Package ch.bailu.gtk.gio

Class Task

java.lang.Object
ch.bailu.gtk.type.Type
ch.bailu.gtk.type.Pointer
ch.bailu.gtk.gobject.Object
ch.bailu.gtk.gio.Task
All Implemented Interfaces:
PointerInterface
public class Task extends Object
A #GTask represents and manages a cancellable "task".

## Asynchronous operations

The most common usage of #GTask is as a #GAsyncResult, to
manage data during an asynchronous operation. You call
g_task_new() in the "start" method, followed by
g_task_set_task_data() and the like if you need to keep some
additional data associated with the task, and then pass the
task object around through your asynchronous operation.
Eventually, you will call a method such as
g_task_return_pointer() or g_task_return_error(), which will
save the value you give it and then invoke the task's callback
function in the
[thread-default main context][g-main-context-push-thread-default]
where it was created (waiting until the next iteration of the main
loop first, if necessary). The caller will pass the #GTask back to
the operation's finish function (as a #GAsyncResult), and you can
use g_task_propagate_pointer() or the like to extract the
return value.

Using #GTask requires the thread-default #GMainContext from when the
#GTask was constructed to be running at least until the task has completed
and its data has been freed.

Here is an example for using GTask as a GAsyncResult: 
<!-- language="C" -->
     typedef struct {
       CakeFrostingType frosting;
       char *message;
     } DecorationData;
 
     static void
     decoration_data_free (DecorationData *decoration)
     {
       g_free (decoration->message);
       g_slice_free (DecorationData, decoration);
     }
 
     static void
     baked_cb (Cake     *cake,
               gpointer  user_data)
     {
       GTask *task = user_data;
       DecorationData *decoration = g_task_get_task_data (task);
       GError *error = NULL;
 
       if (cake == NULL)
         {
           g_task_return_new_error (task, BAKER_ERROR, BAKER_ERROR_NO_FLOUR,
                                    "Go to the supermarket");
           g_object_unref (task);
           return;
         }
 
       if (!cake_decorate (cake, decoration->frosting, decoration->message, &error))
         {
           g_object_unref (cake);
           // g_task_return_error() takes ownership of error
           g_task_return_error (task, error);
           g_object_unref (task);
           return;
         }
 
       g_task_return_pointer (task, cake, g_object_unref);
       g_object_unref (task);
     }
 
     void
     baker_bake_cake_async (Baker               *self,
                            guint                radius,
                            CakeFlavor           flavor,
                            CakeFrostingType     frosting,
                            const char          *message,
                            GCancellable        *cancellable,
                            GAsyncReadyCallback  callback,
                            gpointer             user_data)
     {
       GTask *task;
       DecorationData *decoration;
       Cake  *cake;
 
       task = g_task_new (self, cancellable, callback, user_data);
       if (radius < 3)
         {
           g_task_return_new_error (task, BAKER_ERROR, BAKER_ERROR_TOO_SMALL,
                                    "%ucm radius cakes are silly",
                                    radius);
           g_object_unref (task);
           return;
         }
 
       cake = _baker_get_cached_cake (self, radius, flavor, frosting, message);
       if (cake != NULL)
         {
           // _baker_get_cached_cake() returns a reffed cake
           g_task_return_pointer (task, cake, g_object_unref);
           g_object_unref (task);
           return;
         }
 
       decoration = g_slice_new (DecorationData);
       decoration->frosting = frosting;
       decoration->message = g_strdup (message);
       g_task_set_task_data (task, decoration, (GDestroyNotify) decoration_data_free);
 
       _baker_begin_cake (self, radius, flavor, cancellable, baked_cb, task);
     }
 
     Cake *
     baker_bake_cake_finish (Baker         *self,
                             GAsyncResult  *result,
                             GError       **error)
     {
       g_return_val_if_fail (g_task_is_valid (result, self), NULL);
 
       return g_task_propagate_pointer (G_TASK (result), error);
     }


## Chained asynchronous operations

#GTask also tries to simplify asynchronous operations that
internally chain together several smaller asynchronous
operations. g_task_get_cancellable(), g_task_get_context(),
and g_task_get_priority() allow you to get back the task's
#GCancellable, #GMainContext, and [I/O priority][io-priority]
when starting a new subtask, so you don't have to keep track
of them yourself. g_task_attach_source() simplifies the case
of waiting for a source to fire (automatically using the correct
#GMainContext and priority).

