GObject: substantially rework g_object_new()

Make a number of improvements to g_object_new():

 - instead of looking up the GParamSpec for the named property once in
   g_object_new() (in order to collect) and then again in g_object_newv
   (when actually setting the property), g_object_new_internal() is a
   new function that takes the GParamSpec on the interface to avoid the
   second lookup

 - in the case that ->constructor() is not set, we need not waste time
   creating an array of GObjectConstructParam to pass in.  Just directly
   iterate the list of parameters, calling set_property() on each.

 - instead of playing with linked lists to keep track of the construct
   properties, realise that the number of construct properties that we
   will set is exactly equal to the length of the construct_properties
   list on GObjectClass and the only thing that may change is where the
   value comes from (in the case that it was passed in)

   This assumption was already implicit in the existing code and can be
   seen from the sizing of the array used to hold the construct
   properties, but it wasn't taken advantage of to make things simpler.

 - instead of allocating and filling a separate array of the
   non-construct properties just re-iterate the passed-in list and set
   all properties that were not marked G_PARAM_CONSTRUCT (since the ones
   that were construct params were already used during construction)

 - use the new g_param_spec_get_default_value() API instead of
   allocating and setting the GValue for each construct property that
   wasn't passed from the user

Because we are now iterating the linked list of properties in-order we
need to append to that list during class initialising instead of
prepending.

These changes show a very small improvement on the simple-construction
performance testcase (probably just noise) and they improve the
complex-construction case by ~30%.

Thanks to Alex Larsson for reviews and fixes.

https://bugzilla.gnome.org/show_bug.cgi?id=698056

diff --git a/gobject/gobject.c b/gobject/gobject.c
index 4472254..543fc7d 100644 (file)
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -560,7 +560,7 @@ g_object_class_install_property (GObjectClass *class,
   install_property_internal (G_OBJECT_CLASS_TYPE (class), property_id, pspec);
 
   if (pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY))
-    class->construct_properties = g_slist_prepend (class->construct_properties, pspec);
+    class->construct_properties = g_slist_append (class->construct_properties, pspec);
 
   /* for property overrides of construct properties, we have to get rid
    * of the overidden inherited construct property
@@ -677,7 +677,7 @@ g_object_class_install_properties (GObjectClass  *oclass,
       install_property_internal (oclass_type, i, pspec);
 
       if (pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY))
-        oclass->construct_properties = g_slist_prepend (oclass->construct_properties, pspec);
+        oclass->construct_properties = g_slist_append (oclass->construct_properties, pspec);
 
       /* for property overrides of construct properties, we have to get rid
        * of the overidden inherited construct property
@@ -1586,6 +1586,202 @@ object_in_construction_list (GObject *object)
   return in_construction;
 }
 
