Started on Resource class.

src/shared/ppapi_proxy/plugin_resource_tracker.h

+// Copyright (c) 2010 The Native Client Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
+#define WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
+
+#include <map>
+#include <utility>
+
+#include "native_client/src/include/nacl_base.h"
+#include "native_client/src/include/ref_counted.h"
+#include "ppapi/c/pp_instance.h"
+#include "ppapi/c/pp_module.h"
+#include "ppapi/c/pp_resource.h"
+
+namespace ppapi_proxy {
+
+class PluginInstance;
+class PluginModule;
+class PluginResource;
+
+// This class maintains a global list of all live pepper resources. It allows
+// us to check resource ID validity and to map them to a specific module.
+//
+// This object is threadsafe.
+class PluginResourceTracker {
+ public:
+  // Returns the pointer to the singleton object.
+  static PluginResourceTracker* Get() {
+    static PluginResourceTracker tracker;
+    return &tracker;
+  }
+
+  // PP_Resources --------------------------------------------------------------
+
+  // The returned pointer will be NULL if there is no resource. Note that this
+  // return value is a scoped_refptr so that we ensure the resource is valid
+  // from the point of the lookup to the point that the calling code needs it.
+  // Otherwise, the plugin could Release() the resource on another thread and
+  // the object will get deleted out from under us.
+  scoped_refptr<PluginResource> GetResource(PP_Resource res) const;
+
+  // Increment resource's plugin refcount. See ResourceAndRefCount comments
+  // below.
+  bool AddRefResource(PP_Resource res);
+  bool UnrefResource(PP_Resource res);
+
+ private:
+  friend class PluginResource;
+
+  // Prohibit creation other then by the Singleton class.
+  PluginResourceTracker();
+  ~PluginResourceTracker();
+
+  // Adds the given resource to the tracker and assigns it a resource ID and
+  // refcount of 1. The assigned resource ID will be returned. Used only by the
+  // Resource class.
+  PP_Resource AddResource(PluginResource* resource);
+
+  // Last assigned resource ID.
+  PP_Resource last_id_;
+
+  // For each PP_Resource, keep the Resource* (as refptr) and plugin use count.
+  // This use count is different then Resource's RefCount, and is manipulated
+  // using this RefResource/UnrefResource. When it drops to zero, we just remove
+  // the resource from this resource tracker, but the resource object will be
+  // alive so long as some scoped_refptr still holds it's reference. This
+  // prevents plugins from forcing destruction of Resource objects.
+  typedef std::pair<scoped_refptr<PluginResource>, size_t> ResourceAndRefCount;
+  typedef std::map<PP_Resource, ResourceAndRefCount> ResourceMap;
+  ResourceMap live_resources_;
+
+  DISALLOW_COPY_AND_ASSIGN(PluginResourceTracker);
+};
+
+}  // namespace ppapi_proxy
+
+#endif  // WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
+