Madan Jampani | 1d3494e | 2014-11-20 11:24:22 -0800 | [diff] [blame] | 1 | package org.onlab.onos.store.cluster.impl; |
| 2 | |
| 3 | import static com.google.common.base.Preconditions.checkArgument; |
| 4 | import static com.google.common.base.Verify.verifyNotNull; |
| 5 | import static org.onlab.util.Tools.namedThreads; |
| 6 | import static org.slf4j.LoggerFactory.getLogger; |
| 7 | |
| 8 | import java.util.Map; |
| 9 | import java.util.Set; |
| 10 | import java.util.concurrent.Executors; |
| 11 | import java.util.concurrent.ScheduledExecutorService; |
| 12 | import java.util.concurrent.TimeUnit; |
| 13 | |
| 14 | import org.apache.felix.scr.annotations.Activate; |
| 15 | import org.apache.felix.scr.annotations.Component; |
| 16 | import org.apache.felix.scr.annotations.Deactivate; |
| 17 | import org.apache.felix.scr.annotations.Reference; |
| 18 | import org.apache.felix.scr.annotations.ReferenceCardinality; |
| 19 | import org.apache.felix.scr.annotations.Service; |
| 20 | import org.onlab.onos.cluster.ClusterService; |
| 21 | import org.onlab.onos.cluster.ControllerNode; |
| 22 | import org.onlab.onos.cluster.Leadership; |
| 23 | import org.onlab.onos.cluster.LeadershipEvent; |
| 24 | import org.onlab.onos.cluster.LeadershipEventListener; |
| 25 | import org.onlab.onos.cluster.LeadershipService; |
| 26 | import org.onlab.onos.store.service.Lock; |
| 27 | import org.onlab.onos.store.service.LockService; |
| 28 | import org.onlab.onos.store.service.impl.DistributedLockManager; |
| 29 | import org.slf4j.Logger; |
| 30 | |
| 31 | import com.google.common.collect.Maps; |
| 32 | import com.google.common.collect.Sets; |
| 33 | |
| 34 | /** |
| 35 | * Distributed implementation of LeadershipService that is based on the primitives exposed by |
| 36 | * LockService. |
| 37 | */ |
| 38 | @Component(immediate = true) |
| 39 | @Service |
| 40 | public class LeadershipManager implements LeadershipService { |
| 41 | |
| 42 | private final Logger log = getLogger(getClass()); |
| 43 | |
| 44 | // TODO: Remove this dependency |
| 45 | private static final int TERM_DURATION_MS = |
| 46 | DistributedLockManager.DEAD_LOCK_TIMEOUT_MS; |
| 47 | |
| 48 | // TODO: Appropriate Thread pool sizing. |
| 49 | private static final ScheduledExecutorService THREAD_POOL = |
| 50 | Executors.newScheduledThreadPool(25, namedThreads("leadership-manager-%d")); |
| 51 | |
| 52 | @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) |
| 53 | private ClusterService clusterService; |
| 54 | |
| 55 | @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) |
| 56 | private LockService lockService; |
| 57 | |
| 58 | private Map<String, Lock> openContests = Maps.newHashMap(); |
| 59 | private Set<LeadershipEventListener> listeners = Sets.newIdentityHashSet(); |
| 60 | private ControllerNode localNode; |
| 61 | |
| 62 | @Activate |
| 63 | public void activate() { |
| 64 | localNode = clusterService.getLocalNode(); |
| 65 | log.info("Started."); |
| 66 | } |
| 67 | |
| 68 | @Deactivate |
| 69 | public void deactivate() { |
| 70 | THREAD_POOL.shutdown(); |
| 71 | log.info("Stopped."); |
| 72 | } |
| 73 | |
| 74 | @Override |
| 75 | public void runForLeadership(String path) { |
| 76 | checkArgument(path != null); |
| 77 | if (openContests.containsKey(path)) { |
| 78 | log.info("Already in the leadership contest for {}", path); |
| 79 | return; |
| 80 | } else { |
| 81 | Lock lock = lockService.create(path); |
| 82 | openContests.put(path, lock); |
| 83 | tryAcquireLeadership(path); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | @Override |
| 88 | public void withdraw(String path) { |
| 89 | checkArgument(path != null); |
| 90 | Lock lock = openContests.remove(path); |
| 91 | |
| 92 | if (lock != null && lock.isLocked()) { |
| 93 | lock.unlock(); |
| 94 | notifyListeners( |
| 95 | new LeadershipEvent( |
| 96 | LeadershipEvent.Type.LEADER_BOOTED, |
| 97 | new Leadership(lock.path(), localNode, 0))); |
| 98 | // FIXME: Should set the correct term information. |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | @Override |
| 103 | public void addListener(LeadershipEventListener listener) { |
| 104 | checkArgument(listener != null); |
| 105 | listeners.add(listener); |
| 106 | } |
| 107 | |
| 108 | @Override |
| 109 | public void removeListener(LeadershipEventListener listener) { |
| 110 | checkArgument(listener != null); |
| 111 | listeners.remove(listener); |
| 112 | } |
| 113 | |
| 114 | private void notifyListeners(LeadershipEvent event) { |
| 115 | for (LeadershipEventListener listener : listeners) { |
| 116 | listener.event(event); |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | private void tryAcquireLeadership(String path) { |
| 121 | Lock lock = openContests.get(path); |
| 122 | verifyNotNull(lock, "Lock should not be null"); |
| 123 | lock.lockAsync(TERM_DURATION_MS).whenComplete((response, error) -> { |
| 124 | if (error == null) { |
| 125 | THREAD_POOL.schedule( |
| 126 | new RelectionTask(lock), |
| 127 | TERM_DURATION_MS / 2, |
| 128 | TimeUnit.MILLISECONDS); |
| 129 | notifyListeners( |
| 130 | new LeadershipEvent( |
| 131 | LeadershipEvent.Type.LEADER_ELECTED, |
| 132 | new Leadership(lock.path(), localNode, 0))); |
| 133 | } else { |
| 134 | log.error("Failed to acquire lock for {}", path, error); |
| 135 | // retry |
| 136 | tryAcquireLeadership(path); |
| 137 | } |
| 138 | }); |
| 139 | } |
| 140 | |
| 141 | private class RelectionTask implements Runnable { |
| 142 | |
| 143 | private final Lock lock; |
| 144 | |
| 145 | public RelectionTask(Lock lock) { |
| 146 | this.lock = lock; |
| 147 | } |
| 148 | |
| 149 | @Override |
| 150 | public void run() { |
| 151 | if (lock.extendExpiration(TERM_DURATION_MS)) { |
| 152 | notifyListeners( |
| 153 | new LeadershipEvent( |
| 154 | LeadershipEvent.Type.LEADER_REELECTED, |
| 155 | new Leadership(lock.path(), localNode, 0))); |
| 156 | THREAD_POOL.schedule(this, TERM_DURATION_MS / 2, TimeUnit.MILLISECONDS); |
| 157 | } else { |
| 158 | if (openContests.containsKey(lock.path())) { |
| 159 | notifyListeners( |
| 160 | new LeadershipEvent( |
| 161 | LeadershipEvent.Type.LEADER_BOOTED, |
| 162 | new Leadership(lock.path(), localNode, 0))); |
| 163 | tryAcquireLeadership(lock.path()); |
| 164 | } |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | } |