qdbm::Depot Class Reference

C++ API of Depot, the basic API of QDBM. More...

Inheritance diagram for qdbm::Depot:

List of all members.

Public Member Functions
	Depot (const char *name, int omode=Depot::OREADER, int bnum=-1) throw (Depot_error)
	Get the database handle.
virtual	~Depot () throw ()
	Release the resources.
virtual void	close () throw (Depot_error)
	Close the database handle.
virtual bool	put (const char *kbuf, int ksiz, const char *vbuf, int vsiz, int dmode=Depot::DOVER) throw (Depot_error)
	Store a record.
virtual bool	out (const char *kbuf, int ksiz) throw (Depot_error)
	Delete a record.
virtual char *	get (const char *kbuf, int ksiz, int start=0, int max=-1, int *sp=0) throw (Depot_error)
	Retrieve a record.
virtual int	getwb (const char *kbuf, int ksiz, int start, int max, char *vbuf) throw (Depot_error)
	Retrieve a record and write the value into a buffer.
virtual int	vsiz (const char *kbuf, int ksiz) throw (Depot_error)
	Get the size of the value of a record.
virtual void	iterinit () throw (Depot_error)
	Initialize the iterator of the database handle.
virtual char *	iternext (int *sp=0) throw (Depot_error)
	Get the next key of the iterator.
virtual void	setalign (int align) throw (Depot_error)
	Set alignment of the database handle.
virtual void	setfbpsiz (int size) throw (Depot_error)
	Set the size of the free block pool.
virtual void	sync () throw (Depot_error)
	Synchronize updating contents with the file and the device.
virtual void	optimize (int bnum=-1) throw (Depot_error)
	Optimize the database.
virtual char *	name () throw (Depot_error)
	Get the name of the database.
virtual int	fsiz () throw (Depot_error)
	Get the size of the database file.
virtual int	bnum () throw (Depot_error)
	Get the number of the elements of the bucket array.
virtual int	busenum () throw (Depot_error)
	Get the number of the used elements of the bucket array.
virtual int	rnum () throw (Depot_error)
	Get the number of the records stored in the database.
virtual bool	writable () throw (Depot_error)
	Check whether the database handle is a writer or not.
virtual bool	fatalerror () throw (Depot_error)
	Check whether the database has a fatal error or not.
virtual int	inode () throw (Depot_error)
	Get the inode number of the database file.
virtual time_t	mtime () throw (Depot_error)
	Get the last modified time of the database.
virtual int	fdesc () throw (Depot_error)
	Get the file descriptor of the database file.
virtual void	storerec (const Datum &key, const Datum &val, bool replace=true) throw (Depot_error)
	Store a record.
virtual void	deleterec (const Datum &key) throw (Depot_error)
	Delete a record.
virtual Datum	fetchrec (const Datum &key) throw (Depot_error)
	Fetch a record.
virtual Datum	firstkey () throw (Depot_error)
	Get the first key.
virtual Datum	nextkey () throw (Depot_error)
	Get the next key.
virtual bool	error () throw (Depot_error)
	Check whether a fatal error occured or not.
Static Public Member Functions
static const char *	version () throw ()
	Get the version information.
static void	remove (const char *name) throw (Depot_error)
	Remove a database file.
static char *	snaffle (const char *name, const char *kbuf, int ksiz, int *sp) throw (Depot_error)
	Retrieve a record directly from a database file.
Public Attributes
bool	silent
	whether to repress frequent exceptions
Static Public Attributes
static const int	ENOERR
	error code: no error
static const int	EFATAL
	error code: with fatal error
static const int	EMODE
	error code: invalid mode
static const int	EBROKEN
	error code: broken database file
static const int	EKEEP
	error code: existing record
static const int	ENOITEM
	error code: no item found
static const int	EALLOC
	error code: memory allocation error
static const int	EMAP
	error code: memory mapping error
static const int	EOPEN
	error code: open error
static const int	ECLOSE
	error code: close error
static const int	ETRUNC
	error code: trunc error
static const int	ESYNC
	error code: sync error
static const int	ESTAT
	error code: stat error
static const int	ESEEK
	error code: seek error
static const int	EREAD
	error code: read error
static const int	EWRITE
	error code: write error
static const int	ELOCK
	error code: lock error
static const int	EUNLINK
	error code: unlink error
static const int	EMKDIR
	error code: mkdir error
static const int	ERMDIR
	error code: rmdir error
static const int	EMISC
	error code: miscellaneous error
static const int	OREADER
	open mode: open as a reader
static const int	OWRITER
	open mode: open as a writer
static const int	OCREAT
	open mode: writer creating
static const int	OTRUNC
	open mode: writer truncating
static const int	ONOLCK
	open mode: open without locking
static const int	OLCKNB
	open mode: lock without blocking
static const int	OSPARSE
	open mode: create as a sparse file
static const int	DOVER
	write mode: overwrite the existing value
static const int	DKEEP
	write mode: keep the existing value
static const int	DCAT
	write mode: concatenate values

---

Detailed Description

C++ API of Depot, the basic API of QDBM.

