status: add "incomplete success" code

The name was chosen specifically to avoid linking it to HTTP "206 Partial
Content" which has a different semantics. This can help with
 * nspcc-dev/neofs-node#2721
 * nspcc-dev/neofs-node#3428

Signed-off-by: Roman Khimov <roman@nspcc.ru>

Author: roman-khimov

object/service.proto

@@ -64,6 +64,9 @@ service ObjectService {
   // Statuses:
   // - **OK** (0, SECTION_SUCCESS): \
   //   object has been successfully saved in the container;
+  // - **INCOMPLETE** (1, SECTION_SUCCESS): \
+  //   object was put to some nodes, but the number of replicas is not sufficient
+  //   to satisfy placement policy;
   // - Common failures (SECTION_FAILURE_COMMON);
   // - **ACCESS_DENIED** (2048, SECTION_OBJECT): \
   //   write access to the container is denied;
@@ -99,6 +102,9 @@ service ObjectService {
   // Statuses:
   // - **OK** (0, SECTION_SUCCESS): \
   //   object has been successfully marked to be removed from the container;
+  // - **INCOMPLETE** (1, SECTION_SUCCESS): \
+  //   some nodes have accepted the deletion mark, but some may still store
+  //   the object;
   // - Common failures (SECTION_FAILURE_COMMON);
   // - **ACCESS_DENIED** (2048, SECTION_OBJECT): \
   //   delete access to the object is denied;
@@ -153,6 +159,9 @@ service ObjectService {
   // Statuses:
   // - **OK** (0, SECTION_SUCCESS): \
   //   objects have been successfully selected;
+  // - **INCOMPLETE** (1, SECTION_SUCCESS): \
+  //   some nodes were unable to process the request, so the result may
+  //   not contain all data;
   // - Common failures (SECTION_FAILURE_COMMON);
   // - **ACCESS_DENIED** (2048, SECTION_OBJECT): \
   //   access to operation SEARCH of the object is denied;

proto-docs/status.md

@@ -158,6 +158,7 @@ Section of NeoFS successful return codes.
 | Name | Number | Description |
 | ---- | ------ | ----------- |
 | OK | 0 | [**0**] Default success. Not detailed. If the server cannot match successful outcome to the code, it should use this code. |
+| INCOMPLETE | 1 | [**1**] Incomplete success, only a part of the request done which may or may not be sufficient for the client. Examples are object PUT making 2 out of 3 required replicas or distributed SEARCH getting result from 4 out of 5 nodes. |
 
 
  <!-- end enums -->

status/types.proto

@@ -81,6 +81,12 @@ enum Success {
   // If the server cannot match successful outcome to the code, it should
   // use this code.
   OK = 0;
+
+  // [**1**] Incomplete success, only a part of the request done which may
+  // or may not be sufficient for the client. Examples are object PUT making
+  // 2 out of 3 required replicas or distributed SEARCH getting result from
+  // 4 out of 5 nodes.
+  INCOMPLETE = 1;
 }
 
 // Section of failed statuses independent of the operation.