+static gpointer
+g_object_new_with_custom_constructor (GObjectClass          *class,
+                                      GObjectConstructParam *params,
+                                      guint                  n_params)
+{
+  GObjectNotifyQueue *nqueue = NULL;
+  gboolean newly_constructed;
+  GObjectConstructParam *cparams;
+  GObject *object;
+  GValue *cvalues;
+  gint n_cparams;
+  gint cvals_used;
+  GSList *node;
+  gint i;
+
+  /* If we have ->constructed() then we have to do a lot more work.
+   * It's possible that this is a singleton and it's also possible
+   * that the user's constructor() will attempt to modify the values
+   * that we pass in, so we'll need to allocate copies of them.
+   * It's also possible that the user may attempt to call
+   * g_object_set() from inside of their constructor, so we need to
+   * add ourselves to a list of objects for which that is allowed
+   * while their constructor() is running.
+   */
+
+  /* Create the array of GObjectConstructParams for constructor() */
+  n_cparams = g_slist_length (class->construct_properties);
+  cparams = g_new (GObjectConstructParam, n_cparams);
+  cvalues = g_new0 (GValue, n_cparams);
+  cvals_used = 0;
+  i = 0;
+
+  /* As above, we may find the value in the passed-in params list.
+   *
+   * If we have the value passed in then we can use the GValue from
+   * it directly because it is safe to modify.  If we use the
+   * default value from the class, we had better not pass that in
+   * and risk it being modified, so we create a new one.
+   * */
+  for (node = class->construct_properties; node; node = node->next)
+    {
+      GParamSpec *pspec;
+      GValue *value;
+      gint j;
+
+      pspec = node->data;
+      value = NULL; /* to silence gcc... */
+
+      for (j = 0; j < n_params; j++)
+        if (params[j].pspec == pspec)
+          {
+            value = params[j].value;
+            break;
+          }
+
+      if (j == n_params)
+        {
+          value = &cvalues[cvals_used++];
+          g_value_init (value, pspec->value_type);
+          g_param_value_set_default (pspec, value);
+        }
+
+      cparams[i].pspec = pspec;
+      cparams[i].value = value;
+      i++;
+    }
+
+  /* construct object from construction parameters */
+  object = class->constructor (class->g_type_class.g_type, n_cparams, cparams);
+  /* free construction values */
+  g_free (cparams);
+  while (cvals_used--)
+    g_value_unset (&cvalues[cvals_used]);
+  g_free (cvalues);
+
+  /* g_object_init() will have added us to the construction_objects
+   * list.  Check if we're in it (and remove us) in order to find
+   * out if we were newly-constructed or this is an already-existing
+   * singleton (in which case we should not do 'constructed').
+   */
+  G_LOCK (construction_mutex);
+  newly_constructed = slist_maybe_remove (&construction_objects, object);
+  G_UNLOCK (construction_mutex);
+
+  if (CLASS_HAS_PROPS (class))
+    {
+      /* If this object was newly_constructed then g_object_init()
+       * froze the queue.  We need to freeze it here in order to get
+       * the handle so that we can thaw it below (otherwise it will
+       * be frozen forever).
+       *
+       * We also want to do a freeze if we have any params to set,
+       * even on a non-newly_constructed object.
+       *
+       * It's possible that we have the case of non-newly created
+       * singleton and all of the passed-in params were construct
+       * properties so n_params > 0 but we will actually set no
+       * properties.  This is a pretty lame case to optimise, so
+       * just ignore it and freeze anyway.
+       */
+      if (newly_constructed || n_params)
+        nqueue = g_object_notify_queue_freeze (object, FALSE);
+
+      /* Remember: if it was newly_constructed then g_object_init()
+       * already did a freeze, so we now have two.  Release one.
+       */
+      if (newly_constructed)
+        g_object_notify_queue_thaw (object, nqueue);
+    }
+
+  /* run 'constructed' handler if there is a custom one */
+  if (newly_constructed && CLASS_HAS_CUSTOM_CONSTRUCTED (class))
+    class->constructed (object);
+
+  /* set remaining properties */
+  for (i = 0; i < n_params; i++)
+    if (!(params[i].pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY)))
+      object_set_property (object, params[i].pspec, params[i].value, nqueue);
+
+  /* If nqueue is non-NULL then we are frozen.  Thaw it. */
+  if (nqueue)
+    g_object_notify_queue_thaw (object, nqueue);
+
+  return object;
+}
+
+static gpointer
+g_object_new_internal (GObjectClass          *class,
+                       GObjectConstructParam *params,
+                       guint                  n_params)
+{
+  GObjectNotifyQueue *nqueue = NULL;
+  GObject *object;
+
+  if G_UNLIKELY (CLASS_HAS_CUSTOM_CONSTRUCTOR (class))
+    return g_object_new_with_custom_constructor (class, params, n_params);
+
+  object = (GObject *) g_type_create_instance (class->g_type_class.g_type);
+
+  if (CLASS_HAS_PROPS (class))
+    {
+      GSList *node;
+
+      /* This will have been setup in g_object_init() */
+      nqueue = g_datalist_id_get_data (&object->qdata, quark_notify_queue);
+      g_assert (nqueue != NULL);
+
+      /* We will set exactly n_construct_properties construct
+       * properties, but they may come from either the class default
+       * values or the passed-in parameter list.
+       */
+      for (node = class->construct_properties; node; node = node->next)
+        {
+          const GValue *value;
+          GParamSpec *pspec;
+          gint j;
+
+          pspec = node->data;
+          value = NULL; /* to silence gcc... */
+
+          for (j = 0; j < n_params; j++)
+            if (params[j].pspec == pspec)
+              {
+                value = params[j].value;
+                break;
+              }
+
+          if (j == n_params)
+            value = g_param_spec_get_default_value (pspec);
+
+          object_set_property (object, pspec, value, nqueue);
+        }
+    }
+
+  /* run 'constructed' handler if there is a custom one */
+  if (CLASS_HAS_CUSTOM_CONSTRUCTED (class))
+    class->constructed (object);
+
+  if (nqueue)
+    {
+      gint i;
+
+      /* Set remaining properties.  The construct properties will
+       * already have been taken, so set only the non-construct
+       * ones.
+       */
+      for (i = 0; i < n_params; i++)
+        if (!(params[i].pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY)))
+          object_set_property (object, params[i].pspec, params[i].value, nqueue);
+
+      g_object_notify_queue_thaw (object, nqueue);
+    }
+
+  return object;
+}
+
 /**
  * g_object_newv:
  * @object_type: the type id of the #GObject subtype to instantiate
@@ -1603,160 +1799,75 @@ object_in_construction_list (GObject *object)
  */
 gpointer
 g_object_newv (GType       object_type,
-              guint       n_parameters,
-              GParameter *parameters)
+               guint       n_parameters,
+               GParameter *parameters)
 {
-  GObjectConstructParam *cparams = NULL, *oparams;
-  GObjectNotifyQueue *nqueue = NULL; /* shouldn't be initialized, just to silence compiler */
-  GObject *object;
   GObjectClass *class, *unref_class = NULL;
-  GSList *slist;
-  guint n_total_cparams = 0, n_cparams = 0, n_oparams = 0, n_cvalues;
-  GValue *cvalues;
-  GList *clist = NULL;
-  gboolean newly_constructed;
-  guint i;
+  GObject *object;
 
