Add interface for database context factory

osu.Game.Tests/Visual/TestCasePlaySongSelect.cs

@@ -63,7 +63,7 @@ namespace osu.Game.Tests.Visual
             var storage = new TestStorage(@"TestCasePlaySongSelect");
 
             // this is by no means clean. should be replacing inside of OsuGameBase somehow.
-            DatabaseContextFactory factory = new SingletonContextFactory(new OsuDbContext());
+            IDatabaseContextFactory factory = new SingletonContextFactory(new OsuDbContext());
 
             dependencies.Cache(rulesets = new RulesetStore(factory));
             dependencies.Cache(manager = new BeatmapManager(storage, factory, rulesets, null)

osu.Game/Beatmaps/BeatmapManager.cs

@@ -60,7 +60,7 @@ namespace osu.Game.Beatmaps
         /// </summary>
         public WorkingBeatmap DefaultBeatmap { private get; set; }
 
-        private readonly DatabaseContextFactory contextFactory;
+        private readonly IDatabaseContextFactory contextFactory;
 
         private readonly FileStore files;
 
@@ -85,7 +85,7 @@ namespace osu.Game.Beatmaps
         /// </summary>
         public Func<Storage> GetStableStorage { private get; set; }
 
-        public BeatmapManager(Storage storage, DatabaseContextFactory contextFactory, RulesetStore rulesets, APIAccess api, IIpcHost importHost = null)
+        public BeatmapManager(Storage storage, IDatabaseContextFactory contextFactory, RulesetStore rulesets, APIAccess api, IIpcHost importHost = null)
         {
             this.contextFactory = contextFactory;
 

osu.Game/Beatmaps/BeatmapStore.cs

@@ -20,7 +20,7 @@ namespace osu.Game.Beatmaps
         public event Action<BeatmapInfo> BeatmapHidden;
         public event Action<BeatmapInfo> BeatmapRestored;
 
-        public BeatmapStore(DatabaseContextFactory factory)
+        public BeatmapStore(IDatabaseContextFactory factory)
             : base(factory)
         {
         }

osu.Game/Database/DatabaseBackedStore.cs

@@ -15,7 +15,7 @@ namespace osu.Game.Database
         /// <summary>
         /// Create a new <see cref="OsuDbContext"/> instance (separate from the shared context via <see cref="GetContext"/> for performing isolated operations.
         /// </summary>
-        protected readonly DatabaseContextFactory ContextFactory;
+        protected readonly IDatabaseContextFactory ContextFactory;
 
         /// <summary>
         /// Refresh an instance potentially from a different thread with a local context-tracked instance.
@@ -40,7 +40,7 @@ namespace osu.Game.Database
             }
         }
 
-        protected DatabaseBackedStore(DatabaseContextFactory contextFactory, Storage storage = null)
+        protected DatabaseBackedStore(IDatabaseContextFactory contextFactory, Storage storage = null)
         {
             ContextFactory = contextFactory;
             Storage = storage;

osu.Game/Database/DatabaseContextFactory.cs

@@ -6,7 +6,7 @@ using osu.Framework.Platform;
 
 namespace osu.Game.Database
 {
-    public class DatabaseContextFactory
+    public class DatabaseContextFactory : IDatabaseContextFactory
     {
         private readonly GameHost host;
 

osu.Game/Database/IDatabaseContextFactory.cs

@@ -0,0 +1,20 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Database
+{
+    public interface IDatabaseContextFactory
+    {
+        /// <summary>
+        /// Get a context for read-only usage.
+        /// </summary>
+        OsuDbContext Get();
+
+        /// <summary>
+        /// Request a context for write usage. Can be consumed in a nested fashion (and will return the same underlying context).
+        /// This method may block if a write is already active on a different thread.
+        /// </summary>
+        /// <returns>A usage containing a usable context.</returns>
+        DatabaseWriteUsage GetForWrite();
+    }
+}

osu.Game/Database/SingletonContextFactory.cs

@@ -3,19 +3,17 @@
 
 namespace osu.Game.Database
 {
-    public class SingletonContextFactory : DatabaseContextFactory
+    public class SingletonContextFactory : IDatabaseContextFactory
     {
         private readonly OsuDbContext context;
 
         public SingletonContextFactory(OsuDbContext context)
-            : base(null)
         {
             this.context = context;
         }
 
-        protected override OsuDbContext CreateContext()
-        {
-            return context;
-        }
+        public OsuDbContext Get() => context;
+
+        public DatabaseWriteUsage GetForWrite() => new DatabaseWriteUsage(context, null);
     }
 }

osu.Game/IO/FileStore.cs

@@ -21,7 +21,7 @@ namespace osu.Game.IO
 
         public new Storage Storage => base.Storage;
 
-        public FileStore(DatabaseContextFactory contextFactory, Storage storage) : base(contextFactory, storage.GetStorageForDirectory(@"files"))
+        public FileStore(IDatabaseContextFactory contextFactory, Storage storage) : base(contextFactory, storage.GetStorageForDirectory(@"files"))
         {
             Store = new StorageBackedResourceStore(Storage);
         }

osu.Game/Rulesets/RulesetStore.cs

@@ -25,7 +25,7 @@ namespace osu.Game.Rulesets
                 loadRulesetFromFile(file);
         }
 
-        public RulesetStore(DatabaseContextFactory factory)
+        public RulesetStore(IDatabaseContextFactory factory)
             : base(factory)
         {
             AddMissingRulesets();

osu.Game/osu.Game.csproj

@@ -276,6 +276,7 @@
     <Compile Include="Configuration\SpeedChangeVisualisationMethod.cs" />
     <Compile Include="Database\DatabaseContextFactory.cs" />
     <Compile Include="Database\DatabaseWriteUsage.cs" />
+    <Compile Include="Database\IDatabaseContextFactory.cs" />
     <Compile Include="Database\IHasPrimaryKey.cs" />
     <Compile Include="Database\SingletonContextFactory.cs" />
     <Compile Include="Graphics\Containers\LinkFlowContainer.cs" />