blob: aa80f8fb599508e7af6b64441252317a21f17149 [file] [log] [blame]
/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/system_wrappers/interface/clock.h"
#if defined(_WIN32)
// Windows needs to be included before mmsystem.h
#include <Windows.h>
#include <WinSock.h>
#include <MMSystem.h>
#elif ((defined WEBRTC_LINUX) || (defined WEBRTC_MAC))
#include <sys/time.h>
#include <time.h>
#endif
#include "webrtc/system_wrappers/interface/rw_lock_wrapper.h"
#include "webrtc/system_wrappers/interface/tick_util.h"
namespace webrtc {
const double kNtpFracPerMs = 4.294967296E6;
int64_t Clock::NtpToMs(uint32_t ntp_secs, uint32_t ntp_frac) {
const double ntp_frac_ms = static_cast<double>(ntp_frac) / kNtpFracPerMs;
return 1000 * static_cast<int64_t>(ntp_secs) +
static_cast<int64_t>(ntp_frac_ms + 0.5);
}
#if defined(_WIN32)
struct reference_point {
FILETIME file_time;
LARGE_INTEGER counterMS;
};
struct WindowsHelpTimer {
volatile LONG _timeInMs;
volatile LONG _numWrapTimeInMs;
reference_point _ref_point;
volatile LONG _sync_flag;
};
void Synchronize(WindowsHelpTimer* help_timer) {
const LONG start_value = 0;
const LONG new_value = 1;
const LONG synchronized_value = 2;
LONG compare_flag = new_value;
while (help_timer->_sync_flag == start_value) {
const LONG new_value = 1;
compare_flag = InterlockedCompareExchange(
&help_timer->_sync_flag, new_value, start_value);
}
if (compare_flag != start_value) {
// This thread was not the one that incremented the sync flag.
// Block until synchronization finishes.
while (compare_flag != synchronized_value) {
::Sleep(0);
}
return;
}
// Only the synchronizing thread gets here so this part can be
// considered single threaded.
// set timer accuracy to 1 ms
timeBeginPeriod(1);
FILETIME ft0 = { 0, 0 },
ft1 = { 0, 0 };
//
// Spin waiting for a change in system time. Get the matching
// performance counter value for that time.
//
::GetSystemTimeAsFileTime(&ft0);
do {
::GetSystemTimeAsFileTime(&ft1);
help_timer->_ref_point.counterMS.QuadPart = ::timeGetTime();
::Sleep(0);
} while ((ft0.dwHighDateTime == ft1.dwHighDateTime) &&
(ft0.dwLowDateTime == ft1.dwLowDateTime));
help_timer->_ref_point.file_time = ft1;
timeEndPeriod(1);
}
void get_time(WindowsHelpTimer* help_timer, FILETIME& current_time) {
// we can't use query performance counter due to speed stepping
DWORD t = timeGetTime();
// NOTE: we have a missmatch in sign between _timeInMs(LONG) and
// (DWORD) however we only use it here without +- etc
volatile LONG* timeInMsPtr = &help_timer->_timeInMs;
// Make sure that we only inc wrapper once.
DWORD old = InterlockedExchange(timeInMsPtr, t);
if(old > t) {
// wrap
help_timer->_numWrapTimeInMs++;
}
LARGE_INTEGER elapsedMS;
elapsedMS.HighPart = help_timer->_numWrapTimeInMs;
elapsedMS.LowPart = t;
elapsedMS.QuadPart = elapsedMS.QuadPart -
help_timer->_ref_point.counterMS.QuadPart;
// Translate to 100-nanoseconds intervals (FILETIME resolution)
// and add to reference FILETIME to get current FILETIME.
ULARGE_INTEGER filetime_ref_as_ul;
filetime_ref_as_ul.HighPart =
help_timer->_ref_point.file_time.dwHighDateTime;
filetime_ref_as_ul.LowPart =
help_timer->_ref_point.file_time.dwLowDateTime;
filetime_ref_as_ul.QuadPart +=
(ULONGLONG)((elapsedMS.QuadPart)*1000*10);
// Copy to result
current_time.dwHighDateTime = filetime_ref_as_ul.HighPart;
current_time.dwLowDateTime = filetime_ref_as_ul.LowPart;
}
#endif
class RealTimeClock : public Clock {
// Return a timestamp in milliseconds relative to some arbitrary source; the
// source is fixed for this clock.
virtual int64_t TimeInMilliseconds() OVERRIDE {
return TickTime::MillisecondTimestamp();
}
// Return a timestamp in microseconds relative to some arbitrary source; the
// source is fixed for this clock.
virtual int64_t TimeInMicroseconds() OVERRIDE {
return TickTime::MicrosecondTimestamp();
}
// Retrieve an NTP absolute timestamp in seconds and fractions of a second.
virtual void CurrentNtp(uint32_t& seconds, uint32_t& fractions) OVERRIDE {
timeval tv = CurrentTimeVal();
double microseconds_in_seconds;
Adjust(tv, &seconds, &microseconds_in_seconds);
fractions = static_cast<uint32_t>(
microseconds_in_seconds * kMagicNtpFractionalUnit + 0.5);
}
// Retrieve an NTP absolute timestamp in milliseconds.
