Class (GI Class)

Gio-2.0GioSimpleAsyncResult

As of GLib 2.46, Gio.SimpleAsyncResult is deprecated in favor of Gio.Task, which provides a simpler API.

Gio.SimpleAsyncResult implements Gio.AsyncResult.

Gio.SimpleAsyncResult handles Gio.AsyncReadyCallbacks, error reporting, operation cancellation and the final state of an operation, completely transparent to the application. Results can be returned as a pointer e.g. for functions that return data that is collected asynchronously, a boolean value for checking the success or failure of an operation, or a gssize for operations which return the number of bytes modified by the operation; all of the simple return cases are covered.

Most of the time, an application will not need to know of the details of this API; it is handled transparently, and any necessary operations are handled by Gio.AsyncResult’s interface. However, if implementing a new GIO module, for writing language bindings, or for complex applications that need better control of how asynchronous operations are completed, it is important to understand this functionality.

Gio.SimpleAsyncResults are tagged with the calling function to ensure that asynchronous functions and their finishing functions are used together correctly.

To create a new Gio.SimpleAsyncResult, call Gio.SimpleAsyncResult.new. If the result needs to be created for a GLib.Error, use Gio.SimpleAsyncResult.new_from_error or Gio.SimpleAsyncResult.new_take_error. If a GLib.Error is not available (e.g. the asynchronous operation doesn’t take a GLib.Error argument), but the result still needs to be created for an error condition, use Gio.SimpleAsyncResult.new_error (or Gio.SimpleAsyncResult.set_error_va if your application or binding requires passing a variable argument list directly), and the error can then be propagated through the use of Gio.SimpleAsyncResult.propagate_error.

An asynchronous operation can be made to ignore a cancellation event by calling Gio.SimpleAsyncResult.set_handle_cancellation with a Gio.SimpleAsyncResult for the operation and FALSE. This is useful for operations that are dangerous to cancel, such as close (which would cause a leak if cancelled before being run).

Gio.SimpleAsyncResult can integrate into GLib’s event loop, GLib.MainLoop, or it can use GLib.Threads. Gio.SimpleAsyncResult.complete will finish an I/O task directly from the point where it is called. Gio.SimpleAsyncResult.complete_in_idle will finish it from an idle handler in the thread-default main context (see GLib.MainContext.push_thread_default) where the Gio.SimpleAsyncResult was created. Gio.SimpleAsyncResult.run_in_thread will run the job in a separate thread and then use Gio.SimpleAsyncResult.complete_in_idle to deliver the result.

To set the results of an asynchronous function, Gio.SimpleAsyncResult.set_op_res_gpointer, Gio.SimpleAsyncResult.set_op_res_gboolean, and Gio.SimpleAsyncResult.set_op_res_gssize are provided, setting the operation's result to a gpointer, gboolean, or gssize, respectively.

Likewise, to get the result of an asynchronous function, Gio.SimpleAsyncResult.get_op_res_gpointer, Gio.SimpleAsyncResult.get_op_res_gboolean, and Gio.SimpleAsyncResult.get_op_res_gssize are provided, getting the operation’s result as a gpointer, gboolean, and gssize, respectively.

For the details of the requirements implementations must respect, see Gio.AsyncResult. A typical implementation of an asynchronous operation using Gio.SimpleAsyncResult looks something like this:

static void
baked_cb (Cake *cake,
gpointer user_data)
{
// In this example, this callback is not given a reference to the cake,
// so the GSimpleAsyncResult has to take a reference to it.
GSimpleAsyncResult *result = user_data;

if (cake == NULL)
g_simple_async_result_set_error (result,
BAKER_ERRORS,
BAKER_ERROR_NO_FLOUR,
"Go to the supermarket");
else
g_simple_async_result_set_op_res_gpointer (result,
g_object_ref (cake),
g_object_unref);


