Class Observer

java.lang.Object
org.apache.zookeeper.server.quorum.Learner
org.apache.zookeeper.server.quorum.Observer

public class Observer extends Learner
Observers are peers that do not take part in the atomic broadcast protocol. Instead, they are informed of successful proposals by the Leader. Observers therefore naturally act as a relay point for publishing the proposal stream and can relieve Followers of some of the connection load. Observers may submit proposals, but do not vote in their acceptance. See ZOOKEEPER-368 for a discussion of this feature.
  • Field Details

    • OBSERVER_RECONNECT_DELAY_MS

      public static final String OBSERVER_RECONNECT_DELAY_MS
      When observer lost its connection with the leader, it waits for 0 to the specified value before trying to reconnect with the leader. So that the entire observer fleet won't try to run leader election and reconnect to the leader at once. Default value is zero.
      See Also:
    • OBSERVER_ELECTION_DELAY_MS

      public static final String OBSERVER_ELECTION_DELAY_MS
      Delay the Observer's participation in a leader election upon disconnect so as to prevent unexpected additional load on the voting peers during the process. Default value is 200.
      See Also:
  • Method Details

    • toString

      public String toString()
      Overrides:
      toString in class Object
    • processPacket

      protected void processPacket(QuorumPacket qp) throws Exception
      Controls the response of an observer to the receipt of a quorumpacket
      Parameters:
      qp -
      Throws:
      Exception
    • shutdown

      public void shutdown()
      Shutdown the Observer.
      Overrides:
      shutdown in class Learner
    • getLearnerMasterId

      public long getLearnerMasterId()
    • setLearnerMaster

      public boolean setLearnerMaster(String learnerMaster)
      Prompts the Observer to disconnect from its current learner master and reconnect to the specified server. If that connection attempt fails, the Observer will fail over to the next available learner master.
    • getCurrentLearnerMaster

      public QuorumPeer.QuorumServer getCurrentLearnerMaster()
    • getObserverElectionDelayMs

      public static long getObserverElectionDelayMs()
    • setObserverElectionDelayMs

      public static void setObserverElectionDelayMs(long electionDelayMs)