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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/metrics/histograms_monitor.h"
#include "base/containers/map_util.h"
#include "base/metrics/histogram_samples.h"
#include "base/metrics/statistics_recorder.h"
namespace content {
HistogramsMonitor::HistogramsMonitor() = default;
HistogramsMonitor::~HistogramsMonitor() = default;
void HistogramsMonitor::StartMonitoring() {
histograms_snapshot_.clear();
// Save a snapshot of all current histograms that will be used as a baseline.
for (const auto* histogram : base::StatisticsRecorder::GetHistograms()) {
base::InsertOrAssign(histograms_snapshot_, histogram->histogram_name(),
histogram->SnapshotSamples());
}
}
base::Value::List HistogramsMonitor::GetDiff(const std::string& query) {
base::StatisticsRecorder::Histograms histograms =
base::StatisticsRecorder::Sort(base::StatisticsRecorder::WithName(
base::StatisticsRecorder::GetHistograms(), query,
/*case_sensitive=*/false));
return GetDiffInternal(histograms);
}
base::Value::List HistogramsMonitor::GetDiffInternal(
const base::StatisticsRecorder::Histograms& histograms) {
base::Value::List histograms_list;
for (const base::HistogramBase* const histogram : histograms) {
std::unique_ptr<base::HistogramSamples> snapshot =
histogram->SnapshotSamples();
auto it = histograms_snapshot_.find(histogram->histogram_name());
if (it != histograms_snapshot_.end()) {
snapshot->Subtract(*it->second.get());
}
if (snapshot->TotalCount() > 0) {
base::Value::Dict histogram_dict = snapshot->ToGraphDict(
histogram->histogram_name(), histogram->flags());
histograms_list.Append(std::move(histogram_dict));
}
}
return histograms_list;
}
} // namespace content
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