// In this example, we assume that baked_cb is called as a callback from
// the mainloop, so it's safe to complete the operation synchronously here.
// If, however, _baker_prepare_cake () might call its callback without
// first returning to the mainloop — inadvisable, but some APIs do so —
// we would need to use `g_simple_async_result_complete_in_idle()`.
g_simple_async_result_complete (result);
g_object_unref (result);
}

void
baker_bake_cake_async (Baker *self,
guint radius,
GAsyncReadyCallback callback,
gpointer user_data)
{
GSimpleAsyncResult *simple;
Cake *cake;

if (radius < 3)
{
g_simple_async_report_error_in_idle (G_OBJECT (self),
callback,
user_data,
BAKER_ERRORS,
BAKER_ERROR_TOO_SMALL,
"%ucm radius cakes are silly",
radius);
return;
}

simple = g_simple_async_result_new (G_OBJECT (self),
callback,
user_data,
baker_bake_cake_async);
cake = _baker_get_cached_cake (self, radius);

if (cake != NULL)
{
g_simple_async_result_set_op_res_gpointer (simple,
g_object_ref (cake),
g_object_unref);
g_simple_async_result_complete_in_idle (simple);
g_object_unref (simple);
// Drop the reference returned by _baker_get_cached_cake();
// the GSimpleAsyncResult has taken its own reference.
g_object_unref (cake);
return;
}

_baker_prepare_cake (self, radius, baked_cb, simple);
}

Cake *
baker_bake_cake_finish (Baker *self,
GAsyncResult *result,
GError **error)
{
GSimpleAsyncResult *simple;
Cake *cake;

g_return_val_if_fail (g_simple_async_result_is_valid (result,
G_OBJECT (self),
baker_bake_cake_async),
NULL);

simple = (GSimpleAsyncResult *) result;

if (g_simple_async_result_propagate_error (simple, error))
return NULL;

cake = CAKE (g_simple_async_result_get_op_res_gpointer (simple));
return g_object_ref (cake);
}

Hierarchy (View Summary)

Implements

Index

Constructors

Properties

Compile-time signal type information.

This instance property is generated only for TypeScript type checking. It is not defined at runtime and should not be accessed in JS code.

Methods

  • Creates a binding between source_property on source and target_property on target.

    Whenever the source_property is changed the target_property is updated using the same value. For instance:

      g_object_bind_property (action, "active", widget, "sensitive", 0);
    

    Will result in the "sensitive" property of the widget GObject.Object instance to be updated with the same value of the "active" property of the action GObject.Object instance.

    If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well.

    The binding will automatically be removed when either the source or the target instances are finalized. To remove the binding without affecting the source and the target you can just call g_object_unref() on the returned GObject.Binding instance.

    Removing the binding by calling g_object_unref() on it must only be done if the binding, source and target are only used from a single thread and it is clear that both source and target outlive the binding. Especially it is not safe to rely on this if the binding, source or target can be finalized from different threads. Keep another reference to the binding and use g_binding_unbind() instead to be on the safe side.

    A GObject.Object can have multiple bindings.

    Parameters

    Returns GObject.Binding

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Complete version of g_object_bind_property().

    Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

    If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well. The transform_from function is only used in case of bidirectional bindings, otherwise it will be ignored

    The binding will automatically be removed when either the source or the target instances are finalized. This will release the reference that is being held on the GObject.Binding instance; if you want to hold on to the GObject.Binding instance, you will need to hold a reference to it.

    To remove the binding, call g_binding_unbind().

    A GObject.Object can have multiple bindings.

    The same user_data parameter will be used for both transform_to and transform_from transformation functions; the notify function will be called once, when the binding is removed. If you need different data for each transformation function, please use g_object_bind_property_with_closures() instead.

    Parameters

    • source_property: string

      the property on source to bind

    • target: GObject.Object

      the target GObject.Object

    • target_property: string

      the property on target to bind

    • flags: GObject.BindingFlags

      flags to pass to GObject.Binding

    • Optionaltransform_to: BindingTransformFunc

      the transformation function from the source to the target, or null to use the default

    • Optionaltransform_from: BindingTransformFunc

      the transformation function from the target to the source, or null to use the default

    • Optionalnotify: DestroyNotify

      a function to call when disposing the binding, to free resources used by the transformation functions, or null if not required

    Returns GObject.Binding

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

    This function is the language bindings friendly version of g_object_bind_property_full(), using GClosures instead of function pointers.

    Parameters

    • ...args: never[]

      the property on source to bind

    Returns any

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Completes an asynchronous I/O job immediately. Must be called in the thread where the asynchronous result was to be delivered, as it invokes the callback directly. If you are in a different thread use g_simple_async_result_complete_in_idle().

    Calling this function takes a reference to simple for as long as is needed to complete the call.

    Returns void

  • Completes an asynchronous function in an idle handler in the thread-default main context (see GLib.MainContext.push_thread_default) of the thread that simple was initially created in (and re-pushes that context around the invocation of the callback).

    Calling this function takes a reference to simple for as long as is needed to complete the call.

