149 lines
4.5 KiB
C++
149 lines
4.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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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. See the AUTHORS file for names of contributors.
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#pragma once
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#include "rocksdb/statistics.h"
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#include <cassert>
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#include <string>
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#include <vector>
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#include <map>
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#include <mutex>
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namespace rocksdb {
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class HistogramBucketMapper {
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public:
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HistogramBucketMapper();
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// converts a value to the bucket index.
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size_t IndexForValue(uint64_t value) const;
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// number of buckets required.
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size_t BucketCount() const {
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return bucketValues_.size();
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}
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uint64_t LastValue() const {
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return maxBucketValue_;
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}
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uint64_t FirstValue() const {
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return minBucketValue_;
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}
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uint64_t BucketLimit(const size_t bucketNumber) const {
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assert(bucketNumber < BucketCount());
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return bucketValues_[bucketNumber];
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}
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private:
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const std::vector<uint64_t> bucketValues_;
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const uint64_t maxBucketValue_;
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const uint64_t minBucketValue_;
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std::map<uint64_t, uint64_t> valueIndexMap_;
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};
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struct HistogramStat {
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HistogramStat();
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~HistogramStat() {}
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HistogramStat(const HistogramStat&) = delete;
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HistogramStat& operator=(const HistogramStat&) = delete;
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void Clear();
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bool Empty() const;
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void Add(uint64_t value);
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void Merge(const HistogramStat& other);
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inline uint64_t min() const { return min_.load(std::memory_order_relaxed); }
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inline uint64_t max() const { return max_.load(std::memory_order_relaxed); }
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inline uint64_t num() const { return num_.load(std::memory_order_relaxed); }
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inline uint64_t sum() const { return sum_.load(std::memory_order_relaxed); }
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inline uint64_t sum_squares() const {
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return sum_squares_.load(std::memory_order_relaxed);
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}
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inline uint64_t bucket_at(size_t b) const {
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return buckets_[b].load(std::memory_order_relaxed);
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}
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double Median() const;
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double Percentile(double p) const;
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double Average() const;
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double StandardDeviation() const;
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void Data(HistogramData* const data) const;
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std::string ToString() const;
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// To be able to use HistogramStat as thread local variable, it
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// cannot have dynamic allocated member. That's why we're
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// using manually values from BucketMapper
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std::atomic_uint_fast64_t min_;
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std::atomic_uint_fast64_t max_;
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std::atomic_uint_fast64_t num_;
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std::atomic_uint_fast64_t sum_;
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std::atomic_uint_fast64_t sum_squares_;
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std::atomic_uint_fast64_t buckets_[138]; // 138==BucketMapper::BucketCount()
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const uint64_t num_buckets_;
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};
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class Histogram {
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public:
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Histogram() {}
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virtual ~Histogram() {};
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virtual void Clear() = 0;
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virtual bool Empty() const = 0;
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virtual void Add(uint64_t value) = 0;
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virtual void Merge(const Histogram&) = 0;
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virtual std::string ToString() const = 0;
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virtual const char* Name() const = 0;
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virtual uint64_t min() const = 0;
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virtual uint64_t max() const = 0;
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virtual uint64_t num() const = 0;
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virtual double Median() const = 0;
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virtual double Percentile(double p) const = 0;
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virtual double Average() const = 0;
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virtual double StandardDeviation() const = 0;
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virtual void Data(HistogramData* const data) const = 0;
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};
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class HistogramImpl : public Histogram {
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public:
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HistogramImpl() { Clear(); }
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HistogramImpl(const HistogramImpl&) = delete;
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HistogramImpl& operator=(const HistogramImpl&) = delete;
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virtual void Clear() override;
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virtual bool Empty() const override;
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virtual void Add(uint64_t value) override;
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virtual void Merge(const Histogram& other) override;
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void Merge(const HistogramImpl& other);
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virtual std::string ToString() const override;
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virtual const char* Name() const override { return "HistogramImpl"; }
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virtual uint64_t min() const override { return stats_.min(); }
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virtual uint64_t max() const override { return stats_.max(); }
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virtual uint64_t num() const override { return stats_.num(); }
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virtual double Median() const override;
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virtual double Percentile(double p) const override;
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virtual double Average() const override;
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virtual double StandardDeviation() const override;
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virtual void Data(HistogramData* const data) const override;
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virtual ~HistogramImpl() {}
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private:
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HistogramStat stats_;
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std::mutex mutex_;
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};
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} // namespace rocksdb
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