[97:7] extends: object
As of GLib 2.46, GSimpleAsyncResult is deprecated in favor of
[class@Gio.Task], which provides a simpler API. GSimpleAsyncResult
implements [iface@Gio.AsyncResult]. GSimpleAsyncResult handles
[type@Gio.AsyncReadyCallback]s, 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 [iface@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.
GSimpleAsyncResults are tagged with the calling function to ensure that
asynchronous functions and their finishing functions are used together
correctly. To create a new GSimpleAsyncResult, call
[ctor@Gio.SimpleAsyncResult.new]. If the result needs to be created for a
GError, use [ctor@Gio.SimpleAsyncResult.new_from_error] or
[ctor@Gio.SimpleAsyncResult.new_take_error]. If a GError is not available
(e.g. the asynchronous operation doesn’t take a GError argument), but the
result still needs to be created for an error condition, use
[ctor@Gio.SimpleAsyncResult.new_error] (or
[method@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
[method@Gio.SimpleAsyncResult.propagate_error]. An asynchronous operation can
be made to ignore a cancellation event by calling
[method@Gio.SimpleAsyncResult.set_handle_cancellation] with a
GSimpleAsyncResult 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, [type@GLib.MainLoop], or it can use [type@GLib.Thread]s.
[method@Gio.SimpleAsyncResult.complete] will finish an I/O task directly from
the point where it is called. [method@Gio.SimpleAsyncResult.complete_in_idle]
will finish it from an idle handler in the thread-default main context (see
[method@GLib.MainContext.push_thread_default]) where the GSimpleAsyncResult
was created. [method@Gio.SimpleAsyncResult.run_in_thread] will run the job in
a separate thread and then use
[method@Gio.SimpleAsyncResult.complete_in_idle] to deliver the result. To set
the results of an asynchronous function,
[method@Gio.SimpleAsyncResult.set_op_res_gpointer],
[method@Gio.SimpleAsyncResult.set_op_res_gboolean], and
[method@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,
[method@Gio.SimpleAsyncResult.get_op_res_gpointer],
[method@Gio.SimpleAsyncResult.get_op_res_gboolean], and
[method@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
[iface@Gio.AsyncResult]. A typical implementation of an asynchronous
operation using GSimpleAsyncResult looks something like this: c 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); }
SimpleAsyncResult (Handle = null)
Creates a new
SimpleAsyncResultby wrapping a native handle or another wrapper.
Handle is the native handle or another wrapper whose handle to adopt.toNativeHandle (Source)
Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from
fn.call(...), another generated wrapper exposinghandle(), or null. Returns null when the argument carries no pointer.
Source is the raw handle, raw buffer, wrapper, or null.A raw pointer carrier or null when no pointer is present.getLib ()
Returns the opened native library for this generated wrapper.
The opened native library.handle ()
Returns the wrapped NativeHandle.
The wrapped NativeHandle.isNull ()
Returns true when the wrapped handle is null.
A bool.describe ()
Returns a small string for debugging generated wrappers.
A string.asObject ()
Wraps this handle as
Object.
A Object object.asAsyncResult ()
Wraps this handle as
AsyncResult.
A AsyncResult object.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 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.
None.complete_in_idle ()
Completes an asynchronous function in an idle handler in the thread-default main context (see [method@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
for as long as is needed to complete the call.None.get_op_res_gboolean ()
Gets the operation result boolean from within the asynchronous result.
get_op_res_gpointer ()
Gets a pointer result as returned by the asynchronous function.
get_op_res_gssize ()
Gets a gssize from the asynchronous result.
get_source_tag ()
Gets the source tag for the #GSimpleAsyncResult.
propagate_error ()
Propagates an error from within the simple asynchronous result to a given destination. If the #GCancellable 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.
set_check_cancellable (object check_cancellable)
Sets a #GCancellable 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 (%G_IO_ERROR_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.
check_cancellable is a #GCancellable to check, or %NULL to unset.None.set_from_error (object error)
Sets the result from a #GError.
error is #GError..None.set_handle_cancellation (bool handle_cancellation)
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 #GCancellable passed to g_simple_async_result_run_in_thread().
handle_cancellation is a #gboolean..None.set_op_res_gboolean (bool op_res)
Sets the operation result to a boolean within the asynchronous result.
op_res is a #gboolean..None.set_op_res_gssize (int op_res)
Sets the operation result within the asynchronous result to the given
op_res is a #gssize..None.take_error (object error)
Sets the result from @error, and takes over the caller's ownership of
so the caller does not need to free it any more.error is a #GError.None.
