SimpleAsyncResult

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

gio.SimpleAsyncResult implements GAsyncResult

GSimpleAsyncResult handles GAsyncReadyCallbacks, 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 GAsyncResult'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.

GSimpleAsyncResults 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 SimpleAsyncResult.new. If the result needs to be created for a GError, use SimpleAsyncResult.newFromError or SimpleAsyncResult.newTakeError. If a GError is not available (e.g. the asynchronous operation's doesn't take a GError argument), but the result still needs to be created for an error condition, use SimpleAsyncResult.newError (or SimpleAsyncResult.setErrorVa if your application or binding requires passing a variable argument list directly), and the error can then be propagated through the use of SimpleAsyncResult.propagateError.

An asynchronous operation can be made to ignore a cancellation event by calling SimpleAsyncResult.setHandleCancellation 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).

GSimpleAsyncResult can integrate into GLib's event loop, glib.MainLoop, or it can use glib.Threads SimpleAsyncResult.complete will finish an I/O task directly from the point where it is called. SimpleAsyncResult.completeInIdle will finish it from an idle handler in the [thread-default main context][g-main-context-push-thread-default] where the gio.SimpleAsyncResult was created. SimpleAsyncResult.runInThread will run the job in a separate thread and then use SimpleAsyncResult.completeInIdle to deliver the result.

To set the results of an asynchronous function, SimpleAsyncResult.setOpResGpointer, SimpleAsyncResult.setOpResGboolean, and SimpleAsyncResult.setOpResGssize

are provided, setting the operation's result to a gpointer, gboolean, or gssize, respectively.

Likewise, to get the result of an asynchronous function, SimpleAsyncResult.getOpResGpointer, SimpleAsyncResult.getOpResGboolean, and SimpleAsyncResult.getOpResGssize are provided, getting the operation's result as a gpointer, gboolean, and gssize, respectively.

For the details of the requirements implementations must respect, see GAsyncResult A typical implementation of an asynchronous operation using GSimpleAsyncResult looks something like this:

1 
2 static void
3 baked_cb (Cake    *cake,
4 gpointer user_data)
5 {
6 // In this example, this callback is not given a reference to the cake,
7 // so the GSimpleAsyncResult has to take a reference to it.
8 GSimpleAsyncResult *result = user_data;
9 
10 if (cake == NULL)
11 g_simple_async_result_set_error (result,
12 BAKER_ERRORS,
13 BAKER_ERROR_NO_FLOUR,
14 "Go to the supermarket");
15 else
16 g_simple_async_result_set_op_res_gpointer (result,
17 g_object_ref (cake),
18 g_object_unref);
19 
20 
21 // In this example, we assume that baked_cb is called as a callback from
22 // the mainloop, so it's safe to complete the operation synchronously here.
23 // If, however, _baker_prepare_cake () might call its callback without
24 // first returning to the mainloop — inadvisable, but some APIs do so —
25 // we would need to use [gio.SimpleAsyncResult.SimpleAsyncResult.completeInIdle|SimpleAsyncResult.completeInIdle].
26 g_simple_async_result_complete (result);
27 g_object_unref (result);
28 }
29 
30 void
31 baker_bake_cake_async (Baker              *self,
32 guint               radius,
33 GAsyncReadyCallback callback,
34 gpointer            user_data)
35 {
36 GSimpleAsyncResult *simple;
37 Cake               *cake;
38 
39 if (radius < 3)
40 {
41 g_simple_async_report_error_in_idle (G_OBJECT (self),
42 callback,
43 user_data,
44 BAKER_ERRORS,
45 BAKER_ERROR_TOO_SMALL,
46 "`ucm` radius cakes are silly",
47 radius);
48 return;
49 }
50 
51 simple = g_simple_async_result_new (G_OBJECT (self),
52 callback,
53 user_data,
54 baker_bake_cake_async);
55 cake = _baker_get_cached_cake (self, radius);
56 
57 if (cake != NULL)
58 {
59 g_simple_async_result_set_op_res_gpointer (simple,
60 g_object_ref (cake),
61 g_object_unref);
62 g_simple_async_result_complete_in_idle (simple);
63 g_object_unref (simple);
64 // Drop the reference returned by `_baker_get_cached_cake()`;
65 // the GSimpleAsyncResult has taken its own reference.
66 g_object_unref (cake);
67 return;
68 }
69 
70 _baker_prepare_cake (self, radius, baked_cb, simple);
71 }
72 
73 Cake *
74 baker_bake_cake_finish (Baker        *self,
75 GAsyncResult *result,
76 GError      **error)
77 {
78 GSimpleAsyncResult *simple;
79 Cake               *cake;
80 
81 g_return_val_if_fail (g_simple_async_result_is_valid (result,
82 G_OBJECT (self),
83 baker_bake_cake_async),
84 NULL);
85 
86 simple = (GSimpleAsyncResult *) result;
87 
88 if (g_simple_async_result_propagate_error (simple, error))
89 return NULL;
90 
91 cake = CAKE (g_simple_async_result_get_op_res_gpointer (simple));
92 return g_object_ref (cake);
93 }

