103 lines
3.3 KiB
C++
103 lines
3.3 KiB
C++
/*
|
|
* Copyright 2021 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.
|
|
*/
|
|
|
|
// If WEBRTC_EXCLUDE_SYSTEM_TIME is set, an implementation of
|
|
// rtc::SystemTimeNanos() must be provided externally.
|
|
#ifndef WEBRTC_EXCLUDE_SYSTEM_TIME
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <limits>
|
|
|
|
#if defined(WEBRTC_POSIX)
|
|
#include <sys/time.h>
|
|
#if defined(WEBRTC_MAC)
|
|
#include <mach/mach_time.h>
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(WEBRTC_WIN)
|
|
// clang-format off
|
|
// clang formatting would put <windows.h> last,
|
|
// which leads to compilation failure.
|
|
#include <windows.h>
|
|
#include <mmsystem.h>
|
|
#include <sys/timeb.h>
|
|
// clang-format on
|
|
#endif
|
|
|
|
#include "rtc_base/checks.h"
|
|
#include "rtc_base/numerics/safe_conversions.h"
|
|
#include "rtc_base/system_time.h"
|
|
#include "rtc_base/time_utils.h"
|
|
|
|
namespace rtc {
|
|
|
|
int64_t SystemTimeNanos() {
|
|
int64_t ticks;
|
|
#if defined(WEBRTC_MAC)
|
|
static mach_timebase_info_data_t timebase;
|
|
if (timebase.denom == 0) {
|
|
// Get the timebase if this is the first time we run.
|
|
// Recommended by Apple's QA1398.
|
|
if (mach_timebase_info(&timebase) != KERN_SUCCESS) {
|
|
RTC_DCHECK_NOTREACHED();
|
|
}
|
|
}
|
|
// Use timebase to convert absolute time tick units into nanoseconds.
|
|
const auto mul = [](uint64_t a, uint32_t b) -> int64_t {
|
|
RTC_DCHECK_NE(b, 0);
|
|
RTC_DCHECK_LE(a, std::numeric_limits<int64_t>::max() / b)
|
|
<< "The multiplication " << a << " * " << b << " overflows";
|
|
return rtc::dchecked_cast<int64_t>(a * b);
|
|
};
|
|
ticks = mul(mach_absolute_time(), timebase.numer) / timebase.denom;
|
|
#elif defined(WEBRTC_POSIX)
|
|
struct timespec ts;
|
|
// TODO(deadbeef): Do we need to handle the case when CLOCK_MONOTONIC is not
|
|
// supported?
|
|
clock_gettime(CLOCK_MONOTONIC, &ts);
|
|
ticks = kNumNanosecsPerSec * static_cast<int64_t>(ts.tv_sec) +
|
|
static_cast<int64_t>(ts.tv_nsec);
|
|
#elif defined(WINUWP)
|
|
ticks = WinUwpSystemTimeNanos();
|
|
#elif defined(WEBRTC_WIN)
|
|
// TODO(webrtc:14601): Fix the volatile increment instead of suppressing the
|
|
// warning.
|
|
#pragma clang diagnostic push
|
|
#pragma clang diagnostic ignored "-Wdeprecated-volatile"
|
|
static volatile LONG last_timegettime = 0;
|
|
static volatile int64_t num_wrap_timegettime = 0;
|
|
volatile LONG* last_timegettime_ptr = &last_timegettime;
|
|
DWORD now = timeGetTime();
|
|
// Atomically update the last gotten time
|
|
DWORD old = InterlockedExchange(last_timegettime_ptr, now);
|
|
if (now < old) {
|
|
// If now is earlier than old, there may have been a race between threads.
|
|
// 0x0fffffff ~3.1 days, the code will not take that long to execute
|
|
// so it must have been a wrap around.
|
|
if (old > 0xf0000000 && now < 0x0fffffff) {
|
|
num_wrap_timegettime++;
|
|
}
|
|
}
|
|
ticks = now + (num_wrap_timegettime << 32);
|
|
// TODO(deadbeef): Calculate with nanosecond precision. Otherwise, we're
|
|
// just wasting a multiply and divide when doing Time() on Windows.
|
|
ticks = ticks * kNumNanosecsPerMillisec;
|
|
#pragma clang diagnostic pop
|
|
#else
|
|
#error Unsupported platform.
|
|
#endif
|
|
return ticks;
|
|
}
|
|
|
|
} // namespace rtc
|
|
#endif // WEBRTC_EXCLUDE_SYSTEM_TIME
|