/* GObject - GLib Type, Object, Parameter and Signal Library

 * Copyright (C) 2000-2001 Red Hat, Inc.

 * Copyright (C) 2005 Imendio AB

 * Portions copyright (c) 2006-2009 Nokia Corporation.  All rights reserved.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General

 * Public License along with this library; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/*

 * MT safe with regards to reference counting.

 */

#include "config.h"

#include <string.h>

#include "gclosure.h"

#include "gvalue.h"

#include "gobjectalias.h"

/**

 * SECTION:gclosure

 * @short_description: Functions as first-class objects

 * @title: Closures

 *

 * A #GClosure represents a callback supplied by the programmer. It

 * will generally comprise a function of some kind and a marshaller

 * used to call it. It is the reponsibility of the marshaller to

 * convert the arguments for the invocation from #GValue<!-- -->s into

 * a suitable form, perform the callback on the converted arguments,

 * and transform the return value back into a #GValue.

 *

 * In the case of C programs, a closure usually just holds a pointer

 * to a function and maybe a data argument, and the marshaller

 * converts between #GValue<!-- --> and native C types. The GObject

 * library provides the #GCClosure type for this purpose. Bindings for

 * other languages need marshallers which convert between #GValue<!--

 * -->s and suitable representations in the runtime of the language in

 * order to use functions written in that languages as callbacks.

 *

 * Within GObject, closures play an important role in the

 * implementation of signals. When a signal is registered, the

 * @c_marshaller argument to g_signal_new() specifies the default C

 * marshaller for any closure which is connected to this

 * signal. GObject provides a number of C marshallers for this

 * purpose, see the g_cclosure_marshal_*() functions. Additional C

 * marshallers can be generated with the <link

 * linkend="glib-genmarshal">glib-genmarshal</link> utility.  Closures

 * can be explicitly connected to signals with

 * g_signal_connect_closure(), but it usually more convenient to let

 * GObject create a closure automatically by using one of the

 * g_signal_connect_*() functions which take a callback function/user

 * data pair.

 *

 * Using closures has a number of important advantages over a simple

 * callback function/data pointer combination:

 * <itemizedlist>

 * <listitem><para>

 * Closures allow the callee to get the types of the callback parameters,

 * which means that language bindings don't have to write individual glue

 * for each callback type.

 * </para></listitem>

 * <listitem><para>

 * The reference counting of #GClosure makes it easy to handle reentrancy

 * right; if a callback is removed while it is being invoked, the closure

 * and its parameters won't be freed until the invocation finishes.

 * </para></listitem>

 * <listitem><para>

 * g_closure_invalidate() and invalidation notifiers allow callbacks to be

 * automatically removed when the objects they point to go away.

 * </para></listitem>

 * </itemizedlist>

 */

#define	CLOSURE_MAX_REF_COUNT		((1 << 15) - 1)

#define	CLOSURE_MAX_N_GUARDS		((1 << 1) - 1)

#define	CLOSURE_MAX_N_FNOTIFIERS	((1 << 2) - 1)

#define	CLOSURE_MAX_N_INOTIFIERS	((1 << 8) - 1)

#define	CLOSURE_N_MFUNCS(cl)		((cl)->meta_marshal + \

                                         ((cl)->n_guards << 1L))

/* same as G_CLOSURE_N_NOTIFIERS() (keep in sync) */

#define	CLOSURE_N_NOTIFIERS(cl)		(CLOSURE_N_MFUNCS (cl) + \

                                         (cl)->n_fnotifiers + \

                                         (cl)->n_inotifiers)

typedef union {

  GClosure closure;

  volatile gint vint;

} ClosureInt;

#define CHANGE_FIELD(_closure, _field, _OP, _value, _must_set, _SET_OLD, _SET_NEW)      \

G_STMT_START {                                                                          \

  ClosureInt *cunion = (ClosureInt*) _closure;                 		                \

  gint new_int, old_int, success;                              		                \

  do                                                    		                \

    {                                                   		                \

      ClosureInt tmp;                                   		                \

      tmp.vint = old_int = cunion->vint;                		                \

      _SET_OLD tmp.closure._field;                                                      \

      tmp.closure._field _OP _value;                      		                \

      _SET_NEW tmp.closure._field;                                                      \

      new_int = tmp.vint;                               		                \

      success = g_atomic_int_compare_and_exchange (&cunion->vint, old_int, new_int);    \

    }                                                   		                \

  while (!success && _must_set);                                                        \

} G_STMT_END

#define SWAP(_closure, _field, _value, _oldv)   CHANGE_FIELD (_closure, _field, =, _value, TRUE, *(_oldv) =,     (void) )

#define SET(_closure, _field, _value)           CHANGE_FIELD (_closure, _field, =, _value, TRUE,     (void),     (void) )

