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glib/glib/gdataset.c
Thomas Haller 10d4351ec9 gdataset: add code comment to g_datalist_get_data() 
It's not obvious why we wouldn't use g_quark_try_string(). Add a code
comment that this is intentional and a reference for how to find out
more.

Also, fix typo in another code comment.
2024-02-05 16:49:10 +01:00

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/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* gdataset.c: Generic dataset mechanism, similar to GtkObject data.
* Copyright (C) 1998 Tim Janik
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* 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/>.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe ; except for g_data*_foreach()
*/
#include "config.h"
#include <string.h>
#include "gdataset.h"
#include "gbitlock.h"
#include "gslice.h"
#include "gdatasetprivate.h"
#include "gutilsprivate.h"
#include "ghash.h"
#include "gquark.h"
#include "gstrfuncs.h"
#include "gtestutils.h"
#include "gthread.h"
#include "glib_trace.h"
#include "galloca.h"
/**
* GData:
*
* An opaque data structure that represents a keyed data list.
*
* See also: [Keyed data lists](datalist-and-dataset.html).
**/
/**
* GDestroyNotify:
* @data: the data element.
*
* Specifies the type of function which is called when a data element
* is destroyed. It is passed the pointer to the data element and
* should free any memory and resources allocated for it.
**/
#define G_DATALIST_FLAGS_MASK_INTERNAL 0x7
#define G_DATALIST_CLEAN_POINTER(ptr) \
((GData *) ((gpointer) (((guintptr) (ptr)) & ~((guintptr) G_DATALIST_FLAGS_MASK_INTERNAL))))
/* datalist pointer accesses have to be carried out atomically */
#define G_DATALIST_GET_POINTER(datalist) \
G_DATALIST_CLEAN_POINTER (g_atomic_pointer_get (datalist))
#define G_DATALIST_SET_POINTER(datalist, pointer) G_STMT_START { \
gpointer _oldv = g_atomic_pointer_get (datalist); \
gpointer _newv; \
do { \
_newv = (gpointer) (((guintptr) _oldv & ((guintptr) G_DATALIST_FLAGS_MASK_INTERNAL)) | (guintptr) pointer); \
} while (!g_atomic_pointer_compare_and_exchange_full ((void**) datalist, _oldv, \
_newv, &_oldv)); \
} G_STMT_END
/* --- structures --- */
typedef struct {
GQuark key;
gpointer data;
GDestroyNotify destroy;
} GDataElt;
typedef struct _GDataset GDataset;
struct _GData
{
guint32 len; /* Number of elements */
guint32 alloc; /* Number of allocated elements */
GDataElt data[1]; /* Flexible array */
};
struct _GDataset
{
gconstpointer location;
GData *datalist;
};
/* --- prototypes --- */
static inline GDataset* g_dataset_lookup (gconstpointer dataset_location);
static void g_dataset_destroy_internal (GDataset *dataset);
static inline gpointer g_data_set_internal (GData **datalist,
GQuark key_id,
gpointer data,
GDestroyNotify destroy_func,
GDataset *dataset);
static void g_data_initialize (void);
/* Locking model:
* Each standalone GDataList is protected by a bitlock in the datalist pointer,
* which protects that modification of the non-flags part of the datalist pointer
* and the contents of the datalist.
*
* For GDataSet we have a global lock g_dataset_global that protects
* the global dataset hash and cache, and additionally it protects the
* datalist such that we can avoid to use the bit lock in a few places
* where it is easy.
*/
/* --- variables --- */
G_LOCK_DEFINE_STATIC (g_dataset_global);
static GHashTable *g_dataset_location_ht = NULL;
static GDataset *g_dataset_cached = NULL; /* should this be
thread specific? */
/* --- functions --- */
#define DATALIST_LOCK_BIT 2
G_ALWAYS_INLINE static inline GData *
g_datalist_lock_and_get (GData **datalist)
{
guintptr ptr;
g_pointer_bit_lock_and_get ((void **) datalist, DATALIST_LOCK_BIT, &ptr);
return G_DATALIST_CLEAN_POINTER (ptr);
}
static void
g_datalist_unlock (GData **datalist)
{
g_pointer_bit_unlock ((void **)datalist, DATALIST_LOCK_BIT);
}
static void
g_datalist_unlock_and_set (GData **datalist, gpointer ptr)
{
g_pointer_bit_unlock_and_set ((void **) datalist, DATALIST_LOCK_BIT, ptr, G_DATALIST_FLAGS_MASK_INTERNAL);
}
static gboolean
datalist_append (GData **data, GQuark key_id, gpointer new_data, GDestroyNotify destroy_func)
{
gboolean reallocated;
GData *d;
d = *data;
if (!d)
{
d = g_malloc (G_STRUCT_OFFSET (GData, data) + 2u * sizeof (GDataElt));
d->len = 0;
d->alloc = 2u;
*data = d;
reallocated = TRUE;
}
else if (d->len == d->alloc)
{
d->alloc = d->alloc * 2u;
#if G_ENABLE_DEBUG
/* d->alloc is always a power of two. It thus overflows the first time
* when going to (G_MAXUINT32+1), or when requesting 2^31+1 elements.
