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https://gitlab.gnome.org/GNOME/glib.git
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18a33f72db
If we have an input parameter (or return value) we need to use (nullable). However, if it is an (inout) or (out) parameter, (optional) is sufficient. It looks like (nullable) could be used for everything according to the Annotation documentation, but (optional) is more specific.
457 lines
15 KiB
C
457 lines
15 KiB
C
/* GIO - GLib Input, Output and Streaming Library
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*
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* Copyright (C) 2009 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Alexander Larsson <alexl@redhat.com>
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*/
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#include "config.h"
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#include "gasyncinitable.h"
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#include "gasyncresult.h"
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#include "gsimpleasyncresult.h"
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#include "gtask.h"
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#include "glibintl.h"
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/**
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* SECTION:gasyncinitable
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* @short_description: Asynchronously failable object initialization interface
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* @include: gio/gio.h
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* @see_also: #GInitable
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*
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* This is the asynchronous version of #GInitable; it behaves the same
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* in all ways except that initialization is asynchronous. For more details
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* see the descriptions on #GInitable.
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*
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* A class may implement both the #GInitable and #GAsyncInitable interfaces.
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*
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* Users of objects implementing this are not intended to use the interface
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* method directly; instead it will be used automatically in various ways.
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* For C applications you generally just call g_async_initable_new_async()
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* directly, or indirectly via a foo_thing_new_async() wrapper. This will call
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* g_async_initable_init_async() under the cover, calling back with %NULL and
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* a set %GError on failure.
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*
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* A typical implementation might look something like this:
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*
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* |[<!-- language="C" -->
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* enum {
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* NOT_INITIALIZED,
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* INITIALIZING,
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* INITIALIZED
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* };
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*
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* static void
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* _foo_ready_cb (Foo *self)
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* {
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* GList *l;
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*
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* self->priv->state = INITIALIZED;
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*
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* for (l = self->priv->init_results; l != NULL; l = l->next)
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* {
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* GTask *task = l->data;
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*
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* if (self->priv->success)
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* g_task_return_boolean (task, TRUE);
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* else
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* g_task_return_new_error (task, ...);
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* g_object_unref (task);
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* }
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*
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* g_list_free (self->priv->init_results);
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* self->priv->init_results = NULL;
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* }
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*
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* static void
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* foo_init_async (GAsyncInitable *initable,
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* int io_priority,
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* GCancellable *cancellable,
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* GAsyncReadyCallback callback,
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* gpointer user_data)
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* {
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* Foo *self = FOO (initable);
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* GTask *task;
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*
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* task = g_task_new (initable, cancellable, callback, user_data);
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*
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* switch (self->priv->state)
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* {
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* case NOT_INITIALIZED:
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* _foo_get_ready (self);
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* self->priv->init_results = g_list_append (self->priv->init_results,
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* task);
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* self->priv->state = INITIALIZING;
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* break;
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* case INITIALIZING:
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* self->priv->init_results = g_list_append (self->priv->init_results,
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* task);
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* break;
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* case INITIALIZED:
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* if (!self->priv->success)
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* g_task_return_new_error (task, ...);
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* else
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* g_task_return_boolean (task, TRUE);
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* g_object_unref (task);
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* break;
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* }
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* }
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*
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* static gboolean
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* foo_init_finish (GAsyncInitable *initable,
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* GAsyncResult *result,
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* GError **error)
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* {
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* g_return_val_if_fail (g_task_is_valid (result, initable), FALSE);
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*
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* return g_task_propagate_boolean (G_TASK (result), error);
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* }
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*
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* static void
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* foo_async_initable_iface_init (gpointer g_iface,
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* gpointer data)
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* {
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* GAsyncInitableIface *iface = g_iface;
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*
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* iface->init_async = foo_init_async;
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* iface->init_finish = foo_init_finish;
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* }
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* ]|
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*/
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static void g_async_initable_real_init_async (GAsyncInitable *initable,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data);
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static gboolean g_async_initable_real_init_finish (GAsyncInitable *initable,
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GAsyncResult *res,
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GError **error);
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typedef GAsyncInitableIface GAsyncInitableInterface;
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G_DEFINE_INTERFACE (GAsyncInitable, g_async_initable, G_TYPE_OBJECT)
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static void
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g_async_initable_default_init (GAsyncInitableInterface *iface)
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{
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iface->init_async = g_async_initable_real_init_async;
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iface->init_finish = g_async_initable_real_init_finish;
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}
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/**
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* g_async_initable_init_async:
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* @initable: a #GAsyncInitable.