   g_return_val_if_fail (G_TYPE_IS_OBJECT (object_type), NULL);
+  g_return_val_if_fail (n_parameters == 0 || parameters != NULL, NULL);
 
+  /* Try to avoid thrashing the ref_count if we don't need to (since
+   * it's a locked operation).
+   */
   class = g_type_class_peek_static (object_type);
+
   if (!class)
     class = unref_class = g_type_class_ref (object_type);
-  for (slist = class->construct_properties; slist; slist = slist->next)
-    {
-      clist = g_list_prepend (clist, slist->data);
-      n_total_cparams += 1;
-    }
 
-  if (n_parameters == 0 && n_total_cparams == 0)
+  if (n_parameters)
     {
-      /* This is a simple object with no construct properties, and
-       * no properties are being set, so short circuit the parameter
-       * handling. This speeds up simple object construction.
-       */
-      oparams = NULL;
-      object = class->constructor (object_type, 0, NULL);
-      goto did_construction;
-    }
+      GObjectConstructParam *cparams;
+      guint i, j;
 
-  /* collect parameters, sort into construction and normal ones */
-  oparams = g_new (GObjectConstructParam, n_parameters);
-  cparams = g_new (GObjectConstructParam, n_total_cparams);
-  for (i = 0; i < n_parameters; i++)
-    {
-      GValue *value = &parameters[i].value;
-      GParamSpec *pspec = g_param_spec_pool_lookup (pspec_pool,
-                                                   parameters[i].name,
-                                                   object_type,
-                                                   TRUE);
-      if (!pspec)
-       {
-         g_warning ("%s: object class `%s' has no property named `%s'",
-                    G_STRFUNC,
-                    g_type_name (object_type),
-                    parameters[i].name);
-         continue;
-       }
-      if (!(pspec->flags & G_PARAM_WRITABLE))
-       {
-         g_warning ("%s: property `%s' of object class `%s' is not writable",
-                    G_STRFUNC,
-                    pspec->name,
-                    g_type_name (object_type));
-         continue;
-       }
-      if (pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY))
-       {
-         GList *list = g_list_find (clist, pspec);
+      cparams = g_newa (GObjectConstructParam, n_parameters);
+      j = 0;
 
-         if (!list)
-           {
-             g_warning ("%s: construct property \"%s\" for object `%s' can't be set twice",
-                         G_STRFUNC, pspec->name, g_type_name (object_type));
-             continue;
-           }
-         cparams[n_cparams].pspec = pspec;
-         cparams[n_cparams].value = value;
-         n_cparams++;
-         if (!list->prev)
-           clist = list->next;
-         else
-           list->prev->next = list->next;
-         if (list->next)
-           list->next->prev = list->prev;
-         g_list_free_1 (list);
-       }
-      else
-       {
-         oparams[n_oparams].pspec = pspec;
-         oparams[n_oparams].value = value;
-         n_oparams++;
-       }
-    }
+      for (i = 0; i < n_parameters; i++)
+        {
+          GParamSpec *pspec;
+          gint k;
 
