Merge branch 'master' into fix-beatmap-carousel-lag

osu.Game/Beatmaps/WorkingBeatmap.cs

@@ -32,7 +32,7 @@ namespace osu.Game.Beatmaps
             Mods.ValueChanged += mods => applyRateAdjustments();
 
             beatmap = new AsyncLazy<Beatmap>(populateBeatmap);
-            background = new AsyncLazy<Texture>(populateBackground);
+            background = new AsyncLazy<Texture>(populateBackground, b => b == null || !b.IsDisposed);
             track = new AsyncLazy<Track>(populateTrack);
             waveform = new AsyncLazy<Waveform>(populateWaveform);
             storyboard = new AsyncLazy<Storyboard>(populateStoryboard);
@@ -44,7 +44,7 @@ namespace osu.Game.Beatmaps
         protected virtual Waveform GetWaveform() => new Waveform();
         protected virtual Storyboard GetStoryboard() => new Storyboard();
 
-        public bool BeatmapLoaded => beatmap.IsValueCreated;
+        public bool BeatmapLoaded => beatmap.IsResultAvailable;
         public Beatmap Beatmap => beatmap.Value.Result;
         public async Task<Beatmap> GetBeatmapAsync() => await beatmap.Value;
 
@@ -60,14 +60,14 @@ namespace osu.Game.Beatmaps
             return b;
         }
 
-        public bool BackgroundLoaded => background.IsValueCreated;
+        public bool BackgroundLoaded => background.IsResultAvailable;
         public Texture Background => background.Value.Result;
         public async Task<Texture> GetBackgroundAsync() => await background.Value;
         private AsyncLazy<Texture> background;
 
         private Texture populateBackground() => GetBackground();
 
-        public bool TrackLoaded => track.IsValueCreated;
+        public bool TrackLoaded => track.IsResultAvailable;
         public Track Track => track.Value.Result;
         public async Task<Track> GetTrackAsync() => await track.Value;
         private AsyncLazy<Track> track;
@@ -80,7 +80,7 @@ namespace osu.Game.Beatmaps
             return t;
         }
 
-        public bool WaveformLoaded => waveform.IsValueCreated;
+        public bool WaveformLoaded => waveform.IsResultAvailable;
         public Waveform Waveform => waveform.Value.Result;
         public async Task<Waveform> GetWaveformAsync() => await waveform.Value;
         private readonly AsyncLazy<Waveform> waveform;
@@ -96,10 +96,10 @@ namespace osu.Game.Beatmaps
 
         public void TransferTo(WorkingBeatmap other)
         {
-            if (track.IsValueCreated && Track != null && BeatmapInfo.AudioEquals(other.BeatmapInfo))
+            if (track.IsResultAvailable && Track != null && BeatmapInfo.AudioEquals(other.BeatmapInfo))
                 other.track = track;
 
-            if (background.IsValueCreated && Background != null && BeatmapInfo.BackgroundEquals(other.BeatmapInfo))
+            if (background.IsResultAvailable && Background != null && BeatmapInfo.BackgroundEquals(other.BeatmapInfo))
                 other.background = background;
         }
 
@@ -110,14 +110,15 @@ namespace osu.Game.Beatmaps
             if (StoryboardLoaded) Storyboard?.Dispose();
         }
 
-        public void DisposeTrack()
-        {
-            if (TrackLoaded) Track?.Dispose();
-        }
+        /// <summary>
+        /// Eagerly dispose of the audio track associated with this <see cref="WorkingBeatmap"/> (if any).
+        /// Accessing track again will load a fresh instance.
+        /// </summary>
+        public void RecycleTrack() => track.Recycle();
 
         private void applyRateAdjustments(Track t = null)
         {
-            if (t == null && track.IsValueCreated) t = Track;
+            if (t == null && track.IsResultAvailable) t = Track;
             if (t == null) return;
 
             t.ResetSpeedAdjustments();
@@ -125,12 +126,65 @@ namespace osu.Game.Beatmaps
                 mod.ApplyToClock(t);
         }
 
-        public class AsyncLazy<T> : Lazy<Task<T>>
+        public class AsyncLazy<T>
         {
-            public AsyncLazy(Func<T> valueFactory)
-                : base(() => Task.Run(valueFactory))
+            private Lazy<Task<T>> lazy;
+            private readonly Func<T> valueFactory;
+            private readonly Func<T, bool> stillValidFunction;
+
+            private readonly object initLock = new object();
+
+            public AsyncLazy(Func<T> valueFactory, Func<T, bool> stillValidFunction = null)
             {
+                this.valueFactory = valueFactory;
+                this.stillValidFunction = stillValidFunction;
+
+                recreate();
             }
+
+            public void Recycle()
+            {
+                if (!IsResultAvailable) return;
+
+                (lazy.Value.Result as IDisposable)?.Dispose();
+                recreate();
+            }
+
+            public bool IsResultAvailable
+            {
+                get
+                {
+                    recreateIfInvalid();
+                    return lazy.Value.IsCompleted;
+                }
+            }
+
+            public Task<T> Value
+            {
+                get
+                {
+                    recreateIfInvalid();
+                    return lazy.Value;
+                }
+            }
+
+            private void recreateIfInvalid()
+            {
+                lock (initLock)
+                {
+                    if (!lazy.IsValueCreated || !lazy.Value.IsCompleted)
+                        // we have not yet been initialised or haven't run the task.
+                        return;
+
+                    if (stillValidFunction?.Invoke(lazy.Value.Result) ?? true)
+                        // we are still in a valid state.
+                        return;
+
+                    recreate();
+                }
+            }
+
+            private void recreate() => lazy = new Lazy<Task<T>>(() => Task.Run(valueFactory));
         }
     }
 }