virtual int64_t CurrentNtpInMilliseconds() OVERRIDE {
timeval tv = CurrentTimeVal();
uint32_t seconds;
double microseconds_in_seconds;
Adjust(tv, &seconds, &microseconds_in_seconds);
return 1000 * static_cast<int64_t>(seconds) +
static_cast<int64_t>(1000.0 * microseconds_in_seconds + 0.5);
}
protected:
virtual timeval CurrentTimeVal() const = 0;
static void Adjust(const timeval& tv, uint32_t* adjusted_s,
double* adjusted_us_in_s) {
*adjusted_s = tv.tv_sec + kNtpJan1970;
*adjusted_us_in_s = tv.tv_usec / 1e6;
if (*adjusted_us_in_s >= 1) {
*adjusted_us_in_s -= 1;
++*adjusted_s;
} else if (*adjusted_us_in_s < -1) {
*adjusted_us_in_s += 1;
--*adjusted_s;
}
}
};
#if defined(_WIN32)
class WindowsRealTimeClock : public RealTimeClock {
public:
WindowsRealTimeClock(WindowsHelpTimer* helpTimer)
: _helpTimer(helpTimer) {}
virtual ~WindowsRealTimeClock() {}
protected:
virtual timeval CurrentTimeVal() const OVERRIDE {
const uint64_t FILETIME_1970 = 0x019db1ded53e8000;
FILETIME StartTime;
uint64_t Time;
struct timeval tv;
// We can't use query performance counter since they can change depending on
// speed stepping.
get_time(_helpTimer, StartTime);
Time = (((uint64_t) StartTime.dwHighDateTime) << 32) +
(uint64_t) StartTime.dwLowDateTime;
// Convert the hecto-nano second time to tv format.
Time -= FILETIME_1970;
tv.tv_sec = (uint32_t)(Time / (uint64_t)10000000);
tv.tv_usec = (uint32_t)((Time % (uint64_t)10000000) / 10);
return tv;
}
WindowsHelpTimer* _helpTimer;
};
#elif ((defined WEBRTC_LINUX) || (defined WEBRTC_MAC))
class UnixRealTimeClock : public RealTimeClock {
public:
UnixRealTimeClock() {}
virtual ~UnixRealTimeClock() {}
protected:
virtual timeval CurrentTimeVal() const OVERRIDE {
struct timeval tv;
struct timezone tz;
tz.tz_minuteswest = 0;
tz.tz_dsttime = 0;
gettimeofday(&tv, &tz);
return tv;
}
};
#endif
#if defined(_WIN32)
// Keeps the global state for the Windows implementation of RtpRtcpClock.
// Note that this is a POD. Only PODs are allowed to have static storage
// duration according to the Google Style guide.
//
// Note that on Windows, GetSystemTimeAsFileTime has poorer (up to 15 ms)
// resolution than the media timers, hence the WindowsHelpTimer context
// object and Synchronize API to sync the two.
//
// We only sync up once, which means that on Windows, our realtime clock
// wont respond to system time/date changes without a program restart.
// TODO(henrike): We should probably call sync more often to catch
// drift and time changes for parity with other platforms.
static WindowsHelpTimer *SyncGlobalHelpTimer() {
static WindowsHelpTimer global_help_timer = {0, 0, {{ 0, 0}, 0}, 0};
Synchronize(&global_help_timer);
return &global_help_timer;
}
#endif
Clock* Clock::GetRealTimeClock() {
#if defined(_WIN32)
static WindowsRealTimeClock clock(SyncGlobalHelpTimer());
return &clock;
#elif defined(WEBRTC_LINUX) || defined(WEBRTC_MAC)
static UnixRealTimeClock clock;
return &clock;
#else
return NULL;
#endif
}
SimulatedClock::SimulatedClock(int64_t initial_time_us)
: time_us_(initial_time_us), lock_(RWLockWrapper::CreateRWLock()) {
}
SimulatedClock::~SimulatedClock() {
}
int64_t SimulatedClock::TimeInMilliseconds() {
ReadLockScoped synchronize(*lock_);
return (time_us_ + 500) / 1000;
}
int64_t SimulatedClock::TimeInMicroseconds() {
ReadLockScoped synchronize(*lock_);
return time_us_;
}
void SimulatedClock::CurrentNtp(uint32_t& seconds, uint32_t& fractions) {
int64_t now_ms = TimeInMilliseconds();
seconds = (now_ms / 1000) + kNtpJan1970;
fractions =
static_cast<uint32_t>((now_ms % 1000) * kMagicNtpFractionalUnit / 1000);
}
int64_t SimulatedClock::CurrentNtpInMilliseconds() {
return TimeInMilliseconds() + 1000 * static_cast<int64_t>(kNtpJan1970);
}
void SimulatedClock::AdvanceTimeMilliseconds(int64_t milliseconds) {
AdvanceTimeMicroseconds(1000 * milliseconds);
}
void SimulatedClock::AdvanceTimeMicroseconds(int64_t microseconds) {
WriteLockScoped synchronize(*lock_);
time_us_ += microseconds;
}
}; // namespace webrtc