Pavlin Radoslavov | c91eebe | 2014-11-25 18:45:46 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2014 Open Networking Laboratory |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.onlab.onos.sdnip; |
| 17 | |
| 18 | import java.util.Map; |
| 19 | import java.util.concurrent.ExecutorService; |
| 20 | import java.util.concurrent.Executors; |
| 21 | import java.util.concurrent.Future; |
| 22 | import java.util.concurrent.locks.Lock; |
| 23 | |
| 24 | import org.onlab.onos.cluster.ClusterService; |
| 25 | import org.onlab.onos.cluster.ControllerNode; |
| 26 | import org.onlab.onos.cluster.Leadership; |
| 27 | import org.onlab.onos.cluster.LeadershipEvent; |
| 28 | import org.onlab.onos.cluster.LeadershipEventListener; |
| 29 | import org.onlab.onos.cluster.LeadershipService; |
| 30 | import org.onlab.onos.cluster.NodeId; |
| 31 | import org.onlab.onos.event.AbstractListenerRegistry; |
| 32 | import org.onlab.onos.event.EventDeliveryService; |
| 33 | import org.onlab.onos.store.hz.StoreService; |
| 34 | import org.onlab.onos.store.serializers.KryoNamespaces; |
| 35 | import org.onlab.onos.store.serializers.KryoSerializer; |
| 36 | import org.onlab.util.KryoNamespace; |
| 37 | import static org.onlab.util.Tools.namedThreads; |
| 38 | |
| 39 | import org.slf4j.Logger; |
| 40 | import org.slf4j.LoggerFactory; |
| 41 | import com.google.common.collect.Maps; |
| 42 | import com.hazelcast.config.TopicConfig; |
| 43 | import com.hazelcast.core.ITopic; |
| 44 | import com.hazelcast.core.Message; |
| 45 | import com.hazelcast.core.MessageListener; |
| 46 | |
| 47 | import static com.google.common.base.Preconditions.checkArgument; |
| 48 | |
| 49 | /** |
| 50 | * Distributed implementation of LeadershipService that is based on Hazelcast. |
| 51 | * <p> |
| 52 | * The election is eventually-consistent: if there is Hazelcast partitioning, |
| 53 | * and the partitioning is healed, there could be a short window of time |
| 54 | * until the leaders in each partition discover each other. If this happens, |
| 55 | * the leaders release the leadership and run again for election. |
| 56 | * </p> |
| 57 | * <p> |
| 58 | * The leader election is based on Hazelcast's Global Lock, which is stongly |
| 59 | * consistent. In addition, each leader periodically advertises events |
| 60 | * (using a Hazelcast Topic) that it is the elected leader. Those events are |
| 61 | * used for two purposes: (1) Discover multi-leader collisions (in case of |
| 62 | * healed Hazelcast partitions), and (2) Inform all listeners who is |
| 63 | * the current leader (e.g., for informational purpose). |
| 64 | * </p> |
| 65 | */ |
| 66 | public class SdnIpLeadershipService implements LeadershipService { |
| 67 | private static final Logger log = |
| 68 | LoggerFactory.getLogger(SdnIpLeadershipService.class); |
| 69 | |
| 70 | private static final KryoSerializer SERIALIZER = new KryoSerializer() { |
| 71 | @Override |
| 72 | protected void setupKryoPool() { |
| 73 | serializerPool = KryoNamespace.newBuilder() |
| 74 | .register(KryoNamespaces.API) |
| 75 | .build() |
| 76 | .populate(1); |
| 77 | } |
| 78 | }; |
| 79 | |
| 80 | private static final long LEADERSHIP_PERIODIC_INTERVAL_MS = 5 * 1000; // 5s |
| 81 | private static final long LEADERSHIP_REMOTE_TIMEOUT_MS = 15 * 1000; // 15s |
| 82 | |
| 83 | private ClusterService clusterService; |
| 84 | private StoreService storeService; |
| 85 | private EventDeliveryService eventDispatcher; |
| 86 | |
| 87 | private AbstractListenerRegistry<LeadershipEvent, LeadershipEventListener> |
| 88 | listenerRegistry; |
| 89 | private final Map<String, Topic> topics = Maps.newConcurrentMap(); |
| 90 | private ControllerNode localNode; |
| 91 | |
| 92 | /** |
| 93 | * Constructor. |
| 94 | * |
