C# Class GSF.IO.FileStructure.Media.BufferedFile

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

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Public Methods

Method	Description
BufferedFile ( CustomFileStream stream, MemoryPool pool, FileHeaderBlock header, bool isNewFile ) : System	Creates a file backed memory stream.
ChangeExtension ( string extension, bool isReadOnly, bool isSharingEnabled ) : void	Changes the extension of the current file.
ChangeShareMode ( bool isReadOnly, bool isSharingEnabled ) : void	Reopens the file with different permissions.
CommitChanges ( FileHeaderBlock header ) : void	Executes a commit of data. This will flush the data to the disk use the provided header data to properly execute this function.
CreateIoSession ( ) : BinaryStreamIoSessionBase	Creates a BinaryStreamIoSessionBase that can be used to read from this disk medium.
Dispose ( ) : void	Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
RollbackChanges ( ) : void	Rolls back all edits to the DiskMedium

Private Methods

Method	Description
GetBlock ( PageReplacementAlgorithm pageLock, BlockArguments args ) : void	Populates the pointer data inside args for the desired block as specified in args. This function will block if needing to retrieve data from the disk.
GetBlockFromCommittedSpace ( PageReplacementAlgorithm pageLock, long position, IntPtr &pointer ) : void	Processes the GetBlock from the committed area. The valid length is at least the size of the buffer pools page size.
ReleaseWriteBufferSpace ( ) : void	Releases the buffered data contained in the buffer pool. This is acomplished by disposing of the writer and recreating it.
m_pool_RequestCollection ( object sender, CollectionEventArgs e ) : void	Handles the MemoryPool.RequestCollection event.

Method Details

BufferedFile() public method

Creates a file backed memory stream.

public BufferedFile ( CustomFileStream stream, MemoryPool pool, FileHeaderBlock header, bool isNewFile ) : System
stream	CustomFileStream	The to buffer
pool	GSF.IO.Unmanaged.MemoryPool	The to allocate memory from
header	FileHeaderBlock	The to be managed when modifications occur
isNewFile	bool	Tells if this is a newly created file. This will make sure that the /// first 10 pages have the header data copied to it.
return	System

ChangeExtension() public method

Changes the extension of the current file.

public ChangeExtension ( string extension, bool isReadOnly, bool isSharingEnabled ) : void
extension	string	the new extension
isReadOnly	bool	If the file should be reopened as readonly
isSharingEnabled	bool	If the file should share read privileges.
return	void

ChangeShareMode() public method

Reopens the file with different permissions.

public ChangeShareMode ( bool isReadOnly, bool isSharingEnabled ) : void
isReadOnly	bool	If the file should be reopened as readonly
isSharingEnabled	bool	If the file should share read privileges.
return	void

CommitChanges() public method

Executes a commit of data. This will flush the data to the disk use the provided header data to properly execute this function.

public CommitChanges ( FileHeaderBlock header ) : void
header	FileHeaderBlock
return	void

CreateIoSession() public method

Creates a BinaryStreamIoSessionBase that can be used to read from this disk medium.

public CreateIoSession ( ) : BinaryStreamIoSessionBase
return	GSF.IO.Unmanaged.BinaryStreamIoSessionBase

Dispose() public method

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

public Dispose ( ) : void
return	void

RollbackChanges() public method

Rolls back all edits to the DiskMedium

public RollbackChanges ( ) : void
return	void