[#339] services/netmap: Use dynamic node information

Replace static NodeInfo structure with NodeState interface that provides
method to read node information in runtime.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/services/netmap/executor.go

@@ -9,27 +9,40 @@ import (
 
 type executorSvc struct {
 	version *pkg.Version
-	localNodeInfo *netmap.NodeInfo
+	state   NodeState
 }
 
-func NewExecutionService(ni *netmap.NodeInfo, v *pkg.Version) netmap.Service {
-	if ni == nil || v == nil {
+// NodeState encapsulates information
+// about current node state.
+type NodeState interface {
+	// Must return current node state
+	// in NeoFS API v2 NodeInfo structure.
+	LocalNodeInfo() (*netmap.NodeInfo, error)
+}
+
+func NewExecutionService(s NodeState, v *pkg.Version) netmap.Service {
+	if s == nil || v == nil {
 		// this should never happen, otherwise it programmers bug
 		panic("can't create netmap execution service")
 	}
 
 	return &executorSvc{
 		version: v,
-		localNodeInfo: ni,
+		state:   s,
 	}
 }
 
 func (s *executorSvc) LocalNodeInfo(
 	_ context.Context,
 	_ *netmap.LocalNodeInfoRequest) (*netmap.LocalNodeInfoResponse, error) {
+	ni, err := s.state.LocalNodeInfo()
+	if err != nil {
+		return nil, err
+	}
+
 	body := new(netmap.LocalNodeInfoResponseBody)
 	body.SetVersion(s.version.ToV2())
-	body.SetNodeInfo(s.localNodeInfo)
+	body.SetNodeInfo(ni)
 
 	resp := new(netmap.LocalNodeInfoResponse)
 	resp.SetBody(body)