#define INC(_closure, _field)                   CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void),     (void) )

#define INC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void), *(_newv) = )

#define DEC(_closure, _field)                   CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void),     (void) )

#define DEC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void), *(_newv) = )

#if 0   /* for non-thread-safe closures */

#define SWAP(cl,f,v,o)     (void) (*(o) = cl->f, cl->f = v)

#define SET(cl,f,v)        (void) (cl->f = v)

#define INC(cl,f)          (void) (cl->f += 1)

#define INC_ASSIGN(cl,f,n) (void) (cl->f += 1, *(n) = cl->f)

#define DEC(cl,f)          (void) (cl->f -= 1)

#define DEC_ASSIGN(cl,f,n) (void) (cl->f -= 1, *(n) = cl->f)

#endif

enum {

  FNOTIFY,

  INOTIFY,

  PRE_NOTIFY,

  POST_NOTIFY

};

/* --- functions --- */

/**

 * g_closure_new_simple:

 * @sizeof_closure: the size of the structure to allocate, must be at least

 *                  <literal>sizeof (GClosure)</literal>

 * @data: data to store in the @data field of the newly allocated #GClosure

 *

 * Allocates a struct of the given size and initializes the initial

 * part as a #GClosure. This function is mainly useful when

 * implementing new types of closures.

 *

 * |[

 * typedef struct _MyClosure MyClosure;

 * struct _MyClosure

 * {

 *   GClosure closure;

 *   // extra data goes here

 * };

 *

 * static void

 * my_closure_finalize (gpointer  notify_data,

 *                      GClosure *closure)

 * {

 *   MyClosure *my_closure = (MyClosure *)closure;

 *

 *   // free extra data here

 * }

 *

 * MyClosure *my_closure_new (gpointer data)

 * {

 *   GClosure *closure;

 *   MyClosure *my_closure;

 *

 *   closure = g_closure_new_simple (sizeof (MyClosure), data);

 *   my_closure = (MyClosure *) closure;

 *

 *   // initialize extra data here

 *

 *   g_closure_add_finalize_notifier (closure, notify_data,

 *                                    my_closure_finalize);

 *   return my_closure;

 * }

 * ]|

 *

 * Returns: a newly allocated #GClosure

 */

EXPORT_C GClosure*

g_closure_new_simple (guint           sizeof_closure,

		      gpointer        data)

{

  GClosure *closure;

  g_return_val_if_fail (sizeof_closure >= sizeof (GClosure), NULL);

  closure = g_malloc0 (sizeof_closure);

  SET (closure, ref_count, 1);

  SET (closure, meta_marshal, 0);

  SET (closure, n_guards, 0);

  SET (closure, n_fnotifiers, 0);

  SET (closure, n_inotifiers, 0);

  SET (closure, in_inotify, FALSE);

  SET (closure, floating, TRUE);

  SET (closure, derivative_flag, 0);

  SET (closure, in_marshal, FALSE);

  SET (closure, is_invalid, FALSE);

  closure->marshal = NULL;

  closure->data = data;

  closure->notifiers = NULL;

  memset (G_STRUCT_MEMBER_P (closure, sizeof (*closure)), 0, sizeof_closure - sizeof (*closure));

  return closure;

}

static inline void

closure_invoke_notifiers (GClosure *closure,

			  guint     notify_type)

{

  /* notifier layout:

   *     meta_marshal  n_guards    n_guards     n_fnotif.  n_inotifiers

   * ->[[meta_marshal][pre_guards][post_guards][fnotifiers][inotifiers]]

   *

   * CLOSURE_N_MFUNCS(cl)    = meta_marshal + n_guards + n_guards;

   * CLOSURE_N_NOTIFIERS(cl) = CLOSURE_N_MFUNCS(cl) + n_fnotifiers + n_inotifiers

   *

   * constrains/catches:

   * - closure->notifiers may be reloacted during callback

   * - closure->n_fnotifiers and closure->n_inotifiers may change during callback

   * - i.e. callbacks can be removed/added during invocation

   * - must prepare for callback removal during FNOTIFY and INOTIFY (done via ->marshal= & ->data=)

   * - must distinguish (->marshal= & ->data=) for INOTIFY vs. FNOTIFY (via ->in_inotify)

   * + closure->n_guards is const during PRE_NOTIFY & POST_NOTIFY

   * + closure->meta_marshal is const for all cases

   * + none of the callbacks can cause recursion

   * + closure->n_inotifiers is const 0 during FNOTIFY

   */

  switch (notify_type)

    {

      GClosureNotifyData *ndata;

      guint i, offs;

    case FNOTIFY:

      while (closure->n_fnotifiers)

	{

          guint n;

	  DEC_ASSIGN (closure, n_fnotifiers, &n);

	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + n;

	  closure->marshal = (GClosureMarshal) ndata->notify;

	  closure->data = ndata->data;

	  ndata->notify (ndata->data, closure);

