rocksdb/util/statistics.h
sdong c7742452eb Add Statistics.getHistogramString() to print more detailed outputs of a histogram
Summary:
Provide a way for users to know more detailed ditribution of a histogram metrics. Example outputs:

Manually add statement
  fprintf(stdout, "%s\n", dbstats->getHistogramString(SST_READ_MICROS).c_str());
Will print out something like:

Count: 989151  Average: 1.7659  StdDev: 1.52
Min: 0.0000  Median: 1.2071  Max: 860.0000
Percentiles: P50: 1.21 P75: 1.70 P99: 5.12 P99.9: 13.67 P99.99: 21.70
------------------------------------------------------
[       0,       1 )   390839  39.513%  39.513% ########
[       1,       2 )   500918  50.641%  90.154% ##########
[       2,       3 )    79358   8.023%  98.177% ##
[       3,       4 )     6297   0.637%  98.813%
[       4,       5 )     1712   0.173%  98.986%
[       5,       6 )     1134   0.115%  99.101%
[       6,       7 )     1222   0.124%  99.224%
[       7,       8 )     1529   0.155%  99.379%
[       8,       9 )     1264   0.128%  99.507%
[       9,      10 )      988   0.100%  99.607%
[      10,      12 )     1378   0.139%  99.746%
[      12,      14 )     1828   0.185%  99.931%
[      14,      16 )      410   0.041%  99.972%
[      16,      18 )       72   0.007%  99.980%
[      18,      20 )       67   0.007%  99.986%
[      20,      25 )      106   0.011%  99.997%
[      25,      30 )       24   0.002%  99.999%
[      30,      35 )        1   0.000% 100.000%
[     250,     300 )        2   0.000% 100.000%
[     300,     350 )        1   0.000% 100.000%
[     800,     900 )        1   0.000% 100.000%

Test Plan: Manually add a print in db_bench and make sure it prints out as expected. Will add some codes to cover the function

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D43611
2015-08-05 20:05:56 -07:00

92 lines
2.7 KiB
C++

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
#pragma once
#include "rocksdb/statistics.h"
#include <vector>
#include <atomic>
#include <string>
#include "util/histogram.h"
#include "util/mutexlock.h"
#include "port/likely.h"
namespace rocksdb {
enum TickersInternal : uint32_t {
INTERNAL_TICKER_ENUM_START = TICKER_ENUM_MAX,
INTERNAL_TICKER_ENUM_MAX
};
enum HistogramsInternal : uint32_t {
INTERNAL_HISTOGRAM_START = HISTOGRAM_ENUM_MAX,
INTERNAL_HISTOGRAM_ENUM_MAX
};
class StatisticsImpl : public Statistics {
public:
StatisticsImpl(std::shared_ptr<Statistics> stats,
bool enable_internal_stats);
virtual ~StatisticsImpl();
virtual uint64_t getTickerCount(uint32_t ticker_type) const override;
virtual void histogramData(uint32_t histogram_type,
HistogramData* const data) const override;
std::string getHistogramString(uint32_t histogram_type) const override;
virtual void setTickerCount(uint32_t ticker_type, uint64_t count) override;
virtual void recordTick(uint32_t ticker_type, uint64_t count) override;
virtual void measureTime(uint32_t histogram_type, uint64_t value) override;
virtual std::string ToString() const override;
virtual bool HistEnabledForType(uint32_t type) const override;
private:
std::shared_ptr<Statistics> stats_shared_;
Statistics* stats_;
bool enable_internal_stats_;
struct Ticker {
Ticker() : value(uint_fast64_t()) {}
std::atomic_uint_fast64_t value;
// Pad the structure to make it size of 64 bytes. A plain array of
// std::atomic_uint_fast64_t results in huge performance degradataion
// due to false sharing.
char padding[64 - sizeof(std::atomic_uint_fast64_t)];
};
Ticker tickers_[INTERNAL_TICKER_ENUM_MAX] __attribute__((aligned(64)));
HistogramImpl histograms_[INTERNAL_HISTOGRAM_ENUM_MAX]
__attribute__((aligned(64)));
};
// Utility functions
inline void MeasureTime(Statistics* statistics, uint32_t histogram_type,
uint64_t value) {
if (statistics) {
statistics->measureTime(histogram_type, value);
}
}
inline void RecordTick(Statistics* statistics, uint32_t ticker_type,
uint64_t count = 1) {
if (statistics) {
statistics->recordTick(ticker_type, count);
}
}
inline void SetTickerCount(Statistics* statistics, uint32_t ticker_type,
uint64_t count) {
if (statistics) {
statistics->setTickerCount(ticker_type, count);
}
}
}