private long appendImpl()

in ratis-server/src/main/java/org/apache/ratis/server/raftlog/RaftLogBase.java [175:217]
35 lines of code
7 McCabe index (conditional complexity)

  private long appendImpl(long term, TransactionContext operation) throws StateMachineException {
    checkLogState();
    try(AutoCloseableLock writeLock = writeLock()) {
      final long nextIndex = getNextIndex();

      // This is called here to guarantee strict serialization of callback executions in case
      // the SM wants to attach a logic depending on ordered execution in the log commit order.
      try {
        operation = operation.preAppendTransaction();
      } catch (StateMachineException e) {
        throw e;
      } catch (IOException e) {
        throw new StateMachineException(memberId, e);
      }

      // build the log entry after calling the StateMachine
      final LogEntryProto e = operation.initLogEntry(term, nextIndex);

      int entrySize = e.getSerializedSize();
      if (entrySize > maxBufferSize) {
        throw new StateMachineException(memberId, new RaftLogIOException(
            "Log entry size " + entrySize + " exceeds the max buffer limit of " + maxBufferSize));
      }

      appendEntry(operation.wrap(e), operation).whenComplete((returned, t) -> {
        if (t != null) {
          LOG.error(name + ": Failed to write log entry " + toLogEntryString(e), t);
        } else if (returned != nextIndex) {
          LOG.error("{}: Indices mismatched: returned index={} but nextIndex={} for log entry {}",
              name, returned, nextIndex, toLogEntryString(e));
        } else {
          return; // no error
        }

        try {
          close(); // close due to error
        } catch (IOException ioe) {
          LOG.error("Failed to close " + name, ioe);
        }
      });
      return nextIndex;
    }
  }