Add safe deletion support.

osu.Game/Database/BeatmapDatabase.cs

@@ -8,6 +8,7 @@ using System.IO;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Security.Cryptography;
+using osu.Framework.Logging;
 using osu.Framework.Platform;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.Formats;
@@ -39,16 +40,37 @@ namespace osu.Game.Database
                 try
                 {
                     connection = prepareConnection();
+                    deletePending();
                 }
-                catch
+                catch (Exception e)
                 {
-                    Console.WriteLine(@"Failed to initialise the beatmap database! Trying again with a clean database...");
+                    Logger.Error(e, @"Failed to initialise the beatmap database! Trying again with a clean database...");
                     storage.DeleteDatabase(@"beatmaps");
                     connection = prepareConnection();
                 }
             }
         }
 
+        private void deletePending()
+        {
+            foreach (var b in Query<BeatmapSetInfo>().Where(b => b.DeletePending))
+            {
+                try
+                {
+                    storage.Delete(b.Path);
+                    connection.Delete(b);
+                }
+                catch (Exception e)
+                {
+                    Logger.Error(e, $@"Could not delete beatmap {b.ToString()}");
+                }
+            }
+
+            //this is required because sqlite migrations don't work, initially inserting nulls into this field.
+            //see https://github.com/praeclarum/sqlite-net/issues/326
+            connection.Query<BeatmapSetInfo>("UPDATE BeatmapSetInfo SET DeletePending = 0 WHERE DeletePending IS NULL");
+        }
+
         private SQLiteConnection prepareConnection()
         {
             var conn = storage.GetDatabase(@"beatmaps");
@@ -161,8 +183,9 @@ namespace osu.Game.Database
 
         public void Delete(BeatmapSetInfo beatmapSet)
         {
-            storage.Delete(beatmapSet.Path);
+            beatmapSet.DeletePending = true;
-            connection.Delete(beatmapSet);
+            Update(beatmapSet, false);
+
             BeatmapSetRemoved?.Invoke(beatmapSet);
         }
 

osu.Game/Database/BeatmapSetInfo.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System.Collections.Generic;
+using System.ComponentModel;
 using SQLite.Net.Attributes;
 using SQLiteNetExtensions.Attributes;
 
@@ -23,6 +24,8 @@ namespace osu.Game.Database
         [OneToMany(CascadeOperations = CascadeOperation.All)]
         public List<BeatmapInfo> Beatmaps { get; set; }
 
+        public bool DeletePending { get; set; }
+
         public string Hash { get; set; }
 
         public string Path { get; set; }

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -377,7 +377,7 @@ namespace osu.Game.Screens.Select
 
         private void addBeatmapSets(Framework.Game game, CancellationToken token)
         {
-            foreach (var beatmapSet in database.Query<BeatmapSetInfo>())
+            foreach (var beatmapSet in database.Query<BeatmapSetInfo>().Where(b => !b.DeletePending))
             {
                 if (token.IsCancellationRequested) return;
                 addBeatmapSet(beatmapSet, game);