    Returns void

  • Disconnects a handler from an instance so it will not be called during any future or currently ongoing emissions of the signal it has been connected to.

    Parameters

    • id: number

      Handler ID of the handler to be disconnected

    Returns void

  • This function is intended for GObject.Object implementations to re-enforce a [floating][floating-ref] object reference. Doing this is seldom required: all GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().

    Returns void

  • Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one GObject.Object::notify signal is emitted for each property modified while the object is frozen.

    This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

    Returns void

  • Gets a named field from the objects table of associations (see g_object_set_data()).

    Parameters

    • key: string

      name of the key for that association

    Returns any

    the data if found, or null if no such data exists.

  • Gets the operation result boolean from within the asynchronous result.

    Returns boolean

    true if the operation's result was true, false if the operation's result was false.

  • Gets a gssize from the asynchronous result.

    Returns number

    a gssize returned from the asynchronous function.

  • Gets a property of an object.

    The value can be:

    • an empty GObject.Value initialized by G_VALUE_INIT, which will be automatically initialized with the expected type of the property (since GLib 2.60)
    • a GObject.Value initialized with the expected type of the property
    • a GObject.Value initialized with a type to which the expected type of the property can be transformed

    In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling GObject.Value.unset.

    Note that GObject.Object.get_property is really intended for language bindings, GObject.Object.get is much more convenient for C programming.

    Parameters

    • property_name: string

      The name of the property to get

    • value: any

      Return location for the property value. Can be an empty GObject.Value initialized by G_VALUE_INIT (auto-initialized with expected type since GLib 2.60), a GObject.Value initialized with the expected property type, or a GObject.Value initialized with a transformable type

    Returns any

  • Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.

    Parameters

    • names: string[]

      the names of each property to get

    • values: any[]

      the values of each property to get

    Returns void

  • Checks if res has the given source_tag (generally a function pointer indicating the function res was created by).

    Parameters

    • Optionalsource_tag: any

      an application-defined tag

    Returns boolean

    TRUE if res has the indicated source_tag, FALSE if not.

  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    Parameters

    • property_name: string

      the name of a property installed on the class of object.

    Returns void

  • Emits a "notify" signal for the property specified by pspec on object.

    This function omits the property name lookup, hence it is faster than g_object_notify().

    One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:

      typedef enum
    {
    PROP_FOO = 1,
    PROP_LAST
    } MyObjectProperty;

    static GParamSpec *properties[PROP_LAST];

    static void
    my_object_class_init (MyObjectClass *klass)
    {
    properties[PROP_FOO] = g_param_spec_int ("foo", NULL, NULL,
    0, 100,
    50,
    G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
    g_object_class_install_property (gobject_class,
    PROP_FOO,
    properties[PROP_FOO]);
    }

    and then notify a change on the "foo" property with:

      g_object_notify_by_pspec (self, properties[PROP_FOO]);
    

    Parameters

    Returns void

  • Propagates an error from within the simple asynchronous result to a given destination.

    If the Gio.Cancellable given to a prior call to g_simple_async_result_set_check_cancellable() is cancelled then this function will return true with dest set appropriately.

    Returns boolean

    true if the error was propagated to dest. false otherwise.

  • Increases the reference count of object.

    Since GLib 2.56, if GLIB_VERSION_MAX_ALLOWED is 2.56 or greater, the type of object will be propagated to the return type (using the GCC typeof() extension), so any casting the caller needs to do on the return type must be explicit.

    Returns GObject.Object

    the same object

  • Increase the reference count of object, and possibly remove the [floating][floating-ref] reference, if object has a floating reference.

    In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.

    Since GLib 2.56, the type of object will be propagated to the return type under the same conditions as for g_object_ref().

    Returns GObject.Object

    object

  • Sets multiple properties of an object at once. The properties argument should be a dictionary mapping property names to values.

    Parameters

    • properties: { [key: string]: any }

      Object containing the properties to set

    Returns void

  • Sets a Gio.Cancellable to check before dispatching results.

    This function has one very specific purpose: the provided cancellable is checked at the time of g_simple_async_result_propagate_error() If it is cancelled, these functions will return an "Operation was cancelled" error (Gio.IOErrorEnum.CANCELLED).

    Implementors of cancellable asynchronous functions should use this in order to provide a guarantee to their callers that cancelling an async operation will reliably result in an error being returned for that operation (even if a positive result for the operation has already been sent as an idle to the main context to be dispatched).

