// Copyright 2020 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.

#include "components/performance_manager/public/v8_memory/v8_detailed_memory.h"

#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/check.h"
#include "base/containers/contains.h"
#include "base/containers/flat_set.h"
#include "base/memory/weak_ptr.h"
#include "base/stl_util.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "base/timer/timer.h"
#include "base/types/pass_key.h"
#include "components/performance_manager/public/execution_context/execution_context.h"
#include "components/performance_manager/public/execution_context/execution_context_attached_data.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/node_data_describer_registry.h"
#include "components/performance_manager/public/graph/process_node.h"
#include "components/performance_manager/public/graph/worker_node.h"
#include "components/performance_manager/public/performance_manager.h"
#include "components/performance_manager/public/render_frame_host_proxy.h"
#include "components/performance_manager/public/render_process_host_proxy.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/render_process_host.h"
#include "third_party/blink/public/common/tokens/tokens.h"

namespace performance_manager {

namespace v8_memory {

class V8DetailedMemoryDecorator::MeasurementRequestQueue {
 public:
  MeasurementRequestQueue() = default;

  ~MeasurementRequestQueue();

  const V8DetailedMemoryRequest* GetNextRequest() const;
  const V8DetailedMemoryRequest* GetNextBoundedRequest() const;

  void AddMeasurementRequest(V8DetailedMemoryRequest* request);

  // Removes |request| if it is part of this queue, and returns the number of
  // elements removed (will be 0 or 1).
  size_t RemoveMeasurementRequest(V8DetailedMemoryRequest* request);

  void NotifyObserversOnMeasurementAvailable(
      const ProcessNode* process_node) const;

  void OnOwnerUnregistered();

  // Check the data invariant on the measurement request lists.
  void Validate();

 private:
  void ApplyToAllRequests(
      base::RepeatingCallback<void(V8DetailedMemoryRequest*)> callback) const;

  // Lists of requests sorted by min_time_between_requests (lowest first).
  std::vector<V8DetailedMemoryRequest*> bounded_measurement_requests_
      GUARDED_BY_CONTEXT(sequence_checker_);
  std::vector<V8DetailedMemoryRequest*> lazy_measurement_requests_
      GUARDED_BY_CONTEXT(sequence_checker_);

  SEQUENCE_CHECKER(sequence_checker_);
};

// This class is allowed to access
// V8DetailedMemoryDecorator::NotifyObserversOnMeasurementAvailable.
class V8DetailedMemoryDecorator::ObserverNotifier {
 public:
  void NotifyObserversOnMeasurementAvailable(const ProcessNode* process_node) {
    auto* decorator =
        V8DetailedMemoryDecorator::GetFromGraph(process_node->GetGraph());
    if (decorator)
      decorator->NotifyObserversOnMeasurementAvailable(
          base::PassKey<ObserverNotifier>(), process_node);
  }
};

namespace {

using MeasurementMode = V8DetailedMemoryRequest::MeasurementMode;

// Forwards the pending receiver to the RenderProcessHost and binds it on the
// UI thread.
void BindReceiverOnUIThread(
    mojo::PendingReceiver<blink::mojom::V8DetailedMemoryReporter>
        pending_receiver,
    RenderProcessHostProxy proxy) {
  auto* render_process_host = proxy.Get();
  if (render_process_host) {
    render_process_host->BindReceiver(std::move(pending_receiver));
  }
}

bool IsMeasurementBounded(MeasurementMode mode) {
  switch (mode) {
    case MeasurementMode::kLazy:
      return false;
    case MeasurementMode::kBounded:
      return true;
    case MeasurementMode::kEagerForTesting:
      return true;
  }
}

// Returns the higher priority request of |a| and |b|, either of which can be
// null, or nullptr if both are null.
const V8DetailedMemoryRequest* ChooseHigherPriorityRequest(
    const V8DetailedMemoryRequest* a,
    const V8DetailedMemoryRequest* b) {
  if (!a)
    return b;
  if (!b)
    return a;
  if (a->min_time_between_requests() < b->min_time_between_requests())
    return a;
  if (b->min_time_between_requests() < a->min_time_between_requests())
    return b;
  // Break ties by prioritizing bounded requests.
  if (IsMeasurementBounded(a->mode()))
    return a;
  return b;
}

// May only be used from the performance manager sequence.
internal::BindV8DetailedMemoryReporterCallback* g_test_bind_callback = nullptr;

#if DCHECK_IS_ON()
// May only be used from the performance manager sequence.
bool g_test_eager_measurement_requests_enabled = false;
#endif

// Per-frame memory measurement involves the following classes that live on the
// PM sequence:
//
// V8DetailedMemoryDecorator: Central rendezvous point. Coordinates
//     V8DetailedMemoryRequest and V8DetailedMemoryObserver objects. Owned by
//     the graph; created the first time
//     V8DetailedMemoryRequest::StartMeasurement is called.
//     TODO(b/1080672): Currently this lives forever; should be cleaned up when
//     there are no more measurements scheduled.
//
// V8DetailedMemoryRequest: Indicates that a caller wants memory to be measured
//     at a specific interval. Owned by the caller but must live on the PM
//     sequence. V8DetailedMemoryRequest objects register themselves with
//     V8DetailedMemoryDecorator on creation and unregister themselves on
//     deletion, which cancels the corresponding measurement.
//
// NodeAttachedProcessData: Private class that schedules measurements and holds
//     the results for an individual process. Owned by the ProcessNode; created
//     when measurements start.
//     TODO(b/1080672): Currently this lives forever; should be cleaned up when
//     there are no more measurements scheduled.
//
// V8DetailedMemoryProcessData: Public accessor to the measurement results held
//     in a NodeAttachedProcessData, which owns it.
//
// ExecutionContextAttachedData: Private class that holds the measurement
//     results for an execution context. Owned by the ExecutionContext; created
//     when a measurement result arrives.
//     TODO(b/1080672): Currently this lives forever; should be cleaned up when
//     there are no more measurements scheduled.
//
// V8DetailedMemoryExecutionContextData: Public accessor to the measurement
//     results held in a ExecutionContextAttachedData, which owns it.
//
// V8DetailedMemoryObserver: Callers can implement this and register with
//     V8DetailedMemoryDecorator::AddObserver() to be notified when
//     measurements are available for a process. Owned by the caller but must
//     live on the PM sequence.
//
// Additional wrapper classes can access these classes from other sequences:
//
// V8DetailedMemoryRequestAnySeq: Wraps V8DetailedMemoryRequest. Owned by the
//     caller and lives on any sequence.
//
// V8DetailedMemoryObserverAnySeq: Callers can implement this and register it
//     with V8DetailedMemoryRequestAnySeq::AddObserver() to be notified when
//     measurements are available for a process. Owned by the caller and lives
//     on the same sequence as the V8DetailedMemoryRequestAnySeq.

