private Result sendStartLeaderElection()

in ratis-server/src/main/java/org/apache/ratis/server/impl/TransferLeadership.java [201:239]

35 lines of code
7 McCabe index (conditional complexity)


  private Result sendStartLeaderElection(FollowerInfo follower) {
    final TermIndex lastEntry = server.getState().getLastEntry();

    final Result result = isFollowerUpToDate(follower, lastEntry);
    if (result != Result.SUCCESS) {
      return result;
    }

    final RaftPeerId transferee = follower.getId();
    LOG.info("{}: sendStartLeaderElection to follower {}, lastEntry={}",
        server.getMemberId(), transferee, lastEntry);

    final RaftProtos.StartLeaderElectionRequestProto r = ServerProtoUtils.toStartLeaderElectionRequestProto(
        server.getMemberId(), transferee, lastEntry);
    final CompletableFuture<RaftProtos.StartLeaderElectionReplyProto> f = CompletableFuture.supplyAsync(() -> {
      server.getLeaderElectionMetrics().onTransferLeadership();
      try {
        return server.getServerRpc().startLeaderElection(r);
      } catch (IOException e) {
        throw new CompletionException("Failed to sendStartLeaderElection to follower " + transferee, e);
      }
    }, server.getServerExecutor()).whenComplete((reply, exception) -> {
      if (reply != null) {
        LOG.info("{}: Received startLeaderElection reply from {}: success? {}",
            server.getMemberId(), transferee, reply.getServerReply().getSuccess());
      } else if (exception != null) {
        LOG.warn(server.getMemberId() + ": Failed to startLeaderElection for " + transferee, exception);
      }
    });

    if (f.isCompletedExceptionally()) { // already failed
      try {
        f.join();
      } catch (Throwable t) {
        return new Result(t);
      }
    }
    return Result.SUCCESS;
  }