GTK: Cache our GdkCursor objects, since building them hits the disk.

chrome/common/gtk_util.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/gtk_util.h"
 
 #include <gtk/gtk.h>
 #include <gdk/gdkx.h>
 
 #include <cstdarg>
@@ skipping 40 matching lines @@
 
 // Ownership of |icon_list| is passed to the caller.
 GList* GetIconList() {
   ResourceBundle& rb = ResourceBundle::GetSharedInstance();
   GList* icon_list = NULL;
   icon_list = g_list_append(icon_list, rb.GetPixbufNamed(IDR_PRODUCT_ICON_32));
   icon_list = g_list_append(icon_list, rb.GetPixbufNamed(IDR_PRODUCT_LOGO_16));
   return icon_list;
 }
 
+// A process wide singleton that manages our usage of gdk
+// cursors. gdk_cursor_new() hits the disk in several places and GdkCursor
+// instances can be reused throughout the process.
+class GdkCursorCache {
+ public:
+  ~GdkCursorCache() {
+    for (std::map<GdkCursorType, GdkCursor*>::iterator it =
+             cursor_cache_.begin(); it != cursor_cache_.end(); ++it) {
+      gdk_cursor_unref(it->second);
+    }
+    cursor_cache_.clear();
+  }
+
+  GdkCursor* GetCursorImpl(GdkCursorType type) {
+    std::map<GdkCursorType, GdkCursor*>::iterator it = cursor_cache_.find(type);
+    GdkCursor* cursor = NULL;
+    if (it == cursor_cache_.end()) {
+      cursor = gdk_cursor_new(type);
+      cursor_cache_.insert(std::make_pair(type, cursor));
+    } else {
+      cursor = it->second;
+    }
+
+    // Add a reference to the returned cursor because our consumers mix us with
+    // gdk_cursor_new() calls which return a +1 refcount.
+    gdk_cursor_ref(cursor);

[Evan Martin, 2009/09/12 00:37:05]

Won't this cause a +2 refcount on a cache miss?

+    return cursor;
+  }
+
+  std::map<GdkCursorType, GdkCursor*> cursor_cache_;
+};
+
 }  // namespace
 
 namespace event_utils {
 
 WindowOpenDisposition DispositionFromEventFlags(guint event_flags) {
   if ((event_flags & GDK_BUTTON2_MASK) || (event_flags & GDK_CONTROL_MASK)) {
     return (event_flags & GDK_SHIFT_MASK) ?
         NEW_FOREGROUND_TAB : NEW_BACKGROUND_TAB;
   }
 
@@ skipping 396 matching lines @@
 
 GdkColor AverageColors(GdkColor color_one, GdkColor color_two) {
   GdkColor average_color;
   average_color.pixel = 0;
   average_color.red = (color_one.red + color_two.red) / 2;
   average_color.green = (color_one.green + color_two.green) / 2;
   average_color.blue = (color_one.blue + color_two.blue) / 2;
   return average_color;
 }
 
+GdkCursor* GetCursor(GdkCursorType type) {
+  static GdkCursorCache impl;
+  return impl.GetCursorImpl(type);
+}
+
 }  // namespace gtk_util