components/performance_manager/public/graph/graph.h

// Copyright 2019 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 COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_GRAPH_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_GRAPH_H_

#include <cstdint>
#include <memory>
#include <vector>

#include "base/dcheck_is_on.h"
#include "base/memory/ptr_util.h"

namespace ukm {
class UkmRecorder;
}  // namespace ukm

namespace performance_manager {

class GraphObserver;
class GraphOwned;
class GraphRegistered;
class FrameNode;
class FrameNodeObserver;
class NodeDataDescriberRegistry;
class PageNode;
class PageNodeObserver;
class ProcessNode;
class ProcessNodeObserver;
class SystemNode;
class SystemNodeObserver;
class WorkerNode;
class WorkerNodeObserver;

template <typename DerivedType>
class GraphRegisteredImpl;

// Represents a graph of the nodes representing a single browser. Maintains a
// set of nodes that can be retrieved in different ways, some indexed. Keeps
// a list of observers that are notified of node addition and removal.
class Graph {
 public:
  using Observer = GraphObserver;

  Graph();

  Graph(const Graph&) = delete;
  Graph& operator=(const Graph&) = delete;

  virtual ~Graph();

  // Adds an |observer| on the graph. It is safe for observers to stay
  // registered on the graph at the time of its death.
  virtual void AddGraphObserver(GraphObserver* observer) = 0;
  virtual void AddFrameNodeObserver(FrameNodeObserver* observer) = 0;
  virtual void AddPageNodeObserver(PageNodeObserver* observer) = 0;
  virtual void AddProcessNodeObserver(ProcessNodeObserver* observer) = 0;
  virtual void AddSystemNodeObserver(SystemNodeObserver* observer) = 0;
  virtual void AddWorkerNodeObserver(WorkerNodeObserver* observer) = 0;

  // Removes an |observer| from the graph.
  virtual void RemoveGraphObserver(GraphObserver* observer) = 0;
  virtual void RemoveFrameNodeObserver(FrameNodeObserver* observer) = 0;
  virtual void RemovePageNodeObserver(PageNodeObserver* observer) = 0;
  virtual void RemoveProcessNodeObserver(ProcessNodeObserver* observer) = 0;
  virtual void RemoveSystemNodeObserver(SystemNodeObserver* observer) = 0;
  virtual void RemoveWorkerNodeObserver(WorkerNodeObserver* observer) = 0;

  // For convenience, allows you to pass ownership of an object to the graph.
  // Useful for attaching observers that will live with the graph until it dies.
  // If you can name the object you can also take it back via "TakeFromGraph".
  virtual void PassToGraphImpl(std::unique_ptr<GraphOwned> graph_owned) = 0;
  virtual std::unique_ptr<GraphOwned> TakeFromGraph(
      GraphOwned* graph_owned) = 0;

  // Templated PassToGraph helper that also returns a pointer to the object,
  // which makes it easy to use PassToGraph in constructors.
  template <typename DerivedType>
  DerivedType* PassToGraph(std::unique_ptr<DerivedType> graph_owned) {
    DerivedType* object = graph_owned.get();
    PassToGraphImpl(std::move(graph_owned));
    return object;
  }

  // A TakeFromGraph helper for taking back the ownership of a GraphOwned
  // subclass.
  template <typename DerivedType>
  std::unique_ptr<DerivedType> TakeFromGraphAs(DerivedType* graph_owned) {
    return base::WrapUnique(
        static_cast<DerivedType*>(TakeFromGraph(graph_owned).release()));
  }

  // Registers an object with this graph. It is expected that no more than one
  // object of a given type is registered at a given moment, and that all
  // registered objects are unregistered before graph tear-down.
  virtual void RegisterObject(GraphRegistered* object) = 0;

  // Unregisters the provided |object|, which must previously have been
  // registered with "RegisterObject". It is expected that all registered
  // objects are unregistered before graph tear-down.
  virtual void UnregisterObject(GraphRegistered* object) = 0;

  // Returns the registered object of the given type, nullptr if none has been
  // registered.
  template <typename DerivedType>
  DerivedType* GetRegisteredObjectAs() {
    // Be sure to access the TypeId provided by GraphRegisteredImpl, in case
    // this class has other TypeId implementations.
    GraphRegistered* object =
        GetRegisteredObject(GraphRegisteredImpl<DerivedType>::TypeId());
    return static_cast<DerivedType*>(object);
  }

  // Returns a collection of all known nodes of the given type.