*
* This is not handled, and we just crash. That's because we track the GData
* in a linear list, which horribly degrades long before we add 2 billion entries.
* Don't ever try to do that. */
g_assert (d->alloc > d->len);
#endif
d = g_realloc (d, G_STRUCT_OFFSET (GData, data) + d->alloc * sizeof (GDataElt));
*data = d;
reallocated = TRUE;
}
else
reallocated = FALSE;
d->data[d->len] = (GDataElt){
.key = key_id,
.data = new_data,
.destroy = destroy_func,
};
d->len++;
return reallocated;
}
static void
datalist_remove (GData *data, guint32 idx)
{
#if G_ENABLE_DEBUG
g_assert (idx < data->len);
#endif
/* g_data_remove_internal() relies on the fact, that this function removes
* the entry similar to g_array_remove_index_fast(). That is, the entries up
* to @idx are left unchanged, and the last entry is moved to position @idx.
* */
data->len--;
if (idx != data->len)
data->data[idx] = data->data[data->len];
}
static gboolean
datalist_shrink (GData **data, GData **d_to_free)
{
guint32 alloc_by_4;
guint32 v;
GData *d;
d = *data;
alloc_by_4 = d->alloc / 4u;
if (G_LIKELY (d->len > alloc_by_4))
{
/* No shrinking */
return FALSE;
}
if (d->len == 0)
{
/* The list became empty. We drop the allocated memory altogether. */
/* The caller will free the buffer after releasing the lock, to minimize
* the time we hold the lock. Transfer it out. */
*d_to_free = d;
*data = NULL;
return TRUE;
}
/* If the buffer is filled not more than 25%. Shrink to double the current length. */
v = d->len;
if (v != alloc_by_4)
{
/* d->alloc is a power of two. Usually, we remove one element at a
* time, then we will just reach reach a quarter of that.
*
* However, with g_datalist_id_remove_multiple(), len can be smaller
* at once. In that case, find first the next power of two. */
v = g_nearest_pow (v);
}
v *= 2u;
#if G_ENABLE_DEBUG
g_assert (v > d->len);
g_assert (v <= d->alloc / 2u);
#endif
d->alloc = v;
d = g_realloc (d, G_STRUCT_OFFSET (GData, data) + (v * sizeof (GDataElt)));
*d_to_free = NULL;
*data = d;
return TRUE;
}
static GDataElt *
datalist_find (GData *data, GQuark key_id, guint32 *out_idx)
{
guint32 i;
if (data)
{
for (i = 0; i < data->len; i++)
{
GDataElt *data_elt = &data->data[i];
if (data_elt->key == key_id)
{
if (out_idx)
*out_idx = i;
return data_elt;
}
}
}
if (out_idx)
*out_idx = G_MAXUINT32;
return NULL;
}
/**
* g_datalist_clear: (skip)
* @datalist: a datalist.
*
* Frees all the data elements of the datalist.
* The data elements' destroy functions are called
* if they have been set.
**/
void
g_datalist_clear (GData **datalist)
{
GData *data;
guint i;
g_return_if_fail (datalist != NULL);
data = g_datalist_lock_and_get (datalist);
if (!data)
{
g_datalist_unlock (datalist);
return;
}
g_datalist_unlock_and_set (datalist, NULL);
for (i = 0; i < data->len; i++)
{
if (data->data[i].data && data->data[i].destroy)
data->data[i].destroy (data->data[i].data);
}
g_free (data);
}
/* HOLDS: g_dataset_global_lock */
static inline GDataset*
g_dataset_lookup (gconstpointer dataset_location)
{
GDataset *dataset;
if (g_dataset_cached && g_dataset_cached->location == dataset_location)
return g_dataset_cached;
dataset = g_hash_table_lookup (g_dataset_location_ht, dataset_location);
if (dataset)
g_dataset_cached = dataset;
return dataset;
}
/* HOLDS: g_dataset_global_lock */
static void
g_dataset_destroy_internal (GDataset *dataset)
{
gconstpointer dataset_location;
dataset_location = dataset->location;
while (dataset)
{
GData *data;
guint i;
data = G_DATALIST_GET_POINTER (&dataset->datalist);
if (!data)
{
if (dataset == g_dataset_cached)
g_dataset_cached = NULL;
g_hash_table_remove (g_dataset_location_ht, dataset_location);
g_slice_free (GDataset, dataset);
break;
}
G_DATALIST_SET_POINTER (&dataset->datalist, NULL);
G_UNLOCK (g_dataset_global);
for (i = 0; i < data->len; i++)
{
if (data->data[i].data && data->data[i].destroy)
data->data[i].destroy (data->data[i].data);
}
g_free (data);
G_LOCK (g_dataset_global);
dataset = g_dataset_lookup (dataset_location);
}
}
/**
* g_dataset_destroy:
* @dataset_location: (not nullable): the location identifying the dataset.
