gimp/app/core/gimpasync.c

410 lines
11 KiB
C

/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* gimpasync.c
* Copyright (C) 2018 Ell
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <gdk-pixbuf/gdk-pixbuf.h>
#include <gegl.h>
#include "core-types.h"
#include "gimpasync.h"
/* GimpAsync represents an asynchronous task. Both the public and the
* protected interfaces are intentionally minimal at this point, to keep things
* simple. They may be extended in the future as needed.
*
* Upon creation, a GimpAsync object is in the "running" state. Once the task
* is complete (and before the object's destruction), it should be transitioned
* to the "stopped" state, using either 'gimp_async_finish()' or
* 'gimp_async_abort()'.
*
* Note that certain GimpAsync functions may be only be called during a certain
* state, or on a certain thread, as detailed for each function. When
* referring to threads, the "main thread" is the thread running the main loop,
* and the "async thread" is the thread calling 'gimp_async_finish()' or
* 'gimp_async_abort()' (which may be the main thread). The main thread is
* said to be "synced" with the async thread if both are the same thread, or
* after the execution of any of the callbacks added through
* 'gimp_async_add_callback()' had started, or after calling
* 'gimp_async_wait()' on the main thread.
*/
/* #define TIME_ASYNC_OPS */
typedef struct _GimpAsyncCallbackInfo GimpAsyncCallbackInfo;
struct _GimpAsyncCallbackInfo
{
GimpAsyncCallback callback;
gpointer data;
};
struct _GimpAsyncPrivate
{
GMutex mutex;
GCond cond;
GQueue callbacks;
gpointer result;
GDestroyNotify result_destroy_func;
guint idle_id;
gboolean stopped;
gboolean finished;
gboolean canceled;
#ifdef TIME_ASYNC_OPS
guint64 start_time;
#endif
};
/* local function prototypes */
static void gimp_async_finalize (GObject *object);
static gboolean gimp_async_idle (GimpAsync *async);
static void gimp_async_stop (GimpAsync *async);
G_DEFINE_TYPE (GimpAsync, gimp_async, G_TYPE_OBJECT)
#define parent_class gimp_async_parent_class
/* private functions */
static void
gimp_async_class_init (GimpAsyncClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->finalize = gimp_async_finalize;
g_type_class_add_private (klass, sizeof (GimpAsyncPrivate));
}
static void
gimp_async_init (GimpAsync *async)
{
async->priv = G_TYPE_INSTANCE_GET_PRIVATE (async,
GIMP_TYPE_ASYNC,
GimpAsyncPrivate);
g_mutex_init (&async->priv->mutex);
g_cond_init (&async->priv->cond);
g_queue_init (&async->priv->callbacks);
#ifdef TIME_ASYNC_OPS
async->priv->start_time = g_get_monotonic_time ();
#endif
}
static void
gimp_async_finalize (GObject *object)
{
GimpAsync *async = GIMP_ASYNC (object);
g_warn_if_fail (async->priv->stopped);
g_warn_if_fail (async->priv->idle_id == 0);
g_warn_if_fail (g_queue_is_empty (&async->priv->callbacks));
if (async->priv->finished &&
async->priv->result &&
async->priv->result_destroy_func)
{
async->priv->result_destroy_func (async->priv->result);
async->priv->result = NULL;
}
g_cond_clear (&async->priv->cond);
g_mutex_clear (&async->priv->mutex);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static gboolean
gimp_async_idle (GimpAsync *async)
{
gimp_async_wait (async);
return G_SOURCE_REMOVE;
}
static void
gimp_async_stop (GimpAsync *async)
{
#ifdef TIME_ASYNC_OPS
{
guint64 time = g_get_monotonic_time ();
g_printerr ("Asynchronous operation took %g seconds%s\n",
(time - async->priv->start_time) / 1000000.0,
async->priv->finished ? "" : " (aborted)");
}
#endif
if (! g_queue_is_empty (&async->priv->callbacks))
{
g_object_ref (async);
async->priv->idle_id = g_idle_add_full (G_PRIORITY_DEFAULT,
(GSourceFunc) gimp_async_idle,
async, NULL);
}
async->priv->stopped = TRUE;
g_cond_broadcast (&async->priv->cond);
}
/* public functions */
/* creates a new GimpAsync object, initially placed in the "running" state. */
GimpAsync *
gimp_async_new (void)
{
return g_object_new (GIMP_TYPE_ASYNC,
NULL);
}
/* checks if 'async' is in the "stopped" state */
gboolean
gimp_async_is_stopped (GimpAsync *async)
{
g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
return async->priv->stopped;
}
/* waits for 'async' to transition to the "stopped" state. if 'async' is
* already stopped, returns immediately.
*
* after the call, all callbacks previously added through
* 'gimp_async_add_callback()' are guaranteed to have been called.
*
* may only be called on the main thread.
