DTXManiaプロジェクト/コード/全体/FileStreamSSD.cs

   1 using System;
   2 using System.Collections.Generic;
   3 using System.Linq;
   4 using System.Text;
   5 using System.Threading.Tasks;
   6 using System.IO;
   7 using System.Diagnostics;
   8
   9 namespace DTXMania
  10 {
  11         /// <summary>
  12         /// SSD向けFileStream (ファイルの上書き保存時に、同じファイル内容を保存する場合は、ファイルの更新を行わない)
  13         /// </summary>
  14         public class FileStreamSSD : MemoryStream, IDisposable
  15         {
  16                 private string _filename;
  17                 private FileMode _mode;
  18                 private FileAccess _access;
  19                 private MemoryStream _ms_org = null;
  20                 private FileStream _fs;
  21                 private bool disposed = false;
  22
  23                 /// <summary>
  24                 /// (baseではなく)このクラスのClose()が実行されたかどうか
  25                 /// </summary>
  26                 private bool bClosed = false;
  27
  28
  29
  30                 #region [ コンストラクタ ]
  31                 public FileStreamSSD()
  32                 {
  33                         throw new ArgumentException( "FileStreamSSD: 引数のないコンストラクタは使用できません。" );
  34                 }
  35
  36                 public FileStreamSSD( string path )
  37                         : this(path, FileMode.Create, FileAccess.Write)
  38                 {
  39                 }
  40                 public FileStreamSSD( string path, FileMode mode, FileAccess access )
  41                         : base()
  42                 {
  43                         if (mode != FileMode.Create)
  44                         {
  45                                 throw new ArgumentException(mode.ToString() + "は、FileStreamSSD()でサポートしていません。");
  46                         }
  47                         if (access != FileAccess.Write)
  48                         {
  49                                 throw new ArgumentException(access.ToString() + "は、FileStreamSSD()でサポートしていません。");
  50                         }
  51                         _filename = path;
  52                         _mode = mode;
  53                         _access = access;
  54                 }
  55                 #endregion
  56
  57                 /// <summary>
  58                 /// StreamのClose。元ファイルとのコンペアを行い、一致していればファイルの上書きをしない
  59                 /// </summary>
  60                 public new void Close()
  61                 {
  62                         bool bSame = true;
  63                         Flush();
  64
  65                         // 元ファイルがなければ、無条件に上書きコースへ。
  66                         if ( !File.Exists( _filename ) )
  67                         {
  68                                 bSame = false;
  69                         }
  70                         else
  71                         // まず、既存ファイルをMemoryStreamにコピー
  72                         {
  73                                 using ( _fs = new FileStream( _filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete ) )
  74                                 {
  75                                         // 元ファイルとファイルサイズが異なる場合は、
  76                                         if ( _fs.Length != this.Length )
  77                                         {
  78                                                 bSame = false;
  79                                         }
  80                                         else
  81                                         {
  82                                                 _ms_org = new MemoryStream();
  83                                                 _fs.CopyTo( _ms_org );
  84                                         }
  85                                 };
  86                                 _fs = null;
  87                         }
  88
  89                         if ( bSame )    // まだ新旧ファイルが一致している可能性があれば...
  90                         {
  91                                 // MemoryStream同士のコンペア
  92                                 _ms_org.Seek( 0, SeekOrigin.Begin );
  93                                 this.Seek( 0, SeekOrigin.Begin );
  94
  95                                 try
  96                                 {
  97                                         while (this.Position < this.Length)
  98                                         {
  99                                                 int dorg = _ms_org.ReadByte();
 100                                                 int dnew = this.ReadByte();
 101                                                 if (dorg != dnew)
 102                                                 {
 103                                                         bSame = false;
 104                                                         break;
 105                                                 }
 106                                         }
 107                                 }
 108                                 catch   // ファイルサイズが同じ場合のみtry内に来るため、通常ここには来ないはずだが、念のためbSame=false側に倒しておく
 109                                 {
 110                                         bSame = false;
 111                                 }
 112                         }
 113                         if ( _ms_org != null )
 114                         {
 115                                 _ms_org.Close();
 116                                 _ms_org.Dispose();
 117                                 _ms_org = null;
 118                         }
 119                         this.Seek( 0, SeekOrigin.Begin );
 120
 121                         // 元ファイルと新規ファイルが一致していない場合、新規ファイルで上書きする
 122                         if ( !bSame )
 123                         {
 124                                 Trace.TraceInformation( Path.GetFileName( _filename ) + ": 以前のファイルから変化があったため、書き込みを実行します。" );
 125                                 using ( _fs = new FileStream( _filename, _mode, _access ) )
 126                                 {
 127                                         this.CopyTo( _fs );
 128                                 }       // _fs will be closed and disposed, by using()
 129                                 _fs = null;
 130                         }
 131                         else
 132                         {
 133                                 Trace.TraceInformation( Path.GetFileName( _filename ) + ": 以前のファイルから変化がなかったため、書き込みを行いません。" );
 134                         }
 135
 136                         bClosed = true;         // base.Close()の前にフラグ変更のこと。さもないと、無限に再帰実行される
 137                         Dispose();
 138                 }
 139
 140
 141
 142                 #region [ Dispose-Finallizeパターン実装 ]
 143                 //-----------------
 144                 public new void Dispose()
 145                 {
 146                         this.Dispose( true );
 147                         GC.SuppressFinalize( this );
 148                         base.Dispose();
 149                 }
 150                 protected override void Dispose( bool disposing)
 151                 {
 152                         if (!this.disposed)
 153                         {
 154                                 try
 155                                 {
 156                                         if (this._ms_org != null)
 157                                         {
 158                                                 this._ms_org.Close();
 159                                                 this._ms_org.Dispose();
 160                                                 this._ms_org = null;
 161                                         }
 162                                         if (this._fs != null)
 163                                         {
 164                                                 this._fs.Close();
 165                                                 this._fs.Dispose();
 166                                                 this._fs = null;
 167                                         }
 168                                         if (!bClosed)
 169                                         {
 170                                                 this.Close();               // Close()なしでDispose()された場合用 (DataContractSerializer経由だと、ここに来る)
 171                                         }
 172                                         this.disposed = true;
 173                                 }
 174                                 finally
 175                                 {
 176                                         base.Dispose(disposing);
 177                                 }
 178                         }
 179                 }
 180                 ~FileStreamSSD()
 181                 {
 182                         this.Dispose( false );
 183                 }
 184                 #endregion
 185         }
 186 }