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1 /*
2  * Copyright 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 #include "tuningfork_internal.h"
20 
21 #include <inttypes.h>
22 #include <vector>
23 #include <string>
24 
25 namespace tuningfork {
26 
27 class Histogram {
28     typedef double Sample;
29     static constexpr int kAutoSizeNumStdDev = 3;
30     static constexpr double kAutoSizeMinBucketSizeMs = 0.1;
31     Sample start_ms_, end_ms_, bucket_dt_ms_;
32     uint32_t num_buckets_;
33     std::vector<uint32_t> buckets_;
34     std::vector<Sample> samples_;
35     bool auto_range_;
36     size_t count_;
37 public:
38     static constexpr int kDefaultNumBuckets = 30;
39 
40     explicit Histogram(float start_ms = 0, float end_ms = 0, int num_buckets_between = kDefaultNumBuckets);
41     explicit Histogram(const Settings::Histogram&);
42 
43     // Add a sample delta time
44     void Add(Sample dt_ms);
45 
46     // Reset the histogram
47     void Clear(bool autorange = false);
48 
49     // Get the total number of samples added so far
Count()50     size_t Count() const { return count_; }
51 
52     // Get the histogram as a JSON object, for testing
53     std::string ToJSON() const;
54 
55     // Use the data we have to construct the bucket ranges. This is called automatically after
56     //  sizeAtWhichToRange samples have been collected, if we are auto-ranging.
57     void CalcBucketsFromSamples();
58 
59     friend class ClearcutSerializer;
60 };
61 
62 } // namespace tuningfork {
63