efl/src/benchmarks/eina/ecore_strings.c

#include <stdlib.h>
#include <string.h>

#include "Ecore_Data.h"

static void ecore_string_free_cb(void *data);

static Ecore_Hash *ecore_strings = NULL;
static int ecore_string_init_count = 0;

/**
 * @defgroup Ecore_String_Group String Instance Functions
 *
 * 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.
 */

/**
 * Initialize the ecore string internal structure.
 * @return  Zero on failure, non-zero on successful initialization.
 */
EAPI int
ecore_string_init(void)
{
   /*
    * No strings have been loaded at this point, so create the hash
    * table for storing string info for later.
    */
   if (!ecore_string_init_count)
     {
        ecore_strings = ecore_hash_new(ecore_str_hash, ecore_str_compare);
        if (!ecore_strings)
           return 0;

        ecore_hash_free_value_cb_set(ecore_strings, ecore_string_free_cb);
     }

   ecore_string_init_count++;

   return 1;
}

/**
 * Retrieves an instance of a string for use in an ecore program.
 * @param   string The string to retrieve an instance of.
 * @return  A pointer to an instance of the string on success.
 *          @c NULL on failure.
 * @ingroup Ecore_String_Group
 */
EAPI const char *
ecore_string_instance(const char *string)
{
   Ecore_String *str;

   CHECK_PARAM_POINTER_RETURN("string", string, NULL);

   /*
    * Check for a previous instance of the string, if not found, create
    * it.
    */
   str = ecore_hash_get(ecore_strings, string);
   if (!str)
     {
        int length;

        /*
         * Allocate and initialize a new string reference.
         */
        length = strlen(string) + 1;

        str =
           (Ecore_String *)malloc(sizeof(Ecore_String) + length * sizeof(char));
        if (!str) return NULL;

        str->string = (char *)(str + 1);
        str->references = 0;

        memcpy(str->string, string, length);

        ecore_hash_set(ecore_strings, str->string, str);
     }

   str->references++;

   return str->string;
}

/**
 * Notes that the given string has lost an instance.
 *
 * It will free the string if no other instances are left.
 *
 * @param   string The given string.
 * @ingroup Ecore_String_Group
 */
EAPI void
ecore_string_release(const char *string)
{
   Ecore_String *str;

   CHECK_PARAM_POINTER("string", string);

   str = ecore_hash_get(ecore_strings, (char *)string);
   if (!str)
      return;

   str->references--;
   if (str->references < 1)
     {
        ecore_hash_remove(ecore_strings, (char *)string);
        FREE(str);
     }
}

EAPI void
ecore_string_hash_dump_graph(void)
{
   ecore_hash_dump_graph(ecore_strings);
}

EAPI void
ecore_string_hash_dump_stats(void)
{
   ecore_hash_dump_stats(ecore_strings);
}

/**
 * Shutdown the ecore string internal structures
 * @return 0 when the module is completely shut down, 1 or
 * greater otherwise.
 */
EAPI int
ecore_string_shutdown(void)
{
   --ecore_string_init_count;
   if (!ecore_string_init_count)
     {
        ecore_hash_destroy(ecore_strings);
        ecore_strings = NULL;
     }
   return ecore_string_init_count;
}

static void
ecore_string_free_cb(void *data)
{
   Ecore_String *str;

   str = data;
   FREE(str);
}