Here is an example for chained asynchronous operations: 
<!-- language="C" -->
     typedef struct {
       Cake *cake;
       CakeFrostingType frosting;
       char *message;
     } BakingData;
 
     static void
     decoration_data_free (BakingData *bd)
     {
       if (bd->cake)
         g_object_unref (bd->cake);
       g_free (bd->message);
       g_slice_free (BakingData, bd);
     }
 
     static void
     decorated_cb (Cake         *cake,
                   GAsyncResult *result,
                   gpointer      user_data)
     {
       GTask *task = user_data;
       GError *error = NULL;
 
       if (!cake_decorate_finish (cake, result, &error))
         {
           g_object_unref (cake);
           g_task_return_error (task, error);
           g_object_unref (task);
           return;
         }
 
       // baking_data_free() will drop its ref on the cake, so we have to
       // take another here to give to the caller.
       g_task_return_pointer (task, g_object_ref (cake), g_object_unref);
       g_object_unref (task);
     }
 
     static gboolean
     decorator_ready (gpointer user_data)
     {
       GTask *task = user_data;
       BakingData *bd = g_task_get_task_data (task);
 
       cake_decorate_async (bd->cake, bd->frosting, bd->message,
                            g_task_get_cancellable (task),
                            decorated_cb, task);
 
       return G_SOURCE_REMOVE;
     }
 
     static void
     baked_cb (Cake     *cake,
               gpointer  user_data)
     {
       GTask *task = user_data;
       BakingData *bd = g_task_get_task_data (task);
       GError *error = NULL;
 
       if (cake == NULL)
         {
           g_task_return_new_error (task, BAKER_ERROR, BAKER_ERROR_NO_FLOUR,
                                    "Go to the supermarket");
           g_object_unref (task);
           return;
         }
 
       bd->cake = cake;
 
       // Bail out now if the user has already cancelled
       if (g_task_return_error_if_cancelled (task))
         {
           g_object_unref (task);
           return;
         }
 
       if (cake_decorator_available (cake))
         decorator_ready (task);
       else
         {
           GSource *source;
 
           source = cake_decorator_wait_source_new (cake);
           // Attach @source to @task's GMainContext and have it call
           // decorator_ready() when it is ready.
           g_task_attach_source (task, source, decorator_ready);
           g_source_unref (source);
         }
     }
 
     void
     baker_bake_cake_async (Baker               *self,
                            guint                radius,
                            CakeFlavor           flavor,
                            CakeFrostingType     frosting,
                            const char          *message,
                            gint                 priority,
                            GCancellable        *cancellable,
                            GAsyncReadyCallback  callback,
                            gpointer             user_data)
     {
       GTask *task;
       BakingData *bd;
 
       task = g_task_new (self, cancellable, callback, user_data);
       g_task_set_priority (task, priority);
 
       bd = g_slice_new0 (BakingData);
       bd->frosting = frosting;
       bd->message = g_strdup (message);
       g_task_set_task_data (task, bd, (GDestroyNotify) baking_data_free);
 
       _baker_begin_cake (self, radius, flavor, cancellable, baked_cb, task);
     }
 
     Cake *
     baker_bake_cake_finish (Baker         *self,
                             GAsyncResult  *result,
                             GError       **error)
     {
       g_return_val_if_fail (g_task_is_valid (result, self), NULL);
 
       return g_task_propagate_pointer (G_TASK (result), error);
     }


## Asynchronous operations from synchronous ones

You can use g_task_run_in_thread() to turn a synchronous
operation into an asynchronous one, by running it in a thread.
When it completes, the result will be dispatched to the
[thread-default main context][g-main-context-push-thread-default]
where the #GTask was created.

