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/*
* Copyright 2009, 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 "statsreport/common/highres_timer.h"
bool HighresTimer::perf_freq_collected_ = false;
ULONGLONG HighresTimer::perf_freq_ = 0;
ULONGLONG HighresTimer::GetElapsedMs() const {
ULONGLONG end_time = GetCurrentTicks();
// Scale to ms and round to nearerst ms - rounding is important
// because otherwise the truncation error may accumulate e.g. in sums.
//
// Given infinite resolution, this expression could be written as:
// trunc((end - start (units:freq*sec))/freq (units:sec) *
// 1000 (unit:ms) + 1/2 (unit:ms))
ULONGLONG freq = GetTimerFrequency();
return ((end_time - start_ticks_) * 1000L + freq / 2) / freq;
}
ULONGLONG HighresTimer::GetElapsedSec() const {
ULONGLONG end_time = GetCurrentTicks();
// Scale to ms and round to nearerst ms - rounding is important
// because otherwise the truncation error may accumulate e.g. in sums.
//
// Given infinite resolution, this expression could be written as:
// trunc((end - start (units:freq*sec))/freq (unit:sec) + 1/2 (unit:sec))
ULONGLONG freq = GetTimerFrequency();
return ((end_time - start_ticks_) + freq / 2) / freq;
}
void HighresTimer::CollectPerfFreq() {
LARGE_INTEGER freq;
// Note that this is racy. It's OK, however, because even
// concurrent executions of this are idempotent.
if (::QueryPerformanceFrequency(&freq)) {
perf_freq_ = freq.QuadPart;
perf_freq_collected_ = true;
}
}
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