Deleted OS_WIN and all Windows specific files from base.

base/time/time_win.cc

-// Copyright (c) 2012 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.
-
-
-// Windows Timer Primer
-//
-// A good article:  http://www.ddj.com/windows/184416651
-// A good mozilla bug:  http://bugzilla.mozilla.org/show_bug.cgi?id=363258
-//
-// The default windows timer, GetSystemTimeAsFileTime is not very precise.
-// It is only good to ~15.5ms.
-//
-// QueryPerformanceCounter is the logical choice for a high-precision timer.
-// However, it is known to be buggy on some hardware.  Specifically, it can
-// sometimes "jump".  On laptops, QPC can also be very expensive to call.
-// It's 3-4x slower than timeGetTime() on desktops, but can be 10x slower
-// on laptops.  A unittest exists which will show the relative cost of various
-// timers on any system.
-//
-// The next logical choice is timeGetTime().  timeGetTime has a precision of
-// 1ms, but only if you call APIs (timeBeginPeriod()) which affect all other
-// applications on the system.  By default, precision is only 15.5ms.
-// Unfortunately, we don't want to call timeBeginPeriod because we don't
-// want to affect other applications.  Further, on mobile platforms, use of
-// faster multimedia timers can hurt battery life.  See the intel
-// article about this here:
-// http://softwarecommunity.intel.com/articles/eng/1086.htm
-//
-// To work around all this, we're going to generally use timeGetTime().  We
-// will only increase the system-wide timer if we're not running on battery
-// power.
-
-#include "base/time/time.h"
-
-#pragma comment(lib, "winmm.lib")
-#include <windows.h>
-#include <mmsystem.h>
-#include <stdint.h>
-
-#include "base/basictypes.h"
-#include "base/cpu.h"
-#include "base/lazy_instance.h"
-#include "base/logging.h"
-#include "base/synchronization/lock.h"
-
-using base::ThreadTicks;
-using base::Time;
-using base::TimeDelta;
-using base::TimeTicks;
-using base::TraceTicks;
-
-namespace {
-
-// From MSDN, FILETIME "Contains a 64-bit value representing the number of
-// 100-nanosecond intervals since January 1, 1601 (UTC)."
-int64 FileTimeToMicroseconds(const FILETIME& ft) {
-  // Need to bit_cast to fix alignment, then divide by 10 to convert
-  // 100-nanoseconds to milliseconds. This only works on little-endian
-  // machines.
-  return bit_cast<int64, FILETIME>(ft) / 10;
-}
-
-void MicrosecondsToFileTime(int64 us, FILETIME* ft) {
-  DCHECK_GE(us, 0LL) << "Time is less than 0, negative values are not "
-      "representable in FILETIME";
-
-  // Multiply by 10 to convert milliseconds to 100-nanoseconds. Bit_cast will
-  // handle alignment problems. This only works on little-endian machines.
-  *ft = bit_cast<FILETIME, int64>(us * 10);
-}
-
-int64 CurrentWallclockMicroseconds() {
-  FILETIME ft;
-  ::GetSystemTimeAsFileTime(&ft);
-  return FileTimeToMicroseconds(ft);
-}
-
-// Time between resampling the un-granular clock for this API.  60 seconds.
-const int kMaxMillisecondsToAvoidDrift = 60 * Time::kMillisecondsPerSecond;
-
-int64 initial_time = 0;
-TimeTicks initial_ticks;
-
-void InitializeClock() {
-  initial_ticks = TimeTicks::Now();
-  initial_time = CurrentWallclockMicroseconds();
-}
-
-// The two values that ActivateHighResolutionTimer uses to set the systemwide
-// timer interrupt frequency on Windows. It controls how precise timers are
-// but also has a big impact on battery life.
-const int kMinTimerIntervalHighResMs = 1;
-const int kMinTimerIntervalLowResMs = 4;
-// Track if kMinTimerIntervalHighResMs or kMinTimerIntervalLowResMs is active.
-bool g_high_res_timer_enabled = false;
-// How many times the high resolution timer has been called.
-uint32_t g_high_res_timer_count = 0;
-// The lock to control access to the above two variables.
-base::LazyInstance<base::Lock>::Leaky g_high_res_lock =
-    LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-// Time -----------------------------------------------------------------------
-
-// The internal representation of Time uses FILETIME, whose epoch is 1601-01-01
-// 00:00:00 UTC.  ((1970-1601)*365+89)*24*60*60*1000*1000, where 89 is the
-// number of leap year days between 1601 and 1970: (1970-1601)/4 excluding
-// 1700, 1800, and 1900.
