[glib/halfline/debug-metrics: 3/9] gobject: Add debug metrics for gnome-shell

[Ray Strode <halfline src gnome org>]

commit 6f290decd1227472208d0cfb6521672bb8cb8269
Author: Ray Strode <rstrode redhat com>
Date:   Wed May 26 23:47:11 2021 -0400

    gobject: Add debug metrics for gnome-shell

 gobject/gobject.c | 194 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 191 insertions(+), 3 deletions(-)
---
diff --git a/gobject/gobject.c b/gobject/gobject.c
index d67987437..fa96e58a4 100644
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -23,6 +23,7 @@
 
 #include <string.h>
 #include <signal.h>
+#include <malloc.h>
 
 #include "gobject.h"
 #include "gtype-private.h"
@@ -317,7 +318,8 @@ g_object_notify_queue_add (GObject            *object,
 
 #ifdef G_ENABLE_DEBUG
 G_LOCK_DEFINE_STATIC     (debug_objects);
-static guint            debug_objects_count = 0;
+static gulong           debug_objects_count = 0;
+static gulong           debug_objects_watermark = 0;
 static GHashTable      *debug_objects_ht = NULL;
 
 static void
@@ -340,17 +342,176 @@ debug_objects_foreach (gpointer key,
 G_DEFINE_DESTRUCTOR(debug_objects_atexit)
 #endif /* G_HAS_CONSTRUCTORS */
 
+typedef struct _GTypeMetrics GTypeMetrics;
+struct _GTypeMetrics {
+  long  instance_count;
+  long  instance_change;
+  long  instance_watermark;
+};
+
+static GMetricsFile *objects_by_type_metrics_file;
+static GMetricsFile *object_totals_metrics_file;
+static GMetricsTable *histograms[2] = { NULL };
+static int old_histogram_index = 0;
+static GMetricsTable *old_histogram = NULL;
+
 static void
 debug_objects_atexit (void)
 {
   GOBJECT_IF_DEBUG (OBJECTS,
     {
+      int i;
       G_LOCK (debug_objects);
-      g_message ("stale GObjects: %u", debug_objects_count);
-      g_hash_table_foreach (debug_objects_ht, debug_objects_foreach, NULL);
+      g_message ("stale GObjects: %lu", debug_objects_count);
+      if (debug_objects_ht)
+        {
+          g_hash_table_foreach (debug_objects_ht, debug_objects_foreach, NULL);
+          g_clear_pointer (&debug_objects_ht, g_hash_table_unref);
+        }
+
+      for (i = 0; i < G_N_ELEMENTS (histograms); i++)
+        g_clear_pointer (histograms + i, g_hash_table_unref);
       G_UNLOCK (debug_objects);
     });
 }
+
+static gint
+metrics_sort (GTypeMetrics *a, GTypeMetrics *b)
+{
+  return b->instance_count - a->instance_count;
+}
+
+static void
+on_object_metrics_timeout (void)
+{
+  static gulong old_debug_objects_count = 0;
+
+  if (_g_type_debug_flags & G_TYPE_DEBUG_OBJECTS)
+    {
+      gpointer object;
+      GMetricsTable *histogram;
+      guint new_histogram_index = (old_histogram_index + 1) % G_N_ELEMENTS (histograms);
+      long change;
+
+      old_histogram = histograms[old_histogram_index];
+
+      if (histograms[new_histogram_index] == NULL)
+        histograms[new_histogram_index] = g_metrics_table_new (sizeof (GTypeMetrics));
+
+      histogram = histograms[new_histogram_index];
+      g_metrics_table_clear (histogram);
+      malloc_trim(0);
+
+      G_LOCK (debug_objects);
+      change = debug_objects_count - old_debug_objects_count;
+      old_debug_objects_count = debug_objects_count;
+
+      if (object_totals_metrics_file)
+        {
+          g_metrics_file_start_record (object_totals_metrics_file);
+          g_metrics_file_add_row (object_totals_metrics_file,
+                                  (gpointer) debug_objects_count,
+                                  change > 0? "+" : "",
+                                  change,
+                                  debug_objects_watermark);
+          g_metrics_file_end_record (object_totals_metrics_file);
+        }
+
+      if (objects_by_type_metrics_file)
+        {
+          GHashTableIter iter;
+          g_hash_table_iter_init (&iter, debug_objects_ht);
+          while (g_hash_table_iter_next (&iter, NULL, &object))
+            {
+              GType type;
+              GTypeMetrics *metrics;
+              long old_instance_count = 0, old_instance_watermark = 0;
+              const char *name;
+
+              if (!G_IS_OBJECT (object))
+                continue;
+
+              type = G_OBJECT_TYPE (object);
+              name = g_type_name (type);
+
+              if (old_histogram != NULL)
+                {
+                  GTypeMetrics *old_metrics = NULL;
+
+                  old_metrics = g_metrics_table_get_record (old_histogram, name);
+
+                  if (old_metrics != NULL)
+                    {
+                      old_instance_count = old_metrics->instance_count;
+                      old_instance_watermark = old_metrics->instance_watermark;
+                    }
+                }
+
+              metrics = g_metrics_table_get_record (histogram, name);
+              if (metrics == NULL)
+                {
+                  GTypeMetrics new_metrics = { 0 };
+                  g_metrics_table_set_record (histogram, name, &new_metrics);
+
+                  metrics = g_metrics_table_get_record (histogram, name);
+                }
+
+              metrics->instance_count++;
+              metrics->instance_change = metrics->instance_count - old_instance_count;
+              metrics->instance_watermark = MAX (metrics->instance_watermark, metrics->instance_count);
+              metrics->instance_watermark = MAX (metrics->instance_watermark, old_instance_watermark);
+            }
+
+          if (old_histogram != NULL)
+            {
+              GTypeMetrics *old_metrics = NULL;
+              const char *name = NULL;
+              GMetricsTableIter metrics_iter;
+
+              g_metrics_table_iter_init (&metrics_iter, old_histogram);
+              while (g_metrics_table_iter_next (&metrics_iter, &name, &old_metrics))
+                {
+                  GTypeMetrics *metrics;
+
+                  metrics = g_metrics_table_get_record (histogram, name);
+                  if (metrics == NULL)
+                    {
+                      GTypeMetrics new_metrics = { 0 };
+                      new_metrics.instance_change = -old_metrics->instance_count;
+                      g_metrics_table_set_record (histogram, name, &new_metrics);
+                    }
+                }
+            }
+        }
+      G_UNLOCK (debug_objects);
+
+      if (objects_by_type_metrics_file)
+        {
+          GMetricsTableIter iter;
+          GTypeMetrics *metrics = NULL;
+          const char *name = NULL;
+
+          g_metrics_file_start_record (objects_by_type_metrics_file);
+          g_metrics_table_sorted_iter_init (&iter, histogram, (GCompareFunc) metrics_sort);
+          while (g_metrics_table_iter_next (&iter, &name, &metrics))
+            {
+              if (metrics->instance_change == 0)
+                  continue;
+
+              g_metrics_file_add_row (objects_by_type_metrics_file,
+                                      name,
+                                      metrics->instance_count,
+                                      metrics->instance_change > 0? "+" : "",
+                                      metrics->instance_change,
+                                      metrics->instance_watermark);
+            }
+          g_metrics_file_end_record (objects_by_type_metrics_file);
+        }
+      if (old_histogram != NULL)
+        g_metrics_table_clear (old_histogram);
+      old_histogram_index = new_histogram_index;
+    };
+}
 #endif /* G_ENABLE_DEBUG */
 
