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/* grefstring.c: Reference counted strings
*
* Copyright 2018 Emmanuele Bassi
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/**
* SECTION:refstring
* @Title: Reference counted strings
* @Short_description: Strings with reference counted memory management
*
* Reference counted strings are normal C strings that have been augmented
* with a reference counter to manage their resources. You allocate a new
* reference counted string and acquire and release references as needed,
* instead of copying the string among callers; when the last reference on
* the string is released, the resources allocated for it are freed.
*
* Since: 2.58
*/
#include "config.h"
#include "grefstring.h"
#include "ghash.h"
#include "gmessages.h"
#include "grcbox.h"
#include "gthread.h"
#include <string.h>
G_LOCK_DEFINE_STATIC (interned_ref_strings);
static GHashTable *interned_ref_strings;
/**
* g_ref_string_new:
* @str: (not nullable): a NUL-terminated string
*
* Creates a new reference counted string and copies the contents of @str
* into it.
*
* Returns: (not nullable): the newly created reference counted string
*
* Since: 2.58
*/
char *
g_ref_string_new (const char *str)
{
char *res;
gsize len;
g_return_val_if_fail (str != NULL && *str != '\0', NULL);
len = strlen (str);
res = (char *) g_arc_box_dup (sizeof (char) * len + 1, str);
res[len] = '\0';
return res;
}
/**
* g_ref_string_new_intern:
* @str: (not nullable): a NUL-terminated string
*
* Creates a new reference counted string and copies the content of @str
* into it.
*
* If you call this function multiple times with the same @str, or with
* the same contents of @str, it will return a new reference, instead of
* creating a new string.
*
* Returns: (not nullable): the newly created reference counted string, or
* a new reference to an existing string
*
* Since: 2.58
*/
char *
g_ref_string_new_intern (const char *str)
{
gsize len;
char *res;
g_return_val_if_fail (str != NULL && *str != '\0', NULL);
G_LOCK (interned_ref_strings);
if (G_UNLIKELY (interned_ref_strings == NULL))
interned_ref_strings = g_hash_table_new_full (g_str_hash, g_str_equal,
(GDestroyNotify) g_arc_box_release,
NULL);
res = g_hash_table_lookup (interned_ref_strings, str);
if (res != NULL)
{
G_UNLOCK (interned_ref_strings);
return g_arc_box_acquire (res);
}
len = strlen (str);
res = (char *) g_arc_box_dup (sizeof (char) * len + 1, str);
res[len] = '\0';
g_hash_table_add (interned_ref_strings, g_arc_box_acquire (res));
G_UNLOCK (interned_ref_strings);
return res;
}
/**
* g_ref_string_acquire:
* @str: a reference counted string
*
* Acquires a reference on a string.
*
* Returns: the given string, with its reference count increased
*
* Since: 2.58
*/
char *
g_ref_string_acquire (char *str)
{
g_return_val_if_fail (str != NULL && *str != '\0', NULL);
return g_arc_box_acquire (str);
}
static void
remove_if_interned (gpointer data)
{
char *str = data;
G_LOCK (interned_ref_strings);
if (G_LIKELY (interned_ref_strings != NULL))
{
if (g_hash_table_contains (interned_ref_strings, str))
g_hash_table_remove (interned_ref_strings, str);
if (g_hash_table_size (interned_ref_strings) == 0)
g_clear_pointer (&interned_ref_strings, g_hash_table_destroy);
}
G_UNLOCK (interned_ref_strings);
}
/**
* g_ref_string_release:
* @str: a reference counted string
*
* Releases a reference on a string; if it was the last reference, the
* resources allocated by the string are freed as well.
*
* Since: 2.58
*/
void
g_ref_string_release (char *str)
{
g_return_if_fail (str != NULL && *str != '\0');
g_arc_box_release_full (str, remove_if_interned);
}
/**
* g_ref_string_length:
* @str: a reference counted string
*
* Retrieves the length of @str.
*
* Returns: the length of the given string, in bytes
*
* Since: 2.58
*/
gsize
g_ref_string_length (char *str)
{
g_return_val_if_fail (str != NULL && *str != '\0', 0);
return g_arc_box_get_size (str) - 1;
}
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