rocksdb/include/leveldb/statistics.h

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef STORAGE_LEVELDB_INCLUDE_STATISTICS_H_
#define STORAGE_LEVELDB_INCLUDE_STATISTICS_H_
#include <atomic>
#include <cstddef>
#include <cstdint>
#include <string>
#include <memory>
namespace leveldb {
/**
* Keep adding ticker's here.
* Any ticker should have a value less than TICKER_ENUM_MAX.
* Add a new ticker by assigning it the current value of TICKER_ENUM_MAX
* And incrementing TICKER_ENUM_MAX.
*/
enum Tickers {
BLOCK_CACHE_MISS = 0,
BLOCK_CACHE_HIT = 1,
BLOOM_FILTER_USEFUL = 2, // no. of times bloom filter has avoided file reads.
/**
* COMPACTION_KEY_DROP_* count the reasons for key drop during compaction
* There are 3 reasons currently.
*/
COMPACTION_KEY_DROP_NEWER_ENTRY = 3, // key was written with a newer value.
COMPACTION_KEY_DROP_OBSOLETE = 4, // The key is obsolete.
COMPACTION_KEY_DROP_USER = 5, // user compaction function has dropped the key.
// Number of keys written to the database via the Put and Write call's
NUMBER_KEYS_WRITTEN = 6,
// Number of Keys read,
NUMBER_KEYS_READ = 7,
// Bytes written / read
BYTES_WRITTEN = 8,
BYTES_READ = 9,
NO_FILE_CLOSES = 10,
NO_FILE_OPENS = 11,
NO_FILE_ERRORS = 12,
// Time system had to wait to do LO-L1 compactions
STALL_L0_SLOWDOWN_MICROS = 13,
// Time system had to wait to move memtable to L1.
STALL_MEMTABLE_COMPACTION_MICROS = 14,
// write throttle because of too many files in L0
STALL_L0_NUM_FILES_MICROS = 15,
RATE_LIMIT_DELAY_MILLIS = 16,
NO_ITERATORS = 17, // number of iterators currently open
TICKER_ENUM_MAX = 18
};
/**
* Keep adding histogram's here.
* Any histogram whould have value less than HISTOGRAM_ENUM_MAX
* Add a new Histogram by assigning it the current value of HISTOGRAM_ENUM_MAX
* And increment HISTOGRAM_ENUM_MAX
*/
enum Histograms {
DB_GET = 0,
DB_WRITE = 1,
COMPACTION_TIME = 2,
TABLE_SYNC_MICROS = 3,
COMPACTION_OUTFILE_SYNC_MICROS = 4,
WAL_FILE_SYNC_MICROS = 5,
MANIFEST_FILE_SYNC_MICROS = 6,
HISTOGRAM_ENUM_MAX = 7
};
struct HistogramData {
double median;
double percentile95;
double percentile99;
double average;
double standard_deviation;
};
class Histogram {
public:
// clear's the histogram
virtual void Clear() = 0;
virtual ~Histogram();
// Add a value to be recorded in the histogram.
virtual void Add(uint64_t value) = 0;
virtual std::string ToString() const = 0;
// Get statistics
virtual double Median() const = 0;
virtual double Percentile(double p) const = 0;
virtual double Average() const = 0;
virtual double StandardDeviation() const = 0;
virtual void Data(HistogramData * const data) const = 0;
};
/**
* A dumb ticker which keeps incrementing through its life time.
* Not thread safe. Locking is currently managed by external leveldb lock
*/
class Ticker {
public:
Ticker() : count_(0) { }
inline void recordTick() {
count_++;
}
inline void recordTick(int count) {
count_ += count;
}
inline uint64_t getCount() {
return count_;
}
private:
std::atomic_uint_fast64_t count_;
};
// Analyze the performance of a db
class Statistics {
public:
virtual long getTickerCount(Tickers tickerType) = 0;
virtual void recordTick(Tickers tickerType, uint64_t count = 0) = 0;
virtual void measureTime(Histograms histogramType, uint64_t time) = 0;
virtual void histogramData(Histograms type, HistogramData * const data) = 0;
};
// Create a concrete DBStatistics object
std::shared_ptr<Statistics> CreateDBStatistics();
// Ease of Use functions
inline void RecordTick(std::shared_ptr<Statistics> statistics,
Tickers ticker,
uint64_t count = 1) {
if (statistics) {
statistics->recordTick(ticker, count);
}
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_STATISTICS_H_