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1 | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
2 | // This source code is licensed under the BSD-style license found in the | |
3 | // LICENSE file in the root directory of this source tree. An additional grant | |
4 | // of patent rights can be found in the PATENTS file in the same directory. | |
5 | // | |
6 | // Copyright (c) 2011 The LevelDB Authors. All rights reserved. | |
7 | // Use of this source code is governed by a BSD-style license that can be | |
8 | // found in the LICENSE file. See the AUTHORS file for names of contributors. | |
9 | ||
10 | #pragma once | |
11 | #include "rocksdb/statistics.h" | |
12 | ||
13 | #include <cassert> | |
14 | #include <string> | |
15 | #include <vector> | |
16 | #include <map> | |
17 | #include <mutex> | |
18 | ||
19 | namespace rocksdb { | |
20 | ||
21 | class HistogramBucketMapper { | |
22 | public: | |
23 | ||
24 | HistogramBucketMapper(); | |
25 | ||
26 | // converts a value to the bucket index. | |
27 | size_t IndexForValue(uint64_t value) const; | |
28 | // number of buckets required. | |
29 | ||
30 | size_t BucketCount() const { | |
31 | return bucketValues_.size(); | |
32 | } | |
33 | ||
34 | uint64_t LastValue() const { | |
35 | return maxBucketValue_; | |
36 | } | |
37 | ||
38 | uint64_t FirstValue() const { | |
39 | return minBucketValue_; | |
40 | } | |
41 | ||
42 | uint64_t BucketLimit(const size_t bucketNumber) const { | |
43 | assert(bucketNumber < BucketCount()); | |
44 | return bucketValues_[bucketNumber]; | |
45 | } | |
46 | ||
47 | private: | |
48 | const std::vector<uint64_t> bucketValues_; | |
49 | const uint64_t maxBucketValue_; | |
50 | const uint64_t minBucketValue_; | |
51 | std::map<uint64_t, uint64_t> valueIndexMap_; | |
52 | }; | |
53 | ||
54 | struct HistogramStat { | |
55 | HistogramStat(); | |
56 | ~HistogramStat() {} | |
57 | ||
58 | HistogramStat(const HistogramStat&) = delete; | |
59 | HistogramStat& operator=(const HistogramStat&) = delete; | |
60 | ||
61 | void Clear(); | |
62 | bool Empty() const; | |
63 | void Add(uint64_t value); | |
64 | void Merge(const HistogramStat& other); | |
65 | ||
66 | inline uint64_t min() const { return min_.load(std::memory_order_relaxed); } | |
67 | inline uint64_t max() const { return max_.load(std::memory_order_relaxed); } | |
68 | inline uint64_t num() const { return num_.load(std::memory_order_relaxed); } | |
69 | inline uint64_t sum() const { return sum_.load(std::memory_order_relaxed); } | |
70 | inline uint64_t sum_squares() const { | |
71 | return sum_squares_.load(std::memory_order_relaxed); | |
72 | } | |
73 | inline uint64_t bucket_at(size_t b) const { | |
74 | return buckets_[b].load(std::memory_order_relaxed); | |
75 | } | |
76 | ||
77 | double Median() const; | |
78 | double Percentile(double p) const; | |
79 | double Average() const; | |
80 | double StandardDeviation() const; | |
81 | void Data(HistogramData* const data) const; | |
82 | std::string ToString() const; | |
83 | ||
84 | // To be able to use HistogramStat as thread local variable, it | |
85 | // cannot have dynamic allocated member. That's why we're | |
86 | // using manually values from BucketMapper | |
87 | std::atomic_uint_fast64_t min_; | |
88 | std::atomic_uint_fast64_t max_; | |
89 | std::atomic_uint_fast64_t num_; | |
90 | std::atomic_uint_fast64_t sum_; | |
91 | std::atomic_uint_fast64_t sum_squares_; | |
92 | std::atomic_uint_fast64_t buckets_[138]; // 138==BucketMapper::BucketCount() | |
93 | const uint64_t num_buckets_; | |
94 | }; | |
95 | ||
96 | class Histogram { | |
97 | public: | |
98 | Histogram() {} | |
99 | virtual ~Histogram() {}; | |
100 | ||
101 | virtual void Clear() = 0; | |
102 | virtual bool Empty() const = 0; | |
103 | virtual void Add(uint64_t value) = 0; | |
104 | virtual void Merge(const Histogram&) = 0; | |
105 | ||
106 | virtual std::string ToString() const = 0; | |
107 | virtual const char* Name() const = 0; | |
108 | virtual uint64_t min() const = 0; | |
109 | virtual uint64_t max() const = 0; | |
110 | virtual uint64_t num() const = 0; | |
111 | virtual double Median() const = 0; | |
112 | virtual double Percentile(double p) const = 0; | |
113 | virtual double Average() const = 0; | |
114 | virtual double StandardDeviation() const = 0; | |
115 | virtual void Data(HistogramData* const data) const = 0; | |
116 | }; | |
117 | ||
118 | class HistogramImpl : public Histogram { | |
119 | public: | |
120 | HistogramImpl() { Clear(); } | |
121 | ||
122 | HistogramImpl(const HistogramImpl&) = delete; | |
123 | HistogramImpl& operator=(const HistogramImpl&) = delete; | |
124 | ||
125 | virtual void Clear() override; | |
126 | virtual bool Empty() const override; | |
127 | virtual void Add(uint64_t value) override; | |
128 | virtual void Merge(const Histogram& other) override; | |
129 | void Merge(const HistogramImpl& other); | |
130 | ||
131 | virtual std::string ToString() const override; | |
132 | virtual const char* Name() const override { return "HistogramImpl"; } | |
133 | virtual uint64_t min() const override { return stats_.min(); } | |
134 | virtual uint64_t max() const override { return stats_.max(); } | |
135 | virtual uint64_t num() const override { return stats_.num(); } | |
136 | virtual double Median() const override; | |
137 | virtual double Percentile(double p) const override; | |
138 | virtual double Average() const override; | |
139 | virtual double StandardDeviation() const override; | |
140 | virtual void Data(HistogramData* const data) const override; | |
141 | ||
142 | virtual ~HistogramImpl() {} | |
143 | ||
144 | private: | |
145 | HistogramStat stats_; | |
146 | std::mutex mutex_; | |
147 | }; | |
148 | ||
149 | } // namespace rocksdb |