Package org.opendaylight.controller.cluster.raft.behaviors

Class PreLeader

java.lang.Object
org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior
org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader
org.opendaylight.controller.cluster.raft.behaviors.PreLeader
All Implemented Interfaces:
AutoCloseable
public final class PreLeader extends AbstractLeader
The behavior of a RaftActor when it is in the PreLeader state. This state performs all the duties of Leader with the added behavior of attempting to commit all uncommitted entries from the previous leader's term. Raft does not allow a leader to commit entries from a previous term by simply counting replicas - only entries from the leader's current term can be committed (§5.4.2). Rather then waiting for a client interaction to commit a new entry, the PreLeader state immediately appends a no-op entry (NoopPayload) to the log with the leader's current term. Once the no-op entry is committed, all prior entries are committed indirectly. Once all entries are committed, ie commitIndex matches the last log index, it switches to the normal Leader state.

The use of a no-op entry in this manner is outlined in the last paragraph in §8 of the extended raft version.

Author:
Thomas Pantelis

  • Method Details

    • handleMessage

      public RaftActorBehavior handleMessage(org.apache.pekko.actor.ActorRef sender, Object message)
      Description copied from class: RaftActorBehavior
      Handle a message. If the processing of the message warrants a state change then a new behavior should be returned otherwise this method should return the current behavior.
      Overrides:
      handleMessage in class AbstractLeader
      Parameters:
      sender - The sender of the message
      message - A message that needs to be processed
      Returns:
      The new behavior or current behavior, or null if the message was not handled.