Package ch.bailu.gtk.gio

Class AsyncResult

java.lang.Object
ch.bailu.gtk.type.Type
ch.bailu.gtk.type.Pointer
ch.bailu.gtk.gobject.Object
ch.bailu.gtk.type.Interface
ch.bailu.gtk.gio.AsyncResult
All Implemented Interfaces:
PointerInterface
public class AsyncResult extends Interface
Provides a base class for implementing asynchronous function results.

Asynchronous operations are broken up into two separate operations
which are chained together by a #GAsyncReadyCallback. To begin
an asynchronous operation, provide a #GAsyncReadyCallback to the
asynchronous function. This callback will be triggered when the
operation has completed, and must be run in a later iteration of
the [thread-default main context][g-main-context-push-thread-default]
from where the operation was initiated. It will be passed a
#GAsyncResult instance filled with the details of the operation's
success or failure, the object the asynchronous function was
started for and any error codes returned. The asynchronous callback
function is then expected to call the corresponding "_finish()"
function, passing the object the function was called for, the
#GAsyncResult instance, and (optionally) an @error to grab any
error conditions that may have occurred.

The "_finish()" function for an operation takes the generic result
(of type #GAsyncResult) and returns the specific result that the
operation in question yields (e.g. a #GFileEnumerator for a
"enumerate children" operation). If the result or error status of the
operation is not needed, there is no need to call the "_finish()"
function; GIO will take care of cleaning up the result and error
information after the #GAsyncReadyCallback returns. You can pass
%NULL for the #GAsyncReadyCallback if you don't need to take any
action at all after the operation completes. Applications may also
take a reference to the #GAsyncResult and call "_finish()" later;
however, the "_finish()" function may be called at most once.

Example of a typical asynchronous operation flow: 
<!-- language="C" -->
 void _theoretical_frobnitz_async (Theoretical         *t,
                                   GCancellable        *c,
                                   GAsyncReadyCallback  cb,
                                   gpointer             u);
 
 gboolean _theoretical_frobnitz_finish (Theoretical   *t,
                                        GAsyncResult  *res,
                                        GError       **e);
 
 static void
 frobnitz_result_func (GObject      *source_object,
                 GAsyncResult *res,
                 gpointer      user_data)
 {
   gboolean success = FALSE;
 
   success = _theoretical_frobnitz_finish (source_object, res, NULL);
 
   if (success)
     g_printf ("Hurray!\n");
   else
     g_printf ("Uh oh!\n");
 
   ...
 
 }
 
 int main (int argc, void *argv[])
 {
    ...
 
    _theoretical_frobnitz_async (theoretical_data,
                                 NULL,
                                 frobnitz_result_func,
                                 NULL);
 
    ...
 }


The callback for an asynchronous operation is called only once, and is
always called, even in the case of a cancelled operation. On cancellation
the result is a %G_IO_ERROR_CANCELLED error.

## I/O Priority # {#io-priority}

Many I/O-related asynchronous operations have a priority parameter,
which is used in certain cases to determine the order in which
operations are executed. They are not used to determine system-wide
I/O scheduling. Priorities are integers, with lower numbers indicating
higher priority. It is recommended to choose priorities between
%G_PRIORITY_LOW and %G_PRIORITY_HIGH, with %G_PRIORITY_DEFAULT
as a default.

https://docs.gtk.org/gio/iface.AsyncResult.html

  • Constructor Details

  • Method Details

    • getClassHandler

      public static ClassHandler getClassHandler()

    • getSourceObject

      public Object getSourceObject()
      Gets the source object from a #GAsyncResult.
      Returns:
      a new reference to the source object for the @res, or %NULL if there is none.

    • getUserData

      public Pointer getUserData()
      Gets the user data from a #GAsyncResult.
      Returns:
      the user data for @res.

    • isTagged

      public boolean isTagged(@Nullable Pointer source_tag)
      Checks if @res has the given @source_tag (generally a function
      pointer indicating the function @res was created by).
      Parameters:
      source_tag - an application-defined tag
      Returns:
      %TRUE if @res has the indicated @source_tag, %FALSE if not.

    • legacyPropagateError

      public boolean legacyPropagateError() throws AllocationError
      If @res is a #GSimpleAsyncResult, this is equivalent to
      g_simple_async_result_propagate_error(). Otherwise it returns
      %FALSE.

      This can be used for legacy error handling in async *_finish()
      wrapper functions that traditionally handled #GSimpleAsyncResult
      error returns themselves rather than calling into the virtual method.
      This should not be used in new code; #GAsyncResult errors that are
      set by virtual methods should also be extracted by virtual methods,
      to enable subclasses to chain up correctly.
      Returns:
      %TRUE if @error is has been filled in with an error from @res, %FALSE if not.
      Throws:
      AllocationError

    • getTypeID

      public static long getTypeID()

    • getParentTypeID

      public static long getParentTypeID()

    • getTypeSize

      public static TypeSystem.TypeSize getTypeSize()

    • getParentTypeSize

      public static TypeSystem.TypeSize getParentTypeSize()

    • getInstanceSize

      public static int getInstanceSize()