*
* Destroys the dataset, freeing all memory allocated, and calling any
* destroy functions set for data elements.
*/
void
g_dataset_destroy (gconstpointer dataset_location)
{
g_return_if_fail (dataset_location != NULL);
G_LOCK (g_dataset_global);
if (g_dataset_location_ht)
{
GDataset *dataset;
dataset = g_dataset_lookup (dataset_location);
if (dataset)
g_dataset_destroy_internal (dataset);
}
G_UNLOCK (g_dataset_global);
}
/* HOLDS: g_dataset_global_lock if dataset != null */
static inline gpointer
g_data_set_internal (GData **datalist,
GQuark key_id,
gpointer new_data,
GDestroyNotify new_destroy_func,
GDataset *dataset)
{
GData *d;
GData *new_d = NULL;
GDataElt old, *data;
guint32 idx;
d = g_datalist_lock_and_get (datalist);
data = datalist_find (d, key_id, &idx);
if (new_data == NULL) /* remove */
{
if (data)
{
GData *d_to_free;
old = *data;
datalist_remove (d, idx);
if (datalist_shrink (&d, &d_to_free))
{
g_datalist_unlock_and_set (datalist, d);
/* the dataset destruction *must* be done
* prior to invocation of the data destroy function
*/
if (dataset && !d)
g_dataset_destroy_internal (dataset);
if (d_to_free)
g_free (d_to_free);
}
else
g_datalist_unlock (datalist);
/* We found and removed an old value
* the GData struct *must* already be unlinked
* when invoking the destroy function.
* we use (new_data==NULL && new_destroy_func!=NULL) as
* a special hint combination to "steal"
* data without destroy notification
*/
if (old.destroy && !new_destroy_func)
{
if (dataset)
G_UNLOCK (g_dataset_global);
old.destroy (old.data);
if (dataset)
G_LOCK (g_dataset_global);
old.data = NULL;
}
return old.data;
}
}
else
{
if (data)
{
if (!data->destroy)
{
data->data = new_data;
data->destroy = new_destroy_func;
g_datalist_unlock (datalist);
}
else
{
old = *data;
data->data = new_data;
data->destroy = new_destroy_func;
g_datalist_unlock (datalist);
/* We found and replaced an old value
* the GData struct *must* already be unlinked
* when invoking the destroy function.
*/
if (dataset)
G_UNLOCK (g_dataset_global);
old.destroy (old.data);
if (dataset)
G_LOCK (g_dataset_global);
}
return NULL;
}
/* The key was not found, insert it */
if (datalist_append (&d, key_id, new_data, new_destroy_func))
new_d = d;
}
if (new_d)
g_datalist_unlock_and_set (datalist, new_d);
else
g_datalist_unlock (datalist);
return NULL;
}
static inline void
g_data_remove_internal (GData **datalist,
GQuark *keys,
gsize n_keys)
{
GData *d;
GDataElt *old;
GDataElt *old_to_free = NULL;
GData *d_to_free;
gsize found_keys;
gsize i_keys;
guint32 i_data;
d = g_datalist_lock_and_get (datalist);
if (!d)
{
g_datalist_unlock (datalist);
return;
}
/* Allocate an array of GDataElt to hold copies of the elements
* that are removed from the datalist. Allow enough space for all
* the keys; if a key is not found, the corresponding element of
* old is not populated, so we initialize them all to NULL to
* detect that case.
*
* At most allocate 400 bytes on the stack. Especially since we call
* out to external code, we don't know how much stack we can use. */
if (n_keys <= 400u / sizeof (GDataElt))
old = g_newa0 (GDataElt, n_keys);
else
{
old_to_free = g_new0 (GDataElt, n_keys);
old = old_to_free;
}
i_data = 0;
found_keys = 0;
while (i_data < d->len && found_keys < n_keys)
{
GDataElt *data = &d->data[i_data];
gboolean remove = FALSE;
for (i_keys = 0; i_keys < n_keys; i_keys++)
{
if (data->key == keys[i_keys])
{
/* We must invoke the destroy notifications in the order of @keys.
