A buffered file stream utilizes the MemoryPool to intellectually cache the contents of files.
This class is a special purpose class that can only be used for the TransactionalFileStructure and can not buffer general purpose file. The cache algorithm is a least recently used algorithm. This is accomplised by incrementing a counter every time a page is accessed and dividing by 2 every time a collection occurs from the MemoryPool.
Inheritance: IDiskMediumCoreFunctions
BufferedFile Class Documentation
Exemple #1
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        /// <summary>
        /// Creates a <see cref="DiskMedium"/> from a <see cref="stream"/>.
        /// This will initialize the <see cref="stream"/> as an empty file structure.
        /// </summary>
        /// <param name="stream">An open <see cref="FileStream"/> to use. The <see cref="DiskMedium"/>
        ///     will assume ownership of this <see cref="FileStream"/>.</param>
        /// <param name="pool">the <see cref="MemoryPool"/> to allocate data from</param>
        /// <param name="fileStructureBlockSize">the block size of the file structure. Usually 4kb.</param>
        /// <param name="flags">Flags to write to the file</param>
        /// <returns></returns>
        /// <remarks>
        /// This will not check if the file is truely a new file. If calling this with an existing
        /// archive file, it will overwrite the table of contents, corrupting the file.
        /// </remarks>
        public static DiskMedium CreateFile(CustomFileStream stream, MemoryPool pool, int fileStructureBlockSize, params Guid[] flags)
        {
            FileHeaderBlock header = FileHeaderBlock.CreateNew(fileStructureBlockSize, flags);

            BufferedFile disk = new BufferedFile(stream, pool, header, isNewFile: true);

            return(new DiskMedium(disk, header));
        }
Exemple #2
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        /// <summary>
        /// Creates a <see cref="DiskMedium"/> from a <see cref="stream"/>.
        /// This will read the existing header from the <see cref="stream"/>.
        /// </summary>
        /// <param name="stream">An open <see cref="FileStream"/> to use. The <see cref="DiskMedium"/>
        /// will assume ownership of this <see cref="FileStream"/>.</param>
        /// <param name="pool">The <see cref="MemoryPool"/> to allocate data from.</param>
        /// <param name="fileStructureBlockSize">the block size of the file structure. Usually 4kb.</param>
        /// <returns></returns>
        public static DiskMedium OpenFile(CustomFileStream stream, MemoryPool pool, int fileStructureBlockSize)
        {
            byte[] buffer = new byte[fileStructureBlockSize];
            stream.ReadRaw(0, buffer, fileStructureBlockSize);
            FileHeaderBlock header = FileHeaderBlock.Open(buffer);
            BufferedFile    disk   = new BufferedFile(stream, pool, header, isNewFile: false);

            return(new DiskMedium(disk, header));
        }
Exemple #3
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 /// <summary>
 /// Creates a <see cref="DiskMedium"/> from a <see cref="stream"/>. 
 /// This will read the existing header from the <see cref="stream"/>.
 /// </summary>
 /// <param name="stream">An open <see cref="FileStream"/> to use. The <see cref="DiskMedium"/>
 /// will assume ownership of this <see cref="FileStream"/>.</param>
 /// <param name="pool">The <see cref="MemoryPool"/> to allocate data from.</param>
 /// <param name="fileStructureBlockSize">the block size of the file structure. Usually 4kb.</param>
 /// <returns></returns>
 public static DiskMedium OpenFile(CustomFileStream stream, MemoryPool pool, int fileStructureBlockSize)
 {
     byte[] buffer = new byte[fileStructureBlockSize];
     stream.ReadRaw(0, buffer, fileStructureBlockSize);
     FileHeaderBlock header = FileHeaderBlock.Open(buffer);
     BufferedFile disk = new BufferedFile(stream, pool, header, isNewFile: false);
     return new DiskMedium(disk, header);
 }
Exemple #4
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        /// <summary>
        /// Creates a <see cref="DiskMedium"/> from a <see cref="stream"/>. 
        /// This will initialize the <see cref="stream"/> as an empty file structure.
        /// </summary>
        /// <param name="stream">An open <see cref="FileStream"/> to use. The <see cref="DiskMedium"/>
        ///     will assume ownership of this <see cref="FileStream"/>.</param>
        /// <param name="pool">the <see cref="MemoryPool"/> to allocate data from</param>
        /// <param name="fileStructureBlockSize">the block size of the file structure. Usually 4kb.</param>
        /// <param name="flags">Flags to write to the file</param>
        /// <returns></returns>
        /// <remarks>
        /// This will not check if the file is truely a new file. If calling this with an existing
        /// archive file, it will overwrite the table of contents, corrupting the file.
        /// </remarks>
        public static DiskMedium CreateFile(CustomFileStream stream, MemoryPool pool, int fileStructureBlockSize, params Guid[] flags)
        {
            FileHeaderBlock header = FileHeaderBlock.CreateNew(fileStructureBlockSize, flags);

            BufferedFile disk = new BufferedFile(stream, pool, header, isNewFile: true);
            return new DiskMedium(disk, header);
        }
Exemple #5
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 /// <summary>
 /// Creates a new <see cref="IoSession"/>
 /// </summary>
 /// <param name="stream">the base class</param>
 /// <param name="pageReplacement">The page Replacement Algorithm</param>
 internal IoSession(BufferedFile stream, PageReplacementAlgorithm pageReplacement)
     : base(pageReplacement)
 {
     m_stream = stream;
 }
Exemple #6
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 /// <summary>
 /// Creates a new <see cref="IoSession"/>
 /// </summary>
 /// <param name="stream">the base class</param>
 /// <param name="pageReplacement">The page Replacement Algorithm</param>
 internal IoSession(BufferedFile stream, PageReplacementAlgorithm pageReplacement)
     : base(pageReplacement)
 {
     m_stream = stream;
 }