////////////////////////////////////////////////////////////////////////////////
// ExecutionContextAttachedData

class ExecutionContextAttachedData
    : public execution_context::ExecutionContextAttachedData<
          ExecutionContextAttachedData> {
 public:
  explicit ExecutionContextAttachedData(
      const execution_context::ExecutionContext* ec) {}
  ~ExecutionContextAttachedData() override = default;

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

  const V8DetailedMemoryExecutionContextData* data() const {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    return data_available_ ? &data_ : nullptr;
  }

 private:
  friend class NodeAttachedProcessData;
  friend class performance_manager::v8_memory::
      V8DetailedMemoryExecutionContextData;

  V8DetailedMemoryExecutionContextData data_
      GUARDED_BY_CONTEXT(sequence_checker_);
  bool data_available_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
  SEQUENCE_CHECKER(sequence_checker_);
};

////////////////////////////////////////////////////////////////////////////////
// NodeAttachedProcessData

class NodeAttachedProcessData
    : public ExternalNodeAttachedDataImpl<NodeAttachedProcessData> {
 public:
  explicit NodeAttachedProcessData(const ProcessNode* process_node);
  ~NodeAttachedProcessData() override = default;

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

  // Runs the given |callback| for every ProcessNode in |graph| with type
  // PROCESS_TYPE_RENDERER, passing the NodeAttachedProcessData attached to the
  // node.
  static void ApplyToAllRenderers(
      Graph* graph,
      base::RepeatingCallback<void(NodeAttachedProcessData*)> callback);

  const V8DetailedMemoryProcessData* data() const {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    return data_available_ ? &data_ : nullptr;
  }

  void ScheduleNextMeasurement();

  V8DetailedMemoryDecorator::MeasurementRequestQueue&
  process_measurement_requests() {
    return process_measurement_requests_;
  }

  static V8DetailedMemoryProcessData* GetOrCreateForTesting(  // IN-TEST
      base::PassKey<V8DetailedMemoryProcessData>,
      const ProcessNode* process_node);

 private:
  void StartMeasurement(MeasurementMode mode);
  void ScheduleUpgradeToBoundedMeasurement();
  void UpgradeToBoundedMeasurementIfNeeded(MeasurementMode bounded_mode);
  void EnsureRemote();
  void OnV8MemoryUsage(blink::mojom::PerProcessV8MemoryUsagePtr result);

  const ProcessNode* const process_node_;

  // Measurement requests that will be sent to this process only.
  V8DetailedMemoryDecorator::MeasurementRequestQueue
      process_measurement_requests_ GUARDED_BY_CONTEXT(sequence_checker_);

  mojo::Remote<blink::mojom::V8DetailedMemoryReporter> resource_usage_reporter_
      GUARDED_BY_CONTEXT(sequence_checker_);

  // State transitions:
  //
  //   +-----------------------------------+
  //   |                                   |
  //   |               +-> MeasuringLazy +-+
  //   v               |         +
  // Idle +-> Waiting +>         |
  //   ^               |         v
  //   |               +-> MeasuringBounded +-+
  //   |                                      |
  //   +--------------------------------------+
  enum class State {
    kIdle,              // No measurements scheduled.
    kWaiting,           // Waiting to take a measurement.
    kMeasuringBounded,  // Waiting for results from a bounded measurement.
    kMeasuringLazy,     // Waiting for results from a lazy measurement.
  };
  State state_ GUARDED_BY_CONTEXT(sequence_checker_) = State::kIdle;

  // Used to schedule the next measurement.
  base::TimeTicks last_request_time_ GUARDED_BY_CONTEXT(sequence_checker_);
  base::OneShotTimer request_timer_ GUARDED_BY_CONTEXT(sequence_checker_);
  base::OneShotTimer bounded_upgrade_timer_
      GUARDED_BY_CONTEXT(sequence_checker_);

  V8DetailedMemoryProcessData data_ GUARDED_BY_CONTEXT(sequence_checker_);
  bool data_available_ GUARDED_BY_CONTEXT(sequence_checker_) = false;

  SEQUENCE_CHECKER(sequence_checker_);

  base::WeakPtrFactory<NodeAttachedProcessData> weak_factory_
      GUARDED_BY_CONTEXT(sequence_checker_){this};
};

NodeAttachedProcessData::NodeAttachedProcessData(
    const ProcessNode* process_node)
    : process_node_(process_node) {
  ScheduleNextMeasurement();
}

// static
void NodeAttachedProcessData::ApplyToAllRenderers(
    Graph* graph,
    base::RepeatingCallback<void(NodeAttachedProcessData*)> callback) {
  for (const ProcessNode* node : graph->GetAllProcessNodes()) {
    NodeAttachedProcessData* process_data = NodeAttachedProcessData::Get(node);
    if (!process_data) {
      // NodeAttachedProcessData should have been created for all renderer
      // processes in OnProcessNodeAdded.
      DCHECK_NE(content::PROCESS_TYPE_RENDERER, node->GetProcessType());
      continue;
    }
    callback.Run(process_data);
  }
}

void NodeAttachedProcessData::ScheduleNextMeasurement() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  process_measurement_requests_.Validate();

  if (state_ == State::kMeasuringLazy) {
    // Upgrade to a bounded measurement if the lazy measurement is taking too
    // long. Otherwise do nothing until the current measurement finishes.
    // ScheduleNextMeasurement will be called again at that point.
    ScheduleUpgradeToBoundedMeasurement();
    return;
  }

  if (state_ == State::kMeasuringBounded) {
    // Don't restart the timer until the current measurement finishes.
    // ScheduleNextMeasurement will be called again at that point.
    return;
  }

  // Find the next request for this process, checking both the per-process
  // queue and the global queue.
  const V8DetailedMemoryRequest* next_request =
      process_measurement_requests_.GetNextRequest();
  auto* decorator =
      V8DetailedMemoryDecorator::GetFromGraph(process_node_->GetGraph());
  if (decorator) {
    next_request =
        ChooseHigherPriorityRequest(next_request, decorator->GetNextRequest());
  }

  if (!next_request) {
    // All measurements have been cancelled, or decorator was removed from
    // graph.
    state_ = State::kIdle;
    request_timer_.Stop();
    bounded_upgrade_timer_.Stop();
    last_request_time_ = base::TimeTicks();
    return;
  }

  state_ = State::kWaiting;
  if (last_request_time_.is_null()) {
    // This is the first measurement. Perform it immediately.
    StartMeasurement(next_request->mode());
    return;
  }

  base::TimeTicks next_request_time =
      last_request_time_ + next_request->min_time_between_requests();
  request_timer_.Start(
      FROM_HERE, next_request_time - base::TimeTicks::Now(),
      base::BindOnce(&NodeAttachedProcessData::StartMeasurement,
                     base::Unretained(this), next_request->mode()));
}

void NodeAttachedProcessData::StartMeasurement(MeasurementMode mode) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (IsMeasurementBounded(mode)) {
    DCHECK(state_ == State::kWaiting || state_ == State::kMeasuringLazy);
    state_ = State::kMeasuringBounded;
  } else {
    DCHECK_EQ(state_, State::kWaiting);
    state_ = State::kMeasuringLazy;
    // Ensure this lazy measurement doesn't starve any bounded measurements in
    // the queue.
    ScheduleUpgradeToBoundedMeasurement();
  }

  last_request_time_ = base::TimeTicks::Now();

