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org.apache.camel.component.consul.cluster.ConsulClusterView Maven / Gradle / Ivy
/**
* 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.consul.cluster;
import java.math.BigInteger;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;
import com.orbitz.consul.Consul;
import com.orbitz.consul.KeyValueClient;
import com.orbitz.consul.SessionClient;
import com.orbitz.consul.async.ConsulResponseCallback;
import com.orbitz.consul.model.ConsulResponse;
import com.orbitz.consul.model.kv.Value;
import com.orbitz.consul.model.session.ImmutableSession;
import com.orbitz.consul.model.session.SessionInfo;
import com.orbitz.consul.option.QueryOptions;
import org.apache.camel.cluster.CamelClusterMember;
import org.apache.camel.impl.cluster.AbstractCamelClusterView;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
final class ConsulClusterView extends AbstractCamelClusterView {
private static final Logger LOGGER = LoggerFactory.getLogger(ConsulClusterService.class);
private final ConsulClusterConfiguration configuration;
private final ConsulLocalMember localMember;
private final AtomicReference sessionId;
private final Watcher watcher;
private Consul client;
private SessionClient sessionClient;
private KeyValueClient keyValueClient;
private String path;
ConsulClusterView(ConsulClusterService service, ConsulClusterConfiguration configuration, String namespace) throws Exception {
super(service, namespace);
this.configuration = configuration;
this.localMember = new ConsulLocalMember();
this.sessionId = new AtomicReference<>();
this.watcher = new Watcher();
this.path = configuration.getRootPath() + "/" + namespace;
}
@Override
public Optional getLeader() {
if (keyValueClient == null) {
return Optional.empty();
}
return keyValueClient.getSession(configuration.getRootPath()).map(ConsulClusterMember::new);
}
@Override
public CamelClusterMember getLocalMember() {
return this.localMember;
}
@Override
public List getMembers() {
if (sessionClient == null) {
return Collections.emptyList();
}
return sessionClient.listSessions().stream()
.filter(i -> i.getName().equals(getNamespace()))
.map(ConsulClusterMember::new)
.collect(Collectors.toList());
}
@Override
protected void doStart() throws Exception {
if (sessionId.get() == null) {
client = configuration.createConsulClient(getCamelContext());
sessionClient = client.sessionClient();
keyValueClient = client.keyValueClient();
sessionId.set(
sessionClient.createSession(
ImmutableSession.builder()
.name(getNamespace())
.ttl(configuration.getSessionTtl() + "s")
.lockDelay(configuration.getSessionLockDelay() + "s")
.build()
).getId()
);
LOGGER.debug("Acquired session with id '{}'", sessionId.get());
boolean lock = acquireLock();
LOGGER.debug("Acquire lock on path '{}' with id '{}' result '{}'", path, sessionId.get(), lock);
localMember.setMaster(lock);
watcher.watch();
}
}
@Override
protected void doStop() throws Exception {
if (sessionId.get() != null) {
if (keyValueClient.releaseLock(this.path, sessionId.get())) {
LOGGER.debug("Successfully released lock on path '{}' with id '{}'", path, sessionId.get());
}
synchronized (sessionId) {
sessionClient.destroySession(sessionId.getAndSet(null));
localMember.setMaster(false);
}
}
}
private boolean acquireLock() {
synchronized (sessionId) {
String sid = sessionId.get();
return (sid != null)
? sessionClient.getSessionInfo(sid).map(si -> keyValueClient.acquireLock(path, sid)).orElse(Boolean.FALSE)
: false;
}
}
// ***********************************************
//
// ***********************************************
private final class ConsulLocalMember implements CamelClusterMember {
private AtomicBoolean master = new AtomicBoolean(false);
void setMaster(boolean master) {
if (master && this.master.compareAndSet(false, true)) {
LOGGER.debug("Leadership taken for session id {}", sessionId.get());
fireLeadershipChangedEvent(Optional.of(this));
return;
}
if (!master && this.master.compareAndSet(true, false)) {
LOGGER.debug("Leadership lost for session id {}", sessionId.get());
fireLeadershipChangedEvent(getLeader());
return;
}
}
@Override
public boolean isLeader() {
return master.get();
}
@Override
public boolean isLocal() {
return true;
}
@Override
public String getId() {
return sessionId.get();
}
@Override
public String toString() {
return "ConsulLocalMember{"
+ "master=" + master
+ '}';
}
}
private final class ConsulClusterMember implements CamelClusterMember {
private final String id;
ConsulClusterMember() {
this.id = null;
}
ConsulClusterMember(SessionInfo info) {
this(info.getId());
}
ConsulClusterMember(String id) {
this.id = id;
}
@Override
public String getId() {
return id;
}
@Override
public boolean isLeader() {
if (keyValueClient == null) {
return false;
}
if (id == null) {
return false;
}
return id.equals(keyValueClient.getSession(path));
}
@Override
public boolean isLocal() {
if (id == null) {
return false;
}
return ObjectHelper.equal(id, localMember.getId());
}
@Override
public String toString() {
return "ConsulClusterMember{"
+ "id='" + id + '\''
+ '}';
}
}
// *************************************************************************
// Watch
// *************************************************************************
private class Watcher implements ConsulResponseCallback> {
private final AtomicReference index;
public Watcher() {
this.index = new AtomicReference<>(new BigInteger("0"));
}
@Override
public void onComplete(ConsulResponse> consulResponse) {
if (isStarting() || isStarted()) {
Optional value = consulResponse.getResponse();
if (value.isPresent()) {
Optional sid = value.get().getSession();
if (!sid.isPresent()) {
// If the key is not held by any session, try acquire a
// lock (become leader)
boolean lock = acquireLock();
LOGGER.debug("Try to acquire lock on path '{}' with id '{}', result '{}'", path, sessionId.get(), lock);
localMember.setMaster(lock);
} else {
boolean master = sid.get().equals(sessionId.get());
if (!master) {
LOGGER.debug("Path {} is held by session {}, local session is {}", path, sid.get(), sessionId.get());
}
localMember.setMaster(sid.get().equals(sessionId.get()));
}
}
index.set(consulResponse.getIndex());
watch();
}
}
@Override
public void onFailure(Throwable throwable) {
LOGGER.debug("", throwable);
if (sessionId.get() != null) {
keyValueClient.releaseLock(configuration.getRootPath(), sessionId.get());
}
localMember.setMaster(false);
watch();
}
public void watch() {
if (sessionId.get() == null) {
return;
}
if (isStarting() || isStarted()) {
// Watch for changes
keyValueClient.getValue(
path,
QueryOptions.blockSeconds(configuration.getSessionRefreshInterval(), index.get()).build(),
this
);
if (sessionId.get() != null) {
// Refresh session
sessionClient.renewSession(sessionId.get());
}
}
}
}
}
