glib/gio/glistmodel.c
Christian Hergert 22ba4411cc gio: remove use of generic marshaller from GIO objects
Using the generic marshaller has drawbacks beyond performance. One such
drawback is that it breaks the stack unwinding from the Linux kernel due
to having unsufficient data to walk past ffi_call_unixt64. That means that
performance profiling by application developers looks grouped among
seemingly unrelated code paths.

While we can't fix the kernel unwinding here, we can provide proper
c_marshallers and va_marshallers for objects within Gio so that
performance profiling of applications is more reliable.

Related to GNOME/Initiatives#10
2019-06-17 16:29:09 -07:00

290 lines
9.7 KiB
C

/*
* Copyright 2015 Lars Uebernickel
* Copyright 2015 Ryan Lortie
*
* 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/>.
*
* Authors:
* Lars Uebernickel <lars@uebernic.de>
* Ryan Lortie <desrt@desrt.ca>
*/
#include "config.h"
#include "glistmodel.h"
#include "glibintl.h"
#include "gmarshal-internal.h"
G_DEFINE_INTERFACE (GListModel, g_list_model, G_TYPE_OBJECT)
/**
* SECTION:glistmodel
* @title: GListModel
* @short_description: An interface describing a dynamic list of objects
* @include: gio/gio.h
* @see_also: #GListStore
*
* #GListModel is an interface that represents a mutable list of
* #GObjects. Its main intention is as a model for various widgets in
* user interfaces, such as list views, but it can also be used as a
* convenient method of returning lists of data, with support for
* updates.
*
* Each object in the list may also report changes in itself via some
* mechanism (normally the #GObject::notify signal). Taken together
* with the #GListModel::items-changed signal, this provides for a list
* that can change its membership, and in which the members can change
* their individual properties.
*
* A good example would be the list of visible wireless network access
* points, where each access point can report dynamic properties such as
* signal strength.
*
* It is important to note that the #GListModel itself does not report
* changes to the individual items. It only reports changes to the list
* membership. If you want to observe changes to the objects themselves
* then you need to connect signals to the objects that you are
* interested in.
*
* All items in a #GListModel are of (or derived from) the same type.
* g_list_model_get_item_type() returns that type. The type may be an
* interface, in which case all objects in the list must implement it.
*
* The semantics are close to that of an array:
* g_list_model_get_n_items() returns the number of items in the list and
* g_list_model_get_item() returns an item at a (0-based) position. In
* order to allow implementations to calculate the list length lazily,
* you can also iterate over items: starting from 0, repeatedly call
* g_list_model_get_item() until it returns %NULL.
*
* An implementation may create objects lazily, but must take care to
* return the same object for a given position until all references to
* it are gone.
*
* On the other side, a consumer is expected only to hold references on
* objects that are currently "user visible", in order to faciliate the
* maximum level of laziness in the implementation of the list and to
* reduce the required number of signal connections at a given time.
*
* This interface is intended only to be used from a single thread. The
* thread in which it is appropriate to use it depends on the particular
* implementation, but typically it will be from the thread that owns
* the [thread-default main context][g-main-context-push-thread-default]
* in effect at the time that the model was created.
*/
/**
* GListModelInterface:
* @g_iface: parent #GTypeInterface
* @get_item_type: the virtual function pointer for g_list_model_get_item_type()
* @get_n_items: the virtual function pointer for g_list_model_get_n_items()
* @get_item: the virtual function pointer for g_list_model_get_item()
*
* The virtual function table for #GListModel.
*
* Since: 2.44
*/
/**
* GListModelInterface::get_item:
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (type GObject) (transfer full) (nullable): the object at @position.
*
* Since: 2.44
*/
/**
* GListModel:
*
