opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Leader.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.raft.behaviors;
   9
  10 import akka.actor.ActorRef;
  11 import akka.actor.Cancellable;
  12 import com.google.common.annotations.VisibleForTesting;
  13 import com.google.common.base.Preconditions;
  14 import org.opendaylight.controller.cluster.raft.RaftActorContext;
  15 import org.opendaylight.controller.cluster.raft.base.messages.IsolatedLeaderCheck;
  16 import scala.concurrent.duration.FiniteDuration;
  17
  18 /**
  19  * The behavior of a RaftActor when it is in the Leader state
  20  * <p/>
  21  * Leaders:
  22  * <ul>
  23  * <li> Upon election: send initial empty AppendEntries RPCs
  24  * (heartbeat) to each server; repeat during idle periods to
  25  * prevent election timeouts (§5.2)
  26  * <li> If command received from client: append entry to local log,
  27  * respond after entry applied to state machine (§5.3)
  28  * <li> If last log index ≥ nextIndex for a follower: send
  29  * AppendEntries RPC with log entries starting at nextIndex
  30  * <ul>
  31  * <li> If successful: update nextIndex and matchIndex for
  32  * follower (§5.3)
  33  * <li> If AppendEntries fails because of log inconsistency:
  34  * decrement nextIndex and retry (§5.3)
  35  * </ul>
  36  * <li> If there exists an N such that N > commitIndex, a majority
  37  * of matchIndex[i] ≥ N, and log[N].term == currentTerm:
  38  * set commitIndex = N (§5.3, §5.4).
  39  */
  40 public class Leader extends AbstractLeader {
  41     private Cancellable installSnapshotSchedule = null;
  42     private Cancellable isolatedLeaderCheckSchedule = null;
  43
  44     public Leader(RaftActorContext context) {
  45         super(context);
  46
  47         scheduleIsolatedLeaderCheck(
  48             new FiniteDuration(context.getConfigParams().getHeartBeatInterval().length() * 10,
  49                 context.getConfigParams().getHeartBeatInterval().unit()));
  50     }
  51
  52     @Override public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
  53         Preconditions.checkNotNull(sender, "sender should not be null");
  54
  55         if (originalMessage instanceof IsolatedLeaderCheck) {
  56             if (isLeaderIsolated()) {
  57                 LOG.info("{}: At least {} followers need to be active, Switching {} from Leader to IsolatedLeader",
  58                         context.getId(), minIsolatedLeaderPeerCount, leaderId);
  59                 return switchBehavior(new IsolatedLeader(context));
  60             }
  61         }
  62
  63         return super.handleMessage(sender, originalMessage);
  64     }
  65
  66     protected void stopIsolatedLeaderCheckSchedule() {
  67         if (isolatedLeaderCheckSchedule != null && !isolatedLeaderCheckSchedule.isCancelled()) {
  68             isolatedLeaderCheckSchedule.cancel();
  69         }
  70     }
  71
  72     protected void scheduleIsolatedLeaderCheck(FiniteDuration isolatedCheckInterval) {
  73         isolatedLeaderCheckSchedule = context.getActorSystem().scheduler().schedule(isolatedCheckInterval, isolatedCheckInterval,
  74             context.getActor(), new IsolatedLeaderCheck(),
  75             context.getActorSystem().dispatcher(), context.getActor());
  76     }
  77
  78     @Override
  79     public void close() throws Exception {
  80         stopIsolatedLeaderCheckSchedule();
  81         super.close();
  82     }
  83
  84     @VisibleForTesting
  85     void markFollowerActive(String followerId) {
  86         getFollower(followerId).markFollowerActive();
  87     }
  88
  89     @VisibleForTesting
  90     void markFollowerInActive(String followerId) {
  91         getFollower(followerId).markFollowerInActive();
  92     }
  93 }