class SimpleAsyncResult : ObjectG , AsyncResultIF {

protected

GSimpleAsyncResult* gSimpleAsyncResult;

GSimpleAsyncResult* getSimpleAsyncResultStruct(bool transferOwnership);

void* getStruct();

this(GSimpleAsyncResult* gSimpleAsyncResult, bool ownedRef);

static GType getType();

this(ObjectG sourceObject, GAsyncReadyCallback callback, void* userData, void* sourceTag);

this(ObjectG sourceObject, GAsyncReadyCallback callback, void* userData, ErrorG error);

static bool isValid(AsyncResultIF result, ObjectG source, void* sourceTag);

void complete();

void completeInIdle();

bool getOpResGboolean();

void* getOpResGpointer();

ptrdiff_t getOpResGssize();

void* getSourceTag();

bool propagateError();

void runInThread(GSimpleAsyncThreadFunc func, int ioPriority, Cancellable cancellable);

void setCheckCancellable(Cancellable checkCancellable);

void setErrorVa(GQuark domain, int code, string format, void* args);

void setFromError(ErrorG error);

void setHandleCancellation(bool handleCancellation);

void setOpResGboolean(bool opRes);

void setOpResGpointer(void* opRes, GDestroyNotify destroyOpRes);

void setOpResGssize(ptrdiff_t opRes);

void takeError(ErrorG error);

static void simpleAsyncReportGerrorInIdle(ObjectG object, GAsyncReadyCallback callback, void* userData, ErrorG error);

static void simpleAsyncReportTakeGerrorInIdle(ObjectG object, GAsyncReadyCallback callback, void* userData, ErrorG error);

}

Constructors

this this(GSimpleAsyncResult* gSimpleAsyncResult, bool ownedRef): Sets our main struct and passes it to the parent class.
this this(ObjectG sourceObject, GAsyncReadyCallback callback, void* userData, void* sourceTag): Creates a gio.SimpleAsyncResult
this this(ObjectG sourceObject, GAsyncReadyCallback callback, void* userData, ErrorG error): Creates a gio.SimpleAsyncResult from an error condition.

Members

Functions

complete void complete(): 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 SimpleAsyncResult.completeInIdle.
completeInIdle void completeInIdle(): Completes an asynchronous function in an idle handler in the [thread-default main context][g-main-context-push-thread-default] of the thread that simple was initially created in (and re-pushes that context around the invocation of the callback).
getOpResGboolean bool getOpResGboolean(): Gets the operation result boolean from within the asynchronous result.
getOpResGpointer void* getOpResGpointer(): Gets a pointer result as returned by the asynchronous function.
getOpResGssize ptrdiff_t getOpResGssize(): Gets a gssize from the asynchronous result.
getSimpleAsyncResultStruct GSimpleAsyncResult* getSimpleAsyncResultStruct(bool transferOwnership): Get the main Gtk struct
getSourceTag void* getSourceTag(): Gets the source tag for the gio.SimpleAsyncResult
getStruct void* getStruct(): the main Gtk struct as a void*
propagateError bool propagateError(): Propagates an error from within the simple asynchronous result to a given destination.
runInThread void runInThread(GSimpleAsyncThreadFunc func, int ioPriority, Cancellable cancellable): Runs the asynchronous job in a separate thread and then calls SimpleAsyncResult.completeInIdle on simple to return the result to the appropriate main loop.
setCheckCancellable void setCheckCancellable(Cancellable checkCancellable): Sets a gio.Cancellable to check before dispatching results.
setErrorVa void setErrorVa(GQuark domain, int code, string format, void* args): Sets an error within the asynchronous result without a GError Unless writing a binding, see SimpleAsyncResult.setError.
setFromError void setFromError(ErrorG error): Sets the result from a GError
setHandleCancellation void setHandleCancellation(bool handleCancellation): Sets whether to handle cancellation within the asynchronous operation.
setOpResGboolean void setOpResGboolean(bool opRes): Sets the operation result to a boolean within the asynchronous result.
setOpResGpointer void setOpResGpointer(void* opRes, GDestroyNotify destroyOpRes): Sets the operation result within the asynchronous result to a pointer.
setOpResGssize void setOpResGssize(ptrdiff_t opRes): Sets the operation result within the asynchronous result to the given op_res.
takeError void takeError(ErrorG error): Sets the result from error, and takes over the caller's ownership of error, so the caller does not need to free it any more.

