cc/metrics/events_metrics_manager.cc

   1 // Copyright 2020 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/metrics/events_metrics_manager.h"
   6
   7 #include <utility>
   8
   9 #include "base/bind.h"
  10 #include "base/callback.h"
  11 #include "base/callback_helpers.h"
  12 #include "base/memory/raw_ptr.h"
  13
  14 namespace cc {
  15
  16 class EventsMetricsManager::ScopedMonitorImpl
  17     : public EventsMetricsManager::ScopedMonitor {
  18  public:
  19   ScopedMonitorImpl(EventsMetricsManager* manager, DoneCallback done_callback)
  20       : manager_(manager), done_callback_(std::move(done_callback)) {
  21     DCHECK(manager_);
  22   }
  23
  24   ~ScopedMonitorImpl() override {
  25     if (manager_)
  26       End();
  27   }
  28
  29   void End() {
  30     DCHECK(manager_);
  31     std::unique_ptr<EventMetrics> metrics;
  32     if (!done_callback_.is_null()) {
  33       const bool handled = save_metrics_;
  34       metrics = std::move(done_callback_).Run(handled);
  35
  36       // If `handled` is false, the callback should return nullptr.
  37       DCHECK(handled || !metrics);
  38     }
  39     manager_->OnScopedMonitorEnded(std::move(metrics));
  40     manager_ = nullptr;
  41   }
  42
  43   // Overridden from EventsMetricsManager::ScopedMonitor.
  44   void SetSaveMetrics() override { save_metrics_ = true; }
  45
  46  private:
  47   raw_ptr<EventsMetricsManager> manager_;
  48   DoneCallback done_callback_;
  49   bool save_metrics_ = false;
  50 };
  51
  52 EventsMetricsManager::ScopedMonitor::ScopedMonitor() = default;
  53 EventsMetricsManager::ScopedMonitor::~ScopedMonitor() = default;
  54
  55 EventsMetricsManager::EventsMetricsManager() = default;
  56
  57 EventsMetricsManager::~EventsMetricsManager() {
  58   // If `EventsMetricsManager` is shut down while events are active, end active
  59   // scoped monitors immediately.
  60   while (!active_scoped_monitors_.empty())
  61     active_scoped_monitors_.back()->End();
  62 }
  63
  64 std::unique_ptr<EventsMetricsManager::ScopedMonitor>
  65 EventsMetricsManager::GetScopedMonitor(
  66     ScopedMonitor::DoneCallback done_callback) {
  67   auto monitor =
  68       std::make_unique<ScopedMonitorImpl>(this, std::move(done_callback));
  69   active_scoped_monitors_.push_back(monitor.get());
  70   return monitor;
  71 }
  72
  73 void EventsMetricsManager::SaveActiveEventMetrics() {
  74   if (active_scoped_monitors_.size() > 0) {
  75     // Here we just set the flag to save the active metrics. The actual saving
  76     // happens when the scoped monitor is destroyed to give clients opportunity
  77     // to use/update the metrics object until the end of their processing.
  78     active_scoped_monitors_.back()->SetSaveMetrics();
  79   }
  80 }
  81
  82 EventMetrics::List EventsMetricsManager::TakeSavedEventsMetrics() {
  83   EventMetrics::List result;
  84   result.swap(saved_events_);
  85   return result;
  86 }
  87
  88 void EventsMetricsManager::OnScopedMonitorEnded(
  89     std::unique_ptr<EventMetrics> metrics) {
  90   DCHECK_GT(active_scoped_monitors_.size(), 0u);
  91   active_scoped_monitors_.pop_back();
  92
  93   if (metrics)
  94     saved_events_.push_back(std::move(metrics));
  95 }
  96
  97 }  // namespace cc