SortMapKeys in proto2json for deterministic seriarialization

commit_hash:e64dedae589fa2d16347be4d80e2596f46566b38

3 files changed, 43 insertions, 2 deletions

diff --git a/library/cpp/protobuf/json/config.h b/library/cpp/protobuf/json/config.h
index 98d484cdf4..d0d2d21bcf 100644
--- a/library/cpp/protobuf/json/config.h
+++ b/library/cpp/protobuf/json/config.h
@@ -109,6 +109,9 @@ namespace NProtobufJson {
 
         bool WriteNanAsString = false;
 
+        // Sort keys in maps before serialization.
+        bool SortMapKeys = false;
+
         TSelf& SetDoubleNDigits(ui32 ndigits) {
             DoubleNDigits = ndigits;
             return *this;
@@ -189,6 +192,11 @@ namespace NProtobufJson {
             return *this;
         }
 
+        TSelf& SetSortMapKeys(bool value) {
+            SortMapKeys = value;
+            return *this;
+        }
+
         TSelf& SetStringifyNumbers(EStringifyNumbersMode stringify) {
             StringifyNumbers = stringify;
             return *this;
diff --git a/library/cpp/protobuf/json/proto2json_printer.cpp b/library/cpp/protobuf/json/proto2json_printer.cpp
index 5d0e140615..a9f8c3fce9 100644
--- a/library/cpp/protobuf/json/proto2json_printer.cpp
+++ b/library/cpp/protobuf/json/proto2json_printer.cpp
@@ -8,6 +8,7 @@
 
 #include <library/cpp/protobuf/json/proto/enum_options.pb.h>
 
+#include <util/generic/map.h>
 #include <util/generic/yexception.h>
 #include <util/string/ascii.h>
 #include <util/string/cast.h>
@@ -394,8 +395,22 @@ namespace NProtobufJson {
 
                 case FieldDescriptor::CPPTYPE_MESSAGE: {
                     if (isMap) {
-                        for (size_t i = 0, endI = reflection->FieldSize(proto, &field); i < endI; ++i) {
-                            PrintKeyValue(reflection->GetRepeatedMessage(proto, &field, i), json);
+                        if (GetConfig().SortMapKeys) {
+                            TMap<TString, size_t> keyToIndex;
+                            for (size_t i = 0, endI = reflection->FieldSize(proto, &field); i < endI; ++i) {
+                                const Message& fieldMessage = reflection->GetRepeatedMessage(proto, &field, i);
+                                const FieldDescriptor* keyField = fieldMessage.GetDescriptor()->map_key();
+                                Y_ABORT_UNLESS(keyField, "Map entry key field not found.");
+                                TString key = MakeKey(fieldMessage, *keyField);
+                                keyToIndex[key] = i;
+                            }
+                            for (const auto& [_, i] : keyToIndex) {
+                                PrintKeyValue(reflection->GetRepeatedMessage(proto, &field, i), json);
+                            }
+                        } else {
+                            for (size_t i = 0, endI = reflection->FieldSize(proto, &field); i < endI; ++i) {
+                                PrintKeyValue(reflection->GetRepeatedMessage(proto, &field, i), json);
+                            }
                         }
                     } else {
                         for (size_t i = 0, endI = reflection->FieldSize(proto, &field); i < endI; ++i) {
diff --git a/library/cpp/protobuf/json/ut/proto2json_ut.cpp b/library/cpp/protobuf/json/ut/proto2json_ut.cpp
index 9e98ab8a06..f5bcfac49d 100644
--- a/library/cpp/protobuf/json/ut/proto2json_ut.cpp
+++ b/library/cpp/protobuf/json/ut/proto2json_ut.cpp
@@ -997,6 +997,24 @@ Y_UNIT_TEST(TestMapUsingGeneratedAsJSON) {
     UNIT_ASSERT_JSON_STRINGS_EQUAL(jsonStr.Str(), modelStr);
 } // TestMapUsingGeneratedAsJSON
 
+Y_UNIT_TEST(TestMapSortedKeys) {
+    TMapType proto;
+
+    auto& items = *proto.MutableItems();
+    items["key1"] = "value1";
+    items["key2"] = "value2";
+    items["key3"] = "value3";
+
+    TString modelStr(R"_({"Items":{"key1":"value1","key2":"value2","key3":"value3"}})_");
+
+    TStringStream jsonStr;
+
+    auto config = TProto2JsonConfig().SetMapAsObject(true).SetSortMapKeys(false);
+    UNIT_ASSERT_NO_EXCEPTION(Proto2Json(proto, jsonStr, config));
+
+    UNIT_ASSERT_JSON_STRINGS_EQUAL(jsonStr.Str(), modelStr);
+} // TestMapSortedKeys
+
 Y_UNIT_TEST(TestMapDefaultValue) {
     TMapType proto;