Merge pull request #9627 from RoosterDragon/mix-on-filesystem

Avoid redundant copies of mix files in memory

OpenRA.Game/FileSystem/MixFile.cs

@@ -14,6 +14,7 @@ using System.Globalization;
 using System.IO;
 using System.Linq;
 using OpenRA.FileFormats;
+using OpenRA.Primitives;
 
 namespace OpenRA.FileSystem
 {
@@ -179,9 +180,10 @@ namespace OpenRA.FileSystem
 			if (!index.TryGetValue(hash, out e))
 				return null;
 
-			s.Seek(dataStart + e.Offset, SeekOrigin.Begin);
+			Stream parentStream;
-			var data = s.ReadBytes((int)e.Length);
+			var offset = dataStart + e.Offset + SegmentStream.GetOverallNestedOffset(s, out parentStream);
-			return new MemoryStream(data);
+			var path = ((FileStream)parentStream).Name;
+			return new SegmentStream(File.OpenRead(path), offset, e.Length);
 		}
 
 		public Stream GetContent(string filename)

OpenRA.Game/OpenRA.Game.csproj

@@ -154,6 +154,7 @@
     <Compile Include="Orders\UnitOrderGenerator.cs" />
     <Compile Include="Player.cs" />
     <Compile Include="Primitives\MergedStream.cs" />
+    <Compile Include="Primitives\SegmentStream.cs" />
     <Compile Include="Primitives\SpatiallyPartitioned.cs" />
     <Compile Include="Primitives\ConcurrentCache.cs" />
     <Compile Include="SelectableExts.cs" />

OpenRA.Game/Primitives/SegmentStream.cs

@@ -0,0 +1,102 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.ComponentModel;
+using System.IO;
+
+namespace OpenRA.Primitives
+{
+	public class SegmentStream : Stream
+	{
+		public readonly Stream BaseStream;
+		public readonly long BaseOffset;
+		public readonly long BaseCount;
+
+		public SegmentStream(Stream stream, long offset, long count)
+		{
+			if (stream == null)
+				throw new ArgumentNullException("stream");
+			if (!stream.CanSeek)
+				throw new ArgumentException("stream must be seekable.", "stream");
+			if (offset < 0)
+				throw new ArgumentOutOfRangeException("offset", "offset must be non-negative.");
+			if (count < 0)
+				throw new ArgumentOutOfRangeException("count", "count must be non-negative.");
+
+			BaseStream = stream;
+			BaseOffset = offset;
+			BaseCount = count;
+
+			stream.Seek(BaseOffset, SeekOrigin.Begin);
+		}
+
+		public override bool CanSeek { get { return true; } }
+		public override bool CanRead { get { return BaseStream.CanRead; } }
+		public override bool CanWrite { get { return BaseStream.CanWrite; } }
+
+		public override long Length { get { return BaseCount; } }
+		public override long Position
+		{
+			get { return BaseStream.Position - BaseOffset; }
+			set { BaseStream.Position = BaseOffset + value; }
+		}
+
+		public override int Read(byte[] buffer, int offset, int count) { return BaseStream.Read(buffer, offset, count); }
+		public override void Write(byte[] buffer, int offset, int count) { BaseStream.Write(buffer, offset, count); }
+		public override void Flush() { BaseStream.Flush(); }
+		public override long Seek(long offset, SeekOrigin origin)
+		{
+			switch (origin)
+			{
+				default: throw new InvalidEnumArgumentException("origin", (int)origin, typeof(SeekOrigin));
+				case SeekOrigin.Begin:
+					return BaseStream.Seek(BaseOffset + offset, SeekOrigin.Begin) - offset;
+				case SeekOrigin.Current:
+					return BaseStream.Seek(offset, SeekOrigin.Current) - offset;
+				case SeekOrigin.End:
+					return BaseStream.Seek(offset, SeekOrigin.End) - offset;
+			}
+		}
+
+		public override void SetLength(long value) { throw new NotSupportedException(); }
+
+		public override bool CanTimeout { get { return BaseStream.CanTimeout; } }
+
+		public override int ReadTimeout
+		{
+			get { return BaseStream.ReadTimeout; }
+			set { BaseStream.ReadTimeout = value; }
+		}
+
+		public override int WriteTimeout
+		{
+			get { return BaseStream.WriteTimeout; }
+			set { BaseStream.WriteTimeout = value; }
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			if (disposing)
+				BaseStream.Dispose();
+			base.Dispose(disposing);
+		}
+
+		public static long GetOverallNestedOffset(Stream stream, out Stream overallBaseStream)
+		{
+			var offset = 0L;
+			overallBaseStream = stream;
+			var segmentStream = stream as SegmentStream;
+			if (segmentStream != null)
+				offset += segmentStream.BaseOffset + GetOverallNestedOffset(segmentStream.BaseStream, out overallBaseStream);
+			return offset;
+		}
+	}
+}