* Hence, build up the list @old at index @i_keys. */
old[i_keys] = *data;
found_keys++;
remove = TRUE;
break;
}
}
if (!remove)
{
i_data++;
continue;
}
datalist_remove (d, i_data);
}
if (found_keys > 0 && datalist_shrink (&d, &d_to_free))
{
g_datalist_unlock_and_set (datalist, d);
if (d_to_free)
g_free (d_to_free);
}
else
g_datalist_unlock (datalist);
if (found_keys > 0)
{
for (i_keys = 0; i_keys < n_keys; i_keys++)
{
if (old[i_keys].destroy)
old[i_keys].destroy (old[i_keys].data);
}
}
if (G_UNLIKELY (old_to_free))
g_free (old_to_free);
}
/**
* g_dataset_id_set_data_full: (skip)
* @dataset_location: (not nullable): the location identifying the dataset.
* @key_id: the #GQuark id to identify the data element.
* @data: the data element.
* @destroy_func: the function to call when the data element is
* removed. This function will be called with the data
* element and can be used to free any memory allocated
* for it.
*
* Sets the data element associated with the given #GQuark id, and also
* the function to call when the data element is destroyed. Any
* previous data with the same key is removed, and its destroy function
* is called.
**/
/**
* g_dataset_set_data_full: (skip)
* @l: the location identifying the dataset.
* @k: the string to identify the data element.
* @d: the data element.
* @f: the function to call when the data element is removed. This
* function will be called with the data element and can be used to
* free any memory allocated for it.
*
* Sets the data corresponding to the given string identifier, and the
* function to call when the data element is destroyed.
**/
/**
* g_dataset_id_set_data:
* @l: the location identifying the dataset.
* @k: the #GQuark id to identify the data element.
* @d: the data element.
*
* Sets the data element associated with the given #GQuark id. Any
* previous data with the same key is removed, and its destroy function
* is called.
**/
/**
* g_dataset_set_data:
* @l: the location identifying the dataset.
* @k: the string to identify the data element.
* @d: the data element.
*
* Sets the data corresponding to the given string identifier.
**/
/**
* g_dataset_id_remove_data:
* @l: the location identifying the dataset.
* @k: the #GQuark id identifying the data element.
*
* Removes a data element from a dataset. The data element's destroy
* function is called if it has been set.
**/
/**
* g_dataset_remove_data:
* @l: the location identifying the dataset.
* @k: the string identifying the data element.
*
* Removes a data element corresponding to a string. Its destroy
* function is called if it has been set.
**/
void
g_dataset_id_set_data_full (gconstpointer dataset_location,
GQuark key_id,
gpointer data,
GDestroyNotify destroy_func)
{
GDataset *dataset;
g_return_if_fail (dataset_location != NULL);
if (!data)
g_return_if_fail (destroy_func == NULL);
if (!key_id)
{
if (data)
g_return_if_fail (key_id > 0);
else
return;
}
G_LOCK (g_dataset_global);
if (!g_dataset_location_ht)
g_data_initialize ();
dataset = g_dataset_lookup (dataset_location);
if (!dataset)
{
dataset = g_slice_new (GDataset);
dataset->location = dataset_location;
g_datalist_init (&dataset->datalist);
g_hash_table_insert (g_dataset_location_ht,
(gpointer) dataset->location,
dataset);
}
g_data_set_internal (&dataset->datalist, key_id, data, destroy_func, dataset);
G_UNLOCK (g_dataset_global);
}
/**
* g_datalist_id_set_data_full: (skip)
* @datalist: a datalist.
* @key_id: the #GQuark to identify the data element.
* @data: (nullable): the data element or %NULL to remove any previous element
* corresponding to @key_id.
* @destroy_func: (nullable): the function to call when the data element is
* removed. This function will be called with the data
* element and can be used to free any memory allocated
* for it. If @data is %NULL, then @destroy_func must
* also be %NULL.
*
* Sets the data corresponding to the given #GQuark id, and the
* function to be called when the element is removed from the datalist.
* Any previous data with the same key is removed, and its destroy
* function is called.
**/
/**
* g_datalist_set_data_full: (skip)
* @dl: a datalist.
* @k: the string to identify the data element.
* @d: (nullable): the data element, or %NULL to remove any previous element
* corresponding to @k.
* @f: (nullable): the function to call when the data element is removed.
* This function will be called with the data element and can be used to
* free any memory allocated for it. If @d is %NULL, then @f must
* also be %NULL.
*
* Sets the data element corresponding to the given string identifier,
* and the function to be called when the data element is removed.
**/
/**
* g_datalist_id_set_data:
* @dl: a datalist.
* @q: the #GQuark to identify the data element.
* @d: (nullable): the data element, or %NULL to remove any previous element
* corresponding to @q.
