60 lines
2.0 KiB
C++
60 lines
2.0 KiB
C++
// Copyright 2014 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "components/metrics/histogram_encoder.h"
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#include <memory>
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#include <string>
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#include "base/metrics/histogram.h"
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#include "base/metrics/histogram_samples.h"
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#include "base/metrics/metrics_hashes.h"
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using base::SampleCountIterator;
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namespace metrics {
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void EncodeHistogramDelta(const std::string& histogram_name,
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const base::HistogramSamples& snapshot,
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ChromeUserMetricsExtension* uma_proto) {
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DCHECK_NE(0, snapshot.TotalCount());
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DCHECK(uma_proto);
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// We will ignore the MAX_INT/infinite value in the last element of range[].
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HistogramEventProto* histogram_proto = uma_proto->add_histogram_event();
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histogram_proto->set_name_hash(base::HashMetricName(histogram_name));
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if (snapshot.sum() != 0)
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histogram_proto->set_sum(snapshot.sum());
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for (std::unique_ptr<SampleCountIterator> it = snapshot.Iterator();
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!it->Done(); it->Next()) {
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base::Histogram::Sample min;
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int64_t max;
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base::Histogram::Count count;
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it->Get(&min, &max, &count);
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HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket();
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bucket->set_min(min);
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bucket->set_max(max);
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// Note: The default for count is 1 in the proto, so omit it in that case.
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// The iterator also skips over empty buckets, so no need to manually omit
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// them.
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if (count != 1)
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bucket->set_count(count);
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}
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// Omit fields to save space (see rules in histogram_event.proto comments).
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for (int i = 0; i < histogram_proto->bucket_size(); ++i) {
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HistogramEventProto::Bucket* bucket = histogram_proto->mutable_bucket(i);
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if (i + 1 < histogram_proto->bucket_size() &&
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bucket->max() == histogram_proto->bucket(i + 1).min()) {
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bucket->clear_max();
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} else if (bucket->max() == bucket->min() + 1) {
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bucket->clear_min();
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}
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}
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}
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} // namespace metrics
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