Static functions

getType GType getType()
isValid bool isValid(AsyncResultIF result, ObjectG source, void* sourceTag): Ensures that the data passed to the _finish function of an async operation is consistent. Three checks are performed.
simpleAsyncReportGerrorInIdle void simpleAsyncReportGerrorInIdle(ObjectG object, GAsyncReadyCallback callback, void* userData, ErrorG error): Reports an error in an idle function. Similar to g_simple_async_report_error_in_idle(), but takes a GError rather than building a new one.
simpleAsyncReportTakeGerrorInIdle void simpleAsyncReportTakeGerrorInIdle(ObjectG object, GAsyncReadyCallback callback, void* userData, ErrorG error): Reports an error in an idle function. Similar to g_simple_async_report_gerror_in_idle(), but takes over the caller's ownership of error, so the caller does not have to free it any more.

Variables

gSimpleAsyncResult GSimpleAsyncResult* gSimpleAsyncResult;: the main Gtk struct

Inherited Members

From ObjectG

gObject GObject* gObject;: the main Gtk struct
getObjectGStruct GObject* getObjectGStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
opCast T opCast()
getDObject RT getDObject(U obj, bool ownedRef): Gets a D Object from the objects table of associations.
setProperty void setProperty(string propertyName, T value)
addOnNotify gulong addOnNotify(void delegate(ParamSpec, ObjectG) dlg, string property, ConnectFlags connectFlags): The notify signal is emitted on an object when one of its properties has been changed. Note that getting this signal doesn't guarantee that the value of the property has actually changed, it may also be emitted when the setter for the property is called to reinstate the previous value.
getType GType getType()
compatControl size_t compatControl(size_t what, void* data)
interfaceFindProperty ParamSpec interfaceFindProperty(TypeInterface gIface, string propertyName): Find the gobject.ParamSpec with the given name for an interface. Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
interfaceInstallProperty void interfaceInstallProperty(TypeInterface gIface, ParamSpec pspec): 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 ObjectClass.overrideProperty 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.
interfaceListProperties ParamSpec[] interfaceListProperties(TypeInterface gIface): Lists the properties of an interface.Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
addToggleRef void addToggleRef(GToggleNotify notify, void* data): Increases the reference count of the object by one and sets a callback to be called when all other references to the object are dropped, or when this is already the last reference to the object and another reference is established.
addWeakPointer void addWeakPointer(void* weakPointerLocation): Adds a weak reference from weak_pointer to object to indicate that the pointer located at weak_pointer_location is only valid during the lifetime of object. When the object is finalized, weak_pointer will be set to NULL.
bindProperty Binding bindProperty(string sourceProperty, ObjectG target, string targetProperty, GBindingFlags flags): 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:
bindPropertyFull Binding bindPropertyFull(string sourceProperty, ObjectG target, string targetProperty, GBindingFlags flags, GBindingTransformFunc transformTo, GBindingTransformFunc transformFrom, void* userData, GDestroyNotify notify): Complete version of g_object_bind_property().
bindPropertyWithClosures Binding bindPropertyWithClosures(string sourceProperty, ObjectG target, string targetProperty, GBindingFlags flags, Closure transformTo, Closure transformFrom): 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.
dupData void* dupData(string key, GDuplicateFunc dupFunc, void* userData): This is a variant of g_object_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.
dupQdata void* dupQdata(GQuark quark, GDuplicateFunc dupFunc, void* userData): This is a variant of g_object_get_qdata() 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.
forceFloating void forceFloating(): This function is intended for GObject 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().
freezeNotify void freezeNotify(): 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 notify signal is emitted for each property modified while the object is frozen.
getData void* getData(string key): Gets a named field from the objects table of associations (see g_object_set_data()).
getProperty void getProperty(string propertyName, Value value): Gets a property of an object.
getQdata void* getQdata(GQuark quark): This function gets back user data pointers stored via g_object_set_qdata().
getValist void getValist(string firstPropertyName, void* varArgs): Gets properties of an object.
