[gtk+] GtkPixelCache: Free cache if not used in 20 seconds

[Alexander Larsson <alexl src gnome org>]

commit 8ae7defad5ea93d2d502efcd5b13f5bc7ca0f1dc
Author: Alexander Larsson <alexl redhat com>
Date:   Tue May 7 14:27:17 2013 +0200

    GtkPixelCache: Free cache if not used in 20 seconds
    
    No need to keep a performance enhancing cache around if its not
    actually in use.

 gtk/gtkpixelcache.c |   33 +++++++++++++++++++++++++++++++++
 1 files changed, 33 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkpixelcache.c b/gtk/gtkpixelcache.c
index 91b9d8f..9b2f1d8 100644
--- a/gtk/gtkpixelcache.c
+++ b/gtk/gtkpixelcache.c
@@ -20,6 +20,8 @@
 #include "gtkdebug.h"
 #include "gtkpixelcacheprivate.h"
 
+#define BLOW_CACHE_TIMEOUT_SEC 20
+
 /* The extra size of the offscreen surface we allocate
    to make scrolling more efficient */
 #define EXTRA_SIZE 64
@@ -39,6 +41,8 @@ struct _GtkPixelCache {
 
   /* may be null if not dirty */
   cairo_region_t *surface_dirty;
+
+  guint timeout_tag;
 };
 
 GtkPixelCache *
@@ -57,6 +61,9 @@ _gtk_pixel_cache_free (GtkPixelCache *cache)
   if (cache == NULL)
     return;
 
+  if (cache->timeout_tag)
+    g_source_remove (cache->timeout_tag);
+
   if (cache->surface != NULL)
     cairo_surface_destroy (cache->surface);
 
@@ -322,6 +329,26 @@ _gtk_pixel_cache_repaint (GtkPixelCache *cache,
     }
 }
 
+static gboolean
+blow_cache_cb  (gpointer user_data)
+{
+  GtkPixelCache *cache = user_data;
+
+  cache->timeout_tag = 0;
+
+  if (cache->surface)
+    {
+      cairo_surface_destroy (cache->surface);
+      cache->surface = NULL;
+      if (cache->surface_dirty)
+       cairo_region_destroy (cache->surface_dirty);
+      cache->surface_dirty = NULL;
+    }
+
+  return G_SOURCE_REMOVE;
+}
+
+
 void
 _gtk_pixel_cache_draw (GtkPixelCache *cache,
                       cairo_t *cr,
@@ -333,6 +360,12 @@ _gtk_pixel_cache_draw (GtkPixelCache *cache,
                       GtkPixelCacheDrawFunc draw,
                       gpointer user_data)
 {
+  if (cache->timeout_tag)
+    g_source_remove (cache->timeout_tag);
+
+  cache->timeout_tag = g_timeout_add_seconds (BLOW_CACHE_TIMEOUT_SEC,
+                                             blow_cache_cb, cache);
+
   _gtk_pixel_cache_create_surface_if_needed (cache, window,
                                             view_rect, canvas_rect);
   _gtk_pixel_cache_set_position (cache, view_rect, canvas_rect);