This group discusses functions that allow you to store one copy of a string, and use it throughout your program.

This is a method to reduce the number of duplicated strings kept in the memory. It's pretty common for the same strings to be dynamically allocated repeatedly between applications and libraries, especially in circumstances where you could have multiple copies of a structure that allocates the string. So rather than duplicating and freeing these strings, you request a read-only pointer to an existing string and only incur the overhead of a hash lookup.

It sounds like micro-optimizing, but profiling has shown that this can have a significant impact as you scale the number of copies up. It improves the string creation/destruction speed, reduces memory use, and decreases memory fragmentation, so a win all-around.

Functions
const Eina_Unicode *	eina_ustringshare_add_length (const Eina_Unicode *str, unsigned int slen)
	Retrieves an instance of a string for use in a program.
const Eina_Unicode *	eina_ustringshare_add (const Eina_Unicode *str)
	Retrieves an instance of a string for use in a program.
const Eina_Unicode *	eina_ustringshare_ref (const Eina_Unicode *str)
	Increments references of the given shared string.
void	eina_ustringshare_del (const Eina_Unicode *str)
	Notes that the given string has lost an instance.
int	eina_ustringshare_strlen (const Eina_Unicode *str)
	Notes that the given string must be shared.
void	eina_ustringshare_dump (void)
	Dumps the contents of share_common.
static Eina_Bool	eina_ustringshare_replace (const Eina_Unicode *p_str, const Eina_Unicode news)
	Replace the previously stringshared pointer with new content.
static Eina_Bool	eina_ustringshare_replace_length (const Eina_Unicode *p_str, const Eina_Unicode news, unsigned int slen)
	Replace the previously stringshared pointer with a new content.

Function Documentation

const Eina_Unicode* eina_ustringshare_add ( const Eina_Unicode * str )

Retrieves an instance of a string for use in a program.

This function retrieves an instance of str. If str is NULL, then NULL is returned. If str is already stored, it is just returned and its reference counter is increased. Otherwise it is added to the strings to be searched and a duplicated string of str is returned.

Since :: 2.3.1

Remarks:: The string str must be NULL-terminated ('\0') and its full length should be used. To use part of the string or non-null terminated, use eina_stringshare_add_length() instead.

Parameters:

[in] str The NULL-terminated string to retrieve an instance of

Returns:: A pointer to an instance of the string on success, otherwise NULL on failure

See also:: eina_ustringshare_add_length()

const Eina_Unicode* eina_ustringshare_add_length	(	const Eina_Unicode *	str,
		unsigned int	slen
	)

Retrieves an instance of a string for use in a program.

This function retrieves an instance of str. If str is NULL, then NULL is returned. If str is already stored, it is just returned and its reference counter is increased. Otherwise it is added to the strings to be searched and a duplicated string of str is returned.

Since :: 2.3.1

Remarks:: This function does not check the string size, but uses the exact given size. This can be used to share_common part of a larger buffer or substring.

Parameters:

[in]	str	The string to retrieve an instance of
[in]	slen	The string size (<= strlen(str))

Returns:: A pointer to an instance of the string on success, otherwise NULL on failure

See also:: eina_ustringshare_add()

void eina_ustringshare_del ( const Eina_Unicode * str )

Notes that the given string has lost an instance.

This function decreases the reference counter associated to str if it exists. If that counter reaches 0, the memory associated to str is freed. If str is NULL, the function returns immediately.

Since :: 2.3.1

Remarks:: If the given pointer is not shared, bad things happen, mostly a segmentation fault.

Parameters:

[in] str string The given string

void eina_ustringshare_dump ( void )

Dumps the contents of share_common.

This function dumps all the strings from share_common to stdout with a DDD: prefix per line and a memory usage summary.

Since :: 2.3.1

const Eina_Unicode* eina_ustringshare_ref ( const Eina_Unicode * str )

Increments references of the given shared string.

Since :: 2.3.1

Remarks:: This is similar to eina_share_common_add(), but it's faster since it avoids lookups if possible, but on the down side it requires the parameter to be shared before, in other words, it must be the return of a previous eina_ustringshare_add().; There is no unref since this is the work of eina_ustringshare_del().

Parameters:

[in] str The shared string

Returns:: A pointer to an instance of the string on success, otherwise NULL on failure

static Eina_Bool eina_ustringshare_replace	(	const Eina_Unicode **	p_str,
		const Eina_Unicode *	news
	)		`[static]`

Replace the previously stringshared pointer with new content.

The string pointed by p_str should be previously stringshared or NULL and it will be eina_ustringshare_del(). The new string will be passed to eina_ustringshare_add() and then assigned to *p_str.

Since :: 2.3.1

Parameters:

[in]	p_str	pointer to the stringhare to be replaced. Must not be `NULL`, but `*p_str` may be `NULL` as it is a valid stringshare handle.
[in]	news	new string to be stringshared, may be `NULL`.

Returns:: EINA_TRUE if the strings were different and thus replaced, EINA_FALSE if the strings were the same after shared.

static Eina_Bool eina_ustringshare_replace_length	(	const Eina_Unicode **	p_str,
		const Eina_Unicode *	news,
		unsigned int	slen
	)		`[static]`

Replace the previously stringshared pointer with a new content.

The string pointed by p_str should be previously stringshared or NULL and it will be eina_ustringshare_del(). The new string will be passed to eina_ustringshare_add_length() and then assigned to *p_str.

Since :: 2.3.1

Parameters:

[in]	p_str	pointer to the stringhare to be replaced. Must not be `NULL`, but `*p_str` may be `NULL` as it is a valid stringshare handle.
[in]	news	new string to be stringshared, may be `NULL`.
[in]	slen	The string size (<= strlen(str)).

Returns:: EINA_TRUE if the strings were different and thus replaced, EINA_FALSE if the strings were the same after shared.

int eina_ustringshare_strlen ( const Eina_Unicode * str )

Notes that the given string must be shared.

Since :: 2.3.1

Remarks:: This function is a cheap way to know the length of a shared string.; If the given pointer is not shared, bad things happen, mostly a segmentation fault. If in doubt, try strlen().

Parameters:

[in] str The shared string to know the length
It is safe to give NULL, in which case -1 is returned.

Returns:: The string length

Functions

Function Documentation