base/sys_info.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   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 "base/sys_info.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/base_switches.h"
  10 #include "base/command_line.h"
  11 #include "base/lazy_instance.h"
  12 #include "base/sys_info_internal.h"
  13 #include "base/time/time.h"
  14 #include "build/build_config.h"
  15
  16 namespace base {
  17 namespace {
  18 static const int kLowMemoryDeviceThresholdMB = 512;
  19 }
  20
  21 // static
  22 int64_t SysInfo::AmountOfPhysicalMemory() {
  23   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
  24           switches::kEnableLowEndDeviceMode)) {
  25     return kLowMemoryDeviceThresholdMB * 1024 * 1024;
  26   }
  27
  28   return AmountOfPhysicalMemoryImpl();
  29 }
  30
  31 // static
  32 int64_t SysInfo::AmountOfAvailablePhysicalMemory() {
  33   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
  34           switches::kEnableLowEndDeviceMode)) {
  35     // Estimate the available memory by subtracting our memory used estimate
  36     // from the fake |kLowMemoryDeviceThresholdMB| limit.
  37     size_t memory_used =
  38         AmountOfPhysicalMemoryImpl() - AmountOfAvailablePhysicalMemoryImpl();
  39     size_t memory_limit = kLowMemoryDeviceThresholdMB * 1024 * 1024;
  40     // std::min ensures no underflow, as |memory_used| can be > |memory_limit|.
  41     return memory_limit - std::min(memory_used, memory_limit);
  42   }
  43
  44   return AmountOfAvailablePhysicalMemoryImpl();
  45 }
  46
  47 bool SysInfo::IsLowEndDevice() {
  48   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
  49           switches::kEnableLowEndDeviceMode)) {
  50     return true;
  51   }
  52
  53   return IsLowEndDeviceImpl();
  54 }
  55
  56 #if !defined(OS_ANDROID)
  57
  58 bool DetectLowEndDevice() {
  59   CommandLine* command_line = CommandLine::ForCurrentProcess();
  60   if (command_line->HasSwitch(switches::kEnableLowEndDeviceMode))
  61     return true;
  62   if (command_line->HasSwitch(switches::kDisableLowEndDeviceMode))
  63     return false;
  64
  65   int ram_size_mb = SysInfo::AmountOfPhysicalMemoryMB();
  66   return (ram_size_mb > 0 && ram_size_mb <= kLowMemoryDeviceThresholdMB);
  67 }
  68
  69 static LazyInstance<
  70   internal::LazySysInfoValue<bool, DetectLowEndDevice> >::Leaky
  71   g_lazy_low_end_device = LAZY_INSTANCE_INITIALIZER;
  72
  73 // static
  74 bool SysInfo::IsLowEndDeviceImpl() {
  75   return g_lazy_low_end_device.Get().value();
  76 }
  77 #endif
  78
  79 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
  80 std::string SysInfo::HardwareModelName() {
  81   return std::string();
  82 }
  83 #endif
  84
  85 // static
  86 base::TimeDelta SysInfo::Uptime() {
  87   // This code relies on an implementation detail of TimeTicks::Now() - that
  88   // its return value happens to coincide with the system uptime value in
  89   // microseconds, on Win/Mac/iOS/Linux/ChromeOS and Android.
  90   int64_t uptime_in_microseconds = TimeTicks::Now().ToInternalValue();
  91   return base::TimeDelta::FromMicroseconds(uptime_in_microseconds);
  92 }
  93
  94 }  // namespace base