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/*
* Copyright (C) 2006 Apple Computer, Inc. All rights reserved.
* Copyright (C) 2008 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "CurrentTime.h"
#if PLATFORM(WIN_OS)
// Windows is first since we want to use hires timers, despite PLATFORM(CF)
// being defined.
// If defined, WIN32_LEAN_AND_MEAN disables timeBeginPeriod/timeEndPeriod.
#undef WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <math.h>
#include <stdint.h>
#if HAVE(SYS_TIMEB_H)
#include <sys/timeb.h>
#endif
#if !PLATFORM(WINCE)
#include <sys/types.h>
#endif
#include <time.h>
#elif PLATFORM(CF)
#include <CoreFoundation/CFDate.h>
#elif PLATFORM(GTK)
#include <glib.h>
#elif PLATFORM(WX)
#include <wx/datetime.h>
#else // Posix systems relying on the gettimeofday()
#include <sys/time.h>
#endif
namespace WTF {
const double msPerSecond = 1000.0;
#if PLATFORM(WIN_OS)
static LARGE_INTEGER qpcFrequency;
static bool syncedTime;
static double highResUpTime()
{
// We use QPC, but only after sanity checking its result, due to bugs:
// http://support.microsoft.com/kb/274323
// http://support.microsoft.com/kb/895980
// http://msdn.microsoft.com/en-us/library/ms644904.aspx ("...you can get different results on different processors due to bugs in the basic input/output system (BIOS) or the hardware abstraction layer (HAL)."
static LARGE_INTEGER qpcLast;
static DWORD tickCountLast;
static bool inited;
LARGE_INTEGER qpc;
QueryPerformanceCounter(&qpc);
DWORD tickCount = GetTickCount();
if (inited) {
__int64 qpcElapsed = ((qpc.QuadPart - qpcLast.QuadPart) * 1000) / qpcFrequency.QuadPart;
__int64 tickCountElapsed;
if (tickCount >= tickCountLast)
tickCountElapsed = (tickCount - tickCountLast);
else {
#if COMPILER(MINGW)
__int64 tickCountLarge = tickCount + 0x100000000ULL;
#else
__int64 tickCountLarge = tickCount + 0x100000000I64;
#endif
tickCountElapsed = tickCountLarge - tickCountLast;
}
// force a re-sync if QueryPerformanceCounter differs from GetTickCount by more than 500ms.
// (500ms value is from http://support.microsoft.com/kb/274323)
__int64 diff = tickCountElapsed - qpcElapsed;
if (diff > 500 || diff < -500)
syncedTime = false;
} else
inited = true;
qpcLast = qpc;
tickCountLast = tickCount;
return (1000.0 * qpc.QuadPart) / static_cast<double>(qpcFrequency.QuadPart);
}
static double lowResUTCTime()
{
#if PLATFORM(WINCE)
SYSTEMTIME systemTime;
GetSystemTime(&systemTime);
struct tm tmtime;
tmtime.tm_year = systemTime.wYear - 1900;
tmtime.tm_mon = systemTime.wMonth - 1;
tmtime.tm_mday = systemTime.wDay;
tmtime.tm_wday = systemTime.wDayOfWeek;
tmtime.tm_hour = systemTime.wHour;
tmtime.tm_min = systemTime.wMinute;
tmtime.tm_sec = systemTime.wSecond;
time_t timet = mktime(&tmtime);
return timet * msPerSecond + systemTime.wMilliseconds;
#else
struct _timeb timebuffer;
_ftime(&timebuffer);
return timebuffer.time * msPerSecond + timebuffer.millitm;
#endif
}
static bool qpcAvailable()
{
static bool available;
static bool checked;
if (checked)
return available;
available = QueryPerformanceFrequency(&qpcFrequency);
checked = true;
return available;
}
double currentTime()
{
// Use a combination of ftime and QueryPerformanceCounter.
// ftime returns the information we want, but doesn't have sufficient resolution.
// QueryPerformanceCounter has high resolution, but is only usable to measure time intervals.
// To combine them, we call ftime and QueryPerformanceCounter initially. Later calls will use QueryPerformanceCounter
// by itself, adding the delta to the saved ftime. We periodically re-sync to correct for drift.
static bool started;
static double syncLowResUTCTime;
static double syncHighResUpTime;
static double lastUTCTime;
double lowResTime = lowResUTCTime();
if (!qpcAvailable())
return lowResTime / 1000.0;
double highResTime = highResUpTime();
if (!syncedTime) {
timeBeginPeriod(1); // increase time resolution around low-res time getter
syncLowResUTCTime = lowResTime = lowResUTCTime();
timeEndPeriod(1); // restore time resolution
syncHighResUpTime = highResTime;
syncedTime = true;
}
double highResElapsed = highResTime - syncHighResUpTime;
double utc = syncLowResUTCTime + highResElapsed;
// force a clock re-sync if we've drifted
double lowResElapsed = lowResTime - syncLowResUTCTime;
const double maximumAllowedDriftMsec = 15.625 * 2.0; // 2x the typical low-res accuracy
if (fabs(highResElapsed - lowResElapsed) > maximumAllowedDriftMsec)
syncedTime = false;
// make sure time doesn't run backwards (only correct if difference is < 2 seconds, since DST or clock changes could occur)
const double backwardTimeLimit = 2000.0;
if (utc < lastUTCTime && (lastUTCTime - utc) < backwardTimeLimit)
return lastUTCTime / 1000.0;
lastUTCTime = utc;
return utc / 1000.0;
}
#elif PLATFORM(CF)
double currentTime()
{
return CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970;
}
#elif PLATFORM(GTK)
// Note: GTK on Windows will pick up the PLATFORM(WIN) implementation above which provides
// better accuracy compared with Windows implementation of g_get_current_time:
// (http://www.google.com/codesearch/p?hl=en#HHnNRjks1t0/glib-2.5.2/glib/gmain.c&q=g_get_current_time).
// Non-Windows GTK builds could use gettimeofday() directly but for the sake of consistency lets use GTK function.
double currentTime()
{
GTimeVal now;
g_get_current_time(&now);
return static_cast<double>(now.tv_sec) + static_cast<double>(now.tv_usec / 1000000.0);
}
#elif PLATFORM(WX)
double currentTime()
{
wxDateTime now = wxDateTime::UNow();
return (double)now.GetTicks() + (double)(now.GetMillisecond() / 1000.0);
}
#else // Other Posix systems rely on the gettimeofday().
double currentTime()
{
struct timeval now;
struct timezone zone;
gettimeofday(&now, &zone);
return static_cast<double>(now.tv_sec) + (double)(now.tv_usec / 1000000.0);
}
#endif
} // namespace WTF
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