Running a task in a thread: 
<!-- language="C" -->
     typedef struct {
       guint radius;
       CakeFlavor flavor;
       CakeFrostingType frosting;
       char *message;
     } CakeData;
 
     static void
     cake_data_free (CakeData *cake_data)
     {
       g_free (cake_data->message);
       g_slice_free (CakeData, cake_data);
     }
 
     static void
     bake_cake_thread (GTask         *task,
                       gpointer       source_object,
                       gpointer       task_data,
                       GCancellable  *cancellable)
     {
       Baker *self = source_object;
       CakeData *cake_data = task_data;
       Cake *cake;
       GError *error = NULL;
 
       cake = bake_cake (baker, cake_data->radius, cake_data->flavor,
                         cake_data->frosting, cake_data->message,
                         cancellable, &error);
       if (cake)
         g_task_return_pointer (task, cake, g_object_unref);
       else
         g_task_return_error (task, error);
     }
 
     void
     baker_bake_cake_async (Baker               *self,
                            guint                radius,
                            CakeFlavor           flavor,
                            CakeFrostingType     frosting,
                            const char          *message,
                            GCancellable        *cancellable,
                            GAsyncReadyCallback  callback,
                            gpointer             user_data)
     {
       CakeData *cake_data;
       GTask *task;
 
       cake_data = g_slice_new (CakeData);
       cake_data->radius = radius;
       cake_data->flavor = flavor;
       cake_data->frosting = frosting;
       cake_data->message = g_strdup (message);
       task = g_task_new (self, cancellable, callback, user_data);
       g_task_set_task_data (task, cake_data, (GDestroyNotify) cake_data_free);
       g_task_run_in_thread (task, bake_cake_thread);
       g_object_unref (task);
     }
 
     Cake *
     baker_bake_cake_finish (Baker         *self,
                             GAsyncResult  *result,
                             GError       **error)
     {
       g_return_val_if_fail (g_task_is_valid (result, self), NULL);
 
       return g_task_propagate_pointer (G_TASK (result), error);
     }


## Adding cancellability to uncancellable tasks

Finally, g_task_run_in_thread() and g_task_run_in_thread_sync()
can be used to turn an uncancellable operation into a
cancellable one. If you call g_task_set_return_on_cancel(),
passing %TRUE, then if the task's #GCancellable is cancelled,
it will return control back to the caller immediately, while
allowing the task thread to continue running in the background
(and simply discarding its result when it finally does finish).
Provided that the task thread is careful about how it uses
locks and other externally-visible resources, this allows you
to make "GLib-friendly" asynchronous and cancellable
synchronous variants of blocking APIs.

Cancelling a task: 
<!-- language="C" -->
     static void
     bake_cake_thread (GTask         *task,
                       gpointer       source_object,
                       gpointer       task_data,
                       GCancellable  *cancellable)
     {
       Baker *self = source_object;
       CakeData *cake_data = task_data;
       Cake *cake;
       GError *error = NULL;
 
       cake = bake_cake (baker, cake_data->radius, cake_data->flavor,
                         cake_data->frosting, cake_data->message,
                         &error);
       if (error)
         {
           g_task_return_error (task, error);
           return;
         }
 
       // If the task has already been cancelled, then we don't want to add
       // the cake to the cake cache. Likewise, we don't  want to have the
       // task get cancelled in the middle of updating the cache.
       // g_task_set_return_on_cancel() will return %TRUE here if it managed
       // to disable return-on-cancel, or %FALSE if the task was cancelled
       // before it could.
       if (g_task_set_return_on_cancel (task, FALSE))
         {
           // If the caller cancels at this point, their
           // GAsyncReadyCallback won't be invoked until we return,
           // so we don't have to worry that this code will run at
           // the same time as that code does. But if there were
           // other functions that might look at the cake cache,
           // then we'd probably need a GMutex here as well.
           baker_add_cake_to_cache (baker, cake);
           g_task_return_pointer (task, cake, g_object_unref);
         }
     }
 
     void
     baker_bake_cake_async (Baker               *self,
                            guint                radius,
                            CakeFlavor           flavor,
                            CakeFrostingType     frosting,
                            const char          *message,
                            GCancellable        *cancellable,
                            GAsyncReadyCallback  callback,
                            gpointer             user_data)
     {
       CakeData *cake_data;
       GTask *task;
 
       cake_data = g_slice_new (CakeData);
 
       ...
 
       task = g_task_new (self, cancellable, callback, user_data);
       g_task_set_task_data (task, cake_data, (GDestroyNotify) cake_data_free);
       g_task_set_return_on_cancel (task, TRUE);
       g_task_run_in_thread (task, bake_cake_thread);
     }
 