---

Constructor & Destructor Documentation

qdbm::Depot::Depot	(	const char *	name,
		int	omode = Depot::OREADER,
		int	bnum = -1
	)			throw (Depot_error)

Get the database handle.

Parameters:

	name	the name of a database file.
	omode	the connection mode: `DepotOWRITER' as a writer, `DepotOREADER' as a reader. If the mode is `DepotOWRITER', the following may be added by bitwise or: `DepotOCREAT', which means it creates a new database if not exist, `DepotOTRUNC', which means it creates a new database regardless if one exists. Both of `DepotOREADER' and `DepotOWRITER' can be added to by bitwise or: `DepotONOLCK', which means it opens a database file without file locking, or `DepotOLCKNB', which means locking is performed without blocking. `DepotOCREAT' can be added to by bitwise or: `DepotOSPARSE', which means it creates a database file as a sparse file.
	bnum	the number of elements of the bucket array. If it is not more than 0, the default value is specified. The size of a bucket array is determined on creating, and can not be changed except for by optimization of the database. Suggested size of a bucket array is about from 0.5 to 4 times of the number of all records to store.

Exceptions:

Depot_error

if an error occurs.

Note:

While connecting as a writer, an exclusive lock is invoked to the database file. While connecting as a reader, a shared lock is invoked to the database file. The thread blocks until the lock is achieved. If `DepotONOLCK' is used, the application is responsible for exclusion control.

virtual qdbm::Depot::~Depot

(

)

throw () [virtual]

Release the resources.

Note:

If the database handle is not closed yet, it is closed.

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Member Function Documentation

virtual int qdbm::Depot::bnum

(

)

throw (Depot_error) [virtual]

Get the number of the elements of the bucket array.

Returns:

the number of the elements of the bucket array.

Exceptions:

Depot_error

if an error occurs.

virtual int qdbm::Depot::busenum

(

)

throw (Depot_error) [virtual]

Get the number of the used elements of the bucket array.

Returns:

the number of the used elements of the bucket array.

Exceptions:

Depot_error

if an error occurs.

Note:

This function is inefficient because it accesses all elements of the bucket array.

virtual void qdbm::Depot::close

(

)

throw (Depot_error) [virtual]

Close the database handle.

Exceptions:

Depot_error

if an error occurs.

Note:

Updating a database is assured to be written when the handle is closed. If a writer opens a database but does not close it appropriately, the database will be broken.

Implements qdbm::ADBM.

virtual void qdbm::Depot::deleterec

(

const Datum &

key

)

throw (Depot_error) [virtual]

Delete a record.

Parameters:

key

reference to a key object.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Implements qdbm::ADBM.

virtual bool qdbm::Depot::error

(

)

throw (Depot_error) [virtual]

Check whether a fatal error occured or not.

Returns:

true if the database has a fatal error, false if not.

Exceptions:

Depot_error

if an error occurs.

Implements qdbm::ADBM.

virtual bool qdbm::Depot::fatalerror

(

)

throw (Depot_error) [virtual]

Check whether the database has a fatal error or not.

Returns:

true if the database has a fatal error, false if not.

Exceptions:

Depot_error

if an error occurs.

virtual int qdbm::Depot::fdesc

(

)

throw (Depot_error) [virtual]

Get the file descriptor of the database file.

Returns:

the file descriptor of the database file.

Exceptions:

Depot_error

if an error occurs.

Note:

Handling the file descriptor of a database file directly is not suggested.

virtual Datum qdbm::Depot::fetchrec

(

const Datum &

key

)

throw (Depot_error) [virtual]

Fetch a record.

Parameters:

key

reference to a key object.

Returns:

a temporary instance of the value of the corresponding record.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Implements qdbm::ADBM.

virtual Datum qdbm::Depot::firstkey

(

)

throw (Depot_error) [virtual]

Get the first key.

Returns:

a temporary instance of the key of the first record.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Implements qdbm::ADBM.

virtual int qdbm::Depot::fsiz

(

)

throw (Depot_error) [virtual]

Get the size of the database file.

Returns:

the size of the database file.