  EnsureRemote();

  // TODO(b/1080672): WeakPtr is used in case NodeAttachedProcessData is
  // cleaned up while a request to a renderer is outstanding. Currently this
  // never actually happens (it is destroyed only when the graph is torn down,
  // which should happen after renderers are destroyed). Should clean up
  // NodeAttachedProcessData when the last V8DetailedMemoryRequest is deleted,
  // which could happen at any time.
  blink::mojom::V8DetailedMemoryReporter::Mode mojo_mode;
  switch (mode) {
    case MeasurementMode::kLazy:
      mojo_mode = blink::mojom::V8DetailedMemoryReporter::Mode::LAZY;
      break;
    case MeasurementMode::kBounded:
      mojo_mode = blink::mojom::V8DetailedMemoryReporter::Mode::DEFAULT;
      break;
    case MeasurementMode::kEagerForTesting:
      mojo_mode = blink::mojom::V8DetailedMemoryReporter::Mode::EAGER;
      break;
  }

  resource_usage_reporter_->GetV8MemoryUsage(
      mojo_mode, base::BindOnce(&NodeAttachedProcessData::OnV8MemoryUsage,
                                weak_factory_.GetWeakPtr()));
}

void NodeAttachedProcessData::ScheduleUpgradeToBoundedMeasurement() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(state_, State::kMeasuringLazy);

  const V8DetailedMemoryRequest* bounded_request =
      process_measurement_requests_.GetNextBoundedRequest();
  auto* decorator =
      V8DetailedMemoryDecorator::GetFromGraph(process_node_->GetGraph());
  if (decorator) {
    bounded_request = ChooseHigherPriorityRequest(
        bounded_request, decorator->GetNextBoundedRequest());
  }
  if (!bounded_request) {
    // All measurements have been cancelled, or decorator was removed from
    // graph.
    return;
  }

  base::TimeTicks bounded_request_time =
      last_request_time_ + bounded_request->min_time_between_requests();
  bounded_upgrade_timer_.Start(
      FROM_HERE, bounded_request_time - base::TimeTicks::Now(),
      base::BindOnce(
          &NodeAttachedProcessData::UpgradeToBoundedMeasurementIfNeeded,
          base::Unretained(this), bounded_request->mode()));
}

void NodeAttachedProcessData::UpgradeToBoundedMeasurementIfNeeded(
    MeasurementMode bounded_mode) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (state_ != State::kMeasuringLazy) {
    // State changed before timer expired.
    return;
  }
  DCHECK(IsMeasurementBounded(bounded_mode));
  StartMeasurement(bounded_mode);
}

void NodeAttachedProcessData::OnV8MemoryUsage(
    blink::mojom::PerProcessV8MemoryUsagePtr result) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  // Data has arrived so don't upgrade lazy requests to bounded, even if
  // another lazy request is issued before the timer expires.
  bounded_upgrade_timer_.Stop();

  // Distribute the data to the frames.
  // If a frame doesn't have corresponding data in the result, clear any data
  // it may have had. Any datum in the result that doesn't correspond to an
  // existing frame is likewise accrued to detached bytes.
  uint64_t detached_v8_bytes_used = 0;
  uint64_t shared_v8_bytes_used = 0;
  uint64_t blink_bytes_used = 0;

  // Create a mapping from token to execution context usage for the merge below.
  std::vector<std::pair<blink::ExecutionContextToken,
                        blink::mojom::PerContextV8MemoryUsagePtr>>
      tmp;
  for (auto& isolate : result->isolates) {
    for (auto& entry : isolate->contexts) {
      tmp.emplace_back(entry->token, std::move(entry));
    }
    detached_v8_bytes_used += isolate->detached_bytes_used;
    shared_v8_bytes_used += isolate->shared_bytes_used;
    blink_bytes_used += isolate->blink_bytes_used;
  }

  size_t found_frame_count = tmp.size();

  base::flat_map<blink::ExecutionContextToken,
                 blink::mojom::PerContextV8MemoryUsagePtr>
      associated_memory(std::move(tmp));
  // Validate that the frame tokens were all unique. If there are duplicates,
  // the map will arbitrarily drop all but one record per unique token.
  DCHECK_EQ(associated_memory.size(), found_frame_count);

  std::vector<const execution_context::ExecutionContext*> execution_contexts;
  for (auto* node : process_node_->GetFrameNodes()) {
    execution_contexts.push_back(
        execution_context::ExecutionContext::From(node));
  }
  for (auto* node : process_node_->GetWorkerNodes()) {
    execution_contexts.push_back(
        execution_context::ExecutionContext::From(node));
  }

  for (const execution_context::ExecutionContext* ec : execution_contexts) {
    auto it = associated_memory.find(ec->GetToken());
    if (it == associated_memory.end()) {
      // No data for this node, clear any data associated with it.
      ExecutionContextAttachedData::Destroy(ec);
    } else {
      ExecutionContextAttachedData* ec_data =
          ExecutionContextAttachedData::GetOrCreate(ec);
      DCHECK_CALLED_ON_VALID_SEQUENCE(ec_data->sequence_checker_);

      ec_data->data_available_ = true;
      ec_data->data_.set_v8_bytes_used(it->second->bytes_used);
      ec_data->data_.set_url(std::move(it->second->url));
      // Zero out this datum as its usage has been consumed.
      // We avoid erase() here because it may take O(n) time.
      it->second.reset();
    }
  }

  for (const auto& it : associated_memory) {
    if (it.second.is_null()) {
      // Execution context was already consumed.
      continue;
    }
    // Accrue the data for non-existent frames to detached bytes.
    detached_v8_bytes_used += it.second->bytes_used;
  }

  data_available_ = true;
  data_.set_detached_v8_bytes_used(detached_v8_bytes_used);
  data_.set_shared_v8_bytes_used(shared_v8_bytes_used);
  data_.set_blink_bytes_used(blink_bytes_used);

  // Schedule another measurement for this process node unless one is already
  // scheduled.
  if (state_ != State::kWaiting) {
    state_ = State::kIdle;
    ScheduleNextMeasurement();
  }

  process_measurement_requests_.NotifyObserversOnMeasurementAvailable(
      process_node_);
  V8DetailedMemoryDecorator::ObserverNotifier()
      .NotifyObserversOnMeasurementAvailable(process_node_);
}

void NodeAttachedProcessData::EnsureRemote() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (resource_usage_reporter_.is_bound())
    return;