     Cake *
     baker_bake_cake_sync (Baker               *self,
                           guint                radius,
                           CakeFlavor           flavor,
                           CakeFrostingType     frosting,
                           const char          *message,
                           GCancellable        *cancellable,
                           GError             **error)
     {
       CakeData *cake_data;
       GTask *task;
       Cake *cake;
 
       cake_data = g_slice_new (CakeData);
 
       ...
 
       task = g_task_new (self, cancellable, NULL, NULL);
       g_task_set_task_data (task, cake_data, (GDestroyNotify) cake_data_free);
       g_task_set_return_on_cancel (task, TRUE);
       g_task_run_in_thread_sync (task, bake_cake_thread);
 
       cake = g_task_propagate_pointer (task, error);
       g_object_unref (task);
       return cake;
     }


## Porting from GSimpleAsyncResult

#GTask's API attempts to be simpler than #GSimpleAsyncResult's
in several ways:
- You can save task-specific data with g_task_set_task_data(), and
retrieve it later with g_task_get_task_data(). This replaces the
abuse of g_simple_async_result_set_op_res_gpointer() for the same
purpose with #GSimpleAsyncResult.
- In addition to the task data, #GTask also keeps track of the
[priority][io-priority], #GCancellable, and
#GMainContext associated with the task, so tasks that consist of
a chain of simpler asynchronous operations will have easy access
to those values when starting each sub-task.
- g_task_return_error_if_cancelled() provides simplified
handling for cancellation. In addition, cancellation
overrides any other #GTask return value by default, like
#GSimpleAsyncResult does when
g_simple_async_result_set_check_cancellable() is called.
(You can use g_task_set_check_cancellable() to turn off that
behavior.) On the other hand, g_task_run_in_thread()
guarantees that it will always run your
`task_func`, even if the task's #GCancellable
is already cancelled before the task gets a chance to run;
you can start your `task_func` with a
g_task_return_error_if_cancelled() check if you need the
old behavior.
- The "return" methods (eg, g_task_return_pointer())
automatically cause the task to be "completed" as well, and
there is no need to worry about the "complete" vs "complete
in idle" distinction. (#GTask automatically figures out
whether the task's callback can be invoked directly, or
if it needs to be sent to another #GMainContext, or delayed
until the next iteration of the current #GMainContext.)
- The "finish" functions for #GTask based operations are generally
much simpler than #GSimpleAsyncResult ones, normally consisting
of only a single call to g_task_propagate_pointer() or the like.
Since g_task_propagate_pointer() "steals" the return value from
the #GTask, it is not necessary to juggle pointers around to
prevent it from being freed twice.
- With #GSimpleAsyncResult, it was common to call
g_simple_async_result_propagate_error() from the
`_finish()` wrapper function, and have
virtual method implementations only deal with successful
returns. This behavior is deprecated, because it makes it
difficult for a subclass to chain to a parent class's async
methods. Instead, the wrapper function should just be a
simple wrapper, and the virtual method should call an
appropriate `g_task_propagate_` function.
Note that wrapper methods can now use
g_async_result_legacy_propagate_error() to do old-style
#GSimpleAsyncResult error-returning behavior, and
g_async_result_is_tagged() to check if a result is tagged as
having come from the `_async()` wrapper
function (for "short-circuit" results, such as when passing
0 to g_input_stream_read_async()).

https://docs.gtk.org/gio/class.Task.html

  • Constructor Details

    • Task

      public Task(PointerContainer pointer)

    • Task

      public Task(@Nullable Pointer source_object, @Nullable Cancellable cancellable, Task.OnAsyncReadyCallback callback, @Nullable Pointer callback_data)
      Creates a #GTask acting on @source_object, which will eventually be
      used to invoke @callback in the current
      [thread-default main context][g-main-context-push-thread-default].

      Call this in the "start" method of your asynchronous method, and
      pass the #GTask around throughout the asynchronous operation. You
      can use g_task_set_task_data() to attach task-specific data to the
      object, which you can retrieve later via g_task_get_task_data().

      By default, if @cancellable is cancelled, then the return value of
      the task will always be %G_IO_ERROR_CANCELLED, even if the task had
      already completed before the cancellation. This allows for
      simplified handling in cases where cancellation may imply that
      other objects that the task depends on have been destroyed. If you
      do not want this behavior, you can use
      g_task_set_check_cancellable() to change it.
      Parameters:
      source_object - the #GObject that owns this task, or %NULL.
      cancellable - optional #GCancellable object, %NULL to ignore.
      callback - a #GAsyncReadyCallback.
      callback_data - user data passed to @callback.