Exceptions:

Depot_error

if an error occurs.

virtual char* qdbm::Depot::get	(	const char *	kbuf,
		int	ksiz,
		int	start = 0,
		int	max = -1,
		int *	sp = 0
	)			throw (Depot_error) [virtual]

Retrieve a record.

Parameters:

	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.
	start	the offset address of the beginning of the region of the value to be read.
	max	the max size to read with. If it is negative, the size is unlimited.
	sp	the pointer to a variable to which the size of the region of the return value is assigned. If it is 0, it is not used.

Returns:

the pointer to the region of the value of the corresponding record. If the silent flag is true and no record corresponds, 0 is returned instead of exception.

Exceptions:

Depot_error

if an error occurs, no record corresponds, or the size of the value of the corresponding record is less than `start'.

Note:

Because an additional zero code is appended at the end of the region of the return value, the return value can be treated as a character string. Because the region of the return value is allocated with the `stdmalloc' call, it should be released with the `stdfree' call if it is no longer in use.

virtual int qdbm::Depot::getwb	(	const char *	kbuf,
		int	ksiz,
		int	start,
		int	max,
		char *	vbuf
	)			throw (Depot_error) [virtual]

Retrieve a record and write the value into a buffer.

Parameters:

	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.
	start	the offset address of the beginning of the region of the value to be read.
	max	the max size to be read. It shuld be equal to or less than the size of the writing buffer.
	vbuf	the pointer to a buffer into which the value of the corresponding record is written.

Returns:

the return value is the size of the written data. If the silent flag is true and no record corresponds, -1 is returned instead of exception.

Exceptions:

Depot_error

if an error occurs, no record corresponds, or the size of the value of the corresponding record is less than `start'.

Note:

No additional zero code is appended at the end of the region of the writing buffer.

virtual int qdbm::Depot::inode

(

)

throw (Depot_error) [virtual]

Get the inode number of the database file.

Returns:

the inode number of the database file.

Exceptions:

Depot_error

if an error occurs.

virtual void qdbm::Depot::iterinit

(

)

throw (Depot_error) [virtual]

Initialize the iterator of the database handle.

Exceptions:

Depot_error

if an error occurs.

Note:

The iterator is used in order to access the key of every record stored in a database.

virtual char* qdbm::Depot::iternext

(

int *

sp = 0

)

throw (Depot_error) [virtual]

Get the next key of the iterator.

Parameters:

sp

the pointer to a variable to which the size of the region of the return value is assigned. If it is 0, it is not used.

Returns:

the pointer to the region of the next key. If the silent flag is true and no record corresponds, 0 is returned instead of exception.

Exceptions:

Depot_error

if an error occurs or no record is to be get out of the iterator.

Note:

Because an additional zero code is appended at the end of the region of the return value, the return value can be treated as a character string. Because the region of the return value is allocated with the `stdmalloc' call, it should be released with the `stdfree' call if it is no longer in use. It is possible to access every record by iteration of calling this function. However, it is not assured if updating the database is occurred while the iteration. Besides, the order of this traversal access method is arbitrary, so it is not assured that the order of storing matches the one of the traversal access.

virtual time_t qdbm::Depot::mtime

(

)

throw (Depot_error) [virtual]

Get the last modified time of the database.

Returns:

the last modified time the database.

Exceptions:

Depot_error

if an error occurs.

virtual char* qdbm::Depot::name

(

)

throw (Depot_error) [virtual]

Get the name of the database.

Returns:

the pointer to the region of the name of the database.

Exceptions:

Depot_error

if an error occurs.

Note:

Because the region of the return value is allocated with the `stdmalloc' call, it should be released with the `stdfree' call if it is no longer in use.

virtual Datum qdbm::Depot::nextkey

(

)

throw (Depot_error) [virtual]

Get the next key.

Returns:

a temporary instance of the key of the next record.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Implements qdbm::ADBM.

virtual void qdbm::Depot::optimize

(

int

bnum = -1

)

throw (Depot_error) [virtual]

Optimize the database.

Parameters:

bnum

the number of the elements of the bucket array. If it is not more than 0, the default value is specified.

Exceptions:

Depot_error

if an error occurs.

Note:

In an alternating succession of deleting and storing with overwrite or concatenate, dispensable regions accumulate. This function is useful to do away with them.

virtual bool qdbm::Depot::out	(	const char *	kbuf,
		int	ksiz
	)			throw (Depot_error) [virtual]

Delete a record.

Parameters:

	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.

