ui/display/manager/configure_displays_task.cc

// Copyright 2014 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 "ui/display/manager/configure_displays_task.h"

#include "base/auto_reset.h"
#include "base/bind.h"
#include "base/containers/queue.h"
#include "base/logging.h"
#include "base/metrics/histogram_functions.h"
#include "base/stl_util.h"
#include "ui/display/manager/display_util.h"
#include "ui/display/types/display_configuration_params.h"
#include "ui/display/types/display_snapshot.h"
#include "ui/display/types/native_display_delegate.h"

namespace display {

namespace {

// Find the next best mode after |display_mode|. If none can be found return
// nullptr.
const DisplayMode* FindNextMode(const DisplaySnapshot& display_state,
                                const DisplayMode* display_mode) {
  if (!display_mode)
    return nullptr;

  int best_mode_pixels = 0;
  const DisplayMode* best_mode = nullptr;
  int current_mode_pixels = display_mode->size().GetArea();
  for (const std::unique_ptr<const DisplayMode>& mode : display_state.modes()) {
    int pixel_count = mode->size().GetArea();
    if (pixel_count < current_mode_pixels && pixel_count > best_mode_pixels) {
      best_mode = mode.get();
      best_mode_pixels = pixel_count;
    }
  }

  return best_mode;
}

// Samples used to define buckets used by DisplayResolution enum.
// The enum is used to record screen resolution statistics.
const int32_t kDisplayResolutionSamples[] = {1024, 1280, 1440, 1920,
                                             2560, 3840, 5120, 7680};

// Computes the index of the enum DisplayResolution.
// The index has to match the definition of the enum in enums.xml
int ComputeDisplayResolutionEnum(const DisplayMode* mode) {
  if (!mode)
    return 0;  // Display is powered off

  const gfx::Size size = mode->size();
  uint32_t width_idx = 0;
  uint32_t height_idx = 0;
  for (; width_idx < base::size(kDisplayResolutionSamples); width_idx++) {
    if (size.width() <= kDisplayResolutionSamples[width_idx])
      break;
  }
  for (; height_idx < base::size(kDisplayResolutionSamples); height_idx++) {
    if (size.height() <= kDisplayResolutionSamples[height_idx])
      break;
  }

  if (width_idx == base::size(kDisplayResolutionSamples) ||
      height_idx == base::size(kDisplayResolutionSamples))
    return base::size(kDisplayResolutionSamples) *
               base::size(kDisplayResolutionSamples) +
           1;  // Overflow bucket
  // Computes the index of DisplayResolution, starting from 1, since 0 is used
  // when powering off the display.
  return width_idx * base::size(kDisplayResolutionSamples) + height_idx + 1;
}

std::__wrap_iter<const DisplayConfigureRequest*> GetRequestForDisplayId(
    int64_t display_id,
    const std::vector<DisplayConfigureRequest>& requests) {
  return find_if(requests.begin(), requests.end(),
                 [display_id](const DisplayConfigureRequest& request) {
                   return request.display->display_id() == display_id;
                 });
}

}  // namespace

DisplayConfigureRequest::DisplayConfigureRequest(DisplaySnapshot* display,
                                                 const DisplayMode* mode,
                                                 const gfx::Point& origin)
    : display(display), mode(mode), origin(origin) {}

ConfigureDisplaysTask::ConfigureDisplaysTask(
    NativeDisplayDelegate* delegate,
    const std::vector<DisplayConfigureRequest>& requests,
    ResponseCallback callback)
    : delegate_(delegate),
      requests_(requests),
      callback_(std::move(callback)),
      is_configuring_(false),
      num_displays_configured_(0),
      task_status_(SUCCESS) {
  for (size_t i = 0; i < requests_.size(); ++i)
    pending_request_indexes_.push(i);
  delegate_->AddObserver(this);
}

ConfigureDisplaysTask::~ConfigureDisplaysTask() {
  delegate_->RemoveObserver(this);
}

void ConfigureDisplaysTask::Run() {
  // Synchronous configurators will recursively call Run(). In that case just
  // defer their call to the next iteration in the while-loop. This is done to
  // guard against stack overflows if the display has a large list of broken
  // modes.
  if (is_configuring_)
    return;

  {
    base::AutoReset<bool> recursivity_guard(&is_configuring_, true);
    // The callback passed to delegate_->Configure() could be run synchronously
    // or async. If it runs synchronously and any display fails and tries to
    // reconfigure, new requests will get added to |pending_request_indexes_|,
    // then another attempt to reconfigure will recursively call Run(). However
    // |is_configuring_| will block the run due to the reason mentioned above.
    // Hence, after we configure the first set of pending requests (loop over
    // |current_pending_requests_count|), we check again if the new requests
    // were added (!pending_request_indexes_.empty()).
    while (!pending_request_indexes_.empty()) {
      std::vector<display::DisplayConfigurationParams> config_requests;
      size_t current_pending_requests_count = pending_request_indexes_.size();
      for (size_t i = 0; i < current_pending_requests_count; ++i) {
        size_t index = pending_request_indexes_.front();
        DisplayConfigureRequest* request = &requests_[index];
        pending_request_indexes_.pop();

