GNU CommonC++
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This class defines a database I/O file service that can be shared by multiple processes. More...
#include <file.h>
Public Member Functions | |
SharedFile (const char *path) | |
Open or create a new database file. | |
SharedFile (const SharedFile &file) | |
Create a shared file as a duplicate of an existing shared file. | |
virtual | ~SharedFile () |
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) |
Lock and 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 | clear (ccxx_size_t length=0, off_t pos=-1) |
Clear a lock held from a previous fetch operation without updating. | |
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) |
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.
ost::SharedFile::SharedFile | ( | const char * | path | ) |
Open or create a new database file.
You should also use Initial.
path | pathname of database to open. |
ost::SharedFile::SharedFile | ( | const SharedFile & | file | ) |
Create a shared file as a duplicate of an existing shared file.
file | original file. |
virtual ost::SharedFile::~SharedFile | ( | ) | [virtual] |
Close and finish a database file.
Error ost::SharedFile::append | ( | char * | address = NULL , |
ccxx_size_t | length = 0 |
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) |
Add new data to the end of the file.
Locks file during append.
address | address to use, or NULL if same as last I/O. |
length | length to use, or 0 if same as last I/O. |
Error ost::SharedFile::clear | ( | ccxx_size_t | length = 0 , |
off_t | pos = -1 |
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) |
Clear a lock held from a previous fetch operation without updating.
length | length to use, or 0 if same as last I/O. |
pos | file position to use or -1 if same as last I/O. |
Error ost::SharedFile::fetch | ( | char * | address = NULL , |
ccxx_size_t | length = 0 , |
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off_t | position = -1 |
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) |
Lock and Fetch a portion of the file into physical memory.
This can use state information to fetch the current record multiple times.
address | address to use, or NULL if same as last I/O. |
length | length to use, or 0 if same as last I/O. |
position | file position to use -1 if same as last I/O. |
off_t ost::SharedFile::getPosition | ( | void | ) |
Fetch the current file position marker for this thread.
bool ost::SharedFile::operator++ | ( | void | ) |
bool ost::SharedFile::operator-- | ( | void | ) |
Error ost::SharedFile::restart | ( | void | ) | [inline, virtual] |
Restart an existing database; close and re-open.
Reimplemented from ost::RandomFile.
Error ost::SharedFile::update | ( | char * | address = NULL , |
ccxx_size_t | length = 0 , |
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off_t | position = -1 |
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) |
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.
address | address to use, or NULL if same as last I/O. |
length | length to use, or 0 if same as last I/O. |
position | file position to use or -1 if same as last I/O. |