| GLib Reference Manual | ||||
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#include <glib.h>
GCache;
GCache* g_cache_new (GCacheNewFunc value_new_func,
GCacheDestroyFunc value_destroy_func,
GCacheDupFunc key_dup_func,
GCacheDestroyFunc key_destroy_func,
GHashFunc hash_key_func,
GHashFunc hash_value_func,
GEqualFunc key_equal_func);
gpointer g_cache_insert (GCache *cache,
gpointer key);
void g_cache_remove (GCache *cache,
gconstpointer value);
void g_cache_destroy (GCache *cache);
void g_cache_key_foreach (GCache *cache,
GHFunc func,
gpointer user_data);
void g_cache_value_foreach (GCache *cache,
GHFunc func,
gpointer user_data);
void (*GCacheDestroyFunc) (gpointer value);
gpointer (*GCacheDupFunc) (gpointer value);
gpointer (*GCacheNewFunc) (gpointer key);
A GCache allows sharing of complex data structures, in order to save system resources.
GTK+ uses caches for GtkStyles and GdkGCs. These consume a lot of resources, so a GCache is used to see if a GtkStyle or GdkGC with the required properties already exists. If it does, then the existing object is used instead of creating a new one.
GCache uses keys and values. A GCache key describes the properties of a particular resource. A GCache value is the actual resource.
typedef struct _GCache GCache;
The GCache struct is an opaque data structure containing information about a GCache. It should only be accessed via the following functions.
GCache* g_cache_new (GCacheNewFunc value_new_func,GCacheDestroyFunc value_destroy_func,GCacheDupFunc key_dup_func,GCacheDestroyFunc key_destroy_func,GHashFunc hash_key_func,GHashFunc hash_value_func,GEqualFunc key_equal_func);
Creates a new GCache.
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a function to create a new object given a key.
This is called by g_cache_insert() if an object
with the given key does not already exist.
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a function to destroy an object. It is called
by g_cache_remove() when the object is no
longer needed (i.e. its reference count drops
to 0).
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a function to copy a key. It is called by
g_cache_insert() if the key does not already exist in
the GCache.
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a function to destroy a key. It is called by
g_cache_remove() when the object is no longer
needed (i.e. its reference count drops to 0).
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a function to create a hash value from a key. |
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a function to create a hash value from a value. |
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a function to compare two keys. It should return
TRUE if the two keys are equivalent.
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Returns : |
a new GCache. |
gpointer g_cache_insert (GCache *cache,gpointer key);
Gets the value corresponding to the given key, creating it if
necessary. It first checks if the value already exists in the
GCache, by using the key_equal_func function passed to
g_cache_new(). If it does already exist it is returned, and its
reference count is increased by one. If the value does not currently
exist, if is created by calling the value_new_func. The key is
duplicated by calling key_dup_func and the duplicated key and value
are inserted into the GCache.
void g_cache_remove (GCache *cache,gconstpointer value);
Decreases the reference count of the given value. If it drops to 0
then the value and its corresponding key are destroyed, using the
value_destroy_func and key_destroy_func passed to g_cache_new().
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a GCache. |
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the value to remove. |
void g_cache_destroy (GCache *cache);
Frees the memory allocated for the GCache.
Note that it does not destroy the keys and values which were contained in the GCache.
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a GCache. |
void g_cache_key_foreach (GCache *cache,GHFunc func,gpointer user_data);
Calls the given function for each of the keys in the GCache.
NOTE func is passed three parameters, the value and key of a cache
entry and the user_data. The order of value and key is different
from the order in which g_hash_table_foreach() passes key-value
pairs to its callback function !
void g_cache_value_foreach (GCache *cache,GHFunc func,gpointer user_data);
g_cache_value_foreach has been deprecated since version 2.10 and should not be used in newly-written code. The reason is that it passes pointers to internal
data structures to func; use g_cache_key_foreach()
instead
Calls the given function for each of the values in the GCache.
void (*GCacheDestroyFunc) (gpointer value);
Specifies the type of the value_destroy_func and key_destroy_func
functions passed to g_cache_new(). The functions are passed a
pointer to the GCache key or GCache value and should free any
memory and other resources associated with it.
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the GCache value to destroy. |
gpointer (*GCacheDupFunc) (gpointer value);
Specifies the type of the key_dup_func function passed to
g_cache_new(). The function is passed a key
(not a value as the prototype implies) and
should return a duplicate of the key.