*
* Sets the data corresponding to the given #GQuark id. Any previous
* data with the same key is removed, and its destroy function is
* called.
**/
/**
* g_datalist_set_data:
* @dl: a datalist.
* @k: the string to identify the data element.
* @d: (nullable): the data element, or %NULL to remove any previous element
* corresponding to @k.
*
* Sets the data element corresponding to the given string identifier.
**/
/**
* g_datalist_id_remove_data:
* @dl: a datalist.
* @q: the #GQuark identifying the data element.
*
* Removes an element, using its #GQuark identifier.
**/
/**
* g_datalist_remove_data:
* @dl: a datalist.
* @k: the string identifying the data element.
*
* Removes an element using its string identifier. The data element's
* destroy function is called if it has been set.
**/
void
g_datalist_id_set_data_full (GData **datalist,
GQuark key_id,
gpointer data,
GDestroyNotify destroy_func)
{
g_return_if_fail (datalist != NULL);
if (!data)
g_return_if_fail (destroy_func == NULL);
if (!key_id)
{
if (data)
g_return_if_fail (key_id > 0);
else
return;
}
g_data_set_internal (datalist, key_id, data, destroy_func, NULL);
}
/**
* g_datalist_id_remove_multiple:
* @datalist: a datalist
* @keys: (array length=n_keys): keys to remove
* @n_keys: length of @keys.
*
* Removes multiple keys from a datalist.
*
* This is more efficient than calling g_datalist_id_remove_data()
* multiple times in a row.
*
* Before 2.80, @n_keys had to be not larger than 16. Now it can be larger, but
* note that GData does a linear search, so an excessive number of keys will
* perform badly.
*
* Since: 2.74
*/
void
g_datalist_id_remove_multiple (GData **datalist,
GQuark *keys,
gsize n_keys)
{
g_data_remove_internal (datalist, keys, n_keys);
}
/**
* g_dataset_id_remove_no_notify: (skip)
* @dataset_location: (not nullable): the location identifying the dataset.
* @key_id: the #GQuark ID identifying the data element.
*
* Removes an element, without calling its destroy notification
* function.
*
* Returns: (nullable): the data previously stored at @key_id,
* or %NULL if none.
**/
/**
* g_dataset_remove_no_notify: (skip)
* @l: the location identifying the dataset.
* @k: the string identifying the data element.
*
* Removes an element, without calling its destroy notifier.
**/
gpointer
g_dataset_id_remove_no_notify (gconstpointer dataset_location,
GQuark key_id)
{
gpointer ret_data = NULL;
g_return_val_if_fail (dataset_location != NULL, NULL);
G_LOCK (g_dataset_global);
if (key_id && g_dataset_location_ht)
{
GDataset *dataset;
dataset = g_dataset_lookup (dataset_location);
if (dataset)
ret_data = g_data_set_internal (&dataset->datalist, key_id, NULL, (GDestroyNotify) 42, dataset);
}
G_UNLOCK (g_dataset_global);
return ret_data;
}
/**
* g_datalist_id_remove_no_notify: (skip)
* @datalist: a datalist.
* @key_id: the #GQuark identifying a data element.
*
* Removes an element, without calling its destroy notification
* function.
*
* Returns: (nullable): the data previously stored at @key_id,
* or %NULL if none.
**/
/**
* g_datalist_remove_no_notify: (skip)
* @dl: a datalist.
* @k: the string identifying the data element.
*
* Removes an element, without calling its destroy notifier.
**/
gpointer
g_datalist_id_remove_no_notify (GData **datalist,
GQuark key_id)
{
gpointer ret_data = NULL;
g_return_val_if_fail (datalist != NULL, NULL);
if (key_id)
ret_data = g_data_set_internal (datalist, key_id, NULL, (GDestroyNotify) 42, NULL);
return ret_data;
}
/*< private >
* g_datalist_id_update_atomic:
* @datalist: the data list
* @key_id: the key to add.
* @callback: (scope call): callback to update (set, remove, steal, update) the
* data.
* @user_data: the user data for @callback.
*
* Will call @callback while holding the lock on @datalist. Be careful to not
* end up calling into another data-list function, because the lock is not
* reentrant and deadlock will happen.
*
* The callback receives the current data and destroy function. If @key_id is
* currently not in @datalist, they will be %NULL. The callback can update
* those pointers, and @datalist will be updated with the result. Note that if
* callback modifies a received data, then it MUST steal it and take ownership
* on it. Possibly by freeing it with the provided destroy function.
*
* The point is to atomically access the entry, while holding a lock
* of @datalist. Without this, the user would have to hold their own mutex
* while handling @key_id entry.
*
* The return value of @callback is not used, except it becomes the return
* value of the function. This is an alternative to returning a result via
* @user_data.
*
* Returns: the value returned by @callback.
