Package org.apache.storm.nimbus

Interface ILeaderElector

All Superinterfaces:
AutoCloseable
All Known Implementing Classes:
LeaderElectorImp, MockLeaderElector
public interface ILeaderElector extends AutoCloseable
The interface for leader election.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addToLeaderLockQueue()
    queue up for leadership lock.
    boolean
    awaitLeadership(long timeout, TimeUnit timeUnit)
    Wait for the caller to gain leadership.
    void
    close()
    Method called to allow for cleanup.
    List<NimbusInfo>
    getAllNimbuses()
    Get list of current nimbus addresses.
    NimbusInfo
    getLeader()
    Get the current leader's address.
    boolean
    isLeader()
    Decide if the caller currently has the leader lock.
    void
    prepare(Map<String,Object> conf)
    Method guaranteed to be called as part of initialization of leader elector instance.
    void
    quitElectionFor(int delayMs)
    Removes the caller from leadership election, relinquishing leadership if acquired, then requeues for leadership after the specified delay.

  • Method Details

    • prepare

      void prepare(Map<String,Object> conf)
      Method guaranteed to be called as part of initialization of leader elector instance.
      Parameters:
      conf - configuration

    • addToLeaderLockQueue

      void addToLeaderLockQueue() throws Exception
      queue up for leadership lock. The call returns immediately and the caller must check isLeader() to perform any leadership action. This method can be called multiple times so it needs to be idempotent.
      Throws:
      Exception

    • quitElectionFor

      void quitElectionFor(int delayMs) throws Exception
      Removes the caller from leadership election, relinquishing leadership if acquired, then requeues for leadership after the specified delay.
      Parameters:
      delayMs - The delay to wait before re-entering the election
      Throws:
      Exception

    • isLeader

      boolean isLeader() throws Exception
      Decide if the caller currently has the leader lock.
      Returns:
      true if the caller currently has the leader lock.
      Throws:
      Exception

    • getLeader

      NimbusInfo getLeader()
      Get the current leader's address.
      Returns:
      the current leader's address, may return null if no one has the lock.

    • awaitLeadership

      boolean awaitLeadership(long timeout, TimeUnit timeUnit) throws InterruptedException
      Wait for the caller to gain leadership. This should only be used in single-Nimbus clusters, and is only useful to allow testing code to wait for a LocalCluster's Nimbus to gain leadership before trying to submit topologies.
      Returns:
      true is leadership was acquired, false otherwise
      Throws:
      InterruptedException

    • getAllNimbuses

      List<NimbusInfo> getAllNimbuses() throws Exception
      Get list of current nimbus addresses.
      Returns:
      list of current nimbus addresses, includes leader.
      Throws:
      Exception

    • close

      void close() throws Exception
      Method called to allow for cleanup. Relinquishes leadership if owned by the caller.
      Specified by:
      close in interface AutoCloseable
      Throws:
      Exception