[glib/gobject-speedups4] Apply 6 suggestion(s) to 1 file(s)

[Matthias Clasen <matthiasc src gnome org>]

commit 922f9628323e787807783aae810d07bf21862b9b
Author: Philip Withnall <philip tecnocode co uk>
Date:   Tue Jun 7 12:38:04 2022 +0000

    Apply 6 suggestion(s) to 1 file(s)

 gobject/gobject.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)
---
diff --git a/gobject/gobject.c b/gobject/gobject.c
index 81d06eba40..e644c73178 100644
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -721,16 +721,28 @@ compare_pspec_entry (const void *a,
   return ae->name < be->name ? -1 : (ae->name > be->name ? 1 : 0);
 }
 
+/* This uses pointer comparisons with @property_name, so
+ * will only work with string literals. */
 static inline GParamSpec *
 find_pspec (GObjectClass *class,
             const char   *property_name)
 {
-  PspecEntry *pspecs = (PspecEntry *)class->pspecs;
-  guint n_pspecs = class->n_pspecs;
+  const PspecEntry *pspecs = (const PspecEntry *)class->pspecs;
+  gsize n_pspecs = class->n_pspecs;
 
+  /* The limit for choosing between linear and binary search is
+   * fairly arbitrary.
+   *
+   * Both searches use pointer comparisons against @property_name.
+   * If this function is called with a non-static @property_name,
+   * it will fall through to the g_param_spec_pool_lookup() case.
+   * That’s OK; this is an opportunistic optimisation which relies
+   * on the fact that *most* (but not all) property lookups use
+   * static property names.
+   */
   if (n_pspecs < 10)
     {
-      for (guint i = 0; i < n_pspecs; i++)
+      for (gsize i = 0; i < n_pspecs; i++)
         {
           if (pspecs[i].name == property_name)
             return pspecs[i].pspec;
@@ -868,6 +880,14 @@ g_object_class_install_properties (GObjectClass  *oclass,
         }
     }
 
+  /* Save a copy of the pspec array inside the class struct. This
+   * makes it faster to look up pspecs for the class in future when
+   * acting on those properties.
+   *
+   * If a pspec is not in this cache array, calling code will fall
+   * back to using g_param_spec_pool_lookup(), so a pspec not being
+   * in this array is a (potential) performance problem but not a
+   * correctness problem. */
   if (oclass->pspecs == NULL)
     {
       PspecEntry *entries = g_new (PspecEntry, n_pspecs - 1);