Started on Resource class.

src/shared/ppapi_proxy/plugin_resource.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 NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_PLUGIN_RESOURCE_H_
+#define NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_PLUGIN_RESOURCE_H_
+
+#include "native_client/src/include/nacl_base.h"
+#include "native_client/src/include/ref_counted.h"
+#include "native_client/src/shared/ppapi_proxy/plugin_resource_tracker.h"
+#include "ppapi/c/pp_resource.h"
+
+namespace ppapi_proxy {
+
+class PluginModule;
+
+// If you inherit from resource, make sure you add the class name here.
+#define FOR_ALL_RESOURCES(F) \
+  F(Audio) \
+  F(AudioConfig) \
+  F(Buffer) \
+  F(Graphics2D) \
+  F(Graphics3D) \
+  F(ImageData)
+
+// Forward declaration of PluginResource classes.
+#define DECLARE_RESOURCE_CLASS(RESOURCE) class RESOURCE;
+FOR_ALL_RESOURCES(DECLARE_RESOURCE_CLASS)
+#undef DECLARE_RESOURCE_CLASS
+
+class PluginResource : public nacl::RefCounted<PluginResource> {
+ public:
+  explicit PluginResource(PluginModule* module);
+  virtual ~PluginResource();
+
+  // Returns NULL if the resource is invalid or is a different type.
+  template<typename T>
+  static scoped_refptr<T> GetAs(PP_Resource res) {
+    scoped_refptr<PluginResource> resource =
+        PluginResourceTracker::Get()->GetResource(res);
+    return resource ? resource->Cast<T>() : NULL;
+  }
+
+  PluginModule* module() const { return module_; }
+
+  // Cast the resource into a specified type. This will return NULL if the
+  // resource does not match the specified type. Specializations of this
+  // template call into As* functions.
+  template <typename T> T* Cast() { return NULL; }
+
+  // Returns an resource id of this object. If the object doesn't have a
+  // resource id, new one is created with plugin refcount of 1. If it does,
+  // the refcount is incremented. Use this when you need to return a new
+  // reference to the plugin.
+  PP_Resource GetReference();
+
+  // When you need to ensure that a resource has a reference, but you do not
+  // want to increase the refcount (for example, if you need to call a plugin
+  // callback function with a reference), you can use this class. For example:
+  //
+  // plugin_callback(.., ScopedResourceId(resource).id, ...);
+  class ScopedResourceId {
+   public:
+    explicit ScopedResourceId(PluginResource* resource)
+        : id(resource->GetReference()) {}
+    ~ScopedResourceId() {
+      PluginResourceTracker::Get()->UnrefResource(id);
+    }
+    const PP_Resource id;
+  };
+
+ private:
+  // Type-specific getters for individual resource types. These will return
+  // NULL if the resource does not match the specified type. Used by the Cast()
+  // function.
+  #define DEFINE_TYPE_GETTER(RESOURCE)  \
+      virtual RESOURCE* As##RESOURCE() { return NULL; }
+  FOR_ALL_RESOURCES(DEFINE_TYPE_GETTER)
+  #undef DEFINE_TYPE_GETTER
+
+  // Call this macro in the derived class declaration to actually implement the
+  // type getter.
+  #define IMPLEMENT_RESOURCE(RESOURCE)  \
+      virtual RESOURCE* As##RESOURCE() { return this; }
+
+ private:
+  // If referenced by a plugin, holds the id of this resource object. Do not
+  // access this member directly, because it is possible that the plugin holds
+  // no references to the object, and therefore the resource_id_ is zero. Use
+  // either GetReference() to obtain a new resource_id and increase the
+  // refcount, or TemporaryReference when you do not want to increase the
+  // refcount.
+  PP_Resource resource_id_;
+
+  // Non-owning pointer to our module.
+  PluginModule* module_;
+
+  // Called by the resource tracker when the last plugin reference has been
+  // dropped.
+  friend class PluginResourceTracker;
+  void StoppedTracking();
+
+  DISALLOW_COPY_AND_ASSIGN(PluginResource);
+};
+
+// Cast() specializations.
+#define DEFINE_RESOURCE_CAST(Type)                   \
+  template <> inline Type* PluginResource::Cast<Type>() {  \
+      return As##Type();                             \
+  }
+
+FOR_ALL_RESOURCES(DEFINE_RESOURCE_CAST)
+#undef DEFINE_RESOURCE_CAST
+
+#undef FOR_ALL_RESOURCES
+}  // namespace ppapi_proxy
+
+#endif  // NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_PLUGIN_RESOURCE_H_
+