private void handleRegisterFailure()

in twill-discovery-core/src/main/java/org/apache/twill/discovery/ZKDiscoveryService.java [197:240]
35 lines of code
5 McCabe index (conditional complexity)

  private void handleRegisterFailure(final Discoverable discoverable,
                                     final SettableFuture<String> completion,
                                     final FutureCallback<String> creationCallback,
                                     final Throwable failureCause) {

    final String path = getNodePath(discoverable);
    Futures.addCallback(zkClient.exists(path), new FutureCallback<Stat>() {
      @Override
      public void onSuccess(Stat result) {
        if (result == null) {
          // If the node is gone, simply retry.
          LOG.info("Node {} is gone. Retry registration for {}.", path, discoverable);
          retryRegister(discoverable, creationCallback);
          return;
        }

        long ephemeralOwner = result.getEphemeralOwner();
        if (ephemeralOwner == 0) {
          // it is not an ephemeral node, something wrong.
          LOG.error("Node {} already exists and is not an ephemeral node. Discoverable registration failed: {}.",
                    path, discoverable);
          completion.setException(failureCause);
          return;
        }
        Long sessionId = zkClient.getSessionId();
        if (sessionId == null || ephemeralOwner != sessionId) {
          // This zkClient is not valid or doesn't own the ephemeral node, simply keep retrying.
          LOG.info("Owner of {} is different. Retry registration for {}.", path, discoverable);
          retryRegister(discoverable, creationCallback);
        } else {
          // This client owned the node, treat the registration as completed.
          // This could happen if same client tries to register twice (due to mistake or failure race condition).
          completion.set(path);
        }
      }

      @Override
      public void onFailure(Throwable t) {
        // If exists call failed, simply retry creation.
        LOG.warn("Error when getting stats on {}. Retry registration for {}.", path, discoverable);
        retryRegister(discoverable, creationCallback);
      }
    }, Threads.SAME_THREAD_EXECUTOR);
  }