protected void doStart()

in tephra-core/src/main/java/org/apache/tephra/distributed/TransactionService.java [86:143]
49 lines of code
7 McCabe index (conditional complexity)

  protected void doStart() {
    leaderElection = new LeaderElection(zkClient, "/tx.service/leader", new ElectionHandler() {
      @Override
      public void leader() {
        // if the txManager fails, we should stop the server
        txManager = txManagerProvider.get();
        txManager.addListener(new ServiceListenerAdapter() {
          @Override
          public void failed(State from, Throwable failure) {
            LOG.error("Transaction manager aborted, stopping transaction service");
            TransactionService.this.abort(failure);
          }
        }, MoreExecutors.sameThreadExecutor());

        pruningService = createPruningService(conf, txManager);

        server = ThriftRPCServer.builder(TTransactionServer.class)
          .setHost(address)
          .setPort(port)
          .setWorkerThreads(threads)
          .setMaxReadBufferBytes(maxReadBufferBytes)
          .setIOThreads(ioThreads)
          .build(new TransactionServiceThriftHandler(txManager, pruningService));
        try {
          server.startAndWait();
          pruningService.startAndWait();
          doRegister();
          LOG.info("Transaction Thrift Service started successfully on " + getAddress());
        } catch (Throwable t) {
          LOG.info("Transaction Thrift Service didn't start on " + server.getBindAddress());
          leaderElection.stop();
          notifyFailed(t);
        }
      }

      @Override
      public void follower() {
        ListenableFuture<State> stopFuture = null;
        if (pruningService != null && pruningService.isRunning()) {
          // Wait for pruning service to stop after un-registering from discovery
          stopFuture = pruningService.stop();
        }
        // First stop the transaction server as un-registering from discovery can block sometimes.
        // That can lead to multiple transaction servers being active at the same time.
        if (server != null && server.isRunning()) {
          server.stopAndWait();
        }
        undoRegister();

        if (stopFuture != null) {
          Futures.getUnchecked(stopFuture);
        }
      }
    });
    leaderElection.start();

    notifyStarted();
  }