Returns:

always true. However, if the silent flag is true and no record corresponds, false is returned instead of exception.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

virtual bool qdbm::Depot::put	(	const char *	kbuf,
		int	ksiz,
		const char *	vbuf,
		int	vsiz,
		int	dmode = Depot::DOVER
	)			throw (Depot_error) [virtual]

Store a record.

Parameters:

	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.
	vbuf	the pointer to the region of a value.
	vsiz	the size of the region of the value. If it is negative, the size is assigned with `stdstrlen(vbuf)'.
	dmode	behavior when the key overlaps, by the following values: `DepotDOVER', which means the specified value overwrites the existing one, `DepotDKEEP', which means the existing value is kept, `DepotDCAT', which means the specified value is concatenated at the end of the existing value.

Returns:

always true. However, if the silent flag is true and replace is cancelled, false is returned instead of exception.

Exceptions:

Depot_error

if an error occurs or replace is cancelled.

static void qdbm::Depot::remove

(

const char *

name

)

throw (Depot_error) [static]

Remove a database file.

Parameters:

name

the name of a database file.

Exceptions:

Depot_error

if an error occurs.

virtual int qdbm::Depot::rnum

(

)

throw (Depot_error) [virtual]

Get the number of the records stored in the database.

Returns:

the number of the records stored in the database.

Exceptions:

Depot_error

if an error occurs.

virtual void qdbm::Depot::setalign

(

int

align

)

throw (Depot_error) [virtual]

Set alignment of the database handle.

Parameters:

align

the basic size of alignment.

Exceptions:

Depot_error

if an error occurs.

Note:

If alignment is set to a database, the efficiency of overwriting values is improved. The size of alignment is suggested to be average size of the values of the records to be stored. If alignment is positive, padding whose size is multiple number of the alignment is placed. If alignment is negative, as `vsiz' is the size of a value, the size of padding is calculated with `(vsiz / pow(2, abs(align) - 1))'. Because alignment setting is not saved in a database, you should specify alignment every opening a database.

virtual void qdbm::Depot::setfbpsiz

(

int

size

)

throw (Depot_error) [virtual]

Set the size of the free block pool.

Parameters:

size

the size of the free block pool of a database.

Exceptions:

Depot_error

if an error occurs.

Note:

The default size of the free block pool is 16. If the size is greater, the space efficiency of overwriting values is improved with the time efficiency sacrificed.

static char* qdbm::Depot::snaffle	(	const char *	name,
		const char *	kbuf,
		int	ksiz,
		int *	sp
	)			throw (Depot_error) [static]

Retrieve a record directly from a database file.

Parameters:

	name	the name of a database file.
	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.
	sp	the pointer to a variable to which the size of the region of the return value is assigned. If it is 0, it is not used.

Returns:

the pointer to the region of the value of the corresponding record.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Note:

Because an additional zero code is appended at the end of the region of the return value, the return value can be treated as a character string. Because the region of the return value is allocated with the `stdmalloc' call, it should be released with the `stdfree' call if it is no longer in use. Although this method can be used even while the database file is locked by another process, it is not assured that recent updated is reflected.

virtual void qdbm::Depot::storerec	(	const Datum &	key,
		const Datum &	val,
		bool	replace = true
	)			throw (Depot_error) [virtual]

Store a record.

Parameters:

	key	reference to a key object.
	val	reference to a value object.
	replace	whether the existing value is to be overwritten or not.

Exceptions:

Depot_error

if an error occurs or replace is cancelled.

Implements qdbm::ADBM.

virtual void qdbm::Depot::sync

(

)

throw (Depot_error) [virtual]

Synchronize updating contents with the file and the device.

Exceptions:

Depot_error

if an error occurs.

Note:

This function is useful when another process uses the connected database file.

static const char* qdbm::Depot::version

(

)

throw () [static]

Get the version information.

Returns:

the string of the version information.

virtual int qdbm::Depot::vsiz	(	const char *	kbuf,
		int	ksiz
	)			throw (Depot_error) [virtual]

Get the size of the value of a record.

Parameters:

	kbuf	the pointer to the region of a key.
	ksiz	the size of the region of the key. If it is negative, the size is assigned with `stdstrlen(kbuf)'.

Returns:

the size of the value of the corresponding record. If the silent flag is true and no record corresponds, -1 is returned instead of exception.

Exceptions:

Depot_error

if an error occurs or no record corresponds.

Note:

Because this function does not read the entity of a record, it is faster than `get'.

virtual bool qdbm::Depot::writable

(

)

throw (Depot_error) [virtual]

Check whether the database handle is a writer or not.

Returns:

true if the handle is a writer, false if not.

Exceptions:

Depot_error

if an error occurs.

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The documentation for this class was generated from the following file:

• xdepot.h