gobject/gobjectnotifyqueue.c

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 1998-1999, 2000-2001 Tim Janik and Red Hat, Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General
  15  * Public License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #ifndef __G_OBJECT_NOTIFY_QUEUE_H__
  21 #define __G_OBJECT_NOTIFY_QUEUE_H__
  22
  23 #include <string.h> /* memset */
  24
  25 #include <glib-object.h>
  26
  27 G_BEGIN_DECLS
  28
  29
  30 /* --- typedefs --- */
  31 typedef struct _GObjectNotifyContext          GObjectNotifyContext;
  32 typedef struct _GObjectNotifyQueue            GObjectNotifyQueue;
  33 typedef void (*GObjectNotifyQueueDispatcher) (GObject     *object,
  34                                               guint        n_pspecs,
  35                                               GParamSpec **pspecs);
  36
  37
  38 /* --- structures --- */
  39 struct _GObjectNotifyContext
  40 {
  41   GQuark                       quark_notify_queue;
  42   GObjectNotifyQueueDispatcher dispatcher;
  43   GTrashStack                 *_nqueue_trash; /* unused */
  44 };
  45 struct _GObjectNotifyQueue
  46 {
  47   GObjectNotifyContext *context;
  48   GSList               *pspecs;
  49   guint16               n_pspecs;
  50   guint16               freeze_count;
  51 };
  52
  53 G_LOCK_DEFINE_STATIC(notify_lock);
  54
  55 /* --- functions --- */
  56 static void
  57 g_object_notify_queue_free (gpointer data)
  58 {
  59   GObjectNotifyQueue *nqueue = data;
  60
  61   g_slist_free (nqueue->pspecs);
  62   g_slice_free (GObjectNotifyQueue, nqueue);
  63 }
  64
  65 static inline GObjectNotifyQueue*
  66 g_object_notify_queue_freeze (GObject              *object,
  67                               GObjectNotifyContext *context)
  68 {
  69   GObjectNotifyQueue *nqueue;
  70
  71   G_LOCK(notify_lock);
  72   nqueue = g_datalist_id_get_data (&object->qdata, context->quark_notify_queue);
  73   if (!nqueue)
  74     {
  75       nqueue = g_slice_new0 (GObjectNotifyQueue);
  76       nqueue->context = context;
  77       g_datalist_id_set_data_full (&object->qdata, context->quark_notify_queue,
  78                                    nqueue, g_object_notify_queue_free);
  79     }
  80
  81   if (nqueue->freeze_count >= 65535)
  82     g_critical("Free queue for %s (%p) is larger than 65535,"
  83                " called g_object_freeze_notify() too often."
  84                " Forgot to call g_object_thaw_notify() or infinite loop",
  85                G_OBJECT_TYPE_NAME (object), object);
  86   else
  87     nqueue->freeze_count++;
  88   G_UNLOCK(notify_lock);
  89
  90   return nqueue;
  91 }
  92
  93 static inline void
  94 g_object_notify_queue_thaw (GObject            *object,
  95                             GObjectNotifyQueue *nqueue)
  96 {
  97   GObjectNotifyContext *context = nqueue->context;
  98   GParamSpec *pspecs_mem[16], **pspecs, **free_me = NULL;
  99   GSList *slist;
 100   guint n_pspecs = 0;
 101
 102   g_return_if_fail (nqueue->freeze_count > 0);
 103   g_return_if_fail (g_atomic_int_get(&object->ref_count) > 0);
 104
 105   G_LOCK(notify_lock);
 106
 107   /* Just make sure we never get into some nasty race condition */
 108   if (G_UNLIKELY(nqueue->freeze_count == 0)) {
 109     G_UNLOCK(notify_lock);
 110     g_warning ("%s: property-changed notification for %s(%p) is not frozen",
 111                G_STRFUNC, G_OBJECT_TYPE_NAME (object), object);
 112     return;
 113   }
 114
 115   nqueue->freeze_count--;
 116   if (nqueue->freeze_count) {
 117     G_UNLOCK(notify_lock);
 118     return;
 119   }
 120
 121   pspecs = nqueue->n_pspecs > 16 ? free_me = g_new (GParamSpec*, nqueue->n_pspecs) : pspecs_mem;
 122   /* set first entry to NULL since it's checked unconditionally */
 123   pspecs[0] = NULL;
 124   for (slist = nqueue->pspecs; slist; slist = slist->next)
 125     {
 126       GParamSpec *pspec = slist->data;
 127       guint i;
 128
 129       /* dedup, make pspecs in the list unique */
 130       for (i = 0; i < n_pspecs; i++)
 131         {
 132           if (pspecs[i] == pspec)
 133             break;
 134         }
 135
 136       if (i == n_pspecs) /* if no match was found */
 137         pspecs[n_pspecs++] = pspec;
 138     }
 139   g_datalist_id_set_data (&object->qdata, context->quark_notify_queue, NULL);
 140
 141   G_UNLOCK(notify_lock);
 142
 143   if (n_pspecs)
 144     context->dispatcher (object, n_pspecs, pspecs);
 145   g_free (free_me);
 146 }
 147
 148 static inline void
 149 g_object_notify_queue_clear (GObject            *object,
 150                              GObjectNotifyQueue *nqueue)
 151 {
 152   g_return_if_fail (nqueue->freeze_count > 0);
 153
 154   G_LOCK(notify_lock);
 155
 156   g_slist_free (nqueue->pspecs);
 157   nqueue->pspecs = NULL;
 158   nqueue->n_pspecs = 0;
 159
 160   G_UNLOCK(notify_lock);
 161 }
 162
 163 static inline void
 164 g_object_notify_queue_add (GObject            *object,
 165                            GObjectNotifyQueue *nqueue,
 166                            GParamSpec         *pspec)
 167 {
 168   if (pspec->flags & G_PARAM_READABLE)
 169     {
 170       GParamSpec *redirect;
 171
 172       G_LOCK(notify_lock);
 173
 174       g_return_if_fail (nqueue->n_pspecs < 65535);
 175
 176       redirect = g_param_spec_get_redirect_target (pspec);
 177       if (redirect)
 178         pspec = redirect;
 179
 180       /* we do the deduping in _thaw */
 181       nqueue->pspecs = g_slist_prepend (nqueue->pspecs, pspec);
 182       nqueue->n_pspecs++;
 183
 184       G_UNLOCK(notify_lock);
 185     }
 186 }
 187
 188 /* NB: This function is not threadsafe, do not ever use it if
 189  * you need a threadsafe notify queue.
 190  * Use g_object_notify_queue_freeze() to acquire the queue and
 191  * g_object_notify_queue_thaw() after you are done instead.
 192  */
 193 static inline GObjectNotifyQueue*
 194 g_object_notify_queue_from_object (GObject              *object,
 195                                    GObjectNotifyContext *context)
 196 {
 197   return g_datalist_id_get_data (&object->qdata, context->quark_notify_queue);
 198 }
 199
 200 G_END_DECLS
 201
 202 #endif /* __G_OBJECT_NOTIFY_QUEUE_H__ */