 void
@@ -383,6 +544,9 @@ _g_object_type_init (void)
     g_value_object_lcopy_value,          /* lcopy_value */
   };
   GType type;
+#if G_ENABLE_DEBUG
+  gboolean needs_object_metrics = FALSE, needs_object_totals = FALSE;
+#endif
   
   g_return_if_fail (initialized == FALSE);
   initialized = TRUE;
@@ -395,6 +559,12 @@ _g_object_type_init (void)
   g_value_register_transform_func (G_TYPE_OBJECT, G_TYPE_OBJECT, g_value_object_transform_value);
 
 #if G_ENABLE_DEBUG
+  needs_object_metrics = g_metrics_requested ("objects-by-type");
+  needs_object_totals = g_metrics_requested ("object-totals");
+
+  if (needs_object_metrics || needs_object_totals)
+    _g_type_debug_flags |= G_TYPE_DEBUG_OBJECTS;
+
   /* We cannot use GOBJECT_IF_DEBUG here because of the G_HAS_CONSTRUCTORS
    * conditional in between, as the C spec leaves conditionals inside macro
    * expansions as undefined behavior. Only GCC and Clang are known to work
@@ -408,6 +578,23 @@ _g_object_type_init (void)
 # ifndef G_HAS_CONSTRUCTORS
       g_atexit (debug_objects_atexit);
 # endif /* G_HAS_CONSTRUCTORS */
+
+      if (needs_object_metrics)
+        objects_by_type_metrics_file = g_metrics_file_new ("objects-by-type",
+                                                           "name", "%s",
+                                                           "count", "%ld",
+                                                           "change", "%s%ld",
+                                                           "max seen", "%lu",
+                                                           NULL);
+
+      if (needs_object_totals)
+        object_totals_metrics_file = g_metrics_file_new ("object-totals",
+                                                         "count", "%ld",
+                                                         "change", "%s%ld",
+                                                         "max seen", "%lu",
+                                                         NULL);
+      if (needs_object_totals || needs_object_metrics)
+        g_metrics_start_timeout (on_object_metrics_timeout);
     }
 #endif /* G_ENABLE_DEBUG */
 }
@@ -1009,6 +1196,7 @@ g_object_init (GObject            *object,
     {
       G_LOCK (debug_objects);
       debug_objects_count++;
+      debug_objects_watermark = MAX (debug_objects_count, debug_objects_watermark);
       g_hash_table_add (debug_objects_ht, object);
       G_UNLOCK (debug_objects);
     });