| /* |
| * Copyright 2014 Open Networking Laboratory |
| * |
| * Licensed 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.onosproject.store.cluster.impl; |
| |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.Maps; |
| import com.google.common.collect.Sets; |
| import org.apache.felix.scr.annotations.Activate; |
| import org.apache.felix.scr.annotations.Component; |
| import org.apache.felix.scr.annotations.Deactivate; |
| import org.apache.felix.scr.annotations.Reference; |
| import org.apache.felix.scr.annotations.ReferenceCardinality; |
| import org.apache.felix.scr.annotations.Service; |
| import org.onlab.util.KryoNamespace; |
| import org.onosproject.cluster.ClusterService; |
| import org.onosproject.cluster.Leadership; |
| import org.onosproject.cluster.LeadershipEvent; |
| import org.onosproject.cluster.LeadershipEventListener; |
| import org.onosproject.cluster.LeadershipService; |
| import org.onosproject.cluster.NodeId; |
| import org.onosproject.store.cluster.messaging.ClusterCommunicationService; |
| import org.onosproject.store.cluster.messaging.ClusterMessage; |
| import org.onosproject.store.cluster.messaging.ClusterMessageHandler; |
| import org.onosproject.store.cluster.messaging.MessageSubject; |
| import org.onosproject.store.serializers.KryoNamespaces; |
| import org.onosproject.store.serializers.KryoSerializer; |
| import org.onosproject.store.service.Lock; |
| import org.onosproject.store.service.LockService; |
| import org.onosproject.store.service.impl.DistributedLockManager; |
| import org.slf4j.Logger; |
| |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| |
| import static com.google.common.base.Preconditions.checkArgument; |
| import static org.onlab.util.Tools.namedThreads; |
| import static org.slf4j.LoggerFactory.getLogger; |
| |
| /** |
| * Distributed implementation of LeadershipService that is based on the primitives exposed by |
| * LockService. |
| */ |
| @Component(enabled = false) |
| @Service |
| public class LeadershipManager implements LeadershipService { |
| |
| private final Logger log = getLogger(getClass()); |
| |
| // TODO: Remove this dependency |
| private static final int TERM_DURATION_MS = |
| DistributedLockManager.DEAD_LOCK_TIMEOUT_MS; |
| |
| // Time to wait before retrying leadership after |
| // a unexpected error. |
| private static final int WAIT_BEFORE_RETRY_MS = 2000; |
| |
| // TODO: Make Thread pool size configurable. |
| private final ScheduledExecutorService threadPool = |
| Executors.newScheduledThreadPool(25, namedThreads("onos-leadership-manager-%d")); |
| |
| private static final MessageSubject LEADERSHIP_UPDATES = |
| new MessageSubject("leadership-contest-updates"); |
| |
| @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) |
| private ClusterService clusterService; |
| |
| @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) |
| private ClusterCommunicationService clusterCommunicator; |
| |
| @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) |
| private LockService lockService; |
| |
| private final Map<String, Leadership> leaderBoard = Maps.newHashMap(); |
| |
| private final Map<String, Lock> openContests = Maps.newConcurrentMap(); |
| private final Set<LeadershipEventListener> listeners = Sets.newIdentityHashSet(); |
| private NodeId localNodeId; |
| |
| private final LeadershipEventListener peerAdvertiser = new PeerAdvertiser(); |
| private final LeadershipEventListener leaderBoardUpdater = new LeaderBoardUpdater(); |
| |
| public static final KryoSerializer SERIALIZER = new KryoSerializer() { |
| @Override |
| protected void setupKryoPool() { |
| serializerPool = KryoNamespace.newBuilder() |
| .register(KryoNamespaces.API) |
| .build() |
| .populate(1); |
| } |
| }; |
| |
| @Activate |
| public void activate() { |
| localNodeId = clusterService.getLocalNode().id(); |
| |
| addListener(peerAdvertiser); |
| addListener(leaderBoardUpdater); |
| |
| clusterCommunicator.addSubscriber( |
| LEADERSHIP_UPDATES, |
| new PeerAdvertisementHandler()); |
| |
| log.info("Started."); |
| } |
| |
| @Deactivate |
| public void deactivate() { |
| removeListener(peerAdvertiser); |
| removeListener(leaderBoardUpdater); |
| |
| clusterCommunicator.removeSubscriber(LEADERSHIP_UPDATES); |
| |
| threadPool.shutdown(); |
| |
| log.info("Stopped."); |
| } |
| |
| |
| @Override |
| public NodeId getLeader(String path) { |
| synchronized (leaderBoard) { |
| Leadership leadership = leaderBoard.get(path); |
| if (leadership != null) { |
| return leadership.leader(); |
| } |
| } |
| return null; |
| } |
| |
| @Override |
| public void runForLeadership(String path) { |
| checkArgument(path != null); |
| |
| if (openContests.containsKey(path)) { |
| log.info("Already in the leadership contest for {}", path); |
| return; |
| } else { |
| Lock lock = lockService.create(path); |
| openContests.put(path, lock); |
| threadPool.schedule(new TryLeadership(lock), 0, TimeUnit.MILLISECONDS); |