  // This interface is implemented in //content/renderer/performance_manager.
  mojo::PendingReceiver<blink::mojom::V8DetailedMemoryReporter>
      pending_receiver = resource_usage_reporter_.BindNewPipeAndPassReceiver();

  RenderProcessHostProxy proxy = process_node_->GetRenderProcessHostProxy();

  if (g_test_bind_callback) {
    g_test_bind_callback->Run(std::move(pending_receiver), std::move(proxy));
  } else {
    content::GetUIThreadTaskRunner({})->PostTask(
        FROM_HERE,
        base::BindOnce(&BindReceiverOnUIThread, std::move(pending_receiver),
                       std::move(proxy)));
  }
}

V8DetailedMemoryProcessData* NodeAttachedProcessData::GetOrCreateForTesting(
    base::PassKey<V8DetailedMemoryProcessData>,
    const ProcessNode* process_node) {
  auto* node_data = NodeAttachedProcessData::GetOrCreate(process_node);
  DCHECK_CALLED_ON_VALID_SEQUENCE(node_data->sequence_checker_);
  node_data->data_available_ = true;
  return &node_data->data_;
}

}  // namespace

namespace internal {

void SetBindV8DetailedMemoryReporterCallbackForTesting(
    BindV8DetailedMemoryReporterCallback* callback) {
  g_test_bind_callback = callback;
}

void SetEagerMemoryMeasurementEnabledForTesting(bool enabled) {
#if DCHECK_IS_ON()
  g_test_eager_measurement_requests_enabled = enabled;
#endif
}

void DestroyV8DetailedMemoryDecoratorForTesting(Graph* graph) {
  auto* decorator = V8DetailedMemoryDecorator::GetFromGraph(graph);
  if (decorator)
    graph->TakeFromGraph(decorator);
}

}  // namespace internal

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryRequest

V8DetailedMemoryRequest::V8DetailedMemoryRequest(
    const base::TimeDelta& min_time_between_requests,
    MeasurementMode mode)
    : min_time_between_requests_(min_time_between_requests), mode_(mode) {
#if DCHECK_IS_ON()
  DCHECK_GT(min_time_between_requests_, base::TimeDelta());
  DCHECK(!min_time_between_requests_.is_inf());
  DCHECK(mode != MeasurementMode::kEagerForTesting ||
         g_test_eager_measurement_requests_enabled);
#endif
}

V8DetailedMemoryRequest::V8DetailedMemoryRequest(
    const base::TimeDelta& min_time_between_requests,
    Graph* graph)
    : V8DetailedMemoryRequest(min_time_between_requests,
                              MeasurementMode::kDefault) {
  StartMeasurement(graph);
}

V8DetailedMemoryRequest::V8DetailedMemoryRequest(
    const base::TimeDelta& min_time_between_requests,
    MeasurementMode mode,
    Graph* graph)
    : V8DetailedMemoryRequest(min_time_between_requests, mode) {
  StartMeasurement(graph);
}

// This constructor is called from the V8DetailedMemoryRequestAnySeq's
// sequence.
V8DetailedMemoryRequest::V8DetailedMemoryRequest(
    base::PassKey<V8DetailedMemoryRequestAnySeq>,
    const base::TimeDelta& min_time_between_requests,
    MeasurementMode mode,
    base::Optional<base::WeakPtr<ProcessNode>> process_to_measure,
    base::WeakPtr<V8DetailedMemoryRequestAnySeq> off_sequence_request)
    : V8DetailedMemoryRequest(min_time_between_requests, mode) {
  DETACH_FROM_SEQUENCE(sequence_checker_);
  off_sequence_request_ = std::move(off_sequence_request);
  off_sequence_request_sequence_ = base::SequencedTaskRunnerHandle::Get();
  // Unretained is safe since |this| will be destroyed on the graph sequence
  // from an async task posted after this.
  PerformanceManager::CallOnGraph(
      FROM_HERE,
      base::BindOnce(&V8DetailedMemoryRequest::StartMeasurementFromOffSequence,
                     base::Unretained(this), std::move(process_to_measure)));
}

V8DetailedMemoryRequest::V8DetailedMemoryRequest(
    base::PassKey<V8DetailedMemoryRequestOneShot>,
    MeasurementMode mode,
    base::OnceClosure on_owner_unregistered_closure)
    : min_time_between_requests_(base::TimeDelta()),
      mode_(mode),
      on_owner_unregistered_closure_(std::move(on_owner_unregistered_closure)) {
  // Do not forward to the standard constructor because it disallows the empty
  // TimeDelta.
}

V8DetailedMemoryRequest::~V8DetailedMemoryRequest() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (decorator_)
    decorator_->RemoveMeasurementRequest(
        base::PassKey<V8DetailedMemoryRequest>(), this);
  // TODO(crbug.com/1080672): Delete the decorator and its NodeAttachedData
  // when the last request is destroyed. Make sure this doesn't mess up any
  // measurement that's already in progress.
}

void V8DetailedMemoryRequest::StartMeasurement(Graph* graph) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  StartMeasurementImpl(graph, nullptr);
}

void V8DetailedMemoryRequest::StartMeasurementForProcess(
    const ProcessNode* process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(process_node);
  DCHECK_EQ(process_node->GetProcessType(), content::PROCESS_TYPE_RENDERER);
  StartMeasurementImpl(process_node->GetGraph(), process_node);
}

void V8DetailedMemoryRequest::AddObserver(V8DetailedMemoryObserver* observer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  observers_.AddObserver(observer);
}

void V8DetailedMemoryRequest::RemoveObserver(
    V8DetailedMemoryObserver* observer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(observers_.HasObserver(observer));
  observers_.RemoveObserver(observer);
}

void V8DetailedMemoryRequest::OnOwnerUnregistered(
    base::PassKey<V8DetailedMemoryDecorator::MeasurementRequestQueue>) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  decorator_ = nullptr;
  if (on_owner_unregistered_closure_)
    std::move(on_owner_unregistered_closure_).Run();
}

void V8DetailedMemoryRequest::NotifyObserversOnMeasurementAvailable(
    base::PassKey<V8DetailedMemoryDecorator::MeasurementRequestQueue>,
    const ProcessNode* process_node) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  const auto* process_data =
      V8DetailedMemoryProcessData::ForProcessNode(process_node);
  DCHECK(process_data);