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* @io_priority: the [I/O priority][io-priority] of the operation
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @callback: a #GAsyncReadyCallback to call when the request is satisfied
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* @user_data: the data to pass to callback function
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*
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* Starts asynchronous initialization of the object implementing the
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* interface. This must be done before any real use of the object after
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* initial construction. If the object also implements #GInitable you can
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* optionally call g_initable_init() instead.
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*
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* When the initialization is finished, @callback will be called. You can
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* then call g_async_initable_init_finish() to get the result of the
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* initialization.
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*
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* Implementations may also support cancellation. If @cancellable is not
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* %NULL, then initialization can be cancelled by triggering the cancellable
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* object from another thread. If the operation was cancelled, the error
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* %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL, and
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* the object doesn't support cancellable initialization, the error
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* %G_IO_ERROR_NOT_SUPPORTED will be returned.
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*
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* As with #GInitable, if the object is not initialized, or initialization
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* returns with an error, then all operations on the object except
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* g_object_ref() and g_object_unref() are considered to be invalid, and
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* have undefined behaviour. They will often fail with g_critical() or
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* g_warning(), but this must not be relied on.
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*
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* Implementations of this method must be idempotent: i.e. multiple calls
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* to this function with the same argument should return the same results.
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* Only the first call initializes the object; further calls return the result
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* of the first call. This is so that it's safe to implement the singleton
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* pattern in the GObject constructor function.
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*
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* For classes that also support the #GInitable interface, the default
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* implementation of this method will run the g_initable_init() function
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* in a thread, so if you want to support asynchronous initialization via
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* threads, just implement the #GAsyncInitable interface without overriding
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* any interface methods.
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*
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* Since: 2.22
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*/
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void
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g_async_initable_init_async (GAsyncInitable *initable,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data)
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{
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GAsyncInitableIface *iface;
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g_return_if_fail (G_IS_ASYNC_INITABLE (initable));
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iface = G_ASYNC_INITABLE_GET_IFACE (initable);
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(* iface->init_async) (initable, io_priority, cancellable, callback, user_data);
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}
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/**
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* g_async_initable_init_finish:
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* @initable: a #GAsyncInitable.
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* @res: a #GAsyncResult.
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* @error: a #GError location to store the error occurring, or %NULL to
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* ignore.
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*
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* Finishes asynchronous initialization and returns the result.
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* See g_async_initable_init_async().
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*
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* Returns: %TRUE if successful. If an error has occurred, this function
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* will return %FALSE and set @error appropriately if present.
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*
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* Since: 2.22
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*/
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gboolean
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g_async_initable_init_finish (GAsyncInitable *initable,
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GAsyncResult *res,
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GError **error)
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{
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GAsyncInitableIface *iface;
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g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
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g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
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if (g_async_result_legacy_propagate_error (res, error))
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return FALSE;
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iface = G_ASYNC_INITABLE_GET_IFACE (initable);
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return (* iface->init_finish) (initable, res, error);
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}
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static void
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async_init_thread (GTask *task,
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gpointer source_object,
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gpointer task_data,
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GCancellable *cancellable)
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{
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GError *error = NULL;
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if (g_initable_init (G_INITABLE (source_object), cancellable, &error))
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g_task_return_boolean (task, TRUE);
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else
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g_task_return_error (task, error);
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}
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static void
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g_async_initable_real_init_async (GAsyncInitable *initable,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data)
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{
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GTask *task;
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g_return_if_fail (G_IS_INITABLE (initable));
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task = g_task_new (initable, cancellable, callback, user_data);
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g_task_set_source_tag (task, g_async_initable_real_init_async);
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g_task_set_priority (task, io_priority);
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g_task_run_in_thread (task, async_init_thread);
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g_object_unref (task);
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}
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static gboolean
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g_async_initable_real_init_finish (GAsyncInitable *initable,
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GAsyncResult *res,
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GError **error)
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{
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/* For backward compatibility we have to process GSimpleAsyncResults
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* even though g_async_initable_real_init_async doesn't generate
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* them any more.
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*/
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G_GNUC_BEGIN_IGNORE_DEPRECATIONS
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if (G_IS_SIMPLE_ASYNC_RESULT (res))
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{
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GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
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if (g_simple_async_result_propagate_error (simple, error))
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return FALSE;
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else
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return TRUE;
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}
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G_GNUC_END_IGNORE_DEPRECATIONS
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g_return_val_if_fail (g_task_is_valid (res, initable), FALSE);
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return g_task_propagate_boolean (G_TASK (res), error);
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}
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/**
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* g_async_initable_new_async:
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* @object_type: a #GType supporting #GAsyncInitable.