| } |
| } |
| |
| @Override |
| public void withdraw(String path) { |
| checkArgument(path != null); |
| |
| Lock lock = openContests.remove(path); |
| |
| if (lock != null && lock.isLocked()) { |
| lock.unlock(); |
| notifyListeners( |
| new LeadershipEvent( |
| LeadershipEvent.Type.LEADER_BOOTED, |
| new Leadership(lock.path(), localNodeId, lock.epoch()))); |
| } |
| } |
| |
| @Override |
| public Map<String, Leadership> getLeaderBoard() { |
| return ImmutableMap.copyOf(leaderBoard); |
| } |
| |
| @Override |
| public void addListener(LeadershipEventListener listener) { |
| checkArgument(listener != null); |
| listeners.add(listener); |
| } |
| |
| @Override |
| public void removeListener(LeadershipEventListener listener) { |
| checkArgument(listener != null); |
| listeners.remove(listener); |
| } |
| |
| private void notifyListeners(LeadershipEvent event) { |
| for (LeadershipEventListener listener : listeners) { |
| try { |
| listener.event(event); |
| } catch (Exception e) { |
| log.error("Notifying listener failed with exception.", e); |
| } |
| } |
| } |
| |
| private void tryAcquireLeadership(String path) { |
| Lock lock = openContests.get(path); |
| if (lock == null) { |
| // withdrew from race. |
| return; |
| } |
| lock.lockAsync(TERM_DURATION_MS).whenComplete((response, error) -> { |
| if (error == null) { |
| threadPool.schedule( |
| new ReelectionTask(lock), |
| TERM_DURATION_MS / 2, |
| TimeUnit.MILLISECONDS); |
| notifyListeners( |
| new LeadershipEvent( |
| LeadershipEvent.Type.LEADER_ELECTED, |
| new Leadership(lock.path(), localNodeId, lock.epoch()))); |
| return; |
| } else { |
| log.warn("Failed to acquire lock for {}. Will retry in {} ms", path, WAIT_BEFORE_RETRY_MS, error); |
| threadPool.schedule(new TryLeadership(lock), WAIT_BEFORE_RETRY_MS, TimeUnit.MILLISECONDS); |
| } |
| }); |
| } |
| |
| private class ReelectionTask implements Runnable { |
| |
| private final Lock lock; |
| |
| public ReelectionTask(Lock lock) { |
| this.lock = lock; |
| } |
| |
| @Override |
| public void run() { |
| if (!openContests.containsKey(lock.path())) { |
| log.debug("Node withdrew from leadership race for {}. Cancelling reelection task.", lock.path()); |
| return; |
| } |
| |
| boolean lockExtended = false; |
| try { |
| lockExtended = lock.extendExpiration(TERM_DURATION_MS); |
| } catch (Exception e) { |
| log.warn("Attempt to extend lock failed with an exception.", e); |
| } |
| |
| if (lockExtended) { |
| notifyListeners( |
| new LeadershipEvent( |
| LeadershipEvent.Type.LEADER_REELECTED, |
| new Leadership(lock.path(), localNodeId, lock.epoch()))); |
| threadPool.schedule(this, TERM_DURATION_MS / 2, TimeUnit.MILLISECONDS); |
| } else { |
| // Check if this node already withdrew from the contest, in which case |
| // we don't need to notify here. |
| if (openContests.containsKey(lock.path())) { |
| notifyListeners( |
| new LeadershipEvent( |
| LeadershipEvent.Type.LEADER_BOOTED, |
| new Leadership(lock.path(), localNodeId, lock.epoch()))); |
| // Retry leadership after a brief wait. |
| threadPool.schedule(new TryLeadership(lock), WAIT_BEFORE_RETRY_MS, TimeUnit.MILLISECONDS); |
| } |
| } |
| } |
| } |
| |
| private class TryLeadership implements Runnable { |
| private final Lock lock; |
| |
| public TryLeadership(Lock lock) { |
| this.lock = lock; |
| } |
| |
| @Override |
| public void run() { |
| tryAcquireLeadership(lock.path()); |
| } |
| } |
| |
| private class PeerAdvertiser implements LeadershipEventListener { |
| @Override |
| public void event(LeadershipEvent event) { |
| // publish events originating on this host. |
| if (event.subject().leader().equals(localNodeId)) { |
| clusterCommunicator.broadcast( |
| new ClusterMessage( |
| localNodeId, |
| LEADERSHIP_UPDATES, |
| SERIALIZER.encode(event))); |
| } |
| } |
| } |
| |
| private class PeerAdvertisementHandler implements ClusterMessageHandler { |
| @Override |
| public void handle(ClusterMessage message) { |
| LeadershipEvent event = SERIALIZER.decode(message.payload()); |
| log.trace("Received {} from {}", event, message.sender()); |
| notifyListeners(event); |
| } |
| } |
| |
| private class LeaderBoardUpdater implements LeadershipEventListener { |
| @Override |
| public void event(LeadershipEvent event) { |
| Leadership leadershipUpdate = event.subject(); |
| synchronized (leaderBoard) { |
| Leadership currentLeadership = leaderBoard.get(leadershipUpdate.topic()); |
| switch (event.type()) { |
| case LEADER_ELECTED: |
| case LEADER_REELECTED: |
| if (currentLeadership == null || currentLeadership.epoch() < leadershipUpdate.epoch()) { |
| leaderBoard.put(leadershipUpdate.topic(), leadershipUpdate); |
| } |
| break; |
| case LEADER_BOOTED: |
| if (currentLeadership != null && currentLeadership.epoch() <= leadershipUpdate.epoch()) { |
| leaderBoard.remove(leadershipUpdate.topic()); |
| } |
| break; |
| default: |
| break; |
| } |
| } |
| } |
| } |
| } |