  // If this request was made from off-sequence, notify its off-sequence
  // observers with a copy of the process and frame data.
  if (off_sequence_request_.MaybeValid()) {
    using FrameAndData = std::pair<content::GlobalFrameRoutingId,
                                   V8DetailedMemoryExecutionContextData>;
    std::vector<FrameAndData> all_frame_data;
    process_node->VisitFrameNodes(base::BindRepeating(
        [](std::vector<FrameAndData>* all_frame_data,
           const FrameNode* frame_node) {
          const auto* frame_data =
              V8DetailedMemoryExecutionContextData::ForFrameNode(frame_node);
          if (frame_data) {
            all_frame_data->push_back(std::make_pair(
                frame_node->GetRenderFrameHostProxy().global_frame_routing_id(),
                *frame_data));
          }
          return true;
        },
        base::Unretained(&all_frame_data)));
    off_sequence_request_sequence_->PostTask(
        FROM_HERE,
        base::BindOnce(&V8DetailedMemoryRequestAnySeq::
                           NotifyObserversOnMeasurementAvailable,
                       off_sequence_request_,
                       base::PassKey<V8DetailedMemoryRequest>(),
                       process_node->GetRenderProcessHostId(), *process_data,
                       V8DetailedMemoryObserverAnySeq::FrameDataMap(
                           std::move(all_frame_data))));
  }

  // The observer could delete the request so this must be the last thing in
  // the function.
  for (V8DetailedMemoryObserver& observer : observers_)
    observer.OnV8MemoryMeasurementAvailable(process_node, process_data);
}

void V8DetailedMemoryRequest::StartMeasurementFromOffSequence(
    base::Optional<base::WeakPtr<ProcessNode>> process_to_measure,
    Graph* graph) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (!process_to_measure) {
    // No process was given so measure all renderers in the graph.
    StartMeasurement(graph);
  } else if (!process_to_measure.value()) {
    // V8DetailedMemoryRequestAnySeq was called with a process ID that wasn't
    // found in the graph, or has already been destroyed. Do nothing.
  } else {
    DCHECK_EQ(graph, process_to_measure.value()->GetGraph());
    StartMeasurementForProcess(process_to_measure.value().get());
  }
}

void V8DetailedMemoryRequest::StartMeasurementImpl(
    Graph* graph,
    const ProcessNode* process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(nullptr, decorator_);
  DCHECK(!process_node || graph == process_node->GetGraph());
  decorator_ = V8DetailedMemoryDecorator::GetFromGraph(graph);
  if (!decorator_) {
    // Create the decorator when the first measurement starts.
    auto decorator_ptr = std::make_unique<V8DetailedMemoryDecorator>();
    decorator_ = decorator_ptr.get();
    graph->PassToGraph(std::move(decorator_ptr));
  }

  decorator_->AddMeasurementRequest(base::PassKey<V8DetailedMemoryRequest>(),
                                    this, process_node);
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryRequestOneShot

V8DetailedMemoryRequestOneShot::V8DetailedMemoryRequestOneShot(
    MeasurementMode mode)
    : mode_(mode) {
  InitializeRequest();
}

V8DetailedMemoryRequestOneShot::V8DetailedMemoryRequestOneShot(
    const ProcessNode* process,
    MeasurementCallback callback,
    MeasurementMode mode)
    : mode_(mode) {
  InitializeRequest();
  StartMeasurement(process, std::move(callback));
}

V8DetailedMemoryRequestOneShot::~V8DetailedMemoryRequestOneShot() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DeleteRequest();
}

void V8DetailedMemoryRequestOneShot::StartMeasurement(
    const ProcessNode* process,
    MeasurementCallback callback) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(request_);
  DCHECK(process);
  DCHECK_EQ(process->GetProcessType(), content::PROCESS_TYPE_RENDERER);
#if DCHECK_IS_ON()
  process_ = process;
#endif

  callback_ = std::move(callback);
  request_->StartMeasurementForProcess(process);
}

void V8DetailedMemoryRequestOneShot::OnV8MemoryMeasurementAvailable(
    const ProcessNode* process_node,
    const V8DetailedMemoryProcessData* process_data) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

#if DCHECK_IS_ON()
  DCHECK_EQ(process_node, process_);
#endif

  // Don't send another request now that a response has been received.
  DeleteRequest();

  std::move(callback_).Run(process_node, process_data);
}

// This constructor is called from the V8DetailedMemoryRequestOneShotAnySeq's
// sequence.
V8DetailedMemoryRequestOneShot::V8DetailedMemoryRequestOneShot(
    base::PassKey<V8DetailedMemoryRequestOneShotAnySeq>,
    base::WeakPtr<ProcessNode> process,
    MeasurementCallback callback,
    MeasurementMode mode)
    : mode_(mode) {
  DETACH_FROM_SEQUENCE(sequence_checker_);
  // Unretained is safe since |this| will be destroyed on the graph sequence
  // from an async task posted after this.
  PerformanceManager::CallOnGraph(
      FROM_HERE,
      base::BindOnce(&V8DetailedMemoryRequestOneShot::InitializeRequest,
                     base::Unretained(this)));
  PerformanceManager::CallOnGraph(
      FROM_HERE,
      base::BindOnce(
          &V8DetailedMemoryRequestOneShot::StartMeasurementFromOffSequence,
          base::Unretained(this), std::move(process), std::move(callback)));
}

void V8DetailedMemoryRequestOneShot::InitializeRequest() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  request_ = std::make_unique<V8DetailedMemoryRequest>(
      base::PassKey<V8DetailedMemoryRequestOneShot>(), mode_,
      base::BindOnce(&V8DetailedMemoryRequestOneShot::OnOwnerUnregistered,
                     // Unretained is safe because |this| owns the request
                     // object that will invoke the closure.
                     base::Unretained(this)));
  request_->AddObserver(this);
}

void V8DetailedMemoryRequestOneShot::StartMeasurementFromOffSequence(
    base::WeakPtr<ProcessNode> process,
    MeasurementCallback callback) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (process)
    StartMeasurement(process.get(), std::move(callback));
}

void V8DetailedMemoryRequestOneShot::DeleteRequest() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (request_)
    request_->RemoveObserver(this);
  request_.reset();
}

void V8DetailedMemoryRequestOneShot::OnOwnerUnregistered() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // No results will arrive so clean up the request and callback. This frees
  // any resources that were owned by the callback.
  DeleteRequest();
  std::move(callback_).Reset();
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryExecutionContextData

V8DetailedMemoryExecutionContextData::V8DetailedMemoryExecutionContextData() =
    default;
V8DetailedMemoryExecutionContextData::~V8DetailedMemoryExecutionContextData() =
    default;

V8DetailedMemoryExecutionContextData::V8DetailedMemoryExecutionContextData(
    const V8DetailedMemoryExecutionContextData&) = default;
V8DetailedMemoryExecutionContextData::V8DetailedMemoryExecutionContextData(
    V8DetailedMemoryExecutionContextData&&) = default;
V8DetailedMemoryExecutionContextData&
V8DetailedMemoryExecutionContextData::operator=(
    const V8DetailedMemoryExecutionContextData&) = default;
V8DetailedMemoryExecutionContextData&
V8DetailedMemoryExecutionContextData::operator=(
    V8DetailedMemoryExecutionContextData&&) = default;

// static
const V8DetailedMemoryExecutionContextData*
V8DetailedMemoryExecutionContextData::ForFrameNode(const FrameNode* node) {
  const auto* ec = execution_context::ExecutionContext::From(node);
  return ForExecutionContext(ec);
}