        const bool internal =
            request->display->type() == DISPLAY_CONNECTION_TYPE_INTERNAL;
        base::UmaHistogramExactLinear(
            internal ? "ConfigureDisplays.Internal.Modeset.Resolution"
                     : "ConfigureDisplays.External.Modeset.Resolution",
            ComputeDisplayResolutionEnum(request->mode),
            base::size(kDisplayResolutionSamples) *
                    base::size(kDisplayResolutionSamples) +
                2);
        base::HistogramBase* histogram = base::LinearHistogram::FactoryGet(
            internal ? "ConfigureDisplays.Internal.Modeset.RefreshRate"
                     : "ConfigureDisplays.External.Modeset.RefreshRate",
            1, 240, 18, base::HistogramBase::kUmaTargetedHistogramFlag);
        histogram->Add(request->mode ? std::round(request->mode->refresh_rate())
                                     : 0);

        display::DisplayConfigurationParams display_config_params(
            request->display->display_id(), request->origin, request->mode);
        config_requests.push_back(std::move(display_config_params));
      }
      if (!config_requests.empty()) {
        delegate_->Configure(
            config_requests,
            base::BindOnce(&ConfigureDisplaysTask::OnConfigured,
                           weak_ptr_factory_.GetWeakPtr()));
      }
    }
  }

  // Nothing should be modified after the |callback_| is called since the
  // task may be deleted in the callback.
  if (num_displays_configured_ == requests_.size())
    std::move(callback_).Run(task_status_);
}

void ConfigureDisplaysTask::OnConfigurationChanged() {}

void ConfigureDisplaysTask::OnDisplaySnapshotsInvalidated() {
  base::queue<size_t> empty_queue;
  pending_request_indexes_.swap(empty_queue);
  // From now on, don't access |requests_[index]->display|; they're invalid.
  task_status_ = ERROR;
  weak_ptr_factory_.InvalidateWeakPtrs();
  Run();
}

void ConfigureDisplaysTask::OnConfigured(
    const base::flat_map<int64_t, bool>& statuses) {
  bool config_success = true;

  // Check if all displays are successfully configured.
  for (const auto& status : statuses) {
    int64_t display_id = status.first;
    bool display_success = status.second;
    config_success &= display_success;

    auto request = GetRequestForDisplayId(display_id, requests_);
    DCHECK(request != requests_.end());

    VLOG(2) << "Configured status=" << display_success
            << " display=" << request->display->display_id()
            << " origin=" << request->origin.ToString()
            << " mode=" << (request->mode ? request->mode->ToString() : "null");

    bool internal =
        request->display->type() == DISPLAY_CONNECTION_TYPE_INTERNAL;
    base::UmaHistogramBoolean(
        internal ? "ConfigureDisplays.Internal.Modeset.AttemptSucceeded"
                 : "ConfigureDisplays.External.Modeset.AttemptSucceeded",
        display_success);
  }

  if (config_success) {
    for (const auto& status : statuses) {
      auto request = GetRequestForDisplayId(status.first, requests_);
      request->display->set_current_mode(request->mode);
      request->display->set_origin(request->origin);
    }
  } else {
    bool should_reconfigure = false;
    // For the failing config, check if there is another mode to be requested.
    // If there is one, attempt to reconfigure everything again.
    for (const auto& status : statuses) {
      int64_t display_id = status.first;
      bool display_success = status.second;
      if (!display_success) {
        const DisplayConfigureRequest* request =
            GetRequestForDisplayId(display_id, requests_).base();
        const DisplayMode* next_mode =
            FindNextMode(*request->display, request->mode);
        if (next_mode) {
          const_cast<DisplayConfigureRequest*>(request)->mode = next_mode;
          should_reconfigure = true;
        }
      }
    }
    // When reconfiguring, reconfigure all displays, not only the failing ones
    // as they could potentially depend on each other.
    if (should_reconfigure) {
      for (const auto& status : statuses) {
        auto const_iterator = GetRequestForDisplayId(status.first, requests_);
        auto request = requests_.erase(const_iterator, const_iterator);
        size_t index = std::distance(requests_.begin(), request);
        pending_request_indexes_.push(index);
      }
      if (task_status_ == SUCCESS)
        task_status_ = PARTIAL_SUCCESS;
      Run();
      return;
    }
  }

  // If no reconfigurations are happening, update the final state.
  for (const auto& status : statuses) {
    auto request = GetRequestForDisplayId(status.first, requests_);
    bool internal =
        request->display->type() == DISPLAY_CONNECTION_TYPE_INTERNAL;
    base::UmaHistogramBoolean(
        internal ? "ConfigureDisplays.Internal.Modeset.FinalStatus"
                 : "ConfigureDisplays.External.Modeset.FinalStatus",
        config_success);
  }

  num_displays_configured_ += statuses.size();
  if (!config_success)
    task_status_ = ERROR;
  Run();
}

}  // namespace display