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// Copyright (c) 2010 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.
#ifndef WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
#define WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
#include <set>
#include "base/atomic_sequence_num.h"
#include "base/basictypes.h"
#include "base/hash_tables.h"
#include "base/ref_counted.h"
#include "base/singleton.h"
#include "third_party/ppapi/c/pp_resource.h"
namespace pepper {
class Resource;
// 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 ResourceTracker {
public:
// Returns the pointer to the singleton object.
static ResourceTracker* Get() {
return Singleton<ResourceTracker>::get();
}
// 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<Resource> 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 struct DefaultSingletonTraits<ResourceTracker>;
friend class Resource;
// Prohibit creation other then by the Singleton class.
ResourceTracker() : last_id_(0) {}
~ResourceTracker() {}
// 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(Resource* 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<Resource>, size_t> ResourceAndRefCount;
typedef base::hash_map<PP_Resource, ResourceAndRefCount> ResourceMap;
ResourceMap live_resources_;
DISALLOW_COPY_AND_ASSIGN(ResourceTracker);
};
} // namespace pepper
#endif // WEBKIT_GLUE_PLUGINS_PEPPER_RESOURCE_TRACKER_H_
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