getv void getv(string[] names, Value[] values): 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.
isFloating bool isFloating(): Checks whether object has a floating[floating-ref] reference.
notify void notify(string propertyName): Emits a "notify" signal for the property property_name on object.
notifyByPspec void notifyByPspec(ParamSpec pspec): Emits a "notify" signal for the property specified by pspec on object.
ref_ ObjectG ref_(): Increases the reference count of object.
refSink ObjectG refSink(): Increase the reference count of object, and possibly remove the floating[floating-ref] reference, if object has a floating reference.
removeToggleRef void removeToggleRef(GToggleNotify notify, void* data): Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one.
removeWeakPointer void removeWeakPointer(void* weakPointerLocation): Removes a weak reference from object that was previously added using g_object_add_weak_pointer(). The weak_pointer_location has to match the one used with g_object_add_weak_pointer().
replaceData bool replaceData(string key, void* oldval, void* newval, GDestroyNotify destroy, GDestroyNotify oldDestroy): Compares the user data for the key key on object with oldval, and if they are the same, replaces oldval with newval.
replaceQdata bool replaceQdata(GQuark quark, void* oldval, void* newval, GDestroyNotify destroy, GDestroyNotify oldDestroy): Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval.
runDispose void runDispose(): Releases all references to other objects. This can be used to break reference cycles.
setData void setData(string key, void* data): Each object carries around a table of associations from strings to pointers. This function lets you set an association.
setDataFull void setDataFull(string key, void* data, GDestroyNotify destroy): Like g_object_set_data() except it adds notification for when the association is destroyed, either by setting it to a different value or when the object is destroyed.
setProperty void setProperty(string propertyName, Value value): Sets a property on an object.
setQdata void setQdata(GQuark quark, void* data): This sets an opaque, named pointer on an object. The name is specified through a GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the object with g_object_get_qdata() until the object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.
setQdataFull void setQdataFull(GQuark quark, void* data, GDestroyNotify destroy): This function works like g_object_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with data as argument when the object is finalized, or the data is being overwritten by a call to g_object_set_qdata() with the same quark.
setValist void setValist(string firstPropertyName, void* varArgs): Sets properties on an object.
setv void setv(string[] names, Value[] values): Sets n_properties properties for an object. Properties to be set will be taken from values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
stealData void* stealData(string key): Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
stealQdata void* stealQdata(GQuark quark): 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:
thawNotify void thawNotify(): 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.
unref void unref(): Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).
watchClosure void watchClosure(Closure closure): 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 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.
weakRef void weakRef(GWeakNotify notify, void* data): Adds a weak reference callback to an object. Weak references are used for notification when an object is finalized. They are called "weak references" because they allow you to safely hold a pointer to an object without calling g_object_ref() (g_object_ref() adds a strong reference, that is, forces the object to stay alive).
weakUnref void weakUnref(GWeakNotify notify, void* data): Removes a weak reference callback to an object.
clearObject void clearObject(ObjectG objectPtr): Clears a reference to a GObject

From AsyncResultIF

getAsyncResultStruct GAsyncResult* getAsyncResultStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
getType GType getType()
getSourceObject ObjectG getSourceObject(): Gets the source object from a GAsyncResult
getUserData void* getUserData(): Gets the user data from a GAsyncResult
isTagged bool isTagged(void* sourceTag): Checks if res has the given source_tag (generally a function pointer indicating the function res was created by).
legacyPropagateError bool legacyPropagateError(): If res is a gio.SimpleAsyncResult, this is equivalent to SimpleAsyncResult.propagateError. Otherwise it returns FALSE.

gio SimpleAsyncResult classes

SimpleAsyncResult