-// static
-const int64 Time::kTimeTToMicrosecondsOffset = INT64_C(11644473600000000);
-
-// static
-Time Time::Now() {
-  if (initial_time == 0)
-    InitializeClock();
-
-  // We implement time using the high-resolution timers so that we can get
-  // timeouts which are smaller than 10-15ms.  If we just used
-  // CurrentWallclockMicroseconds(), we'd have the less-granular timer.
-  //
-  // To make this work, we initialize the clock (initial_time) and the
-  // counter (initial_ctr).  To compute the initial time, we can check
-  // the number of ticks that have elapsed, and compute the delta.
-  //
-  // To avoid any drift, we periodically resync the counters to the system
-  // clock.
-  while (true) {
-    TimeTicks ticks = TimeTicks::Now();
-
-    // Calculate the time elapsed since we started our timer
-    TimeDelta elapsed = ticks - initial_ticks;
-
-    // Check if enough time has elapsed that we need to resync the clock.
-    if (elapsed.InMilliseconds() > kMaxMillisecondsToAvoidDrift) {
-      InitializeClock();
-      continue;
-    }
-
-    return Time(elapsed + Time(initial_time));
-  }
-}
-
-// static
-Time Time::NowFromSystemTime() {
-  // Force resync.
-  InitializeClock();
-  return Time(initial_time);
-}
-
-// static
-Time Time::FromFileTime(FILETIME ft) {
-  if (bit_cast<int64, FILETIME>(ft) == 0)
-    return Time();
-  if (ft.dwHighDateTime == std::numeric_limits<DWORD>::max() &&
-      ft.dwLowDateTime == std::numeric_limits<DWORD>::max())
-    return Max();
-  return Time(FileTimeToMicroseconds(ft));
-}
-
-FILETIME Time::ToFileTime() const {
-  if (is_null())
-    return bit_cast<FILETIME, int64>(0);
-  if (is_max()) {
-    FILETIME result;
-    result.dwHighDateTime = std::numeric_limits<DWORD>::max();
-    result.dwLowDateTime = std::numeric_limits<DWORD>::max();
-    return result;
-  }
-  FILETIME utc_ft;
-  MicrosecondsToFileTime(us_, &utc_ft);
-  return utc_ft;
-}
-
-// static
-void Time::EnableHighResolutionTimer(bool enable) {
-  base::AutoLock lock(g_high_res_lock.Get());
-  if (g_high_res_timer_enabled == enable)
-    return;
-  g_high_res_timer_enabled = enable;
-  if (!g_high_res_timer_count)
-    return;
-  // Since g_high_res_timer_count != 0, an ActivateHighResolutionTimer(true)
-  // was called which called timeBeginPeriod with g_high_res_timer_enabled
-  // with a value which is the opposite of |enable|. With that information we
-  // call timeEndPeriod with the same value used in timeBeginPeriod and
-  // therefore undo the period effect.
-  if (enable) {
-    timeEndPeriod(kMinTimerIntervalLowResMs);
-    timeBeginPeriod(kMinTimerIntervalHighResMs);
-  } else {
-    timeEndPeriod(kMinTimerIntervalHighResMs);
-    timeBeginPeriod(kMinTimerIntervalLowResMs);
-  }
-}
-
-// static
-bool Time::ActivateHighResolutionTimer(bool activating) {
-  // We only do work on the transition from zero to one or one to zero so we
-  // can easily undo the effect (if necessary) when EnableHighResolutionTimer is
-  // called.
-  const uint32_t max = std::numeric_limits<uint32_t>::max();
-
-  base::AutoLock lock(g_high_res_lock.Get());
-  UINT period = g_high_res_timer_enabled ? kMinTimerIntervalHighResMs
-                                         : kMinTimerIntervalLowResMs;
-  if (activating) {
-    DCHECK_NE(g_high_res_timer_count, max);
-    ++g_high_res_timer_count;
-    if (g_high_res_timer_count == 1)
-      timeBeginPeriod(period);
-  } else {
-    DCHECK_NE(g_high_res_timer_count, 0u);
-    --g_high_res_timer_count;
-    if (g_high_res_timer_count == 0)
-      timeEndPeriod(period);
-  }
-  return (period == kMinTimerIntervalHighResMs);
-}
-
-// static
-bool Time::IsHighResolutionTimerInUse() {
-  base::AutoLock lock(g_high_res_lock.Get());
-  return g_high_res_timer_enabled && g_high_res_timer_count > 0;
-}
-
-// static
-Time Time::FromExploded(bool is_local, const Exploded& exploded) {
-  // Create the system struct representing our exploded time. It will either be
-  // in local time or UTC.