| 95 | * @param clusterService the cluster service to use |
| 96 | * @param storeService the store service to use |
| 97 | * @param eventDispatcher the event dispacher to use |
| 98 | */ |
| 99 | SdnIpLeadershipService(ClusterService clusterService, |
| 100 | StoreService storeService, |
| 101 | EventDeliveryService eventDispatcher) { |
| 102 | this.clusterService = clusterService; |
| 103 | this.storeService = storeService; |
| 104 | this.eventDispatcher = eventDispatcher; |
| 105 | } |
| 106 | |
| 107 | /** |
| 108 | * Starts operation. |
| 109 | */ |
| 110 | void start() { |
| 111 | localNode = clusterService.getLocalNode(); |
| 112 | listenerRegistry = new AbstractListenerRegistry<>(); |
| 113 | eventDispatcher.addSink(LeadershipEvent.class, listenerRegistry); |
| 114 | |
| 115 | log.info("SDN-IP Leadership Service started"); |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Stops operation. |
| 120 | */ |
| 121 | void stop() { |
| 122 | eventDispatcher.removeSink(LeadershipEvent.class); |
| 123 | |
| 124 | for (Topic topic : topics.values()) { |
| 125 | topic.stop(); |
| 126 | } |
| 127 | topics.clear(); |
| 128 | |
| 129 | log.info("SDN-IP Leadership Service stopped"); |
| 130 | } |
| 131 | |
| 132 | @Override |
| 133 | public ControllerNode getLeader(String path) { |
| 134 | Topic topic = topics.get(path); |
| 135 | if (topic == null) { |
| 136 | return null; |
| 137 | } |
| 138 | return topic.leader(); |
| 139 | } |
| 140 | |
| 141 | @Override |
| 142 | public void runForLeadership(String path) { |
| 143 | checkArgument(path != null); |
| 144 | Topic topic = new Topic(path); |
| 145 | Topic oldTopic = topics.putIfAbsent(path, topic); |
| 146 | if (oldTopic == null) { |
| 147 | topic.start(); |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | @Override |
| 152 | public void withdraw(String path) { |
| 153 | checkArgument(path != null); |
| 154 | Topic topic = topics.get(path); |
| 155 | if (topic != null) { |
| 156 | topic.stop(); |
| 157 | topics.remove(path, topic); |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | @Override |
Yuta HIGUCHI | c2bf3d8 | 2014-11-28 18:50:41 -0800 | [diff] [blame^] | 162 | public Map<String, Leadership> getLeaderBoard() { |
| 163 | throw new UnsupportedOperationException("I don't know what to do." + |
| 164 | " I wish you luck."); |
| 165 | } |
| 166 | |
| 167 | @Override |
Pavlin Radoslavov | c91eebe | 2014-11-25 18:45:46 -0800 | [diff] [blame] | 168 | public void addListener(LeadershipEventListener listener) { |
| 169 | listenerRegistry.addListener(listener); |
| 170 | } |
| 171 | |
| 172 | @Override |
| 173 | public void removeListener(LeadershipEventListener listener) { |
| 174 | listenerRegistry.removeListener(listener); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Class for keeping per-topic information. |
| 179 | */ |
| 180 | private final class Topic implements MessageListener<byte[]> { |
| 181 | private final String topicName; |
| 182 | private volatile boolean isShutdown = true; |
| 183 | private volatile long lastLeadershipUpdateMs = 0; |
| 184 | private ExecutorService leaderElectionExecutor; |
| 185 | |
| 186 | private ControllerNode leader; |
| 187 | private Lock leaderLock; |
| 188 | private Future<?> getLockFuture; |
| 189 | private Future<?> periodicProcessingFuture; |
| 190 | private ITopic<byte[]> leaderTopic; |
| 191 | private String leaderTopicRegistrationId; |
| 192 | |
| 193 | /** |
| 194 | * Constructor. |
| 195 | * |
| 196 | * @param topicName the topic name |
| 197 | */ |
| 198 | private Topic(String topicName) { |
| 199 | this.topicName = topicName; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * Gets the leader for the topic. |
| 204 | * |
| 205 | * @return the leader for the topic |
| 206 | */ |
