL of the lease {} is {} seconds", id, keepAliveResponse.getTTL());
return true;
} catch (ExecutionException e) {
boolean notFound = false;
if (e.getCause() instanceof EtcdException) {
EtcdException ex = (EtcdException) e.getCause();
notFound = ex.getErrorCode() == ErrorCode.NOT_FOUND;
}
if (notFound) {
LOGGER.debug("The lease {} doesn't exist anymore", id);
leaseId.set(0);
} else {
LOGGER.debug("Could not renew the lease {}", id, e);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (TimeoutException e) {
LOGGER.debug("Timeout while trying to renew the lease {}", id);
}
return false;
}
/**
* Grants a new lease and tries to put a key-value pair corresponding to the {@code servicePath} if it is absent.
*
* @return {@code true} if the put operation is successful indicating that the leadership has been taken,
* {@code false} otherwise.
*/
private boolean tryTakeLeadership() {
try {
long id = lease.get().grant(ttl, timeout, TimeUnit.SECONDS).get(timeout, TimeUnit.SECONDS).getID();
Txn transaction = kv.get().txn();
ByteSequence key = ByteSequence.from(servicePath.getBytes());
// Put if absent
TxnResponse response = transaction.If(new Cmp(key, Cmp.Op.EQUAL, CmpTarget.version(0)))
.Then(Op.put(key, ByteSequence.from(serviceName.getBytes()),
PutOption.newBuilder().withLeaseId(id).build()))
.commit()
.get(timeout, TimeUnit.SECONDS);
boolean succeeded = response.isSucceeded();
if (succeeded) {
leaseId.set(id);
} else {
lease.get().revoke(id);
}
return succeeded;
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (ExecutionException e) {
LOGGER.debug("Could not try to take the leadership", e);
} catch (TimeoutException e) {
LOGGER.debug("Timeout while trying to take the leadership");
}
return false;
}
}