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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "cc/base/histograms.h"
#include <algorithm>
#include <cmath>
#include <limits>
#include "base/numerics/safe_conversions.h"
namespace cc {
// Minimum elapsed time of 1us to limit weighting of fast calls.
static const int64 kMinimumTimeMicroseconds = 1;
ScopedUMAHistogramAreaTimerBase::ScopedUMAHistogramAreaTimerBase() : area_(0) {
}
ScopedUMAHistogramAreaTimerBase::~ScopedUMAHistogramAreaTimerBase() {
}
bool ScopedUMAHistogramAreaTimerBase::GetHistogramValues(
Sample* time_microseconds,
Sample* pixels_per_ms) const {
return GetHistogramValues(
timer_.Elapsed(), area_.ValueOrDefault(std::numeric_limits<int>::max()),
time_microseconds, pixels_per_ms);
}
// static
bool ScopedUMAHistogramAreaTimerBase::GetHistogramValues(
base::TimeDelta elapsed,
int area,
Sample* time_microseconds,
Sample* pixels_per_ms) {
elapsed = std::max(
elapsed, base::TimeDelta::FromMicroseconds(kMinimumTimeMicroseconds));
double area_per_time = area / elapsed.InMillisecondsF();
// It is not clear how NaN can get here, but we've gotten crashes from
// saturated_cast. http://crbug.com/486214
if (std::isnan(area_per_time))
return false;
*time_microseconds = base::saturated_cast<Sample>(elapsed.InMicroseconds());
*pixels_per_ms = base::saturated_cast<Sample>(area_per_time);
return true;
}
} // namespace cc
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