// static
const V8DetailedMemoryExecutionContextData*
V8DetailedMemoryExecutionContextData::ForWorkerNode(const WorkerNode* node) {
  const auto* ec = execution_context::ExecutionContext::From(node);
  return ForExecutionContext(ec);
}

// static
const V8DetailedMemoryExecutionContextData*
V8DetailedMemoryExecutionContextData::ForExecutionContext(
    const execution_context::ExecutionContext* ec) {
  auto* node_data = ExecutionContextAttachedData::Get(ec);
  return node_data ? node_data->data() : nullptr;
}

V8DetailedMemoryExecutionContextData*
V8DetailedMemoryExecutionContextData::CreateForTesting(const FrameNode* node) {
  auto* node_data = ExecutionContextAttachedData::GetOrCreate(node);
  DCHECK_CALLED_ON_VALID_SEQUENCE(node_data->sequence_checker_);
  node_data->data_available_ = true;
  return &node_data->data_;
}

V8DetailedMemoryExecutionContextData*
V8DetailedMemoryExecutionContextData::CreateForTesting(const WorkerNode* node) {
  auto* node_data = ExecutionContextAttachedData::GetOrCreate(node);
  DCHECK_CALLED_ON_VALID_SEQUENCE(node_data->sequence_checker_);
  node_data->data_available_ = true;
  return &node_data->data_;
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryProcessData

const V8DetailedMemoryProcessData* V8DetailedMemoryProcessData::ForProcessNode(
    const ProcessNode* node) {
  auto* node_data = NodeAttachedProcessData::Get(node);
  return node_data ? node_data->data() : nullptr;
}

V8DetailedMemoryProcessData* V8DetailedMemoryProcessData::GetOrCreateForTesting(
    const ProcessNode* process_node) {
  return NodeAttachedProcessData::GetOrCreateForTesting(
      base::PassKey<V8DetailedMemoryProcessData>(), process_node);
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryDecorator

V8DetailedMemoryDecorator::V8DetailedMemoryDecorator()
    : measurement_requests_(std::make_unique<MeasurementRequestQueue>()) {}

V8DetailedMemoryDecorator::~V8DetailedMemoryDecorator() = default;

void V8DetailedMemoryDecorator::OnPassedToGraph(Graph* graph) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(nullptr, graph_);
  graph_ = graph;

  graph->RegisterObject(this);

  // Iterate over the existing process nodes to put them under observation.
  for (const ProcessNode* process_node : graph->GetAllProcessNodes())
    OnProcessNodeAdded(process_node);

  graph->AddProcessNodeObserver(this);
  graph->GetNodeDataDescriberRegistry()->RegisterDescriber(
      this, "V8DetailedMemoryDecorator");
}

void V8DetailedMemoryDecorator::OnTakenFromGraph(Graph* graph) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(graph, graph_);

  ApplyToAllRequestQueues(
      base::BindRepeating(&MeasurementRequestQueue::OnOwnerUnregistered));
  UpdateProcessMeasurementSchedules();

  graph->GetNodeDataDescriberRegistry()->UnregisterDescriber(this);
  graph->RemoveProcessNodeObserver(this);
  graph->UnregisterObject(this);
  graph_ = nullptr;
}

void V8DetailedMemoryDecorator::OnProcessNodeAdded(
    const ProcessNode* process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(nullptr, NodeAttachedProcessData::Get(process_node));

  // Only renderer processes have frames. Don't attempt to connect to other
  // process types.
  if (process_node->GetProcessType() != content::PROCESS_TYPE_RENDERER)
    return;

  // Creating the NodeAttachedProcessData will start a measurement.
  NodeAttachedProcessData::GetOrCreate(process_node);
}

void V8DetailedMemoryDecorator::OnBeforeProcessNodeRemoved(
    const ProcessNode* process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // Only renderer processes have data.
  if (process_node->GetProcessType() != content::PROCESS_TYPE_RENDERER)
    return;

  auto* process_data = NodeAttachedProcessData::Get(process_node);
  DCHECK(process_data);
  process_data->process_measurement_requests().OnOwnerUnregistered();
}

base::Value V8DetailedMemoryDecorator::DescribeFrameNodeData(
    const FrameNode* frame_node) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  const auto* const frame_data =
      V8DetailedMemoryExecutionContextData::ForFrameNode(frame_node);
  if (!frame_data)
    return base::Value();

  base::Value dict(base::Value::Type::DICTIONARY);
  dict.SetIntKey("v8_bytes_used", frame_data->v8_bytes_used());
  return dict;
}

base::Value V8DetailedMemoryDecorator::DescribeProcessNodeData(
    const ProcessNode* process_node) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  const auto* const process_data =
      V8DetailedMemoryProcessData::ForProcessNode(process_node);
  if (!process_data)
    return base::Value();

  DCHECK_EQ(content::PROCESS_TYPE_RENDERER, process_node->GetProcessType());

  base::Value dict(base::Value::Type::DICTIONARY);
  dict.SetIntKey("detached_v8_bytes_used",
                 process_data->detached_v8_bytes_used());
  dict.SetIntKey("shared_v8_bytes_used", process_data->shared_v8_bytes_used());
  return dict;
}

const V8DetailedMemoryRequest* V8DetailedMemoryDecorator::GetNextRequest()
    const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  return measurement_requests_->GetNextRequest();
}

const V8DetailedMemoryRequest*
V8DetailedMemoryDecorator::GetNextBoundedRequest() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  return measurement_requests_->GetNextBoundedRequest();
}

void V8DetailedMemoryDecorator::AddMeasurementRequest(
    base::PassKey<V8DetailedMemoryRequest> key,
    V8DetailedMemoryRequest* request,
    const ProcessNode* process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (process_node) {
    auto* process_data = NodeAttachedProcessData::Get(process_node);
    DCHECK(process_data);
    process_data->process_measurement_requests().AddMeasurementRequest(request);
  } else {
    measurement_requests_->AddMeasurementRequest(request);
  }
  UpdateProcessMeasurementSchedules();
}

void V8DetailedMemoryDecorator::RemoveMeasurementRequest(
    base::PassKey<V8DetailedMemoryRequest> key,
    V8DetailedMemoryRequest* request) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // Attempt to remove this request from all process-specific queues and the
  // global queue. It will only be in one of them.
  size_t removal_count = 0;
  ApplyToAllRequestQueues(base::BindRepeating(
      // Raw pointers are safe because this callback is synchronous.
      [](V8DetailedMemoryRequest* request, size_t* removal_count,
         MeasurementRequestQueue* queue) {
        (*removal_count) += queue->RemoveMeasurementRequest(request);
      },
      request, &removal_count));
  DCHECK_EQ(removal_count, 1ULL);
  UpdateProcessMeasurementSchedules();
}

void V8DetailedMemoryDecorator::ApplyToAllRequestQueues(
    RequestQueueCallback callback) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  callback.Run(measurement_requests_.get());
  NodeAttachedProcessData::ApplyToAllRenderers(
      graph_, base::BindRepeating(
                  [](RequestQueueCallback callback,
                     NodeAttachedProcessData* process_data) {
                    callback.Run(&process_data->process_measurement_requests());
                  },
                  std::move(callback)));
}

void V8DetailedMemoryDecorator::UpdateProcessMeasurementSchedules() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(graph_);
  measurement_requests_->Validate();
  NodeAttachedProcessData::ApplyToAllRenderers(
      graph_,
      base::BindRepeating(&NodeAttachedProcessData::ScheduleNextMeasurement));
}

void V8DetailedMemoryDecorator::NotifyObserversOnMeasurementAvailable(
    base::PassKey<ObserverNotifier> key,
    const ProcessNode* process_node) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  measurement_requests_->NotifyObserversOnMeasurementAvailable(process_node);
}