*
* Since: 2.80
*/
gpointer
g_datalist_id_update_atomic (GData **datalist,
GQuark key_id,
GDataListUpdateAtomicFunc callback,
gpointer user_data)
{
GData *d;
GDataElt *data;
gpointer new_data;
gpointer result;
GDestroyNotify new_destroy;
guint32 idx;
gboolean to_unlock = TRUE;
d = g_datalist_lock_and_get (datalist);
data = datalist_find (d, key_id, &idx);
if (data)
{
new_data = data->data;
new_destroy = data->destroy;
}
else
{
new_data = NULL;
new_destroy = NULL;
}
result = callback (key_id, &new_data, &new_destroy, user_data);
if (data && !new_data)
{
GData *d_to_free;
/* Remove. The callback indicates to drop the entry.
*
* The old data->data was stolen by callback(). */
datalist_remove (d, idx);
if (datalist_shrink (&d, &d_to_free))
{
g_datalist_unlock_and_set (datalist, d);
if (d_to_free)
g_free (d_to_free);
to_unlock = FALSE;
}
}
else if (data)
{
/* Update. The callback may have provided new pointers to an existing
* entry.
*
* The old data was stolen by callback(). We only update the pointers and
* are done. */
data->data = new_data;
data->destroy = new_destroy;
}
else if (!data && !new_data)
{
/* Absent. No change. The entry didn't exist and still does not. */
}
else
{
/* Add. Add a new entry that didn't exist previously. */
if (datalist_append (&d, key_id, new_data, new_destroy))
{
g_datalist_unlock_and_set (datalist, d);
to_unlock = FALSE;
}
}
if (to_unlock)
g_datalist_unlock (datalist);
return result;
}
/**
* g_dataset_id_get_data:
* @dataset_location: (not nullable): the location identifying the dataset.
* @key_id: the #GQuark id to identify the data element.
*
* Gets the data element corresponding to a #GQuark.
*
* Returns: (transfer none) (nullable): the data element corresponding to
* the #GQuark, or %NULL if it is not found.
**/
/**
* g_dataset_get_data:
* @l: the location identifying the dataset.
* @k: the string identifying the data element.
*
* Gets the data element corresponding to a string.
*
* Returns: (transfer none) (nullable): the data element corresponding to
* the string, or %NULL if it is not found.
**/
gpointer
g_dataset_id_get_data (gconstpointer dataset_location,
GQuark key_id)
{
gpointer retval = NULL;
g_return_val_if_fail (dataset_location != NULL, NULL);
G_LOCK (g_dataset_global);
if (key_id && g_dataset_location_ht)
{
GDataset *dataset;
dataset = g_dataset_lookup (dataset_location);
if (dataset)
retval = g_datalist_id_get_data (&dataset->datalist, key_id);
}
G_UNLOCK (g_dataset_global);
return retval;
}
/**
* g_datalist_id_get_data:
* @datalist: a datalist.
* @key_id: the #GQuark identifying a data element.
*
* Retrieves the data element corresponding to @key_id.
*
* Returns: (transfer none) (nullable): the data element, or %NULL if
* it is not found.
*/
gpointer
g_datalist_id_get_data (GData **datalist,
GQuark key_id)
{
return g_datalist_id_dup_data (datalist, key_id, NULL, NULL);
}
/**
* GDuplicateFunc:
* @data: the data to duplicate
* @user_data: (closure): user data that was specified in
* g_datalist_id_dup_data()
*
* The type of functions that are used to 'duplicate' an object.
* What this means depends on the context, it could just be
* incrementing the reference count, if @data is a ref-counted
* object.
*
* Returns: a duplicate of data
*/
/**
* g_datalist_id_dup_data: (skip)
* @datalist: location of a datalist
* @key_id: the #GQuark identifying a data element
* @dup_func: (scope call) (closure user_data) (nullable): function to
* duplicate the old value
* @user_data: passed as user_data to @dup_func
*
* This is a variant of g_datalist_id_get_data() which
* returns a 'duplicate' of the value. @dup_func defines the
* meaning of 'duplicate' in this context, it could e.g.
* take a reference on a ref-counted object.
*
* If the @key_id is not set in the datalist then @dup_func
* will be called with a %NULL argument.
*
* Note that @dup_func is called while the datalist is locked, so it
* is not allowed to read or modify the datalist.
*
* This function can be useful to avoid races when multiple
* threads are using the same datalist and the same key.
*
* Returns: (nullable): the result of calling @dup_func on the value
* associated with @key_id in @datalist, or %NULL if not set.
* If @dup_func is %NULL, the value is returned unmodified.