*/
void
gimp_async_wait (GimpAsync *async)
{
g_return_if_fail (GIMP_IS_ASYNC (async));
g_mutex_lock (&async->priv->mutex);
while (! async->priv->stopped)
g_cond_wait (&async->priv->cond, &async->priv->mutex);
g_mutex_unlock (&async->priv->mutex);
if (async->priv->idle_id)
{
GimpAsyncCallbackInfo *callback_info;
g_source_remove (async->priv->idle_id);
async->priv->idle_id = 0;
while ((callback_info = g_queue_pop_head (&async->priv->callbacks)))
{
callback_info->callback (async, callback_info->data);
g_slice_free (GimpAsyncCallbackInfo, callback_info);
}
g_object_unref (async);
}
}
/* registers a callback to be called when 'async' transitions to the "stopped"
* state. if 'async' is already stopped, the callback may be called directly.
*
* callbacks are called in the order in which they were added. 'async' is
* guaranteed to be kept alive, even without an external reference, between the
* point where it was stopped, and until all callbacks added while 'async' was
* externally referenced have been called.
*
* the callback is guaranteed to be called on the main thread.
*
* may only be called on the main thread.
*/
void
gimp_async_add_callback (GimpAsync *async,
GimpAsyncCallback callback,
gpointer data)
{
GimpAsyncCallbackInfo *callback_info;
g_return_if_fail (GIMP_IS_ASYNC (async));
g_return_if_fail (callback != NULL);
g_mutex_lock (&async->priv->mutex);
if (async->priv->stopped && g_queue_is_empty (&async->priv->callbacks))
{
g_mutex_unlock (&async->priv->mutex);
callback (async, data);
return;
}
callback_info = g_slice_new (GimpAsyncCallbackInfo);
callback_info->callback = callback;
callback_info->data = data;
g_queue_push_tail (&async->priv->callbacks, callback_info);
g_mutex_unlock (&async->priv->mutex);
}
/* transitions 'async' to the "stopped" state, indicating that the task
* completed normally, possibly providing a result.
*
* 'async' shall be in the "running" state.
*
* may only be called on the async thread.
*/
void
gimp_async_finish (GimpAsync *async,
gpointer result)
{
gimp_async_finish_full (async, result, NULL);
}
/* same as 'gimp_async_finish()', taking an additional GDestroyNotify function,
* used for freeing the result when 'async' is destroyed.
*/
void
gimp_async_finish_full (GimpAsync *async,
gpointer result,
GDestroyNotify result_destroy_func)
{
g_return_if_fail (GIMP_IS_ASYNC (async));
g_return_if_fail (! async->priv->stopped);
g_mutex_lock (&async->priv->mutex);
async->priv->finished = TRUE;
async->priv->result = result;
async->priv->result_destroy_func = result_destroy_func;
gimp_async_stop (async);
g_mutex_unlock (&async->priv->mutex);
}
/* checks if 'async' completed normally, using 'gimp_async_finish()' (in
* contrast to 'gimp_async_abort()').
*
* 'async' shall be in the "stopped" state.
*
* may only be called on the async thread, or on the main thread when synced
* with the async thread.
*/
gboolean
gimp_async_is_finished (GimpAsync *async)
{
g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
g_return_val_if_fail (async->priv->stopped, FALSE);
return async->priv->finished;
}
/* returns the result of 'async', as passed to 'gimp_async_finish()'.
*
* 'async' shall be in the "stopped" state, and should have completed normally.
*
* may only be called on the async thread, or on the main thread when synced
* with the async thread.
*/
gpointer
gimp_async_get_result (GimpAsync *async)
{
g_return_val_if_fail (GIMP_IS_ASYNC (async), NULL);
g_return_val_if_fail (async->priv->stopped, NULL);
g_return_val_if_fail (async->priv->finished, NULL);
return async->priv->result;
}
/* transitions 'async' to the "stopped" state, indicating that the task
* was stopped before completion (normally, in response to a
* 'gimp_async_cancel()' call).
*
* 'async' shall be in the "running" state.
*
* may only be called on the async thread.
*/
void
gimp_async_abort (GimpAsync *async)
{
g_return_if_fail (GIMP_IS_ASYNC (async));
g_return_if_fail (! async->priv->stopped);
g_mutex_lock (&async->priv->mutex);
gimp_async_stop (async);
g_mutex_unlock (&async->priv->mutex);
}
/* requests the cancellation of the task managed by 'async'.
*
* note that 'gimp_async_cancel()' doesn't directly cause 'async' to be
* stopped, nor does it cause the main thread to become synced with the async
* thread. furthermore, 'async' may still complete successfully even when
* cancellation has been requested.
*/
void
gimp_async_cancel (GimpAsync *async)
{
g_return_if_fail (GIMP_IS_ASYNC (async));
async->priv->canceled = TRUE;
}
/* checks if cancellation of 'async' has been requested.
*
* note that a return value of TRUE only indicates that 'gimp_async_cancel()'
* has been called for 'async', and not that 'async' is stopped, or, if it is
* stopped, that it was aborted.
*/
gboolean
gimp_async_is_canceled (GimpAsync *async)
{
g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
return async->priv->canceled;
}