    The checking described above is done regardless of any call to the unrelated g_simple_async_result_set_handle_cancellation() function.

    Parameters

    Returns void

  • Each object carries around a table of associations from strings to pointers. This function lets you set an association.

    If the object already had an association with that name, the old association will be destroyed.

    Internally, the key is converted to a GLib.Quark using g_quark_from_string(). This means a copy of key is kept permanently (even after object has been finalized) — so it is recommended to only use a small, bounded set of values for key in your program, to avoid the GLib.Quark storage growing unbounded.

    Parameters

    • key: string

      name of the key

    • Optionaldata: any

      data to associate with that key

    Returns void

  • Sets whether to handle cancellation within the asynchronous operation.

    This function has nothing to do with g_simple_async_result_set_check_cancellable(). It only refers to the Gio.Cancellable passed to g_simple_async_result_run_in_thread().

    Parameters

    • handle_cancellation: boolean

      a gboolean.

    Returns void

  • Sets the operation result to a boolean within the asynchronous result.

    Parameters

    • op_res: boolean

      a gboolean.

    Returns void

  • Sets the operation result within the asynchronous result to the given op_res.

    Parameters

    • op_res: number

      a gssize.

    Returns void

  • Remove a specified datum from the object's data associations, without invoking the association's destroy handler.

    Parameters

    • key: string

      name of the key

    Returns any

    the data if found, or null if no such data exists.

  • This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:

    void
    object_add_to_user_list (GObject *object,
    const gchar *new_string)
    {
    // the quark, naming the object data
    GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
    // retrieve the old string list
    GList *list = g_object_steal_qdata (object, quark_string_list);

    // prepend new string
    list = g_list_prepend (list, g_strdup (new_string));
    // this changed 'list', so we need to set it again
    g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
    }
    static void
    free_string_list (gpointer data)
    {
    GList *node, *list = data;

    for (node = list; node; node = node->next)
    g_free (node->data);
    g_list_free (list);
    }

    Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().

    Parameters

    • quark: number

      A GLib.Quark, naming the user data pointer

    Returns any

    The user data pointer set, or null

  • Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.

    Duplicate notifications for each property are squashed so that at most one GObject.Object::notify signal is emitted for each property, in the reverse order in which they have been queued.

    It is an error to call this function when the freeze count is zero.

    Returns void

  • Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).

    If the pointer to the GObject.Object may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to null rather than retain a dangling pointer to a potentially invalid GObject.Object instance. Use g_clear_object() for this.

    Returns void

  • the constructed function is called by g_object_new() as the final step of the object creation process. At the point of the call, all construction properties have been set on the object. The purpose of this call is to allow for object initialisation steps that can only be performed after construction properties have been set. constructed implementors should chain up to the constructed call of their parent class to allow it to complete its initialisation.

    Returns void

  • the dispose function is supposed to drop all references to other objects, but keep the instance otherwise intact, so that client method invocations still work. It may be run multiple times (due to reference loops). Before returning, dispose should chain up to the dispose method of the parent class.

    Returns void

  • Checks if res has the given source_tag (generally a function pointer indicating the function res was created by).

    Parameters

    • Optionalsource_tag: any

      an application-defined tag

    Returns boolean

  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    Parameters

    Returns void

  • the generic setter for all properties of this type. Should be overridden for every type with properties. If implementations of set_property don't emit property change notification explicitly, this will be done implicitly by the type system. However, if the notify signal is emitted explicitly, the type system will not emit it a second time.

    Parameters

    Returns void

  • This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.

    Parameters

    Returns void

  • Ensures that the data passed to the _finish function of an async operation is consistent. Three checks are performed.

    First, result is checked to ensure that it is really a Gio.SimpleAsyncResult. Second, source is checked to ensure that it matches the source object of result. Third, source_tag is checked to ensure that it is equal to the source_tag argument given to g_simple_async_result_new() (which, by convention, is a pointer to the _async function corresponding to the _finish function from which this function is called). (Alternatively, if either source_tag or result's source tag is null, then the source tag check is skipped.)

    Parameters

    Returns boolean

Methods - Inherited from GObject

  • Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created GObject.ParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.

    This function is meant to be called from the interface's default vtable initialization function (the class_init member of GObject.TypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface.

    If pspec is a floating reference, it will be consumed.

    Parameters

    Returns void

  • Parameters

    • property_id: number

      the new property ID

    • name: string

      the name of a property registered in a parent class or in an interface of this class.

    Returns void

Interfaces

ConstructorProps
SignalSignatures