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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 "components/metrics/histogram_encoder.h"
#include <memory>
#include <string>
#include "base/metrics/histogram.h"
#include "base/metrics/histogram_samples.h"
#include "base/metrics/metrics_hashes.h"
using base::SampleCountIterator;
namespace metrics {
void EncodeHistogramDelta(const std::string& histogram_name,
const base::HistogramSamples& snapshot,
ChromeUserMetricsExtension* uma_proto) {
DCHECK_NE(0, snapshot.TotalCount());
DCHECK(uma_proto);
// We will ignore the MAX_INT/infinite value in the last element of range[].
HistogramEventProto* histogram_proto = uma_proto->add_histogram_event();
histogram_proto->set_name_hash(base::HashMetricName(histogram_name));
if (snapshot.sum() != 0)
histogram_proto->set_sum(snapshot.sum());
for (std::unique_ptr<SampleCountIterator> it = snapshot.Iterator();
!it->Done(); it->Next()) {
base::Histogram::Sample min;
int64_t max;
base::Histogram::Count count;
it->Get(&min, &max, &count);
HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket();
bucket->set_min(min);
bucket->set_max(max);
// Note: The default for count is 1 in the proto, so omit it in that case.
// The iterator also skips over empty buckets, so no need to manually omit
// them.
if (count != 1)
bucket->set_count(count);
}
// Omit fields to save space (see rules in histogram_event.proto comments).
for (int i = 0; i < histogram_proto->bucket_size(); ++i) {
HistogramEventProto::Bucket* bucket = histogram_proto->mutable_bucket(i);
if (i + 1 < histogram_proto->bucket_size() &&
bucket->max() == histogram_proto->bucket(i + 1).min()) {
bucket->clear_max();
} else if (bucket->max() == bucket->min() + 1) {
bucket->clear_min();
}
}
}
} // namespace metrics
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