1
    2
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
  100
  101
  102
  103
  104
  105
  106
  107
  108
  109
  110
  111
  112
  113
  114
  115
  116
  117
  118
  119
  120
  121
  122
  123
  124
  125
  126
  127
  128
  129
  130
  131
  132
  133
  134
  135
  136
  137
  138
  139
  140
  141
  142
  143
  144
  145
  146
  147
  148
  149
  150
  151

base / features.cc [blame]

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/features.h"

#include "base/cpu_reduction_experiment.h"
#include "base/task/sequence_manager/sequence_manager_impl.h"
#include "base/threading/platform_thread.h"
#include "build/buildflag.h"

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
#include "base/message_loop/message_pump_epoll.h"
#endif

#if BUILDFLAG(IS_APPLE)
#include "base/files/file.h"
#include "base/message_loop/message_pump_apple.h"
#include "base/message_loop/message_pump_kqueue.h"
#include "base/synchronization/condition_variable.h"
#endif

#if BUILDFLAG(IS_ANDROID)
#include "base/android/input_hint_checker.h"
#endif

#if BUILDFLAG(IS_WIN)
#include "base/task/sequence_manager/thread_controller_power_monitor.h"
#include "base/threading/platform_thread_win.h"
#endif

namespace base::features {

// Alphabetical:

// Activate base::FeatureParamWithCache internal cache.
// TODO(https://crbug.com/340824113): Remove the feature flag below.
BASE_FEATURE(kFeatureParamWithCache,
             "FeatureParamWithCache",
             FEATURE_ENABLED_BY_DEFAULT);

// Use the Rust JSON parser. Enabled everywhere except Android, where the switch
// from using the C++ parser in-thread to using the Rust parser in a thread-pool
// introduces too much latency.
BASE_FEATURE(kUseRustJsonParser,
             "UseRustJsonParser",
#if BUILDFLAG(IS_ANDROID)
             FEATURE_DISABLED_BY_DEFAULT
#else
             FEATURE_ENABLED_BY_DEFAULT
#endif  // BUILDFLAG(IS_ANDROID)
);

// If true, use the Rust JSON parser in-thread; otherwise, it runs in a thread
// pool.
const base::FeatureParam<bool> kUseRustJsonParserInCurrentSequence{
    &kUseRustJsonParser, "UseRustJsonParserInCurrentSequence", false};

// Use non default low memory device threshold.
// Value should be given via |LowMemoryDeviceThresholdMB|.
#if BUILDFLAG(IS_IOS)
// For M99, 45% of devices have 2GB of RAM, and 55% have more.
#define LOW_MEMORY_DEVICE_THRESHOLD_MB 1024
#else
// Updated Desktop default threshold to match the Android 2021 definition.
#define LOW_MEMORY_DEVICE_THRESHOLD_MB 2048
#endif
BASE_FEATURE(kLowEndMemoryExperiment,
             "LowEndMemoryExperiment",
             FEATURE_DISABLED_BY_DEFAULT);
const base::FeatureParam<int> kLowMemoryDeviceThresholdMB{
    &kLowEndMemoryExperiment, "LowMemoryDeviceThresholdMB",
    LOW_MEMORY_DEVICE_THRESHOLD_MB};

#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)
// Force to enable LowEndDeviceMode partially on Android 3Gb devices.
// (see PartialLowEndModeOnMidRangeDevices below)
BASE_FEATURE(kPartialLowEndModeOn3GbDevices,
             "PartialLowEndModeOn3GbDevices",
             FEATURE_DISABLED_BY_DEFAULT);

// Used to enable LowEndDeviceMode partially on Android and ChromeOS mid-range
// devices. Such devices aren't considered low-end, but we'd like experiment
// with a subset of low-end features to see if we get a good memory vs.
// performance tradeoff.
//
// TODO(crbug.com/40264947): |#if| out 32-bit before launching or going to
// high Stable %, because we will enable the feature only for <8GB 64-bit
// devices, where we didn't ship yet. However, we first need a larger
// population to collect data.
BASE_FEATURE(kPartialLowEndModeOnMidRangeDevices,
             "PartialLowEndModeOnMidRangeDevices",
#if BUILDFLAG(IS_ANDROID)
             FEATURE_ENABLED_BY_DEFAULT);
#elif BUILDFLAG(IS_CHROMEOS)
             FEATURE_DISABLED_BY_DEFAULT);
#endif

#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)

#if BUILDFLAG(IS_ANDROID)
// Whether to report frame metrics to the Android.FrameTimeline.* histograms.
BASE_FEATURE(kCollectAndroidFrameTimelineMetrics,
             "CollectAndroidFrameTimelineMetrics",
             FEATURE_DISABLED_BY_DEFAULT);

// If enabled, post registering PowerMonitor broadcast receiver to a background
// thread,
BASE_FEATURE(kPostPowerMonitorBroadcastReceiverInitToBackground,
             "PostPowerMonitorBroadcastReceiverInitToBackground",
             FEATURE_ENABLED_BY_DEFAULT);
// If enabled, getMyMemoryState IPC will be posted to background.
BASE_FEATURE(kPostGetMyMemoryStateToBackground,
             "PostGetMyMemoryStateToBackground",
             FEATURE_ENABLED_BY_DEFAULT);
#endif  // BUILDFLAG(IS_ANDROID)

void Init(EmitThreadControllerProfilerMetadata
              emit_thread_controller_profiler_metadata) {
  InitializeCpuReductionExperiment();
  sequence_manager::internal::SequenceManagerImpl::InitializeFeatures();
  sequence_manager::internal::ThreadController::InitializeFeatures(
      emit_thread_controller_profiler_metadata);

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
  MessagePumpEpoll::InitializeFeatures();
#endif

#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_CHROMEOS)
  PlatformThread::InitializeFeatures();
#endif

#if BUILDFLAG(IS_APPLE)
  ConditionVariable::InitializeFeatures();
  File::InitializeFeatures();
  MessagePumpCFRunLoopBase::InitializeFeatures();
  MessagePumpKqueue::InitializeFeatures();
#endif

#if BUILDFLAG(IS_ANDROID)
  android::InputHintChecker::InitializeFeatures();
#endif

#if BUILDFLAG(IS_WIN)
  sequence_manager::internal::ThreadControllerPowerMonitor::
      InitializeFeatures();
  InitializePlatformThreadFeatures();
#endif
}

}  // namespace base::features