Raft member change fails and still returns success to meta

[cangfengzhs]

Example:

// src/kvstore/Part.cpp
      case OP_REMOVE_PEER: {
        auto peer = decodeHost(OP_REMOVE_PEER, log);
        auto ts = getTimestamp(log);
        if (ts > startTimeMs_) {
          LOG(INFO) << idStr_ << "preprocess remove peer " << peer;
          preProcessRemovePeer(peer);          //  <-- Here may be failed.
        } else {
          LOG(INFO) << idStr_ << "Skip stale remove peer " << peer << ", the part is opened at "
                    << startTimeMs_ << ", but the log timestamp is " << ts;
        }
        break;
      }

All member changes, not just preProcessRemovePeer, did not return the change result. Meta will consider the operation to be successful. This leads to the possibility of more copies or loss during the balance process.

https://discuss.nebula-graph.com.cn/t/topic/6616

[critical27]

Case closed, the plan is not generated properly