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99 lines
3.3 KiB
C++
99 lines
3.3 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/system_wrappers/interface/tick_util.h"
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#include <assert.h>
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namespace webrtc {
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bool TickTime::use_fake_clock_ = false;
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int64_t TickTime::fake_ticks_ = 0;
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void TickTime::UseFakeClock(int64_t start_millisecond) {
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use_fake_clock_ = true;
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fake_ticks_ = MillisecondsToTicks(start_millisecond);
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}
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void TickTime::AdvanceFakeClock(int64_t milliseconds) {
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assert(use_fake_clock_);
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fake_ticks_ += MillisecondsToTicks(milliseconds);
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}
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int64_t TickTime::QueryOsForTicks() {
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TickTime result;
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#if _WIN32
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// TODO(wu): Remove QueryPerformanceCounter implementation.
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#ifdef USE_QUERY_PERFORMANCE_COUNTER
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// QueryPerformanceCounter returns the value from the TSC which is
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// incremented at the CPU frequency. The algorithm used requires
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// the CPU frequency to be constant. Technology like speed stepping
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// which has variable CPU frequency will therefore yield unpredictable,
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// incorrect time estimations.
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LARGE_INTEGER qpcnt;
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QueryPerformanceCounter(&qpcnt);
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result.ticks_ = qpcnt.QuadPart;
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#else
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static volatile LONG last_time_get_time = 0;
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static volatile int64_t num_wrap_time_get_time = 0;
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volatile LONG* last_time_get_time_ptr = &last_time_get_time;
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DWORD now = timeGetTime();
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// Atomically update the last gotten time
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DWORD old = InterlockedExchange(last_time_get_time_ptr, now);
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if (now < old) {
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// If now is earlier than old, there may have been a race between
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// threads.
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// 0x0fffffff ~3.1 days, the code will not take that long to execute
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// so it must have been a wrap around.
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if (old > 0xf0000000 && now < 0x0fffffff) {
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num_wrap_time_get_time++;
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}
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}
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result.ticks_ = now + (num_wrap_time_get_time << 32);
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#endif
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#elif defined(WEBRTC_LINUX)
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struct timespec ts;
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// TODO(wu): Remove CLOCK_REALTIME implementation.
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#ifdef WEBRTC_CLOCK_TYPE_REALTIME
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clock_gettime(CLOCK_REALTIME, &ts);
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#else
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clock_gettime(CLOCK_MONOTONIC, &ts);
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#endif
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result.ticks_ = 1000000000LL * static_cast<int64_t>(ts.tv_sec) +
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static_cast<int64_t>(ts.tv_nsec);
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#elif defined(WEBRTC_MAC)
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static mach_timebase_info_data_t timebase;
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if (timebase.denom == 0) {
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// Get the timebase if this is the first time we run.
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// Recommended by Apple's QA1398.
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kern_return_t retval = mach_timebase_info(&timebase);
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if (retval != KERN_SUCCESS) {
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// TODO(wu): Implement CHECK similar to chrome for all the platforms.
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// Then replace this with a CHECK(retval == KERN_SUCCESS);
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#ifndef WEBRTC_IOS
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asm("int3");
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#else
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__builtin_trap();
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#endif // WEBRTC_IOS
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}
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}
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// Use timebase to convert absolute time tick units into nanoseconds.
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result.ticks_ = mach_absolute_time() * timebase.numer / timebase.denom;
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#else
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struct timeval tv;
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gettimeofday(&tv, NULL);
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result.ticks_ = 1000000LL * static_cast<int64_t>(tv.tv_sec) +
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static_cast<int64_t>(tv.tv_usec);
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#endif
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return result.ticks_;
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}
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} // namespace webrtc
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