1 // Copyright 2014 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "components/metrics/histogram_encoder.h" 6 7 #include <memory> 8 #include <string> 9 10 #include "base/metrics/histogram.h" 11 #include "base/metrics/histogram_samples.h" 12 #include "base/metrics/metrics_hashes.h" 13 14 using base::SampleCountIterator; 15 16 namespace metrics { 17 EncodeHistogramDelta(const std::string & histogram_name,const base::HistogramSamples & snapshot,ChromeUserMetricsExtension * uma_proto)18void EncodeHistogramDelta(const std::string& histogram_name, 19 const base::HistogramSamples& snapshot, 20 ChromeUserMetricsExtension* uma_proto) { 21 DCHECK_NE(0, snapshot.TotalCount()); 22 DCHECK(uma_proto); 23 24 // We will ignore the MAX_INT/infinite value in the last element of range[]. 25 26 HistogramEventProto* histogram_proto = uma_proto->add_histogram_event(); 27 histogram_proto->set_name_hash(base::HashMetricName(histogram_name)); 28 if (snapshot.sum() != 0) 29 histogram_proto->set_sum(snapshot.sum()); 30 31 for (std::unique_ptr<SampleCountIterator> it = snapshot.Iterator(); 32 !it->Done(); it->Next()) { 33 base::Histogram::Sample min; 34 int64_t max; 35 base::Histogram::Count count; 36 it->Get(&min, &max, &count); 37 HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket(); 38 bucket->set_min(min); 39 bucket->set_max(max); 40 // Note: The default for count is 1 in the proto, so omit it in that case. 41 // The iterator also skips over empty buckets, so no need to manually omit 42 // them. 43 if (count != 1) 44 bucket->set_count(count); 45 } 46 47 // Omit fields to save space (see rules in histogram_event.proto comments). 48 for (int i = 0; i < histogram_proto->bucket_size(); ++i) { 49 HistogramEventProto::Bucket* bucket = histogram_proto->mutable_bucket(i); 50 if (i + 1 < histogram_proto->bucket_size() && 51 bucket->max() == histogram_proto->bucket(i + 1).min()) { 52 bucket->clear_max(); 53 } else if (bucket->max() == bucket->min() + 1) { 54 bucket->clear_min(); 55 } 56 } 57 } 58 59 } // namespace metrics 60