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* @io_priority: the [I/O priority][io-priority] of the operation
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @callback: a #GAsyncReadyCallback to call when the initialization is
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* finished
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* @user_data: the data to pass to callback function
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* @first_property_name: (nullable): the name of the first property, or %NULL if no
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* properties
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* @...: the value of the first property, followed by other property
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* value pairs, and ended by %NULL.
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*
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* Helper function for constructing #GAsyncInitable object. This is
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* similar to g_object_new() but also initializes the object asynchronously.
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*
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* When the initialization is finished, @callback will be called. You can
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* then call g_async_initable_new_finish() to get the new object and check
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* for any errors.
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*
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* Since: 2.22
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*/
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void
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g_async_initable_new_async (GType object_type,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data,
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const gchar *first_property_name,
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...)
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{
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va_list var_args;
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va_start (var_args, first_property_name);
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g_async_initable_new_valist_async (object_type,
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first_property_name, var_args,
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io_priority, cancellable,
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callback, user_data);
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va_end (var_args);
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}
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/**
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* g_async_initable_newv_async:
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* @object_type: a #GType supporting #GAsyncInitable.
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* @n_parameters: the number of parameters in @parameters
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* @parameters: the parameters to use to construct the object
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* @io_priority: the [I/O priority][io-priority] of the operation
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @callback: a #GAsyncReadyCallback to call when the initialization is
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* finished
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* @user_data: the data to pass to callback function
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*
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* Helper function for constructing #GAsyncInitable object. This is
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* similar to g_object_newv() but also initializes the object asynchronously.
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*
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* When the initialization is finished, @callback will be called. You can
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* then call g_async_initable_new_finish() to get the new object and check
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* for any errors.
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*
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* Since: 2.22
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*/
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void
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g_async_initable_newv_async (GType object_type,
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guint n_parameters,
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GParameter *parameters,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data)
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{
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GObject *obj;
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g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
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obj = g_object_newv (object_type, n_parameters, parameters);
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g_async_initable_init_async (G_ASYNC_INITABLE (obj),
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io_priority, cancellable,
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callback, user_data);
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g_object_unref (obj); /* Passed ownership to async call */
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}
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/**
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* g_async_initable_new_valist_async:
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* @object_type: a #GType supporting #GAsyncInitable.
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* @first_property_name: the name of the first property, followed by
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* the value, and other property value pairs, and ended by %NULL.
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* @var_args: The var args list generated from @first_property_name.
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* @io_priority: the [I/O priority][io-priority] of the operation
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @callback: a #GAsyncReadyCallback to call when the initialization is
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* finished
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* @user_data: the data to pass to callback function
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*
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* Helper function for constructing #GAsyncInitable object. This is
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* similar to g_object_new_valist() but also initializes the object
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* asynchronously.
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*
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* When the initialization is finished, @callback will be called. You can
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* then call g_async_initable_new_finish() to get the new object and check
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* for any errors.
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*
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* Since: 2.22
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*/
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void
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g_async_initable_new_valist_async (GType object_type,
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const gchar *first_property_name,
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va_list var_args,
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int io_priority,
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GCancellable *cancellable,
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GAsyncReadyCallback callback,
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gpointer user_data)
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{
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GObject *obj;
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g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
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obj = g_object_new_valist (object_type,
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first_property_name,
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var_args);
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g_async_initable_init_async (G_ASYNC_INITABLE (obj),
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io_priority, cancellable,
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callback, user_data);
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g_object_unref (obj); /* Passed ownership to async call */
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}
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/**
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* g_async_initable_new_finish:
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* @initable: the #GAsyncInitable from the callback
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* @res: the #GAsyncResult from the callback
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* @error: return location for errors, or %NULL to ignore
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*
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* Finishes the async construction for the various g_async_initable_new
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* calls, returning the created object or %NULL on error.
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*
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* Returns: (type GObject.Object) (transfer full): a newly created #GObject,
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* or %NULL on error. Free with g_object_unref().
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*
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* Since: 2.22
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*/
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GObject *
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g_async_initable_new_finish (GAsyncInitable *initable,
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GAsyncResult *res,
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GError **error)
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{
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if (g_async_initable_init_finish (initable, res, error))
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return g_object_ref (initable);
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else
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return NULL;
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}
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