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SharedFile Class Reference This class defines a database I/O file service that can be shared by multiple processes. This class defines a database I/O file service that can be shared by multiple processes. More... #include <file.h> Inheritance diagram for SharedFile: List of all members. Public Methods   SharedFile (const char *path)   Open or create a new database file. More...   SharedFile (const SharedFile &file)   Create a shared file as a duplicate of an existing shared file. More...   ~SharedFile ()   Close and finish a database file. fileerror_t  Restart (void)   Restart an existing database; close and re-open. More... fileerror_t  Fetch (caddr_t address = NULL, size_t length = 0, off_t position = - 1)   Lock and Fetch a portion of the file into physical memory. More... fileerror_t  Update (caddr_t address = NULL, size_t length = 0, off_t position = -1)   Update a portion of a file from physical memory. More... fileerror_t  Clear (size_t length = 0, off_t pos = -1)   Clear a lock held from a previous fetch operation without updating. More... fileerror_t  Append (caddr_t address = NULL, size_t length = 0)   Add new data to the end of the file. More... off_t  getPosition (void)   Fetch the current file position marker for this thread. More... bool  operator++ (void) bool  operator-- (void) Detailed Description This class defines a database I/O file service that can be shared by multiple processes. This class defines a database I/O file service that can be shared by multiple processes. Each thread should access a dup of the database object, and mutex locks can be used to preserve transaction integrety if multiple threads are used. SharedFile is used when a database may be shared between multiple processes. SharedFile automatically applies low level byte-range "file locks", and provides an interface to fetch and release byte-range locked portions of a file. Author(s): David Sugar <dyfet@ostel.com> Constructor & Destructor Documentation SharedFile::SharedFile ( const char * path )   Open or create a new database file. You should also use Initial. Parameters: pathname   of database to open. file   access mode. SharedFile::SharedFile ( const SharedFile & file )   Create a shared file as a duplicate of an existing shared file. Parameters: original   file. SharedFile::~SharedFile ( )   Close and finish a database file. Member Function Documentation fileerror_t SharedFile::Append ( caddr_t address = NULL, size_t length = 0 )   Add new data to the end of the file. Locks file during append. Parameters: address   to use, or NULL if same as last I/O. length   to use, or 0 if same as last I/O. fileerror_t SharedFile::Clear ( size_t length = 0, off_t pos = -1 )   Clear a lock held from a previous fetch operation without updating. Returns: FILE_SUCCESS on success. Parameters: length   to use, or 0 if same as last I/O. file   position to use or -1 if same as last I/O. fileerror_t SharedFile::Fetch ( caddr_t address = NULL, size_t length = 0, off_t position = - 1 )   Lock and Fetch a portion of the file into physical memory. This can use state information to fetch the current record multiple times. Returns: FILE_SUCCESS on success. Parameters: address   to use, or NULL if same as last I/O. length   to use, or 0 if same as last I/O. file   position to use -1 if same as last I/O. fileerror_t SharedFile::Restart ( void ) [inline, virtual]   Restart an existing database; close and re-open. Returns: FILE_SUCCESS if successful. Reimplemented from RandomFile. fileerror_t SharedFile::Update ( caddr_t address = NULL, size_t length = 0, off_t position = -1 )   Update a portion of a file from physical memory. This can use state information to commit the last read record. The current lock is also cleared. Returns: FILE_SUCCESS on success. Parameters: address   to use, or NULL if same as last I/O. length   to use, or 0 if same as last I/O. file   position to use or -1 if same as last I/O. off_t SharedFile::getPosition ( void )   Fetch the current file position marker for this thread. Returns: file position offset. bool SharedFile::operator++ ( void ) bool SharedFile::operator-- ( void ) The documentation for this class was generated from the following file: file.h