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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <cmath>
#include <utility>
#include "cc/base/rolling_time_delta_history.h"
namespace cc {
RollingTimeDeltaHistory::RollingTimeDeltaHistory(size_t max_size)
: max_size_(max_size) {}
RollingTimeDeltaHistory::~RollingTimeDeltaHistory() = default;
void RollingTimeDeltaHistory::InsertSample(base::TimeDelta time) {
if (max_size_ == 0)
return;
if (sample_set_.size() == max_size_) {
sample_set_.erase(chronological_sample_deque_.front());
chronological_sample_deque_.pop_front();
}
auto it = sample_set_.insert(time);
chronological_sample_deque_.push_back(it);
percentile_cache_.clear();
}
void RollingTimeDeltaHistory::RemoveOldestSample() {
if (sample_set_.size() > 0) {
sample_set_.erase(chronological_sample_deque_.front());
chronological_sample_deque_.pop_front();
}
}
void RollingTimeDeltaHistory::Clear() {
chronological_sample_deque_.clear();
sample_set_.clear();
percentile_cache_.clear();
}
base::TimeDelta RollingTimeDeltaHistory::Percentile(double percent) const {
auto pair =
percentile_cache_.insert(std::make_pair(percent, base::TimeDelta()));
auto it = pair.first;
bool inserted = pair.second;
if (inserted)
it->second = ComputePercentile(percent);
return it->second;
}
base::TimeDelta RollingTimeDeltaHistory::ComputePercentile(
double percent) const {
if (sample_set_.size() == 0)
return base::TimeDelta();
double fraction = percent / 100.0;
if (fraction <= 0.0)
return *(sample_set_.begin());
if (fraction >= 1.0)
return *(sample_set_.rbegin());
size_t num_smaller_samples =
static_cast<size_t>(std::ceil(fraction * sample_set_.size())) - 1;
if (num_smaller_samples > sample_set_.size() / 2) {
size_t num_larger_samples = sample_set_.size() - num_smaller_samples - 1;
auto it = sample_set_.rbegin();
for (size_t i = 0; i < num_larger_samples; i++)
it++;
return *it;
}
auto it = sample_set_.begin();
for (size_t i = 0; i < num_smaller_samples; i++)
it++;
return *it;
}
} // namespace cc
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