-  /* set remaining construction properties to default values */
-  n_cvalues = n_total_cparams - n_cparams;
-  cvalues = g_new (GValue, n_cvalues);
-  while (clist)
-    {
-      GList *tmp = clist->next;
-      GParamSpec *pspec = clist->data;
-      GValue *value = cvalues + n_total_cparams - n_cparams - 1;
+          pspec = g_param_spec_pool_lookup (pspec_pool, parameters[i].name, object_type, TRUE);
 
-      value->g_type = 0;
-      g_value_init (value, pspec->value_type);
-      g_param_value_set_default (pspec, value);
+          if G_UNLIKELY (!pspec)
+            {
+              g_critical ("%s: object class `%s' has no property named `%s'",
+                          G_STRFUNC, g_type_name (object_type), parameters[i].name);
+              continue;
+            }
 
-      cparams[n_cparams].pspec = pspec;
-      cparams[n_cparams].value = value;
-      n_cparams++;
+          if G_UNLIKELY (~pspec->flags & G_PARAM_WRITABLE)
+            {
+              g_critical ("%s: property `%s' of object class `%s' is not writable",
+                          G_STRFUNC, pspec->name, g_type_name (object_type));
+              continue;
+            }
 
-      g_list_free_1 (clist);
-      clist = tmp;
-    }
+          if (pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY))
+            {
+              for (k = 0; k < j; k++)
+                if (cparams[k].pspec == pspec)
+                    break;
+              if G_UNLIKELY (k != j)
+                {
+                  g_critical ("%s: construct property `%s' for type `%s' cannot be set twice",
+                              G_STRFUNC, parameters[i].name, g_type_name (object_type));
+                  continue;
+                }
+            }
 
-  /* construct object from construction parameters */
-  object = class->constructor (object_type, n_total_cparams, cparams);
-  /* free construction values */
-  g_free (cparams);
-  while (n_cvalues--)
-    g_value_unset (cvalues + n_cvalues);
-  g_free (cvalues);
+          cparams[j].pspec = pspec;
+          cparams[j].value = &parameters[i].value;
+          j++;
+        }
 
- did_construction:
-  if (CLASS_HAS_CUSTOM_CONSTRUCTOR (class))
-    {
-      /* adjust freeze_count according to g_object_init() and remaining properties */
-      G_LOCK (construction_mutex);
-      newly_constructed = slist_maybe_remove (&construction_objects, object);
-      G_UNLOCK (construction_mutex);
+      object = g_object_new_internal (class, cparams, j);
     }
   else
-    newly_constructed = TRUE;
-
-  if (CLASS_HAS_PROPS (class))
-    {
-      if (newly_constructed || n_oparams)
-       nqueue = g_object_notify_queue_freeze (object, FALSE);
-      if (newly_constructed)
-       g_object_notify_queue_thaw (object, nqueue);
-    }
-
-  /* run 'constructed' handler if there is a custom one */
-  if (newly_constructed && CLASS_HAS_CUSTOM_CONSTRUCTED (class))
-    class->constructed (object);
-
-  /* set remaining properties */
-  for (i = 0; i < n_oparams; i++)
-    object_set_property (object, oparams[i].pspec, oparams[i].value, nqueue);
-  g_free (oparams);
-
-  if (CLASS_HAS_PROPS (class))
-    {
-      /* release our own freeze count and handle notifications */
-      if (newly_constructed || n_oparams)
-       g_object_notify_queue_thaw (object, nqueue);
-    }
+    /* Fast case: no properties passed in. */
+    object = g_object_new_internal (class, NULL, 0);
 
   if (unref_class)
     g_type_class_unref (unref_class);
@@ -1779,67 +1890,109 @@ g_object_newv (GType       object_type,
  * Returns: a new instance of @object_type
  */
 GObject*
-g_object_new_valist (GType       object_type,
-                    const gchar *first_property_name,
-                    va_list      var_args)
+g_object_new_valist (GType        object_type,
+                     const gchar *first_property_name,
+                     va_list      var_args)
 {
-  GObjectClass *class;
-  GParameter *params;
-  const gchar *name;
+  GObjectClass *class, *unref_class = NULL;
   GObject *object;
-  guint n_params = 0, n_alloced_params = 16;
-  
+
   g_return_val_if_fail (G_TYPE_IS_OBJECT (object_type), NULL);
 