V8DetailedMemoryDecorator::MeasurementRequestQueue::~MeasurementRequestQueue() {
  DCHECK(bounded_measurement_requests_.empty());
  DCHECK(lazy_measurement_requests_.empty());
}

const V8DetailedMemoryRequest*
V8DetailedMemoryDecorator::MeasurementRequestQueue::GetNextRequest() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  return ChooseHigherPriorityRequest(GetNextBoundedRequest(),
                                     lazy_measurement_requests_.empty()
                                         ? nullptr
                                         : lazy_measurement_requests_.front());
}

const V8DetailedMemoryRequest*
V8DetailedMemoryDecorator::MeasurementRequestQueue::GetNextBoundedRequest()
    const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  return bounded_measurement_requests_.empty()
             ? nullptr
             : bounded_measurement_requests_.front();
}

void V8DetailedMemoryDecorator::MeasurementRequestQueue::AddMeasurementRequest(
    V8DetailedMemoryRequest* request) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(request);
  std::vector<V8DetailedMemoryRequest*>& measurement_requests =
      IsMeasurementBounded(request->mode()) ? bounded_measurement_requests_
                                            : lazy_measurement_requests_;
  DCHECK(!base::Contains(measurement_requests, request))
      << "V8DetailedMemoryRequest object added twice";
  // Each user of the decorator is expected to issue a single
  // V8DetailedMemoryRequest, so the size of measurement_requests is too low
  // to make the complexity of real priority queue worthwhile.
  for (std::vector<V8DetailedMemoryRequest*>::const_iterator it =
           measurement_requests.begin();
       it != measurement_requests.end(); ++it) {
    if (request->min_time_between_requests() <
        (*it)->min_time_between_requests()) {
      measurement_requests.insert(it, request);
      return;
    }
  }
  measurement_requests.push_back(request);
}

size_t
V8DetailedMemoryDecorator::MeasurementRequestQueue::RemoveMeasurementRequest(
    V8DetailedMemoryRequest* request) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(request);
  return base::Erase(IsMeasurementBounded(request->mode())
                         ? bounded_measurement_requests_
                         : lazy_measurement_requests_,
                     request);
}

void V8DetailedMemoryDecorator::MeasurementRequestQueue::
    NotifyObserversOnMeasurementAvailable(
        const ProcessNode* process_node) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  // Raw pointers are safe because the callback is synchronous.
  ApplyToAllRequests(base::BindRepeating(
      [](const ProcessNode* process_node, V8DetailedMemoryRequest* request) {
        request->NotifyObserversOnMeasurementAvailable(
            base::PassKey<MeasurementRequestQueue>(), process_node);
      },
      process_node));
}

void V8DetailedMemoryDecorator::MeasurementRequestQueue::OnOwnerUnregistered() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  ApplyToAllRequests(base::BindRepeating([](V8DetailedMemoryRequest* request) {
    request->OnOwnerUnregistered(base::PassKey<MeasurementRequestQueue>());
  }));
  bounded_measurement_requests_.clear();
  lazy_measurement_requests_.clear();
}

void V8DetailedMemoryDecorator::MeasurementRequestQueue::Validate() {
#if DCHECK_IS_ON()
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  auto check_invariants =
      [](const std::vector<V8DetailedMemoryRequest*>& measurement_requests,
         bool is_bounded) {
        for (size_t i = 1; i < measurement_requests.size(); ++i) {
          DCHECK(measurement_requests[i - 1]);
          DCHECK(measurement_requests[i]);
          DCHECK_EQ(IsMeasurementBounded(measurement_requests[i - 1]->mode()),
                    is_bounded);
          DCHECK_EQ(IsMeasurementBounded(measurement_requests[i]->mode()),
                    is_bounded);
          DCHECK_LE(measurement_requests[i - 1]->min_time_between_requests(),
                    measurement_requests[i]->min_time_between_requests());
        }
      };
  check_invariants(bounded_measurement_requests_, true);
  check_invariants(lazy_measurement_requests_, false);
#endif
}

void V8DetailedMemoryDecorator::MeasurementRequestQueue::ApplyToAllRequests(
    base::RepeatingCallback<void(V8DetailedMemoryRequest*)> callback) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // First collect all requests to notify. The callback may add or remove
  // requests from the queue, invalidating iterators.
  std::vector<V8DetailedMemoryRequest*> requests_to_notify;
  requests_to_notify.insert(requests_to_notify.end(),
                            bounded_measurement_requests_.begin(),
                            bounded_measurement_requests_.end());
  requests_to_notify.insert(requests_to_notify.end(),
                            lazy_measurement_requests_.begin(),
                            lazy_measurement_requests_.end());
  for (V8DetailedMemoryRequest* request : requests_to_notify) {
    callback.Run(request);
    // The callback may have deleted |request| so it is no longer safe to
    // reference.
  }
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryRequestAnySeq

V8DetailedMemoryRequestAnySeq::V8DetailedMemoryRequestAnySeq(
    const base::TimeDelta& min_time_between_requests,
    MeasurementMode mode,
    base::Optional<RenderProcessHostId> process_to_measure) {
  base::Optional<base::WeakPtr<ProcessNode>> process_node;
  if (process_to_measure) {
    // GetProcessNodeForRenderProcessHostId must be called from the UI thread.
    auto ui_task_runner = content::GetUIThreadTaskRunner({});
    if (!ui_task_runner->RunsTasksInCurrentSequence()) {
      ui_task_runner->PostTaskAndReplyWithResult(
          FROM_HERE,
          base::BindOnce(
              &PerformanceManager::GetProcessNodeForRenderProcessHostId,
              process_to_measure.value()),
          base::BindOnce(
              &V8DetailedMemoryRequestAnySeq::InitializeWrappedRequest,
              weak_factory_.GetWeakPtr(), min_time_between_requests, mode));
      return;
    }
    process_node = PerformanceManager::GetProcessNodeForRenderProcessHostId(
        process_to_measure.value());
  }
  InitializeWrappedRequest(min_time_between_requests, mode,
                           std::move(process_node));
}