| 207 | private ControllerNode leader() { |
| 208 | return leader; |
| 209 | } |
| 210 | |
| 211 | /** |
| 212 | * Starts leadership election for the topic. |
| 213 | */ |
| 214 | private void start() { |
| 215 | isShutdown = false; |
| 216 | String lockHzId = "LeadershipService/" + topicName + "/lock"; |
| 217 | String topicHzId = "LeadershipService/" + topicName + "/topic"; |
| 218 | leaderLock = storeService.getHazelcastInstance().getLock(lockHzId); |
| 219 | |
| 220 | String threadPoolName = |
| 221 | "sdnip-leader-election-" + topicName + "-%d"; |
| 222 | leaderElectionExecutor = Executors.newScheduledThreadPool(2, |
| 223 | namedThreads(threadPoolName)); |
| 224 | |
| 225 | TopicConfig topicConfig = new TopicConfig(); |
| 226 | topicConfig.setGlobalOrderingEnabled(true); |
| 227 | topicConfig.setName(topicHzId); |
| 228 | storeService.getHazelcastInstance().getConfig().addTopicConfig(topicConfig); |
| 229 | |
| 230 | leaderTopic = |
| 231 | storeService.getHazelcastInstance().getTopic(topicHzId); |
| 232 | leaderTopicRegistrationId = leaderTopic.addMessageListener(this); |
| 233 | |
| 234 | getLockFuture = leaderElectionExecutor.submit(new Runnable() { |
| 235 | @Override |
| 236 | public void run() { |
| 237 | doLeaderElectionThread(); |
| 238 | } |
| 239 | }); |
| 240 | periodicProcessingFuture = |
| 241 | leaderElectionExecutor.submit(new Runnable() { |
| 242 | @Override |
| 243 | public void run() { |
| 244 | doPeriodicProcessing(); |
| 245 | } |
| 246 | }); |
| 247 | } |
| 248 | |
| 249 | /** |
| 250 | * Stops leadership election for the topic. |
| 251 | */ |
| 252 | private void stop() { |
| 253 | isShutdown = true; |
| 254 | leaderTopic.removeMessageListener(leaderTopicRegistrationId); |
| 255 | // getLockFuture.cancel(true); |
| 256 | // periodicProcessingFuture.cancel(true); |
| 257 | leaderElectionExecutor.shutdownNow(); |
| 258 | } |
| 259 | |
| 260 | @Override |
| 261 | public void onMessage(Message<byte[]> message) { |
| 262 | LeadershipEvent leadershipEvent = |
| 263 | SERIALIZER.decode(message.getMessageObject()); |
| 264 | NodeId eventLeaderId = leadershipEvent.subject().leader().id(); |
| 265 | |
| 266 | log.debug("SDN-IP Leadership Event: time = {} type = {} event = {}", |
| 267 | leadershipEvent.time(), leadershipEvent.type(), |
| 268 | leadershipEvent); |
| 269 | if (!leadershipEvent.subject().topic().equals(topicName)) { |
| 270 | return; // Not our topic: ignore |
| 271 | } |
| 272 | if (eventLeaderId.equals(localNode.id())) { |
| 273 | return; // My own message: ignore |
| 274 | } |
| 275 | |
| 276 | synchronized (this) { |
| 277 | switch (leadershipEvent.type()) { |
| 278 | case LEADER_ELECTED: |
| 279 | // FALLTHROUGH |
| 280 | case LEADER_REELECTED: |
| 281 | // |
| 282 | // Another leader: if we are also a leader, then give up |
| 283 | // leadership and run for re-election. |
| 284 | // |
| 285 | if ((leader != null) && |
| 286 | leader.id().equals(localNode.id())) { |
| 287 | getLockFuture.cancel(true); |
| 288 | } else { |
| 289 | // Just update the current leader |
| 290 | leader = leadershipEvent.subject().leader(); |
| 291 | lastLeadershipUpdateMs = System.currentTimeMillis(); |
| 292 | } |
| 293 | eventDispatcher.post(leadershipEvent); |
| 294 | break; |
| 295 | case LEADER_BOOTED: |
| 296 | // Remove the state for the current leader |
| 297 | if ((leader != null) && |
| 298 | eventLeaderId.equals(leader.id())) { |
| 299 | leader = null; |
| 300 | } |
| 301 | eventDispatcher.post(leadershipEvent); |
| 302 | break; |
| 303 | default: |
| 304 | break; |
| 305 | } |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | private void doPeriodicProcessing() { |
| 310 | |
| 311 | while (!isShutdown) { |
| 312 | |
| 313 | // |
| 314 | // Periodic tasks: |
| 315 | // (a) Advertise ourselves as the leader |