	}

      closure->marshal = NULL;

      closure->data = NULL;

      break;

    case INOTIFY:

      SET (closure, in_inotify, TRUE);

      while (closure->n_inotifiers)

	{

          guint n;

          DEC_ASSIGN (closure, n_inotifiers, &n);

	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + n;

	  closure->marshal = (GClosureMarshal) ndata->notify;

	  closure->data = ndata->data;

	  ndata->notify (ndata->data, closure);

	}

      closure->marshal = NULL;

      closure->data = NULL;

      SET (closure, in_inotify, FALSE);

      break;

    case PRE_NOTIFY:

      i = closure->n_guards;

      offs = closure->meta_marshal;

      while (i--)

	{

	  ndata = closure->notifiers + offs + i;

	  ndata->notify (ndata->data, closure);

	}

      break;

    case POST_NOTIFY:

      i = closure->n_guards;

      offs = closure->meta_marshal + i;

      while (i--)

	{

	  ndata = closure->notifiers + offs + i;

	  ndata->notify (ndata->data, closure);

	}

      break;

    }

}

/**

 * g_closure_set_meta_marshal:

 * @closure: a #GClosure

 * @marshal_data: context-dependent data to pass to @meta_marshal

 * @meta_marshal: a #GClosureMarshal function

 *

 * Sets the meta marshaller of @closure.  A meta marshaller wraps

 * @closure->marshal and modifies the way it is called in some

 * fashion. The most common use of this facility is for C callbacks.

 * The same marshallers (generated by <link

 * linkend="glib-genmarshal">glib-genmarshal</link>) are used

 * everywhere, but the way that we get the callback function

 * differs. In most cases we want to use @closure->callback, but in

 * other cases we want to use some different technique to retrieve the

 * callback function.

 *

 * For example, class closures for signals (see

 * g_signal_type_cclosure_new()) retrieve the callback function from a

 * fixed offset in the class structure.  The meta marshaller retrieves

 * the right callback and passes it to the marshaller as the

 * @marshal_data argument.

 */

EXPORT_C void

g_closure_set_meta_marshal (GClosure       *closure,

			    gpointer        marshal_data,

			    GClosureMarshal meta_marshal)

{

  GClosureNotifyData *notifiers;

  g_return_if_fail (closure != NULL);

  g_return_if_fail (meta_marshal != NULL);

  g_return_if_fail (closure->is_invalid == FALSE);

  g_return_if_fail (closure->in_marshal == FALSE);

  g_return_if_fail (closure->meta_marshal == 0);

  notifiers = closure->notifiers;

  closure->notifiers = g_renew (GClosureNotifyData, NULL, CLOSURE_N_NOTIFIERS (closure) + 1);

  if (notifiers)

    {

      /* usually the meta marshal will be setup right after creation, so the

       * g_memmove() should be rare-case scenario

       */

      g_memmove (closure->notifiers + 1, notifiers, CLOSURE_N_NOTIFIERS (closure) * sizeof (notifiers[0]));

      g_free (notifiers);

    }

  closure->notifiers[0].data = marshal_data;

  closure->notifiers[0].notify = (GClosureNotify) meta_marshal;

  SET (closure, meta_marshal, 1);

}

/**

 * g_closure_add_marshal_guards:

 * @closure: a #GClosure

 * @pre_marshal_data: data to pass to @pre_marshal_notify

 * @pre_marshal_notify: a function to call before the closure callback

 * @post_marshal_data: data to pass to @post_marshal_notify

 * @post_marshal_notify: a function to call after the closure callback

 *

 * Adds a pair of notifiers which get invoked before and after the

 * closure callback, respectively. This is typically used to protect

 * the extra arguments for the duration of the callback. See

 * g_object_watch_closure() for an example of marshal guards.

 */

EXPORT_C void

g_closure_add_marshal_guards (GClosure      *closure,

			      gpointer       pre_marshal_data,

			      GClosureNotify pre_marshal_notify,

			      gpointer       post_marshal_data,

			      GClosureNotify post_marshal_notify)

{

  guint i;

  g_return_if_fail (closure != NULL);

  g_return_if_fail (pre_marshal_notify != NULL);

  g_return_if_fail (post_marshal_notify != NULL);

  g_return_if_fail (closure->is_invalid == FALSE);

  g_return_if_fail (closure->in_marshal == FALSE);

  g_return_if_fail (closure->n_guards < CLOSURE_MAX_N_GUARDS);

  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 2);

  if (closure->n_inotifiers)

    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			closure->n_fnotifiers +

			closure->n_inotifiers + 1)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

									  closure->n_fnotifiers + 0)];

  if (closure->n_inotifiers > 1)

    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			closure->n_fnotifiers +

			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

								      closure->n_fnotifiers + 1)];

  if (closure->n_fnotifiers)

