#include <file.h>
Inheritance diagram for ost::ThreadFile:
Public Member Functions | |
ThreadFile (const char *path) | |
Open or create a new database file. | |
virtual | ~ThreadFile () |
Close and finish a database file. | |
Error | restart (void) |
Restart an existing database; close and re-open. | |
Error | fetch (char *address=NULL, ccxx_size_t length=0, off_t position=-1) |
Fetch a portion of the file into physical memory. | |
Error | update (char *address=NULL, ccxx_size_t length=0, off_t position=-1) |
Update a portion of a file from physical memory. | |
Error | append (char *address=NULL, ccxx_size_t length=0) |
Add new data to the end of the file. | |
off_t | getPosition (void) |
Fetch the current file position marker for this thread. | |
bool | operator++ (void) |
bool | operator-- (void) |
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 is meant for use by a threaded database server where multiple threads may each perform semi-independent operations on a given database table stored on disk. A special "fcb" structure is used to hold file "state", and pread/pwrite is used whenever possible for optimized I/O. On systems that do not offer pwread/pwrite, a Mutex lock is used to protect concurrent lseek and read/write operations. ThreadFile managed databases are assumed to be used only by the local server and through a single file descriptor.
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Open or create a new database file. You should also use Initial.
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Close and finish a database file.
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Add new data to the end of the file.
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Fetch a portion of the file into physical memory. This can use state information to fetch the current record multiple times.
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Fetch the current file position marker for this thread.
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Restart an existing database; close and re-open.
Reimplemented from ost::RandomFile. |
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Update a portion of a file from physical memory. This can use state information to commit the last read record.
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