| 316 | // OR |
| 317 | // (b) Expire a stale (remote) leader |
| 318 | // |
| 319 | synchronized (this) { |
| 320 | LeadershipEvent leadershipEvent; |
| 321 | if (leader != null) { |
| 322 | if (leader.id().equals(localNode.id())) { |
| 323 | // |
| 324 | // Advertise ourselves as the leader |
| 325 | // |
| 326 | leadershipEvent = new LeadershipEvent( |
| 327 | LeadershipEvent.Type.LEADER_REELECTED, |
| 328 | new Leadership(topicName, localNode, 0)); |
| 329 | // Dispatch to all remote instances |
| 330 | leaderTopic.publish(SERIALIZER.encode(leadershipEvent)); |
| 331 | } else { |
| 332 | // |
| 333 | // Test if time to expire a stale leader |
| 334 | // |
| 335 | long delta = System.currentTimeMillis() - |
| 336 | lastLeadershipUpdateMs; |
| 337 | if (delta > LEADERSHIP_REMOTE_TIMEOUT_MS) { |
| 338 | leadershipEvent = new LeadershipEvent( |
| 339 | LeadershipEvent.Type.LEADER_BOOTED, |
| 340 | new Leadership(topicName, leader, 0)); |
| 341 | // Dispatch only to the local listener(s) |
| 342 | eventDispatcher.post(leadershipEvent); |
| 343 | leader = null; |
| 344 | } |
| 345 | } |
| 346 | } |
| 347 | } |
| 348 | |
| 349 | // Sleep before re-advertising |
| 350 | try { |
| 351 | Thread.sleep(LEADERSHIP_PERIODIC_INTERVAL_MS); |
| 352 | } catch (InterruptedException e) { |
| 353 | log.debug("SDN-IP Leader Election periodic thread interrupted"); |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | /** |
| 359 | * Performs the leader election by using Hazelcast. |
| 360 | */ |
| 361 | private void doLeaderElectionThread() { |
| 362 | |
| 363 | while (!isShutdown) { |
| 364 | LeadershipEvent leadershipEvent; |
| 365 | // |
| 366 | // Try to acquire the lock and keep it until the instance is |
| 367 | // shutdown. |
| 368 | // |
| 369 | log.debug("SDN-IP Leader Election begin for topic {}", |
| 370 | topicName); |
| 371 | try { |
| 372 | // Block until it becomes the leader |
| 373 | leaderLock.lockInterruptibly(); |
| 374 | } catch (InterruptedException e) { |
| 375 | // |
| 376 | // Thread interrupted. Either shutdown or run for |
| 377 | // re-election. |
| 378 | // |
| 379 | log.debug("SDN-IP Election interrupted for topic {}", |
| 380 | topicName); |
| 381 | continue; |
| 382 | } |
| 383 | |
| 384 | synchronized (this) { |
| 385 | // |
| 386 | // This instance is now the leader |
| 387 | // |
| 388 | log.info("SDN-IP Leader Elected for topic {}", topicName); |
| 389 | leader = localNode; |
| 390 | leadershipEvent = new LeadershipEvent( |
| 391 | LeadershipEvent.Type.LEADER_ELECTED, |
| 392 | new Leadership(topicName, localNode, 0)); |
| 393 | eventDispatcher.post(leadershipEvent); |
| 394 | leaderTopic.publish(SERIALIZER.encode(leadershipEvent)); |
| 395 | } |
| 396 | |
| 397 | try { |
| 398 | // Sleep forever until interrupted |
| 399 | Thread.sleep(Long.MAX_VALUE); |
| 400 | } catch (InterruptedException e) { |
| 401 | // |
| 402 | // Thread interrupted. Either shutdown or run for |
| 403 | // re-election. |
| 404 | // |
| 405 | log.debug("SDN-IP Leader Interrupted for topic {}", |
| 406 | topicName); |
| 407 | } |
| 408 | |
| 409 | synchronized (this) { |
| 410 | // If we reach here, we should release the leadership |
| 411 | log.debug("SDN-IP Leader Lock Released for topic {}", |
| 412 | topicName); |
| 413 | if ((leader != null) && |
| 414 | leader.id().equals(localNode.id())) { |
| 415 | leader = null; |
| 416 | } |
| 417 | leadershipEvent = new LeadershipEvent( |
| 418 | LeadershipEvent.Type.LEADER_BOOTED, |
| 419 | new Leadership(topicName, localNode, 0)); |
| 420 | eventDispatcher.post(leadershipEvent); |
| 421 | leaderTopic.publish(SERIALIZER.encode(leadershipEvent)); |
| 422 | leaderLock.unlock(); |
| 423 | } |
| 424 | } |
| 425 | } |
| 426 | } |
| 427 | } |