Functions
const Eina_Unicode *	eina_ustringshare_add_length (const Eina_Unicode *str, unsigned int slen)
	Retrieve an instance of a string for use in a program.
const Eina_Unicode *	eina_ustringshare_add (const Eina_Unicode *str)
	Retrieve an instance of a string for use in a program.
const Eina_Unicode *	eina_ustringshare_ref (const Eina_Unicode *str)
	Increment references of the given shared string.
void	eina_ustringshare_del (const Eina_Unicode *str)
	Note that the given string has lost an instance.
int	eina_ustringshare_strlen (const Eina_Unicode *str)
	Note that the given string must be shared.
void	eina_ustringshare_dump (void)
	Dump the contents of the 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.

These functions 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 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 this can have a significant impact as you scale the number of copies up. It improves string creation/destruction speed, reduces memory use and decreases memory fragmentation, so a win all-around.

For more information, you can look at the tutorial_ustringshare_page.

Function Documentation

const Eina_Unicode* eina_ustringshare_add ( const Eina_Unicode * str )

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

Since :: 2.3

Parameters:

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

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

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

See also:: eina_ustringshare_add_length()

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

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

Since :: 2.3

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. NULL on failure.

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

See also:: eina_ustringshare_add()

void eina_ustringshare_del ( const Eina_Unicode * str )

Note that the given string has lost an instance.

Since :: 2.3

Parameters:

[in] str string The given string.

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

void eina_ustringshare_dump ( void )

Dump the contents of the share_common.

Since :: 2.3

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

const Eina_Unicode* eina_ustringshare_ref ( const Eina_Unicode * str )

Increment references of the given shared string.

Since :: 2.3

Parameters:

[in] str The shared string.

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

Remarks:: This is similar to eina_share_common_add(), but it's faster since it will avoid 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().

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

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

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 )

Note that the given string must be shared.

Since :: 2.3

Parameters:

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

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

Functions

Function Documentation