class ThreadFile

This class defines a database I/O file service that can be shared by multiple threads. More...

Definition#include <file.h>
InheritsRandomFile
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Detailed Description

This class defines a database I/O file service that can be shared by multiple threads. All threads access a global copy of the database object, and mutex locks can be used to preserve transaction integrety. pread/pwrite calls can be used for optimized I/O when supported.

ThreadFile (const char *path)

Open or create a new database file. You should also use Initial.

Parameters:
pathnameof database to open.

~ThreadFile ()

Close and finish a database file.

fileerror_t Restart (void)

Restart an existing database; close and re-open.

Returns: FILE_SUCCESS if successful.

Reimplemented from RandomFile

fileerror_t Fetch (caddr_t address = NULL, size_t length = 0, off_t position = - 1)

Fetch a portion of the file into physical memory. This can use state information to fetch the current record multiple times.

Parameters:
addressto use, or NULL if same as last I/O.
lengthto use, or 0 if same as last I/O.
fileposition to use -1 if same as last I/O.

Returns: FILE_SUCCESS on success.

fileerror_t 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.

Parameters:
addressto use, or NULL if same as last I/O.
lengthto use, or 0 if same as last I/O.
fileposition to use or -1 if same as last I/O.

Returns: FILE_SUCCESS on success.

fileerror_t Append (caddr_t address = NULL, size_t length = 0)

Add new data to the end of the file.

Parameters:
addressto use, or NULL if same as last I/O.
lengthto use, or 0 if same as last I/O.

off_t getPosition (void)

Fetch the current file position marker for this thread.

Returns: file position offset.


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