*
* Since: 2.34
*/
gpointer
g_datalist_id_dup_data (GData **datalist,
GQuark key_id,
GDuplicateFunc dup_func,
gpointer user_data)
{
gpointer val = NULL;
gpointer retval = NULL;
GData *d;
GDataElt *data;
d = g_datalist_lock_and_get (datalist);
data = datalist_find (d, key_id, NULL);
if (data)
val = data->data;
if (dup_func)
retval = dup_func (val, user_data);
else
retval = val;
g_datalist_unlock (datalist);
return retval;
}
/**
* g_datalist_id_replace_data: (skip)
* @datalist: location of a datalist
* @key_id: the #GQuark identifying a data element
* @oldval: (nullable): the old value to compare against
* @newval: (nullable): the new value to replace it with
* @destroy: (nullable): destroy notify for the new value
* @old_destroy: (out) (optional): destroy notify for the existing value
*
* Compares the member that is associated with @key_id in
* @datalist to @oldval, and if they are the same, replace
* @oldval with @newval.
*
* This is like a typical atomic compare-and-exchange
* operation, for a member of @datalist.
*
* If the previous value was replaced then ownership of the
* old value (@oldval) is passed to the caller, including
* the registered destroy notify for it (passed out in @old_destroy).
* Its up to the caller to free this as they wish, which may
* or may not include using @old_destroy as sometimes replacement
* should not destroy the object in the normal way.
*
* Returns: %TRUE if the existing value for @key_id was replaced
* by @newval, %FALSE otherwise.
*
* Since: 2.34
*/
gboolean
g_datalist_id_replace_data (GData **datalist,
GQuark key_id,
gpointer oldval,
gpointer newval,
GDestroyNotify destroy,
GDestroyNotify *old_destroy)
{
gpointer val = NULL;
GData *d;
GDataElt *data;
GData *d_to_free = NULL;
gboolean set_d = FALSE;
guint32 idx;
g_return_val_if_fail (datalist != NULL, FALSE);
g_return_val_if_fail (key_id != 0, FALSE);
if (old_destroy)
*old_destroy = NULL;
d = g_datalist_lock_and_get (datalist);
data = datalist_find (d, key_id, &idx);
if (data)
{
val = data->data;
if (val == oldval)
{
if (old_destroy)
*old_destroy = data->destroy;
if (newval != NULL)
{
data->data = newval;
data->destroy = destroy;
}
else
{
datalist_remove (d, idx);
if (datalist_shrink (&d, &d_to_free))
set_d = TRUE;
}
}
}
if (val == NULL && oldval == NULL && newval != NULL)
{
if (datalist_append (&d, key_id, newval, destroy))
{
set_d = TRUE;
}
}
if (set_d)
g_datalist_unlock_and_set (datalist, d);
else
g_datalist_unlock (datalist);
if (d_to_free)
g_free (d_to_free);
return val == oldval;
}
/**
* g_datalist_get_data:
* @datalist: a datalist.
* @key: the string identifying a data element.
*
* Gets a data element, using its string identifier. This is slower than
* g_datalist_id_get_data() because it compares strings.
*
* Returns: (transfer none) (nullable): the data element, or %NULL if it
* is not found.
**/
gpointer
g_datalist_get_data (GData **datalist,
const gchar *key)
{
gpointer res = NULL;
GData *d;
GDataElt *data, *data_end;
g_return_val_if_fail (datalist != NULL, NULL);
d = g_datalist_lock_and_get (datalist);
if (d)
{
data = d->data;
data_end = data + d->len;
while (data < data_end)
{
/* Here we intentionally compare by strings, instead of calling
* g_quark_try_string() first.
*
* See commit 1cceda49b60b ('Make g_datalist_get_data not look up the
* quark').
*/
if (g_strcmp0 (g_quark_to_string (data->key), key) == 0)
{
res = data->data;
break;
}
data++;
}
}
g_datalist_unlock (datalist);
return res;
}
/**
* GDataForeachFunc:
* @key_id: the #GQuark id to identifying the data element.
* @data: the data element.
* @user_data: (closure): user data passed to g_dataset_foreach().
*
* Specifies the type of function passed to g_dataset_foreach(). It is
* called with each #GQuark id and associated data element, together
* with the @user_data parameter supplied to g_dataset_foreach().
**/
/**
* g_dataset_foreach:
* @dataset_location: (not nullable): the location identifying the dataset.
* @func: (scope call) (closure user_data): the function to call for each data element.
* @user_data: user data to pass to the function.
*
* Calls the given function for each data element which is associated
* with the given location. Note that this function is NOT thread-safe.
* So unless @dataset_location can be protected from any modifications
* during invocation of this function, it should not be called.
*
* @func can make changes to the dataset, but the iteration will not
* reflect changes made during the g_dataset_foreach() call, other
* than skipping over elements that are removed.
