fix: add mutex to support concurrency raft.cluster join (#52)

* fix: add mutex to support concurrency `raft.cluster join`

#25

Signed-off-by: HappyUncle <code4happy@gmail.com>

* fix: add `change_peer_mutex_` in `PRaft::AddPeer` and `PRaft::RemovePeer`

Signed-off-by: HappyUncle <code4happy@gmail.com>

---------

Signed-off-by: HappyUncle <code4happy@gmail.com>

src/praft/praft.cc

@@ -533,9 +533,11 @@ int PRaft::ProcessClusterRemoveCmdResponse(PClient* client, const char* start, i
 
 butil::Status PRaft::AddPeer(const std::string& peer) {
   if (!node_) {
-    ERROR_LOG_AND_STATUS("Node is not initialized");
+    return ERROR_LOG_AND_STATUS("Node is not initialized");
   }
 
+  std::unique_lock<std::mutex> lck(change_peer_mutex_);
+
   braft::SynchronizedClosure done;
   node_->add_peer(peer, &done);
   done.wait();
@@ -553,6 +555,8 @@ butil::Status PRaft::RemovePeer(const std::string& peer) {
     return ERROR_LOG_AND_STATUS("Node is not initialized");
   }
 
+  std::unique_lock<std::mutex> lck(change_peer_mutex_);
+
   braft::SynchronizedClosure done;
   node_->remove_peer(peer, &done);
   done.wait();

src/praft/praft.h

@@ -171,6 +171,9 @@ class PRaft : public braft::StateMachine {
   int db_id_ = 0;                      // db_id
 
   bool is_node_first_start_up_ = true;
+
+  // Concurrency `raft.cluster join` will throw an error, so use a mutex for restriction.
+  std::mutex change_peer_mutex_;
 };
 
 }  // namespace kiwi