* #GListModel is an opaque data structure and can only be accessed
* using the following functions.
**/
static guint g_list_model_changed_signal;
static void
g_list_model_default_init (GListModelInterface *iface)
{
/**
* GListModel::items-changed:
* @list: the #GListModel that changed
* @position: the position at which @list changed
* @removed: the number of items removed
* @added: the number of items added
*
* This signal is emitted whenever items were added or removed to
* @list. At @position, @removed items were removed and @added items
* were added in their place.
*
* Since: 2.44
*/
g_list_model_changed_signal = g_signal_new (I_("items-changed"),
G_TYPE_LIST_MODEL,
G_SIGNAL_RUN_LAST,
0,
NULL, NULL,
_g_cclosure_marshal_VOID__UINT_UINT_UINT,
G_TYPE_NONE,
3, G_TYPE_UINT, G_TYPE_UINT, G_TYPE_UINT);
g_signal_set_va_marshaller (g_list_model_changed_signal,
G_TYPE_FROM_INTERFACE (iface),
_g_cclosure_marshal_VOID__UINT_UINT_UINTv);
}
/**
* g_list_model_get_item_type:
* @list: a #GListModel
*
* Gets the type of the items in @list. All items returned from
* g_list_model_get_type() are of that type or a subtype, or are an
* implementation of that interface.
*
* The item type of a #GListModel can not change during the life of the
* model.
*
* Returns: the #GType of the items contained in @list.
*
* Since: 2.44
*/
GType
g_list_model_get_item_type (GListModel *list)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), G_TYPE_NONE);
return G_LIST_MODEL_GET_IFACE (list)->get_item_type (list);
}
/**
* g_list_model_get_n_items:
* @list: a #GListModel
*
* Gets the number of items in @list.
*
* Depending on the model implementation, calling this function may be
* less efficient than iterating the list with increasing values for
* @position until g_list_model_get_item() returns %NULL.
*
* Returns: the number of items in @list.
*
* Since: 2.44
*/
guint
g_list_model_get_n_items (GListModel *list)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), 0);
return G_LIST_MODEL_GET_IFACE (list)->get_n_items (list);
}
/**
* g_list_model_get_item: (skip)
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (transfer full) (nullable): the item at @position.
*
* Since: 2.44
*/
gpointer
g_list_model_get_item (GListModel *list,
guint position)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), NULL);
return G_LIST_MODEL_GET_IFACE (list)->get_item (list, position);
}
/**
* g_list_model_get_object: (rename-to g_list_model_get_item)
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (transfer full) (nullable): the object at @position.
*
* Since: 2.44
*/
GObject *
g_list_model_get_object (GListModel *list,
guint position)
{
gpointer item;
g_return_val_if_fail (G_IS_LIST_MODEL (list), NULL);
item = g_list_model_get_item (list, position);
return G_OBJECT (item);
}
/**
* g_list_model_items_changed:
* @list: a #GListModel
* @position: the position at which @list changed
* @removed: the number of items removed
* @added: the number of items added
*
* Emits the #GListModel::items-changed signal on @list.
*
* This function should only be called by classes implementing
* #GListModel. It has to be called after the internal representation
* of @list has been updated, because handlers connected to this signal
* might query the new state of the list.
*
* Implementations must only make changes to the model (as visible to
* its consumer) in places that will not cause problems for that
* consumer. For models that are driven directly by a write API (such
* as #GListStore), changes can be reported in response to uses of that
* API. For models that represent remote data, changes should only be
* made from a fresh mainloop dispatch. It is particularly not
* permitted to make changes in response to a call to the #GListModel
* consumer API.
*
* Stated another way: in general, it is assumed that code making a
* series of accesses to the model via the API, without returning to the
* mainloop, and without calling other code, will continue to view the
* same contents of the model.
*
* Since: 2.44
*/
void
g_list_model_items_changed (GListModel *list,
guint position,
guint removed,
guint added)
{
g_return_if_fail (G_IS_LIST_MODEL (list));
g_signal_emit (list, g_list_model_changed_signal, 0, position, removed, added);
}