-  if (!first_property_name)
-    return g_object_newv (object_type, 0, NULL);
+  /* Try to avoid thrashing the ref_count if we don't need to (since
+   * it's a locked operation).
+   */
+  class = g_type_class_peek_static (object_type);
 
-  class = g_type_class_ref (object_type);
+  if (!class)
+    class = unref_class = g_type_class_ref (object_type);
 
-  params = g_new0 (GParameter, n_alloced_params);
-  name = first_property_name;
-  while (name)
+  if (first_property_name)
     {
-      gchar *error = NULL;
-      GParamSpec *pspec = g_param_spec_pool_lookup (pspec_pool,
-                                                   name,
-                                                   object_type,
-                                                   TRUE);
-      if (!pspec)
-       {
-         g_warning ("%s: object class `%s' has no property named `%s'",
-                    G_STRFUNC,
-                    g_type_name (object_type),
-                    name);
-         break;
-       }
-      if (n_params >= n_alloced_params)
-       {
-         n_alloced_params += 16;
-         params = g_renew (GParameter, params, n_alloced_params);
-         memset (params + n_params, 0, 16 * (sizeof *params));
-       }
-      params[n_params].name = name;
-      G_VALUE_COLLECT_INIT (&params[n_params].value, pspec->value_type,
-                           var_args, 0, &error);
-      if (error)
-       {
-         g_warning ("%s: %s", G_STRFUNC, error);
-         g_free (error);
-          g_value_unset (&params[n_params].value);
-         break;
-       }
-      n_params++;
-      name = va_arg (var_args, gchar*);
-    }
+      GObjectConstructParam stack_params[16];
+      GObjectConstructParam *params;
+      const gchar *name;
+      gint n_params = 0;
+
+      name = first_property_name;
+      params = stack_params;
 
-  object = g_object_newv (object_type, n_params, params);
+      do
+        {
+          gchar *error = NULL;
+          GParamSpec *pspec;
+          gint i;
 
-  while (n_params--)
-    g_value_unset (&params[n_params].value);
-  g_free (params);
+          pspec = g_param_spec_pool_lookup (pspec_pool, name, object_type, TRUE);
 
-  g_type_class_unref (class);
+          if G_UNLIKELY (!pspec)
+            {
+              g_critical ("%s: object class `%s' has no property named `%s'",
+                          G_STRFUNC, g_type_name (object_type), name);
+              /* Can't continue because arg list will be out of sync. */
+              break;
+            }
+
+          if G_UNLIKELY (~pspec->flags & G_PARAM_WRITABLE)
+            {
+              g_critical ("%s: property `%s' of object class `%s' is not writable",
+                          G_STRFUNC, pspec->name, g_type_name (object_type));
+              break;
+            }
+
+          if (pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY))
+            {
+              for (i = 0; i < n_params; i++)
+                if (params[i].pspec == pspec)
+                    break;
+              if G_UNLIKELY (i != n_params)
+                {
+                  g_critical ("%s: property `%s' for type `%s' cannot be set twice",
+                              G_STRFUNC, name, g_type_name (object_type));
+                  break;
+                }
+            }
+
+          if (n_params == 16)
+            {
+              params = g_new (GObjectConstructParam, n_params + 1);
+              memcpy (params, stack_params, sizeof stack_params);
+            }
+          else if (n_params > 16)
+            params = g_renew (GObjectConstructParam, params, n_params + 1);
+
+          params[n_params].pspec = pspec;
+          params[n_params].value = g_newa (GValue, 1);
+          memset (params[n_params].value, 0, sizeof (GValue));
+
+          G_VALUE_COLLECT_INIT (params[n_params].value, pspec->value_type, var_args, 0, &error);
+
+          if (error)
+            {
+              g_critical ("%s: %s", G_STRFUNC, error);
+              g_value_unset (params[n_params].value);
+              g_free (error);
+              break;
+            }
+
+          n_params++;
+        }
+      while ((name = va_arg (var_args, const gchar *)));
+
+      object = g_object_new_internal (class, params, n_params);
+
+      while (n_params--)
+        g_value_unset (params[n_params].value);
+
+      if (params != stack_params)
+        g_free (params);
+    }
+  else
+    /* Fast case: no properties passed in. */
+    object = g_object_new_internal (class, NULL, 0);
+
+  if (unref_class)
+    g_type_class_unref (unref_class);
 
   return object;
 }