    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			closure->n_fnotifiers + 1)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 0];

  if (closure->n_fnotifiers > 1)

    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			closure->n_fnotifiers)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 1];

  if (closure->n_guards)

    closure->notifiers[(closure->meta_marshal +

			closure->n_guards +

			closure->n_guards + 1)] = closure->notifiers[closure->meta_marshal + closure->n_guards];

  i = closure->n_guards;

  closure->notifiers[closure->meta_marshal + i].data = pre_marshal_data;

  closure->notifiers[closure->meta_marshal + i].notify = pre_marshal_notify;

  closure->notifiers[closure->meta_marshal + i + 1].data = post_marshal_data;

  closure->notifiers[closure->meta_marshal + i + 1].notify = post_marshal_notify;

  INC (closure, n_guards);

}

/**

 * g_closure_add_finalize_notifier:

 * @closure: a #GClosure

 * @notify_data: data to pass to @notify_func

 * @notify_func: the callback function to register

 *

 * Registers a finalization notifier which will be called when the

 * reference count of @closure goes down to 0. Multiple finalization

 * notifiers on a single closure are invoked in unspecified order. If

 * a single call to g_closure_unref() results in the closure being

 * both invalidated and finalized, then the invalidate notifiers will

 * be run before the finalize notifiers.

 */

EXPORT_C void

g_closure_add_finalize_notifier (GClosure      *closure,

				 gpointer       notify_data,

				 GClosureNotify notify_func)

{

  guint i;

  g_return_if_fail (closure != NULL);

  g_return_if_fail (notify_func != NULL);

  g_return_if_fail (closure->n_fnotifiers < CLOSURE_MAX_N_FNOTIFIERS);

  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);

  if (closure->n_inotifiers)

    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			closure->n_fnotifiers +

			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

								      closure->n_fnotifiers + 0)];

  i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers;

  closure->notifiers[i].data = notify_data;

  closure->notifiers[i].notify = notify_func;

  INC (closure, n_fnotifiers);

}

/**

 * g_closure_add_invalidate_notifier:

 * @closure: a #GClosure

 * @notify_data: data to pass to @notify_func

 * @notify_func: the callback function to register

 *

 * Registers an invalidation notifier which will be called when the

 * @closure is invalidated with g_closure_invalidate(). Invalidation

 * notifiers are invoked before finalization notifiers, in an

 * unspecified order.

 */

EXPORT_C void

g_closure_add_invalidate_notifier (GClosure      *closure,

				   gpointer       notify_data,

				   GClosureNotify notify_func)

{

  guint i;

  g_return_if_fail (closure != NULL);

  g_return_if_fail (notify_func != NULL);

  g_return_if_fail (closure->is_invalid == FALSE);

  g_return_if_fail (closure->n_inotifiers < CLOSURE_MAX_N_INOTIFIERS);

  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);

  i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + closure->n_inotifiers;

  closure->notifiers[i].data = notify_data;

  closure->notifiers[i].notify = notify_func;

  INC (closure, n_inotifiers);

}

static inline gboolean

closure_try_remove_inotify (GClosure       *closure,

			    gpointer       notify_data,

			    GClosureNotify notify_func)

{

  GClosureNotifyData *ndata, *nlast;

  nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - 1;

  for (ndata = nlast + 1 - closure->n_inotifiers; ndata <= nlast; ndata++)

    if (ndata->notify == notify_func && ndata->data == notify_data)

      {

	DEC (closure, n_inotifiers);

	if (ndata < nlast)

	  *ndata = *nlast;

	return TRUE;

      }

  return FALSE;

}

static inline gboolean

closure_try_remove_fnotify (GClosure       *closure,

			    gpointer       notify_data,

			    GClosureNotify notify_func)

{

  GClosureNotifyData *ndata, *nlast;

  nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - closure->n_inotifiers - 1;

  for (ndata = nlast + 1 - closure->n_fnotifiers; ndata <= nlast; ndata++)

    if (ndata->notify == notify_func && ndata->data == notify_data)

      {

	DEC (closure, n_fnotifiers);

	if (ndata < nlast)

	  *ndata = *nlast;

	if (closure->n_inotifiers)

	  closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

			      closure->n_fnotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

									    closure->n_fnotifiers +

									    closure->n_inotifiers)];

	return TRUE;

      }

  return FALSE;

}

/**

 * g_closure_ref:

 * @closure: #GClosure to increment the reference count on

 *

 * Increments the reference count on a closure to force it staying

 * alive while the caller holds a pointer to it.

 *

 * Returns: The @closure passed in, for convenience

 */

EXPORT_C GClosure*

g_closure_ref (GClosure *closure)

{

  guint new_ref_count;

  g_return_val_if_fail (closure != NULL, NULL);