  • Method Details

    • getClassHandler

      public static ClassHandler getClassHandler()

    • attachSource

      public void attachSource(@Nonnull Source source, Task.OnSourceFunc callback)
      A utility function for dealing with async operations where you need
      to wait for a #GSource to trigger. Attaches @source to @task's
      #GMainContext with @task's [priority][io-priority], and sets @source's
      callback to @callback, with @task as the callback's `user_data`.

      It will set the @source’s name to the task’s name (as set with
      g_task_set_name()), if one has been set.

      This takes a reference on @task until @source is destroyed.
      Parameters:
      source - the source to attach
      callback - the callback to invoke when @source triggers

    • getCancellable

      public Cancellable getCancellable()
      Gets @task's #GCancellable
      Returns:
      @task's #GCancellable

    • getCheckCancellable

      public boolean getCheckCancellable()
      Gets @task's check-cancellable flag. See
      g_task_set_check_cancellable() for more details.
      Returns:

    • getCompleted

      public boolean getCompleted()
      Gets the value of #GTask:completed. This changes from %FALSE to %TRUE after
      the task’s callback is invoked, and will return %FALSE if called from inside
      the callback.
      Returns:
      %TRUE if the task has completed, %FALSE otherwise.

    • getContext

      public MainContext getContext()
      Gets the #GMainContext that @task will return its result in (that
      is, the context that was the
      [thread-default main context][g-main-context-push-thread-default]
      at the point when @task was created).

      This will always return a non-%NULL value, even if the task's
      context is the default #GMainContext.
      Returns:
      @task's #GMainContext

    • getName

      public Str getName()
      Gets @task’s name. See g_task_set_name().
      Returns:
      @task’s name, or %NULL

    • getPriority

      public int getPriority()
      Gets @task's priority
      Returns:
      @task's priority

    • getReturnOnCancel

      public boolean getReturnOnCancel()
      Gets @task's return-on-cancel flag. See
      g_task_set_return_on_cancel() for more details.
      Returns:

    • getSourceObject

      public Pointer getSourceObject()
      Gets the source object from @task. Like
      g_async_result_get_source_object(), but does not ref the object.
      Returns:
      @task's source object, or %NULL

    • getSourceTag

      public Pointer getSourceTag()
      Gets @task's source tag. See g_task_set_source_tag().
      Returns:
      @task's source tag

    • getTaskData

      public Pointer getTaskData()
      Gets @task's `task_data`.
      Returns:
      @task's `task_data`.

    • hadError

      public boolean hadError()
      Tests if @task resulted in an error.
      Returns:
      %TRUE if the task resulted in an error, %FALSE otherwise.

    • propagateBoolean

      public boolean propagateBoolean() throws AllocationError
      Gets the result of @task as a #gboolean.

      If the task resulted in an error, or was cancelled, then this will
      instead return %FALSE and set @error.

      Since this method transfers ownership of the return value (or
      error) to the caller, you may only call it once.
      Returns:
      the task result, or %FALSE on error
      Throws:
      AllocationError

    • propagateInt

      public long propagateInt() throws AllocationError
      Gets the result of @task as an integer (#gssize).

      If the task resulted in an error, or was cancelled, then this will
      instead return -1 and set @error.

      Since this method transfers ownership of the return value (or
      error) to the caller, you may only call it once.
      Returns:
      the task result, or -1 on error
      Throws:
      AllocationError

    • propagatePointer

      public Pointer propagatePointer() throws AllocationError
      Gets the result of @task as a pointer, and transfers ownership
      of that value to the caller.

      If the task resulted in an error, or was cancelled, then this will
      instead return %NULL and set @error.

      Since this method transfers ownership of the return value (or
      error) to the caller, you may only call it once.
      Returns:
      the task result, or %NULL on error
      Throws:
      AllocationError

    • propagateValue

      public boolean propagateValue(@Nonnull Value value) throws AllocationError
      Gets the result of @task as a #GValue, and transfers ownership of
      that value to the caller. As with g_task_return_value(), this is
      a generic low-level method; g_task_propagate_pointer() and the like
      will usually be more useful for C code.

