lib/ui/volatile_path_tracker.cc

// Copyright 2013 The Flutter 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 "flutter/lib/ui/volatile_path_tracker.h"

namespace flutter {

VolatilePathTracker::VolatilePathTracker(
    fml::RefPtr<fml::TaskRunner> ui_task_runner,
    bool enabled)
    : ui_task_runner_(ui_task_runner), enabled_(enabled) {}

void VolatilePathTracker::Track(std::shared_ptr<TrackedPath> path) {
  FML_DCHECK(ui_task_runner_->RunsTasksOnCurrentThread());
  FML_DCHECK(path);
  FML_DCHECK(path->path.isVolatile());
  if (!enabled_) {
    path->path.setIsVolatile(false);
    return;
  }
  paths_.push_back(path);
}

void VolatilePathTracker::OnFrame() {
  FML_DCHECK(ui_task_runner_->RunsTasksOnCurrentThread());
  if (!enabled_) {
    return;
  }
#if !FLUTTER_RELEASE
  std::string total_count = std::to_string(paths_.size());
  TRACE_EVENT1("flutter", "VolatilePathTracker::OnFrame", "total_count",
               total_count.c_str());
#else
  TRACE_EVENT0("flutter", "VolatilePathTracker::OnFrame");
#endif

  paths_.erase(std::remove_if(paths_.begin(), paths_.end(),
                              [](std::weak_ptr<TrackedPath> weak_path) {
                                auto path = weak_path.lock();
                                if (!path) {
                                  return true;
                                }
                                path->frame_count++;
                                if (path->frame_count >= kFramesOfVolatility) {
                                  path->path.setIsVolatile(false);
                                  path->tracking_volatility = false;
                                  return true;
                                }
                                return false;
                              }),
               paths_.end());

#if !FLUTTER_RELEASE
  std::string post_removal_count = std::to_string(paths_.size());
  TRACE_EVENT_INSTANT1("flutter", "VolatilePathTracker::OnFrame",
                       "remaining_count", post_removal_count.c_str());
#endif
}

}  // namespace flutter