Java Code Examples for org.apache.ratis.statemachine.SnapshotInfo#getTermIndex()

private TermIndex getPrevious(long nextIndex) {
  if (nextIndex == RaftLog.LEAST_VALID_LOG_INDEX) {
    return null;
  }

  final long previousIndex = nextIndex - 1;
  final TermIndex previous = raftLog.getTermIndex(previousIndex);
  if (previous != null) {
    return previous;
  }

  final SnapshotInfo snapshot = server.getState().getLatestSnapshot();
  if (snapshot != null) {
    final TermIndex snapshotTermIndex = snapshot.getTermIndex();
    if (snapshotTermIndex.getIndex() == previousIndex) {
      return snapshotTermIndex;
    }
  }

  return null;
}
 

boolean isLogUpToDate(TermIndex candidateLastEntry) {
  TermIndex local = log.getLastEntryTermIndex();
  // need to take into account snapshot
  SnapshotInfo snapshot = server.getStateMachine().getLatestSnapshot();
   if (local == null && snapshot == null) {
    return true;
  } else if (candidateLastEntry == null) {
    return false;
  }
  if (local == null || (snapshot != null && snapshot.getIndex() > local.getIndex())) {
    local = snapshot.getTermIndex();
  }
  return local.compareTo(candidateLastEntry) <= 0;
}
 

boolean isLogUpToDate(TermIndex candidateLastEntry) {
  TermIndex local = log.getLastEntryTermIndex();
  // need to take into account snapshot
  SnapshotInfo snapshot = server.getStateMachine().getLatestSnapshot();
   if (local == null && snapshot == null) {
    return true;
  } else if (candidateLastEntry == null) {
    return false;
  }
  if (local == null || (snapshot != null && snapshot.getIndex() > local.getIndex())) {
    local = snapshot.getTermIndex();
  }
  return local.compareTo(candidateLastEntry) <= 0;
}
 

private TermIndex getPrevious() {
  TermIndex previous = raftLog.getTermIndex(follower.getNextIndex() - 1);
  if (previous == null) {
    // if previous is null, nextIndex must be equal to the log start
    // index (otherwise we will install snapshot).
    Preconditions.assertTrue(follower.getNextIndex() == raftLog.getStartIndex(),
        "%s: follower's next index %s, local log start index %s",
        this, follower.getNextIndex(), raftLog.getStartIndex());
    SnapshotInfo snapshot = server.getState().getLatestSnapshot();
    previous = snapshot == null ? null : snapshot.getTermIndex();
  }
  return previous;
}
 

/**
 * After a peer changes its role to candidate, it invokes this method to
 * send out requestVote rpc to all other peers.
 */
private void askForVotes() throws InterruptedException, IOException {
  final ServerState state = server.getState();
  while (shouldRun()) {
    // one round of requestVotes
    final long electionTerm;
    final RaftConfiguration conf;
    synchronized (server) {
      if (!shouldRun()) {
        break;
      }
      electionTerm = state.initElection();
      conf = state.getRaftConf();
      state.persistMetadata();
    }
    LOG.info("{}: begin an election at term {} for {}", this, electionTerm, conf);

    TermIndex lastEntry = state.getLog().getLastEntryTermIndex();
    if (lastEntry == null) {
      // lastEntry may need to be derived from snapshot
      SnapshotInfo snapshot = state.getLatestSnapshot();
      if (snapshot != null) {
        lastEntry = snapshot.getTermIndex();
      }
    }

    final ResultAndTerm r;
    final Collection<RaftPeer> others = conf.getOtherPeers(server.getId());
    if (others.isEmpty()) {
      r = new ResultAndTerm(Result.PASSED, electionTerm);
    } else {
      final Executor voteExecutor = new Executor(this, others.size());
      try {
        final int submitted = submitRequests(electionTerm, lastEntry, others, voteExecutor);
        r = waitForResults(electionTerm, submitted, conf, voteExecutor);
      } finally {
        voteExecutor.shutdown();
      }
    }

    synchronized (server) {
      if (!shouldRun(electionTerm)) {
        return; // term already passed or this should not run anymore.
      }

      switch (r.result) {
        case PASSED:
          server.changeToLeader();
          return;
        case SHUTDOWN:
          LOG.info("{} received shutdown response when requesting votes.", this);
          server.getProxy().close();
          return;
        case REJECTED:
        case DISCOVERED_A_NEW_TERM:
          final long term = Math.max(r.term, state.getCurrentTerm());
          server.changeToFollowerAndPersistMetadata(term, Result.DISCOVERED_A_NEW_TERM);
          return;
        case TIMEOUT: // should start another election
          continue;
        default: throw new IllegalArgumentException("Unable to process result " + r.result);
      }
    }
  }
}
 

/**
 * After a peer changes its role to candidate, it invokes this method to
 * send out requestVote rpc to all other peers.
 */
private void askForVotes() throws InterruptedException, IOException {
  final ServerState state = server.getState();
  while (running && server.isCandidate()) {
    // one round of requestVotes
    final long electionTerm;
    synchronized (server) {
      electionTerm = state.initElection();
      server.getState().persistMetadata();
    }
    LOG.info(state.getSelfId() + ": begin an election in Term "
        + electionTerm);

    TermIndex lastEntry = state.getLog().getLastEntryTermIndex();
    if (lastEntry == null) {
      // lastEntry may need to be derived from snapshot
      SnapshotInfo snapshot = state.getLatestSnapshot();
      if (snapshot != null) {
        lastEntry = snapshot.getTermIndex();
      }
    }

    final ResultAndTerm r;
    if (others.isEmpty()) {
      r = new ResultAndTerm(Result.PASSED, electionTerm);
    } else {
      try {
        initExecutor();
        int submitted = submitRequests(electionTerm, lastEntry);
        r = waitForResults(electionTerm, submitted);
      } finally {
        if (executor != null) {
          executor.shutdown();
        }
      }
    }

    synchronized (server) {
      if (electionTerm != state.getCurrentTerm() || !running ||
          !server.isCandidate()) {
        return; // term already passed or no longer a candidate.
      }

      switch (r.result) {
        case PASSED:
          server.changeToLeader();
          return;
        case SHUTDOWN:
          LOG.info("{} received shutdown response when requesting votes.",
              server.getId());
          server.getProxy().close();
          return;
        case REJECTED:
        case DISCOVERED_A_NEW_TERM:
          final long term = r.term > server.getState().getCurrentTerm() ?
              r.term : server.getState().getCurrentTerm();
          server.changeToFollowerAndPersistMetadata(term, Result.DISCOVERED_A_NEW_TERM);
          return;
        case TIMEOUT:
          // should start another election
      }
    }
  }
}