Add g_datalist_id_remove_multiple

This is more efficient than calling
g_datalist_id_remove() multiple times
in a row, since it only takes the locks
once.

Allow up to 16 keys to be removed in one go.
That is enough for the use we have in GObject,
and it avoids any danger of blowing the stack.

docs/reference/glib/glib-sections.txt

@@ -3220,6 +3220,7 @@ g_datalist_id_set_data_full
 g_datalist_id_get_data
 g_datalist_id_remove_data
 g_datalist_id_remove_no_notify
+g_datalist_id_remove_multiple
 GDuplicateFunc
 g_datalist_id_dup_data
 g_datalist_id_replace_data

glib/gdataset.c

@@ -46,6 +46,7 @@
 #include "gtestutils.h"
 #include "gthread.h"
 #include "glib_trace.h"
+#include "galloca.h"
 
 /**
  * SECTION:datasets
@@ -487,6 +488,85 @@ g_data_set_internal (GData	  **datalist,
 
 }
 
+static inline void
+g_data_remove_internal (GData  **datalist,
+                        GQuark  *keys,
+                        gsize    n_keys)
+{
+  GData *d;
+
+  g_datalist_lock (datalist);
+
+  d = G_DATALIST_GET_POINTER (datalist);
+
+  if (d)
+    {
+      GDataElt *old, *data, *data_end;
+      gsize found_keys;
+
+      old = g_newa (GDataElt, n_keys);
+
+      data = d->data;
+      data_end = data + d->len;
+      found_keys = 0;
+
+      while (data < data_end && found_keys < n_keys)
+        {
+          gboolean remove = FALSE;
+
+          for (gsize i = 0; i < n_keys; i++)
+            {
+              if (data->key == keys[i])
+                {
+                  remove = TRUE;
+                  break;
+                }
+            }
+
+          if (remove)
+            {
+              old[found_keys] = *data;
+              found_keys++;
+
+              if (data < data_end)
+                {
+                  data_end--;
+                  *data = *data_end;
+                }
+
+              d->len--;
+
+              /* We don't bother to shrink, but if all data are now gone
+               * we at least free the memory
+               */
+              if (d->len == 0)
+                {
+                  G_DATALIST_SET_POINTER (datalist, NULL);
+                  g_free (d);
+                  break;
+                }
+            }
+
+          data++;
+        }
+
+      if (found_keys > 0)
+        {
+          g_datalist_unlock (datalist);
+
+          for (gsize i = 0; i < found_keys; i++)
+            {
+              if (old[i].destroy)
+                old[i].destroy (old[i].data);
+            }
+
+          return;
+        }
+    }
+
+  g_datalist_unlock (datalist);
+}
+
 /**
  * g_dataset_id_set_data_full: (skip)
  * @dataset_location: (not nullable): the location identifying the dataset.
@@ -672,6 +752,29 @@ g_datalist_id_set_data_full (GData	  **datalist,
   g_data_set_internal (datalist, key_id, data, destroy_func, NULL);
 }
 
+/**
+ * g_datalist_id_remove_multiple:
+ * @datalist: a datalist
+ * @keys: (array length=n_keys): keys to remove
+ * @n_keys: length of @keys, must be <= 16
+ *
+ * Removes multiple keys from a datalist.
+ *
+ * This is more efficient than calling g_datalist_id_remove_data()
+ * multiple times in a row.
+ *
+ * Since: 2.74
+ */
+void
+g_datalist_id_remove_multiple (GData  **datalist,
+                               GQuark  *keys,
+                               gsize    n_keys)
+{
+  g_return_if_fail (n_keys <= 16);
+
+  g_data_remove_internal (datalist, keys, n_keys);
+}
+
 /**
  * g_dataset_id_remove_no_notify: (skip)
  * @dataset_location: (not nullable): the location identifying the dataset.

glib/gdataset.h

@@ -55,6 +55,10 @@ void     g_datalist_id_set_data_full    (GData            **datalist,
 					 GQuark             key_id,
 					 gpointer           data,
 					 GDestroyNotify     destroy_func);
+GLIB_AVAILABLE_IN_2_74
+void     g_datalist_id_remove_multiple  (GData            **datalist,
+                                         GQuark            *keys,
+                                         gsize              n_keys);
 
 typedef gpointer (*GDuplicateFunc) (gpointer data, gpointer user_data);