**/
void
g_dataset_foreach (gconstpointer dataset_location,
GDataForeachFunc func,
gpointer user_data)
{
GDataset *dataset;
g_return_if_fail (dataset_location != NULL);
g_return_if_fail (func != NULL);
G_LOCK (g_dataset_global);
if (g_dataset_location_ht)
{
dataset = g_dataset_lookup (dataset_location);
G_UNLOCK (g_dataset_global);
if (dataset)
g_datalist_foreach (&dataset->datalist, func, user_data);
}
else
{
G_UNLOCK (g_dataset_global);
}
}
/**
* g_datalist_foreach:
* @datalist: a datalist.
* @func: (scope call) (closure user_data): the function to call for each data element.
* @user_data: user data to pass to the function.
*
* Calls the given function for each data element of the datalist. The
* function is called with each data element's #GQuark id and data,
* together with the given @user_data parameter. Note that this
* function is NOT thread-safe. So unless @datalist can be protected
* from any modifications during invocation of this function, it should
* not be called.
*
* @func can make changes to @datalist, but the iteration will not
* reflect changes made during the g_datalist_foreach() call, other
* than skipping over elements that are removed.
**/
void
g_datalist_foreach (GData **datalist,
GDataForeachFunc func,
gpointer user_data)
{
GData *d;
guint i, j, len;
GQuark *keys;
g_return_if_fail (datalist != NULL);
g_return_if_fail (func != NULL);
d = G_DATALIST_GET_POINTER (datalist);
if (d == NULL)
return;
/* We make a copy of the keys so that we can handle it changing
in the callback */
len = d->len;
keys = g_new (GQuark, len);
for (i = 0; i < len; i++)
keys[i] = d->data[i].key;
for (i = 0; i < len; i++)
{
/* A previous callback might have removed a later item, so always check that
it still exists before calling */
d = G_DATALIST_GET_POINTER (datalist);
if (d == NULL)
break;
for (j = 0; j < d->len; j++)
{
if (d->data[j].key == keys[i]) {
func (d->data[i].key, d->data[i].data, user_data);
break;
}
}
}
g_free (keys);
}
/**
* g_datalist_init: (skip)
* @datalist: a pointer to a pointer to a datalist.
*
* Resets the datalist to %NULL. It does not free any memory or call
* any destroy functions.
**/
void
g_datalist_init (GData **datalist)
{
g_return_if_fail (datalist != NULL);
g_atomic_pointer_set (datalist, NULL);
}
/**
* g_datalist_set_flags:
* @datalist: pointer to the location that holds a list
* @flags: the flags to turn on. The values of the flags are
* restricted by %G_DATALIST_FLAGS_MASK (currently
* 3; giving two possible boolean flags).
* A value for @flags that doesn't fit within the mask is
* an error.
*
* Turns on flag values for a data list. This function is used
* to keep a small number of boolean flags in an object with
* a data list without using any additional space. It is
* not generally useful except in circumstances where space
* is very tight. (It is used in the base #GObject type, for
* example.)
*
* Since: 2.8
**/
void
g_datalist_set_flags (GData **datalist,
guint flags)
{
g_return_if_fail (datalist != NULL);
g_return_if_fail ((flags & ~G_DATALIST_FLAGS_MASK) == 0);
g_atomic_pointer_or (datalist, (gsize)flags);
}
/**
* g_datalist_unset_flags:
* @datalist: pointer to the location that holds a list
* @flags: the flags to turn off. The values of the flags are
* restricted by %G_DATALIST_FLAGS_MASK (currently
* 3: giving two possible boolean flags).
* A value for @flags that doesn't fit within the mask is
* an error.
*
* Turns off flag values for a data list. See g_datalist_unset_flags()
*
* Since: 2.8
**/
void
g_datalist_unset_flags (GData **datalist,
guint flags)
{
g_return_if_fail (datalist != NULL);
g_return_if_fail ((flags & ~G_DATALIST_FLAGS_MASK) == 0);
g_atomic_pointer_and (datalist, ~(gsize)flags);
}
/**
* g_datalist_get_flags:
* @datalist: pointer to the location that holds a list
*
* Gets flags values packed in together with the datalist.
* See g_datalist_set_flags().
*
* Returns: the flags of the datalist
*
* Since: 2.8
**/
guint
g_datalist_get_flags (GData **datalist)
{
g_return_val_if_fail (datalist != NULL, 0);
return G_DATALIST_GET_FLAGS (datalist); /* atomic macro */
}
/* HOLDS: g_dataset_global_lock */
static void
g_data_initialize (void)
{
g_return_if_fail (g_dataset_location_ht == NULL);
g_dataset_location_ht = g_hash_table_new (g_direct_hash, NULL);
g_dataset_cached = NULL;
}
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