-  SYSTEMTIME st;
-  st.wYear = static_cast<WORD>(exploded.year);
-  st.wMonth = static_cast<WORD>(exploded.month);
-  st.wDayOfWeek = static_cast<WORD>(exploded.day_of_week);
-  st.wDay = static_cast<WORD>(exploded.day_of_month);
-  st.wHour = static_cast<WORD>(exploded.hour);
-  st.wMinute = static_cast<WORD>(exploded.minute);
-  st.wSecond = static_cast<WORD>(exploded.second);
-  st.wMilliseconds = static_cast<WORD>(exploded.millisecond);
-
-  FILETIME ft;
-  bool success = true;
-  // Ensure that it's in UTC.
-  if (is_local) {
-    SYSTEMTIME utc_st;
-    success = TzSpecificLocalTimeToSystemTime(NULL, &st, &utc_st) &&
-              SystemTimeToFileTime(&utc_st, &ft);
-  } else {
-    success = !!SystemTimeToFileTime(&st, &ft);
-  }
-
-  if (!success) {
-    NOTREACHED() << "Unable to convert time";
-    return Time(0);
-  }
-  return Time(FileTimeToMicroseconds(ft));
-}
-
-void Time::Explode(bool is_local, Exploded* exploded) const {
-  if (us_ < 0LL) {
-    // We are not able to convert it to FILETIME.
-    ZeroMemory(exploded, sizeof(*exploded));
-    return;
-  }
-
-  // FILETIME in UTC.
-  FILETIME utc_ft;
-  MicrosecondsToFileTime(us_, &utc_ft);
-
-  // FILETIME in local time if necessary.
-  bool success = true;
-  // FILETIME in SYSTEMTIME (exploded).
-  SYSTEMTIME st = {0};
-  if (is_local) {
-    SYSTEMTIME utc_st;
-    // We don't use FileTimeToLocalFileTime here, since it uses the current
-    // settings for the time zone and daylight saving time. Therefore, if it is
-    // daylight saving time, it will take daylight saving time into account,
-    // even if the time you are converting is in standard time.
-    success = FileTimeToSystemTime(&utc_ft, &utc_st) &&
-              SystemTimeToTzSpecificLocalTime(NULL, &utc_st, &st);
-  } else {
-    success = !!FileTimeToSystemTime(&utc_ft, &st);
-  }
-
-  if (!success) {
-    NOTREACHED() << "Unable to convert time, don't know why";
-    ZeroMemory(exploded, sizeof(*exploded));
-    return;
-  }
-
-  exploded->year = st.wYear;
-  exploded->month = st.wMonth;
-  exploded->day_of_week = st.wDayOfWeek;
-  exploded->day_of_month = st.wDay;
-  exploded->hour = st.wHour;
-  exploded->minute = st.wMinute;
-  exploded->second = st.wSecond;
-  exploded->millisecond = st.wMilliseconds;
-}
-
-// TimeTicks ------------------------------------------------------------------
-namespace {
-
-// We define a wrapper to adapt between the __stdcall and __cdecl call of the
-// mock function, and to avoid a static constructor.  Assigning an import to a
-// function pointer directly would require setup code to fetch from the IAT.
-DWORD timeGetTimeWrapper() {
-  return timeGetTime();
-}
-
-DWORD (*g_tick_function)(void) = &timeGetTimeWrapper;
-
-// Accumulation of time lost due to rollover (in milliseconds).
-int64 g_rollover_ms = 0;
-
-// The last timeGetTime value we saw, to detect rollover.
-DWORD g_last_seen_now = 0;
-
-// Lock protecting rollover_ms and last_seen_now.
-// Note: this is a global object, and we usually avoid these. However, the time
-// code is low-level, and we don't want to use Singletons here (it would be too
-// easy to use a Singleton without even knowing it, and that may lead to many
-// gotchas). Its impact on startup time should be negligible due to low-level
-// nature of time code.
-base::Lock g_rollover_lock;
-
-// We use timeGetTime() to implement TimeTicks::Now().  This can be problematic
-// because it returns the number of milliseconds since Windows has started,
-// which will roll over the 32-bit value every ~49 days.  We try to track
-// rollover ourselves, which works if TimeTicks::Now() is called at least every
-// 49 days.
