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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_EXECUTION_CONTEXT_EXECUTION_CONTEXT_ATTACHED_DATA_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_EXECUTION_CONTEXT_EXECUTION_CONTEXT_ATTACHED_DATA_H_
#include <type_traits>
#include "components/performance_manager/public/execution_context/execution_context.h"
#include "components/performance_manager/public/execution_context/execution_context_registry.h"
#include "components/performance_manager/public/graph/frame_node.h"
#include "components/performance_manager/public/graph/graph.h"
#include "components/performance_manager/public/graph/node_attached_data.h"
#include "components/performance_manager/public/graph/worker_node.h"
namespace performance_manager {
namespace execution_context {
// An adapter that can be used to associate NodeAttachedData with all node
// types that represent execution contexts. Under the hood this wraps
// ExternalNodeAttachedDataImpl for each of the underlying node types.
// It is expected that UserDataType have a constructor with the signature
// "UserDataType(const ExecutionContext*)".
template <typename UserDataType>
class ExecutionContextAttachedData {
public:
ExecutionContextAttachedData() = default;
ExecutionContextAttachedData(const ExecutionContextAttachedData&) = delete;
ExecutionContextAttachedData& operator=(const ExecutionContextAttachedData&) =
delete;
virtual ~ExecutionContextAttachedData() = default;
// Gets the user data for the given |object|, creating it if it doesn't yet
// exist.
template <typename NodeTypeOrExecutionContext>
static UserDataType* GetOrCreate(const NodeTypeOrExecutionContext* object) {
return Dispatch<GetOrCreateFunctor>(ExecutionContext::From(object));
}
// Gets the user data for the given |object|, returning nullptr if it doesn't
// exist.
template <typename NodeTypeOrExecutionContext>
static UserDataType* Get(const NodeTypeOrExecutionContext* object) {
return Dispatch<GetFunctor>(ExecutionContext::From(object));
}
// Destroys the user data associated with the given |object|, returning true
// on success or false if the user data did not exist to begin with.
template <typename NodeTypeOrExecutionContext>
static bool Destroy(const NodeTypeOrExecutionContext* object) {
return Dispatch<DestroyFunctor>(ExecutionContext::From(object));
}
private:
// A small adapter for UserDataType that makes it compatible with
// underlying node types.
class UserDataWrapper : public ExternalNodeAttachedDataImpl<UserDataWrapper>,
public UserDataType {
public:
explicit UserDataWrapper(const FrameNode* frame_node)
: UserDataType(
ExecutionContextRegistry::GetFromGraph(frame_node->GetGraph())
->GetExecutionContextForFrameNode(frame_node)) {}
explicit UserDataWrapper(const WorkerNode* worker_node)
: UserDataType(
ExecutionContextRegistry::GetFromGraph(worker_node->GetGraph())
->GetExecutionContextForWorkerNode(worker_node)) {}
};
// Helpers for dynamic dispatch to various functions based on the underlying
// node type.
struct GetOrCreateFunctor {
using ReturnType = UserDataType*;
template <typename NodeType>
static UserDataType* Do(const NodeType* node) {
return ExternalNodeAttachedDataImpl<UserDataWrapper>::GetOrCreate(node);
}
};
struct GetFunctor {
using ReturnType = UserDataType*;
template <typename NodeType>
static UserDataType* Do(const NodeType* node) {
return ExternalNodeAttachedDataImpl<UserDataWrapper>::Get(node);
}
};
struct DestroyFunctor {
using ReturnType = bool;
template <typename NodeType>
static bool Do(const NodeType* node) {
return ExternalNodeAttachedDataImpl<UserDataWrapper>::Destroy(node);
}
};
// Helper for dynamic dispatching based on underlying node type.
template <typename Functor>
static typename Functor::ReturnType Dispatch(const ExecutionContext* ec) {
switch (ec->GetType()) {
case ExecutionContextType::kFrameNode:
return Functor::Do(ec->GetFrameNode());
case ExecutionContextType::kWorkerNode:
return Functor::Do(ec->GetWorkerNode());
}
}
};
} // namespace execution_context
} // namespace performance_manager
#endif // COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_EXECUTION_CONTEXT_EXECUTION_CONTEXT_ATTACHED_DATA_H_
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