Bump beatmap set last update date even if the contents didn't change

osu.Server.BeatmapSubmission.Tests/BeatmapSubmissionControllerTest.cs

@@ -1839,6 +1839,44 @@ osu file format v14
             }
         }
 
+        [Fact]
+        public async Task TestPatch_BeatmapWithNoChanges_BumpsLastUpdateDate()
+        {
+            using var db = await DatabaseAccess.GetConnectionAsync();
+            await db.ExecuteAsync(
+                "INSERT INTO `phpbb_users` (`user_id`, `username`, `username_clean`, `country_acronym`, `user_permissions`, `user_sig`, `user_occ`, `user_interests`) VALUES (1000, 'test', 'test', 'JP', '', '', '', '')");
+
+            await db.ExecuteAsync(
+                @"INSERT INTO `osu_beatmapsets` (`beatmapset_id`, `user_id`, `creator`, `approved`, `thread_id`, `active`, `submit_date`) VALUES (241526, 1000, 'test user', -1, 0, -1, CURRENT_TIMESTAMP)");
+
+            foreach (uint beatmapId in new uint[] { 557815, 557814, 557821, 557816, 557817, 557818, 557812, 557810, 557811, 557820, 557813, 557819 })
+                await db.ExecuteAsync(@"INSERT INTO `osu_beatmaps` (`beatmap_id`, `user_id`, `beatmapset_id`, `approved`) VALUES (@beatmapId, 1000, 241526, -1)", new { beatmapId = beatmapId });
+
+            // do a full upload first - required to correctly populate versioning tables
+            var putRequest = new HttpRequestMessage(HttpMethod.Put, "/beatmapsets/241526");
+
+            using var content = new MultipartFormDataContent($"{Guid.NewGuid()}----");
+            using var stream = TestResources.GetResource(osz_filename)!;
+            content.Add(new StreamContent(stream), "beatmapArchive", osz_filename);
+            putRequest.Content = content;
+            putRequest.Headers.Add(HeaderBasedAuthenticationHandler.USER_ID_HEADER, "1000");
+
+            var putResponse = await Client.SendAsync(putRequest);
+            Assert.True(putResponse.IsSuccessStatusCode);
+
+            // manually doctor the beatmapset's last update date to make sure it's bumped on a no-op patch
+            await db.ExecuteAsync(@"UPDATE `osu_beatmapsets` SET `last_update` = '2020-01-01 00:00:00' WHERE `beatmapset_id` = 241526");
+
+            // perform a no-op patch
+            var patchRequest = new HttpRequestMessage(HttpMethod.Patch, "/beatmapsets/241526");
+            patchRequest.Headers.Add(HeaderBasedAuthenticationHandler.USER_ID_HEADER, "1000");
+
+            var response = await Client.SendAsync(patchRequest);
+            Assert.True(response.IsSuccessStatusCode);
+
+            WaitForDatabaseState(@"SELECT COUNT(1) FROM `osu_beatmapsets` WHERE `beatmapset_id` = 241526 AND `last_update` > '2020-01-01 00:00:00'", 1, CancellationToken);
+        }
+
         [Fact]
         public async Task TestSubmitGuestDifficulty_OldStyle()
         {

osu.Server.BeatmapSubmission/BeatmapSubmissionController.cs

@@ -421,7 +421,8 @@ private async Task<bool> updateBeatmapSetFromArchiveAsync(osu_beatmapset beatmap
 
                 if (fileSet.SetEquals(parseResult.Files))
                 {
-                    await transaction.RollbackAsync();
+                    await db.MarkBeatmapSetUpdatedAsync(beatmapSet, transaction);
+                    await transaction.CommitAsync();
                     return false;
                 }
             }

osu.Server.BeatmapSubmission/DatabaseOperationExtensions.cs

@@ -295,6 +295,17 @@ public static Task UpdateBeatmapSetAsync(this MySqlConnection db, osu_beatmapset
                 transaction);
         }
 
+        /// <summary>
+        /// Only bumps the <paramref name="beatmapset"/>'s <c>last_update</c> date without performing any other changes.
+        /// Used in scenarios where a submission occurred for a beatmap with no changes.
+        /// Bumping the update date is important in such cases, because if it is e.g. an update after reviving the beatmap,
+        /// not bumping the update date will cause the beatmap to move to the graveyard again on the next day after the update.
+        /// </summary>
+        public static Task MarkBeatmapSetUpdatedAsync(this MySqlConnection db, osu_beatmapset beatmapset, MySqlTransaction? transaction = null)
+        {
+            return db.ExecuteAsync("UPDATE `osu_beatmapsets` SET `last_update` = CURRENT_TIMESTAMP WHERE `beatmapset_id` = @beatmapset_id", beatmapset, transaction);
+        }
+
         public static async Task<ulong> InsertBeatmapsetFileAsync(this MySqlConnection db, beatmapset_file file, MySqlTransaction? transaction = null)
         {
             var existing = await db.QuerySingleOrDefaultAsync<beatmapset_file?>(