-TimeDelta RolloverProtectedNow() {
-  base::AutoLock locked(g_rollover_lock);
-  // We should hold the lock while calling tick_function to make sure that
-  // we keep last_seen_now stay correctly in sync.
-  DWORD now = g_tick_function();
-  if (now < g_last_seen_now)
-    g_rollover_ms += 0x100000000I64;  // ~49.7 days.
-  g_last_seen_now = now;
-  return TimeDelta::FromMilliseconds(now + g_rollover_ms);
-}
-
-// Discussion of tick counter options on Windows:
-//
-// (1) CPU cycle counter. (Retrieved via RDTSC)
-// The CPU counter provides the highest resolution time stamp and is the least
-// expensive to retrieve. However, on older CPUs, two issues can affect its
-// reliability: First it is maintained per processor and not synchronized
-// between processors. Also, the counters will change frequency due to thermal
-// and power changes, and stop in some states.
-//
-// (2) QueryPerformanceCounter (QPC). The QPC counter provides a high-
-// resolution (<1 microsecond) time stamp. On most hardware running today, it
-// auto-detects and uses the constant-rate RDTSC counter to provide extremely
-// efficient and reliable time stamps.
-//
-// On older CPUs where RDTSC is unreliable, it falls back to using more
-// expensive (20X to 40X more costly) alternate clocks, such as HPET or the ACPI
-// PM timer, and can involve system calls; and all this is up to the HAL (with
-// some help from ACPI). According to
-// http://blogs.msdn.com/oldnewthing/archive/2005/09/02/459952.aspx, in the
-// worst case, it gets the counter from the rollover interrupt on the
-// programmable interrupt timer. In best cases, the HAL may conclude that the
-// RDTSC counter runs at a constant frequency, then it uses that instead. On
-// multiprocessor machines, it will try to verify the values returned from
-// RDTSC on each processor are consistent with each other, and apply a handful
-// of workarounds for known buggy hardware. In other words, QPC is supposed to
-// give consistent results on a multiprocessor computer, but for older CPUs it
-// can be unreliable due bugs in BIOS or HAL.
-//
-// (3) System time. The system time provides a low-resolution (from ~1 to ~15.6
-// milliseconds) time stamp but is comparatively less expensive to retrieve and
-// more reliable. Time::EnableHighResolutionTimer() and
-// Time::ActivateHighResolutionTimer() can be called to alter the resolution of
-// this timer; and also other Windows applications can alter it, affecting this
-// one.
-
-using NowFunction = TimeDelta (*)(void);
-
-TimeDelta InitialNowFunction();
-TimeDelta InitialSystemTraceNowFunction();
-
-// See "threading notes" in InitializeNowFunctionPointers() for details on how
-// concurrent reads/writes to these globals has been made safe.
-NowFunction g_now_function = &InitialNowFunction;
-NowFunction g_system_trace_now_function = &InitialSystemTraceNowFunction;
-int64 g_qpc_ticks_per_second = 0;
-
-// As of January 2015, use of <atomic> is forbidden in Chromium code. This is
-// what std::atomic_thread_fence does on Windows on all Intel architectures when
-// the memory_order argument is anything but std::memory_order_seq_cst:
-#define ATOMIC_THREAD_FENCE(memory_order) _ReadWriteBarrier();
-
-TimeDelta QPCValueToTimeDelta(LONGLONG qpc_value) {
-  // Ensure that the assignment to |g_qpc_ticks_per_second|, made in
-  // InitializeNowFunctionPointers(), has happened by this point.
-  ATOMIC_THREAD_FENCE(memory_order_acquire);
-
-  DCHECK_GT(g_qpc_ticks_per_second, 0);
-
-  // If the QPC Value is below the overflow threshold, we proceed with
-  // simple multiply and divide.
-  if (qpc_value < Time::kQPCOverflowThreshold) {
-    return TimeDelta::FromMicroseconds(
-        qpc_value * Time::kMicrosecondsPerSecond / g_qpc_ticks_per_second);
-  }
-  // Otherwise, calculate microseconds in a round about manner to avoid
-  // overflow and precision issues.
