Use lock_guard with scope instead of unique_lock

plugins/net_plugin/net_plugin.cpp

@@ -4497,10 +4497,11 @@ namespace eosio {
  return "invalid peer address";
  }
 
- std::unique_lock g( connections_mtx );
- if( find_connection_i( peer_address ) )
- return "already connected";
- g.unlock();
+ {
+ std::lock_guard g(connections_mtx);
+ if (find_connection_i(peer_address))
+ return "already connected";
+ }
 
  auto [host, port, type] = split_host_port_type(peer_address);
 
@@ -4511,12 +4512,13 @@ namespace eosio {
  connection_ptr c = std::make_shared<connection>( peer_address, listen_address );
  c->strand.post([this, resolver, c, err, results, host, port, peer_address]() {
  c->set_heartbeat_timeout( heartbeat_timeout );
- std::unique_lock g( connections_mtx );
- connections.emplace( connection_detail{
- .host = peer_address,
- .c = c,
- });
- g.unlock();
+ {
+ std::lock_guard g( connections_mtx );
+ connections.emplace( connection_detail{
+ .host = peer_address,
+ .c = c,
+ });
+ }
  if( !err ) {
  c->connect( results );
  } else {
@@ -4544,10 +4546,11 @@ namespace eosio {
  }
 
  void connections_manager::reconnect(const connection_ptr& c) {
- std::unique_lock g( connections_mtx );
- auto& index = connections.get<by_connection>();
- index.erase(c);
- g.unlock();
+ {
+ std::lock_guard g( connections_mtx );
+ auto& index = connections.get<by_connection>();
+ index.erase(c);
+ }
  resolve_and_connect(c->peer_address(), c->listen_address);
  }