public void onNext()

in ratis-grpc/src/main/java/org/apache/ratis/grpc/server/GrpcLogAppender.java [679:742]
61 lines of code
11 McCabe index (conditional complexity)

    public void onNext(InstallSnapshotReplyProto reply) {
      if (LOG.isInfoEnabled()) {
        LOG.info("{}: received {} reply {}", this, replyState.isFirstReplyReceived()? "a" : "the first",
            ServerStringUtils.toInstallSnapshotReplyString(reply));
      }

      // update the last rpc time
      getFollower().updateLastRpcResponseTime();
      replyState.process(Event.SNAPSHOT_REPLY);

      final long followerSnapshotIndex;
      switch (reply.getResult()) {
        case SUCCESS:
          LOG.info("{}: Completed InstallSnapshot. Reply: {}", this, reply);
          getFollower().setAttemptedToInstallSnapshot();
          removePending(reply);
          break;
        case IN_PROGRESS:
          LOG.info("{}: InstallSnapshot in progress.", this);
          removePending(reply);
          break;
        case ALREADY_INSTALLED:
          followerSnapshotIndex = reply.getSnapshotIndex();
          LOG.info("{}: Follower snapshot is already at index {}.", this, followerSnapshotIndex);
          getFollower().setSnapshotIndex(followerSnapshotIndex);
          getFollower().setAttemptedToInstallSnapshot();
          getLeaderState().onFollowerCommitIndex(getFollower(), followerSnapshotIndex);
          increaseNextIndex(followerSnapshotIndex, reply.getResult());
          removePending(reply);
          break;
        case NOT_LEADER:
          onFollowerTerm(reply.getTerm());
          break;
        case CONF_MISMATCH:
          LOG.error("{}: Configuration Mismatch ({}): Leader {} has it set to {} but follower {} has it set to {}",
              this, RaftServerConfigKeys.Log.Appender.INSTALL_SNAPSHOT_ENABLED_KEY,
              getServer().getId(), installSnapshotEnabled, getFollowerId(), !installSnapshotEnabled);
          break;
        case SNAPSHOT_INSTALLED:
          followerSnapshotIndex = reply.getSnapshotIndex();
          LOG.info("{}: Follower installed snapshot at index {}", this, followerSnapshotIndex);
          getFollower().setSnapshotIndex(followerSnapshotIndex);
          getFollower().setAttemptedToInstallSnapshot();
          getLeaderState().onFollowerCommitIndex(getFollower(), followerSnapshotIndex);
          increaseNextIndex(followerSnapshotIndex, reply.getResult());
          onFollowerCatchup(followerSnapshotIndex);
          removePending(reply);
          break;
        case SNAPSHOT_UNAVAILABLE:
          LOG.info("{}: Follower could not install snapshot as it is not available.", this);
          getFollower().setAttemptedToInstallSnapshot();
          notifyInstallSnapshotFinished(InstallSnapshotResult.SNAPSHOT_UNAVAILABLE, RaftLog.INVALID_LOG_INDEX);
          removePending(reply);
          break;
        case UNRECOGNIZED:
          LOG.error("Unrecognized the reply result {}: Leader is {}, follower is {}",
              reply.getResult(), getServer().getId(), getFollowerId());
          break;
        case SNAPSHOT_EXPIRED:
          LOG.warn("{}: Follower could not install snapshot as it is expired.", this);
        default:
          break;
      }
    }