      If the task resulted in an error, or was cancelled, then this will
      instead set @error and return %FALSE.

      Since this method transfers ownership of the return value (or
      error) to the caller, you may only call it once.
      Parameters:
      value - return location for the #GValue
      Returns:
      %TRUE if @task succeeded, %FALSE on error.
      Throws:
      AllocationError

    • returnBoolean

      public void returnBoolean(boolean result)
      Sets @task's result to @result and completes the task (see
      g_task_return_pointer() for more discussion of exactly what this
      means).
      Parameters:
      result - the #gboolean result of a task function.

    • returnError

      public void returnError(@Nonnull Error error)
      Sets @task's result to @error (which @task assumes ownership of)
      and completes the task (see g_task_return_pointer() for more
      discussion of exactly what this means).

      Note that since the task takes ownership of @error, and since the
      task may be completed before returning from g_task_return_error(),
      you cannot assume that @error is still valid after calling this.
      Call g_error_copy() on the error if you need to keep a local copy
      as well.

      See also g_task_return_new_error().
      Parameters:
      error - the #GError result of a task function.

    • returnErrorIfCancelled

      public boolean returnErrorIfCancelled()
      Checks if @task's #GCancellable has been cancelled, and if so, sets
      @task's error accordingly and completes the task (see
      g_task_return_pointer() for more discussion of exactly what this
      means).
      Returns:
      %TRUE if @task has been cancelled, %FALSE if not

    • returnInt

      public void returnInt(long result)
      Sets @task's result to @result and completes the task (see
      g_task_return_pointer() for more discussion of exactly what this
      means).
      Parameters:
      result - the integer (#gssize) result of a task function.

    • returnNewError

      public void returnNewError(int domain, int code, @Nonnull Str format, Object... _elipse)
      Sets @task's result to a new #GError created from @domain, @code,
      @format, and the remaining arguments, and completes the task (see
      g_task_return_pointer() for more discussion of exactly what this
      means).

      See also g_task_return_error().
      Parameters:
      domain - a #GQuark.
      code - an error code.
      format - a string with format characters.
      _elipse - a list of values to insert into @format.

    • returnNewError

      public void returnNewError(int domain, int code, String format, Object... _elipse)
      Sets @task's result to a new #GError created from @domain, @code,
      @format, and the remaining arguments, and completes the task (see
      g_task_return_pointer() for more discussion of exactly what this
      means).

      See also g_task_return_error().
      Parameters:
      domain - a #GQuark.
      code - an error code.
      format - a string with format characters.
      _elipse - a list of values to insert into @format.

    • returnPointer

      public void returnPointer(@Nullable Pointer result, Task.OnDestroyNotify result_destroy)
      Sets @task's result to @result and completes the task. If @result
      is not %NULL, then @result_destroy will be used to free @result if
      the caller does not take ownership of it with
      g_task_propagate_pointer().

      "Completes the task" means that for an ordinary asynchronous task
      it will either invoke the task's callback, or else queue that
      callback to be invoked in the proper #GMainContext, or in the next
      iteration of the current #GMainContext. For a task run via
      g_task_run_in_thread() or g_task_run_in_thread_sync(), calling this
      method will save @result to be returned to the caller later, but
      the task will not actually be completed until the #GTaskThreadFunc
      exits.

      Note that since the task may be completed before returning from
      g_task_return_pointer(), you cannot assume that @result is still
      valid after calling this, unless you are still holding another
      reference on it.
      Parameters:
      result - the pointer result of a task function
      result_destroy - a #GDestroyNotify function.

    • returnValue

      public void returnValue(@Nullable Value result)
      Sets @task's result to @result (by copying it) and completes the task.

      If @result is %NULL then a #GValue of type %G_TYPE_POINTER
      with a value of %NULL will be used for the result.

      This is a very generic low-level method intended primarily for use
      by language bindings; for C code, g_task_return_pointer() and the
      like will normally be much easier to use.
      Parameters:
      result - the #GValue result of a task function

    • runInThread

      public void runInThread(Task.OnTaskThreadFunc task_func)
      Runs @task_func in another thread. When @task_func returns, @task's
      #GAsyncReadyCallback will be invoked in @task's #GMainContext.

