S4

A database backend for XMMS2. More...

Topics
	Condition
	Functions to create and use S4 search conditions.
	Fetch Specifications
	Specifies what to fetch in a query.
	Lock
	Locks entries so only one transaction can use tham at a time.
	Log
	Logs every action so we can redo changes if something crashes.
	Pattern
	Functions to create and match glob-like patterns.
	Entry
	The in-memory database.
	Result
	Handles results returned from S4.
	Result Set
	A set of results.
	Source Preferences
	Handles source preferences.
	Transactions
	Functions dealing with transactions.
	UUID
	Functions dealing with UUID.
	Value
	The way values are represented in S4.

Macros
#define	S4_MAGIC   ("s4db")
#define	S4_MAGIC_LEN   (4)
#define	S4_VERSION   1

Functions
s4_t *	s4_open (const char *filename, const char **indices, int open_flags)
	Opens an S4 database.
int	s4_close (s4_t *s4)
	Closes an open S4 database.
void	s4_sync (s4_t *s4)
	Writes all changes to disk.
s4_errno_t	s4_errno ()
	Returns the last error number set.
void	s4_set_errno (s4_errno_t err)
	Sets errno to the given error number.
int	_reread_file (s4_t *s4)
void	_start_sync (s4_t *s4)
void	_sync (s4_t *s4)

Detailed Description

A database backend for XMMS2.

Macro Definition Documentation

S4_MAGIC

#define S4_MAGIC   ("s4db")

S4_MAGIC_LEN

#define S4_MAGIC_LEN   (4)

S4_VERSION

#define S4_VERSION   1

Function Documentation

_reread_file()

int _reread_file

(

s4_t *

s4

)

_start_sync()

void _start_sync

(

s4_t *

s4

)

Referenced by _log_write().

_sync()

void _sync

(

s4_t *

s4

)

Referenced by s4_commit().

s4_close()

int s4_close

(

s4_t *

s4

)

Closes an open S4 database.

Parameters

s4	The database to close

Referenced by CASE(), and main().

s4_errno()

s4_errno_t s4_errno

(

void

)

Returns the last error number set.

This function is thread safe, error numbers set in one thread will NOT be seen in another thread.

Returns

The last error number set, or S4E_NOERROR if none has been set

Referenced by CASE(), CASE(), and CASE().

s4_open()

s4_t * s4_open	(	const char *	filename,
		const char **	indices,
		int	open_flags )

Opens an S4 database.

The different flags you can pass:

S4_NEW
It will create a new file if one does not already exists. If one exists it will fail and return NULL.

S4_EXISTS
If the file does not exists it will fail and return NULL. s4_errno may be used to get more information about what went wrong.

S4_MEMORY Creates a memory-only database. It will not read any files on startup or write files on shutdown. Use this if you want a temporary database.

Parameters

filename	The name of the file containing the database
indices	An array of keys to have indices on
open_flags	Zero or more of the flags bitwise-or'd.

Returns

A pointer to an s4_t, or NULL if something went wrong.

Referenced by CASE(), CASE(), and main().

s4_set_errno()

void s4_set_errno

(

s4_errno_t

err

)

Sets errno to the given error number.

Parameters

err	The error number to set

Referenced by _lock_exclusive(), _lock_shared(), _log_open(), _oplist_execute(), and s4_commit().

s4_sync()

void s4_sync

(

s4_t *

s4

)

Writes all changes to disk.

Parameters

s4	The database to sync

Referenced by s4_open().