fe10200ddc
Summary: * Introduce is histogram in statistics.h * stop watch to measure time. * introduce two timers as a poc. Replaced NULL with nullptr to fight some lint errors Should be useful for google. Test Plan: ran db_bench and check stats. make all check Reviewers: dhruba, heyongqiang Reviewed By: dhruba CC: leveldb Differential Revision: https://reviews.facebook.net/D8637
145 lines
3.8 KiB
C++
145 lines
3.8 KiB
C++
// 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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#ifndef STORAGE_LEVELDB_INCLUDE_STATISTICS_H_
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#define STORAGE_LEVELDB_INCLUDE_STATISTICS_H_
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#include <cstddef>
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#include <cstdint>
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#include <string>
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#include <memory>
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namespace leveldb {
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/**
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* Keep adding ticker's here.
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* Any ticker should have a value less than TICKER_ENUM_MAX.
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* Add a new ticker by assigning it the current value of TICKER_ENUM_MAX
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* And incrementing TICKER_ENUM_MAX.
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*/
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enum Tickers {
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BLOCK_CACHE_MISS = 0,
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BLOCK_CACHE_HIT = 1,
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BLOOM_FILTER_USEFUL = 2, // no. of times bloom filter has avoided file reads.
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/**
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* COMPACTION_KEY_DROP_* count the reasons for key drop during compaction
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* There are 3 reasons currently.
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*/
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COMPACTION_KEY_DROP_NEWER_ENTRY = 3, // key was written with a newer value.
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COMPACTION_KEY_DROP_OBSOLETE = 4, // The key is obsolete.
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COMPACTION_KEY_DROP_USER = 5, // user compaction function has dropped the key.
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// Number of keys written to the database via the Put and Write call's
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NUMBER_KEYS_WRITTEN = 6,
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// Number of Keys read,
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NUMBER_KEYS_READ = 7,
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TICKER_ENUM_MAX = 8,
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};
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/**
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* Keep adding histogram's here.
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* Any histogram whould have value less than HISTOGRAM_ENUM_MAX
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* Add a new Histogram by assigning it the current value of HISTOGRAM_ENUM_MAX
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* And increment HISTOGRAM_ENUM_MAX
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*/
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enum Histograms {
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DB_GET = 0,
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DB_WRITE = 1,
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HISTOGRAM_ENUM_MAX = 2,
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};
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struct HistogramData {
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double median;
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double percentile95;
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double percentile99;
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double average;
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double standard_deviation;
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};
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class Histogram {
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public:
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// clear's the histogram
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virtual void Clear() = 0;
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virtual ~Histogram();
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// Add a value to be recorded in the histogram.
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virtual void Add(uint64_t value) = 0;
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virtual void Add(double value) = 0;
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virtual std::string ToString() const = 0;
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// Get statistics
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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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/**
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* A dumb ticker which keeps incrementing through its life time.
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* Not thread safe. Locking is currently managed by external leveldb lock
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*/
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class Ticker {
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public:
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Ticker() : count_(0) { }
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inline void recordTick() {
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count_++;
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}
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inline void recordTick(int count) {
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count_ += count;
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}
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inline uint64_t getCount() {
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return count_;
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}
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private:
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uint64_t count_;
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};
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// Analyze the performance of a db
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class Statistics {
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public:
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// Create an Statistics object with default values for all fields.
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Statistics() : numFileOpens_(0), numFileCloses_(0),
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numFileErrors_(0) {}
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virtual void incNumFileOpens() = 0;
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virtual void incNumFileCloses() = 0;
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virtual void incNumFileErrors() = 0;
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virtual long getNumFileOpens() { return numFileOpens_;}
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virtual long getNumFileCloses() { return numFileCloses_;}
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virtual long getNumFileErrors() { return numFileErrors_;}
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~Statistics() {}
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virtual long getTickerCount(Tickers tickerType) = 0;
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virtual void recordTick(Tickers tickerType, uint64_t count = 0) = 0;
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virtual void measureTime(Histograms histogramType, uint64_t count) = 0;
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virtual void measureTime(Histograms histogramType, double count) = 0;
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virtual void histogramData(Histograms type, HistogramData * const data) = 0;
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protected:
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long numFileOpens_;
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long numFileCloses_;
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long numFileErrors_;
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};
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// Ease of Use functions
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inline void RecordTick(Statistics* const statistics,
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Tickers ticker,
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uint64_t count = 1) {
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if (statistics != nullptr) {
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statistics->recordTick(ticker, count);
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}
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}
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_INCLUDE_STATISTICS_H_
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