      This takes a ref on @task until the task completes.

      See #GTaskThreadFunc for more details about how @task_func is handled.

      Although GLib currently rate-limits the tasks queued via
      g_task_run_in_thread(), you should not assume that it will always
      do this. If you have a very large number of tasks to run (several tens of
      tasks), but don't want them to all run at once, you should only queue a
      limited number of them (around ten) at a time.
      Parameters:
      task_func - a #GTaskThreadFunc

    • runInThreadSync

      public void runInThreadSync(Task.OnTaskThreadFunc task_func)
      Runs @task_func in another thread, and waits for it to return or be
      cancelled. You can use g_task_propagate_pointer(), etc, afterward
      to get the result of @task_func.

      See #GTaskThreadFunc for more details about how @task_func is handled.

      Normally this is used with tasks created with a %NULL
      `callback`, but note that even if the task does
      have a callback, it will not be invoked when @task_func returns.
      #GTask:completed will be set to %TRUE just before this function returns.

      Although GLib currently rate-limits the tasks queued via
      g_task_run_in_thread_sync(), you should not assume that it will
      always do this. If you have a very large number of tasks to run,
      but don't want them to all run at once, you should only queue a
      limited number of them at a time.
      Parameters:
      task_func - a #GTaskThreadFunc

    • setCheckCancellable

      public void setCheckCancellable(boolean check_cancellable)
      Sets or clears @task's check-cancellable flag. If this is %TRUE
      (the default), then g_task_propagate_pointer(), etc, and
      g_task_had_error() will check the task's #GCancellable first, and
      if it has been cancelled, then they will consider the task to have
      returned an "Operation was cancelled" error
      (%G_IO_ERROR_CANCELLED), regardless of any other error or return
      value the task may have had.

      If @check_cancellable is %FALSE, then the #GTask will not check the
      cancellable itself, and it is up to @task's owner to do this (eg,
      via g_task_return_error_if_cancelled()).

      If you are using g_task_set_return_on_cancel() as well, then
      you must leave check-cancellable set %TRUE.
      Parameters:
      check_cancellable - whether #GTask will check the state of its #GCancellable for you.

    • setName

      public void setName(@Nullable Str name)
      Sets @task’s name, used in debugging and profiling. The name defaults to
      %NULL.

      The task name should describe in a human readable way what the task does.
      For example, ‘Open file’ or ‘Connect to network host’. It is used to set the
      name of the #GSource used for idle completion of the task.

      This function may only be called before the @task is first used in a thread
      other than the one it was constructed in. It is called automatically by
      g_task_set_source_tag() if not called already.
      Parameters:
      name - a human readable name for the task, or %NULL to unset it

    • setName

      public void setName(String name)
      Sets @task’s name, used in debugging and profiling. The name defaults to
      %NULL.

      The task name should describe in a human readable way what the task does.
      For example, ‘Open file’ or ‘Connect to network host’. It is used to set the
      name of the #GSource used for idle completion of the task.

      This function may only be called before the @task is first used in a thread
      other than the one it was constructed in. It is called automatically by
      g_task_set_source_tag() if not called already.
      Parameters:
      name - a human readable name for the task, or %NULL to unset it

    • setPriority

      public void setPriority(int priority)
      Sets @task's priority. If you do not call this, it will default to
      %G_PRIORITY_DEFAULT.

      This will affect the priority of #GSources created with
      g_task_attach_source() and the scheduling of tasks run in threads,
      and can also be explicitly retrieved later via
      g_task_get_priority().
      Parameters:
      priority - the [priority][io-priority] of the request

    • setReturnOnCancel

      public boolean setReturnOnCancel(boolean return_on_cancel)
      Sets or clears @task's return-on-cancel flag. This is only
      meaningful for tasks run via g_task_run_in_thread() or
      g_task_run_in_thread_sync().

      If @return_on_cancel is %TRUE, then cancelling @task's
      #GCancellable will immediately cause it to return, as though the
      task's #GTaskThreadFunc had called
      g_task_return_error_if_cancelled() and then returned.