-  int64 whole_seconds = qpc_value / g_qpc_ticks_per_second;
-  int64 leftover_ticks = qpc_value - (whole_seconds * g_qpc_ticks_per_second);
-  return TimeDelta::FromMicroseconds(
-      (whole_seconds * Time::kMicrosecondsPerSecond) +
-      ((leftover_ticks * Time::kMicrosecondsPerSecond) /
-       g_qpc_ticks_per_second));
-}
-
-TimeDelta QPCNow() {
-  LARGE_INTEGER now;
-  QueryPerformanceCounter(&now);
-  return QPCValueToTimeDelta(now.QuadPart);
-}
-
-bool IsBuggyAthlon(const base::CPU& cpu) {
-  // On Athlon X2 CPUs (e.g. model 15) QueryPerformanceCounter is unreliable.
-  return cpu.vendor_name() == "AuthenticAMD" && cpu.family() == 15;
-}
-
-void InitializeNowFunctionPointers() {
-  LARGE_INTEGER ticks_per_sec = {0};
-  if (!QueryPerformanceFrequency(&ticks_per_sec))
-    ticks_per_sec.QuadPart = 0;
-
-  // If Windows cannot provide a QPC implementation, both TimeTicks::Now() and
-  // TraceTicks::Now() must use the low-resolution clock.
-  //
-  // If the QPC implementation is expensive and/or unreliable, TimeTicks::Now()
-  // will use the low-resolution clock, but TraceTicks::Now() will use the QPC
-  // (in the hope that it is still useful for tracing purposes). A CPU lacking a
-  // non-stop time counter will cause Windows to provide an alternate QPC
-  // implementation that works, but is expensive to use. Certain Athlon CPUs are
-  // known to make the QPC implementation unreliable.
-  //
-  // Otherwise, both Now functions can use the high-resolution QPC clock. As of
-  // 4 January 2015, ~68% of users fall within this category.
-  NowFunction now_function;
-  NowFunction system_trace_now_function;
-  base::CPU cpu;
-  if (ticks_per_sec.QuadPart <= 0) {
-    now_function = system_trace_now_function = &RolloverProtectedNow;
-  } else if (!cpu.has_non_stop_time_stamp_counter() || IsBuggyAthlon(cpu)) {
-    now_function = &RolloverProtectedNow;
-    system_trace_now_function = &QPCNow;
-  } else {
-    now_function = system_trace_now_function = &QPCNow;
-  }
-
-  // Threading note 1: In an unlikely race condition, it's possible for two or
-  // more threads to enter InitializeNowFunctionPointers() in parallel. This is
-  // not a problem since all threads should end up writing out the same values
-  // to the global variables.
-  //
-  // Threading note 2: A release fence is placed here to ensure, from the
-  // perspective of other threads using the function pointers, that the
-  // assignment to |g_qpc_ticks_per_second| happens before the function pointers
-  // are changed.
-  g_qpc_ticks_per_second = ticks_per_sec.QuadPart;
-  ATOMIC_THREAD_FENCE(memory_order_release);
-  g_now_function = now_function;
-  g_system_trace_now_function = system_trace_now_function;
-}
-
-TimeDelta InitialNowFunction() {
-  InitializeNowFunctionPointers();
-  return g_now_function();
-}
-
-TimeDelta InitialSystemTraceNowFunction() {
-  InitializeNowFunctionPointers();
-  return g_system_trace_now_function();
-}
-
-}  // namespace
-
-// static
-TimeTicks::TickFunctionType TimeTicks::SetMockTickFunction(
-    TickFunctionType ticker) {
-  base::AutoLock locked(g_rollover_lock);
-  TickFunctionType old = g_tick_function;
-  g_tick_function = ticker;
-  g_rollover_ms = 0;
-  g_last_seen_now = 0;
-  return old;
-}
-
-// static
-TimeTicks TimeTicks::Now() {
-  return TimeTicks() + g_now_function();
-}
-
-// static
-bool TimeTicks::IsHighResolution() {
-  if (g_now_function == &InitialNowFunction)
-    InitializeNowFunctionPointers();
-  return g_now_function == &QPCNow;
-}
-
-// static
-ThreadTicks ThreadTicks::Now() {
-  NOTREACHED();
-  return ThreadTicks();
-}
-
-// static
-TraceTicks TraceTicks::Now() {
-  return TraceTicks() + g_system_trace_now_function();
-}
-
-// static
-TimeTicks TimeTicks::FromQPCValue(LONGLONG qpc_value) {
-  return TimeTicks() + QPCValueToTimeDelta(qpc_value);
-}
-
-// TimeDelta ------------------------------------------------------------------
-
-// static
-TimeDelta TimeDelta::FromQPCValue(LONGLONG qpc_value) {
-  return QPCValueToTimeDelta(qpc_value);
-}