Lazy parse beatmap; Don't reload audio track if it hasn't changed.

osu.Desktop.VisualTests/Tests/TestCasePlayer.cs

@@ -44,13 +44,15 @@ namespace osu.Desktop.VisualTests.Tests
                 time += 500;
             }
 
-            Add(new Player()
+            Add(new Player
             {
-                Beatmap = new WorkingBeatmap(
+                Beatmap = new WorkingBeatmap
-                    new Beatmap
+                {
+                    Beatmap = new Beatmap
                     {
                         HitObjects = objects
-                    })
+                    }
+                }
             });
         }
 

osu.Game/Beatmaps/WorkingBeatmap.cs

@@ -2,15 +2,38 @@
 //Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System;
+using System.IO;
 using osu.Framework.Audio.Track;
+using osu.Game.Beatmaps.Formats;
 using osu.Game.Beatmaps.IO;
+using osu.Game.Database;
 
 namespace osu.Game.Beatmaps
 {
     public class WorkingBeatmap : IDisposable
     {
+        private BeatmapInfo beatmapInfo;
+
         public readonly ArchiveReader Reader;
-        public readonly Beatmap Beatmap;
+
+        private Beatmap beatmap;
+        public Beatmap Beatmap
+        {
+            get
+            {
+                if (beatmap != null) return beatmap;
+
+                try
+                {
+                    using (var stream = new StreamReader(Reader.ReadFile(beatmapInfo.Path)))
+                        beatmap = BeatmapDecoder.GetDecoder(stream)?.Decode(stream);
+                }
+                catch { }
+
+                return beatmap;
+            }
+            set { beatmap = value; }
+        }
 
         private AudioTrack track;
         public AudioTrack Track
@@ -21,7 +44,7 @@ namespace osu.Game.Beatmaps
 
                 try
                 {
-                    var trackData = Reader.ReadFile(Beatmap.Metadata.AudioFile);
+                    var trackData = Reader.ReadFile(beatmapInfo.Metadata.AudioFile);
                     if (trackData != null)
                         track = new AudioTrackBass(trackData);
                 }
@@ -32,9 +55,9 @@ namespace osu.Game.Beatmaps
             set { track = value; }
         }
 
-        public WorkingBeatmap(Beatmap beatmap, ArchiveReader reader = null)
+        public WorkingBeatmap(BeatmapInfo beatmapInfo = null, ArchiveReader reader = null)
         {
-            Beatmap = beatmap;
+            this.beatmapInfo = beatmapInfo;
             Reader = reader;
         }
 
@@ -54,5 +77,11 @@ namespace osu.Game.Beatmaps
         {
             Dispose(true);
         }
+
+        public void TransferTo(WorkingBeatmap working)
+        {
+            if (track != null && working.beatmapInfo.Metadata.AudioFile == beatmapInfo.Metadata.AudioFile && working.beatmapInfo.BeatmapSet.Path == beatmapInfo.BeatmapSet.Path)
+                working.track = track;
+        }
     }
 }

osu.Game/Database/BeatmapDatabase.cs

@@ -136,16 +136,26 @@ namespace osu.Game.Database
             return Query<BeatmapSetInfo>().Where(s => s.BeatmapSetID == id).FirstOrDefault();
         }
 
-        public WorkingBeatmap GetWorkingBeatmap(BeatmapInfo beatmapInfo)
+        public WorkingBeatmap GetWorkingBeatmap(BeatmapInfo beatmapInfo, WorkingBeatmap previous = null)
         {
-            var beatmapSet = Query<BeatmapSetInfo>().Where(s => s.BeatmapSetID == beatmapInfo.BeatmapSetID).FirstOrDefault();
+            var beatmapSetInfo = Query<BeatmapSetInfo>().FirstOrDefault(s => s.BeatmapSetID == beatmapInfo.BeatmapSetID);
-            if (beatmapSet == null)
+
+            //we need metadata
+            GetChildren(beatmapSetInfo);
+
+            if (beatmapSetInfo == null)
                 throw new InvalidOperationException($@"Beatmap set {beatmapInfo.BeatmapSetID} is not in the local database.");
 
-            var reader = GetReader(beatmapSet);
+            var reader = GetReader(beatmapSetInfo);
 
-            using (var stream = new StreamReader(reader.ReadFile(beatmapInfo.Path)))
+            if (beatmapInfo.Metadata == null)
-                return new WorkingBeatmap(BeatmapDecoder.GetDecoder(stream)?.Decode(stream), reader);
+                beatmapInfo.Metadata = beatmapSetInfo.Metadata;
+
+            var working = new WorkingBeatmap(beatmapInfo, reader);
+
+            previous?.TransferTo(working);
+
+            return working;
         }
 
         public Beatmap GetBeatmap(BeatmapInfo beatmapInfo)

osu.Game/GameModes/Play/PlaySongSelect.cs

@@ -152,7 +152,6 @@ namespace osu.Game.GameModes.Play
         protected override void OnResuming(GameMode last)
         {
             ensurePlayingSelected();
-
             base.OnResuming(last);
         }
 
@@ -195,7 +194,7 @@ namespace osu.Game.GameModes.Play
 
             if (!beatmap.Equals(Beatmap?.Beatmap?.BeatmapInfo))
             {
-                Beatmap = database.GetWorkingBeatmap(beatmap);
+                Beatmap = database.GetWorkingBeatmap(beatmap, Beatmap);
             }
 
             ensurePlayingSelected();