V8DetailedMemoryRequestAnySeq::~V8DetailedMemoryRequestAnySeq() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  PerformanceManager::CallOnGraph(
      FROM_HERE, base::BindOnce(
                     [](std::unique_ptr<V8DetailedMemoryRequest> request) {
                       request.reset();
                     },
                     std::move(request_)));
}

bool V8DetailedMemoryRequestAnySeq::HasObserver(
    V8DetailedMemoryObserverAnySeq* observer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  return observers_.HasObserver(observer);
}

void V8DetailedMemoryRequestAnySeq::AddObserver(
    V8DetailedMemoryObserverAnySeq* observer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  observers_.AddObserver(observer);
}

void V8DetailedMemoryRequestAnySeq::RemoveObserver(
    V8DetailedMemoryObserverAnySeq* observer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(observers_.HasObserver(observer));
  observers_.RemoveObserver(observer);
}

void V8DetailedMemoryRequestAnySeq::NotifyObserversOnMeasurementAvailable(
    base::PassKey<V8DetailedMemoryRequest>,
    RenderProcessHostId render_process_host_id,
    const V8DetailedMemoryProcessData& process_data,
    const V8DetailedMemoryObserverAnySeq::FrameDataMap& frame_data) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  for (V8DetailedMemoryObserverAnySeq& observer : observers_)
    observer.OnV8MemoryMeasurementAvailable(render_process_host_id,
                                            process_data, frame_data);
}

void V8DetailedMemoryRequestAnySeq::InitializeWrappedRequest(
    const base::TimeDelta& min_time_between_requests,
    MeasurementMode mode,
    base::Optional<base::WeakPtr<ProcessNode>> process_to_measure) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // Can't use make_unique since this calls the private any-sequence
  // constructor. After construction the V8DetailedMemoryRequest must only be
  // accessed on the graph sequence.
  request_ = base::WrapUnique(new V8DetailedMemoryRequest(
      base::PassKey<V8DetailedMemoryRequestAnySeq>(), min_time_between_requests,
      mode, std::move(process_to_measure), weak_factory_.GetWeakPtr()));
}

////////////////////////////////////////////////////////////////////////////////
// V8DetailedMemoryRequestOneShotAnySeq

V8DetailedMemoryRequestOneShotAnySeq::V8DetailedMemoryRequestOneShotAnySeq(
    MeasurementMode mode)
    : mode_(mode) {}

V8DetailedMemoryRequestOneShotAnySeq::V8DetailedMemoryRequestOneShotAnySeq(
    RenderProcessHostId process_id,
    MeasurementCallback callback,
    MeasurementMode mode)
    : mode_(mode) {
  StartMeasurement(process_id, std::move(callback));
}

V8DetailedMemoryRequestOneShotAnySeq::~V8DetailedMemoryRequestOneShotAnySeq() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  PerformanceManager::CallOnGraph(
      FROM_HERE,
      base::BindOnce(
          [](std::unique_ptr<V8DetailedMemoryRequestOneShot> request) {
            request.reset();
          },
          std::move(request_)));
}

void V8DetailedMemoryRequestOneShotAnySeq::StartMeasurement(
    RenderProcessHostId process_id,
    MeasurementCallback callback) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // GetProcessNodeForRenderProcessHostId must be called from the UI thread.
  auto ui_task_runner = content::GetUIThreadTaskRunner({});
  if (ui_task_runner->RunsTasksInCurrentSequence()) {
    InitializeWrappedRequest(
        std::move(callback), mode_,
        PerformanceManager::GetProcessNodeForRenderProcessHostId(process_id));
  } else {
    ui_task_runner->PostTaskAndReplyWithResult(
        FROM_HERE,
        base::BindOnce(
            &PerformanceManager::GetProcessNodeForRenderProcessHostId,
            process_id),
        base::BindOnce(
            &V8DetailedMemoryRequestOneShotAnySeq::InitializeWrappedRequest,
            weak_factory_.GetWeakPtr(), std::move(callback), mode_));
  }
}

void V8DetailedMemoryRequestOneShotAnySeq::InitializeWrappedRequest(
    MeasurementCallback callback,
    MeasurementMode mode,
    base::WeakPtr<ProcessNode> process_node) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  // Pass ownership of |callback| to a wrapper, |wrapped_callback|, that will
  // be owned by the wrapped request. The wrapper will be invoked and destroyed
  // on the PM sequence. However, |callback| must be both called and destroyed
  // on this sequence, so indirect all accesses to it through SequenceBound.
  auto wrapped_callback = base::BindOnce(
      &V8DetailedMemoryRequestOneShotAnySeq::OnMeasurementAvailable,
      base::SequenceBound<MeasurementCallback>(
          base::SequencedTaskRunnerHandle::Get(), std::move(callback)));

  // Can't use make_unique since this calls the private any-sequence
  // constructor. After construction the V8DetailedMemoryRequestOneShot must
  // only be accessed on the graph sequence.
  request_ = base::WrapUnique(new V8DetailedMemoryRequestOneShot(
      base::PassKey<V8DetailedMemoryRequestOneShotAnySeq>(),
      std::move(process_node), std::move(wrapped_callback), mode));
}

// static
void V8DetailedMemoryRequestOneShotAnySeq::OnMeasurementAvailable(
    base::SequenceBound<MeasurementCallback> sequence_bound_callback,
    const ProcessNode* process_node,
    const V8DetailedMemoryProcessData* process_data) {
  DCHECK(process_node);
  DCHECK_ON_GRAPH_SEQUENCE(process_node->GetGraph());

  using FrameAndData = std::pair<content::GlobalFrameRoutingId,
                                 V8DetailedMemoryExecutionContextData>;
  std::vector<FrameAndData> all_frame_data;
  process_node->VisitFrameNodes(base::BindRepeating(
      [](std::vector<FrameAndData>* all_frame_data,
         const FrameNode* frame_node) {
        const auto* frame_data =
            V8DetailedMemoryExecutionContextData::ForFrameNode(frame_node);
        if (frame_data) {
          all_frame_data->push_back(std::make_pair(
              frame_node->GetRenderFrameHostProxy().global_frame_routing_id(),
              *frame_data));
        }
        return true;
      },
      base::Unretained(&all_frame_data)));

  sequence_bound_callback.PostTaskWithThisObject(
      FROM_HERE,
      base::BindOnce(
          [](RenderProcessHostId process_id,
             const V8DetailedMemoryProcessData& process_data,
             const FrameDataMap& frame_data, MeasurementCallback* callback) {
            std::move(*callback).Run(process_id, process_data, frame_data);
          },
          process_node->GetRenderProcessHostId(), *process_data,
          std::move(all_frame_data)));
}

}  // namespace v8_memory

}  // namespace performance_manager