Initial documentation pass on BeatmapDatabase

Also a bit of tidying up.

osu.Desktop.VisualTests/Tests/TestCasePlaySongSelect.cs

@@ -33,12 +33,8 @@ public TestCasePlaySongSelect()
                 rulesets = new RulesetDatabase(backingDatabase);
                 store = new BeatmapStore(storage, null, backingDatabase, rulesets);
 
-                var sets = new List<BeatmapSetInfo>();
-
                 for (int i = 0; i < 100; i += 10)
-                    sets.Add(createTestBeatmapSet(i));
-
-                store.Database.Import(sets);
+                    store.Database.Add(createTestBeatmapSet(i));
             }
 
             Add(songSelect = new PlaySongSelect());

osu.Game/Beatmaps/BeatmapDatabase.cs

@@ -48,38 +48,40 @@ protected override void Prepare(bool reset = false)
             Connection.CreateTable<BeatmapSetFileInfo>();
             Connection.CreateTable<BeatmapInfo>();
 
-            deletePending();
+            cleanupPendingDeletions();
         }
 
-        public void Update(BeatmapSetInfo setInfo) => Connection.Update(setInfo);
-
-        public void Import(IEnumerable<BeatmapSetInfo> beatmapSets)
+        /// <summary>
+        /// Add a <see cref="BeatmapSetInfo"/> to the database.
+        /// </summary>
+        /// <param name="beatmapSet">The beatmap to add.</param>
+        public void Add(BeatmapSetInfo beatmapSet)
         {
-            lock (Connection)
-            {
-                Connection.BeginTransaction();
-
-                foreach (var s in beatmapSets)
-                {
-                    Connection.InsertOrReplaceWithChildren(s, true);
-                    BeatmapSetAdded?.Invoke(s);
-                }
-
-                Connection.Commit();
-            }
+            Connection.InsertOrReplaceWithChildren(beatmapSet, true);
+            BeatmapSetAdded?.Invoke(beatmapSet);
         }
 
-        public bool Delete(BeatmapSetInfo set)
+        /// <summary>
+        /// Delete a <see cref="BeatmapSetInfo"/> to the database.
+        /// </summary>
+        /// <param name="beatmapSet">The beatmap to delete.</param>
+        /// <returns>Whether the beatmap's <see cref="BeatmapSetInfo.DeletePending"/> was changed.</returns>
+        public bool Delete(BeatmapSetInfo beatmapSet)
         {
-            if (set.DeletePending) return false;
+            if (beatmapSet.DeletePending) return false;
 
-            set.DeletePending = true;
-            Connection.Update(set);
+            beatmapSet.DeletePending = true;
+            Connection.Update(beatmapSet);
 
-            BeatmapSetRemoved?.Invoke(set);
+            BeatmapSetRemoved?.Invoke(beatmapSet);
             return true;
         }
 
+        /// <summary>
+        /// Restore a previously deleted <see cref="BeatmapSetInfo"/>.
+        /// </summary>
+        /// <param name="beatmapSet">The beatmap to restore.</param>
+        /// <returns>Whether the beatmap's <see cref="BeatmapSetInfo.DeletePending"/> was changed.</returns>
         public bool Undelete(BeatmapSetInfo set)
         {
             if (!set.DeletePending) return false;
@@ -91,7 +93,7 @@ public bool Undelete(BeatmapSetInfo set)
             return true;
         }
 
-        private void deletePending()
+        private void cleanupPendingDeletions()
         {
             foreach (var b in GetAllWithChildren<BeatmapSetInfo>(b => b.DeletePending && !b.Protected))
             {
@@ -119,4 +121,4 @@ private void deletePending()
             Connection.Query<BeatmapSetInfo>("UPDATE BeatmapSetInfo SET DeletePending = 0 WHERE DeletePending IS NULL");
         }
     }
-}
+}

osu.Game/Beatmaps/BeatmapStore.cs

@@ -109,7 +109,7 @@ public BeatmapSetInfo Import(ArchiveReader archiveReader)
 
             //If we have an ID then we already exist in the database.
             if (set.ID == 0)
-                Database.Import(new[] { set });
+                Database.Add(set);
 
             return set;
         }