      This allows you to create a cancellable wrapper around an
      uninterruptible function. The #GTaskThreadFunc just needs to be
      careful that it does not modify any externally-visible state after
      it has been cancelled. To do that, the thread should call
      g_task_set_return_on_cancel() again to (atomically) set
      return-on-cancel %FALSE before making externally-visible changes;
      if the task gets cancelled before the return-on-cancel flag could
      be changed, g_task_set_return_on_cancel() will indicate this by
      returning %FALSE.

      You can disable and re-enable this flag multiple times if you wish.
      If the task's #GCancellable is cancelled while return-on-cancel is
      %FALSE, then calling g_task_set_return_on_cancel() to set it %TRUE
      again will cause the task to be cancelled at that point.

      If the task's #GCancellable is already cancelled before you call
      g_task_run_in_thread()/g_task_run_in_thread_sync(), then the
      #GTaskThreadFunc will still be run (for consistency), but the task
      will also be completed right away.
      Parameters:
      return_on_cancel - whether the task returns automatically when it is cancelled.
      Returns:
      %TRUE if @task's return-on-cancel flag was changed to match @return_on_cancel. %FALSE if @task has already been cancelled.

    • setSourceTag

      public void setSourceTag(@Nullable Pointer source_tag)
      Sets @task's source tag.

      You can use this to tag a task return
      value with a particular pointer (usually a pointer to the function
      doing the tagging) and then later check it using
      g_task_get_source_tag() (or g_async_result_is_tagged()) in the
      task's "finish" function, to figure out if the response came from a
      particular place.

      A macro wrapper around this function will automatically set the
      task’s name to the string form of @source_tag if it’s not already
      set, for convenience.
      Parameters:
      source_tag - an opaque pointer indicating the source of this task

    • setTaskData

      public void setTaskData(@Nullable Pointer task_data, Task.OnDestroyNotify task_data_destroy)
      Sets @task's task data (freeing the existing task data, if any).
      Parameters:
      task_data - task-specific data
      task_data_destroy - #GDestroyNotify for @task_data

    • isValid

      public static boolean isValid(@Nonnull Pointer result, @Nullable Pointer source_object)
      Checks that @result is a #GTask, and that @source_object is its
      source object (or that @source_object is %NULL and @result has no
      source object). This can be used in g_return_if_fail() checks.
      Parameters:
      result - A #GAsyncResult
      source_object - the source object expected to be associated with the task
      Returns:
      %TRUE if @result and @source_object are valid, %FALSE if not

    • reportError

      public static void reportError(@Nullable Pointer source_object, Task.OnAsyncReadyCallback callback, @Nullable Pointer callback_data, @Nullable Pointer source_tag, @Nonnull Error error)
      Creates a #GTask and then immediately calls g_task_return_error()
      on it. Use this in the wrapper function of an asynchronous method
      when you want to avoid even calling the virtual method. You can
      then use g_async_result_is_tagged() in the finish method wrapper to
      check if the result there is tagged as having been created by the
      wrapper method, and deal with it appropriately if so.

      See also g_task_report_new_error().
      Parameters:
      source_object - the #GObject that owns this task, or %NULL.
      callback - a #GAsyncReadyCallback.
      callback_data - user data passed to @callback.
      source_tag - an opaque pointer indicating the source of this task
      error - error to report

    • reportNewError

      public static void reportNewError(@Nullable Pointer source_object, Task.OnAsyncReadyCallback callback, @Nullable Pointer callback_data, @Nullable Pointer source_tag, int domain, int code, @Nonnull Str format, Object... _elipse)
      Creates a #GTask and then immediately calls
      g_task_return_new_error() on it. Use this in the wrapper function
      of an asynchronous method when you want to avoid even calling the
      virtual method. You can then use g_async_result_is_tagged() in the
      finish method wrapper to check if the result there is tagged as
      having been created by the wrapper method, and deal with it
      appropriately if so.

      See also g_task_report_error().
      Parameters:
      source_object - the #GObject that owns this task, or %NULL.
      callback - a #GAsyncReadyCallback.
      callback_data - user data passed to @callback.
      source_tag - an opaque pointer indicating the source of this task
      domain - a #GQuark.
      code - an error code.
      format - a string with format characters.
      _elipse - a list of values to insert into @format.

    • asAsyncResult

      public AsyncResult asAsyncResult()
      Implements interface AsyncResult. Call this to get access to interface functions.
      Returns:
      AsyncResult

    • 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()