rust-librocksdb-sys 0.43.0+11.0.4

Native bindings to librocksdb
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148

//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
#pragma once
#include "monitoring/statistics_impl.h"
#include "rocksdb/system_clock.h"

namespace ROCKSDB_NAMESPACE {
// Auto-scoped.
// When statistics is not nullptr, records the measured time into any enabled
// histograms supplied to the constructor. A histogram argument may be omitted
// by setting it to Histograms::HISTOGRAM_ENUM_MAX. It is also saved into
// *elapsed if the pointer is not nullptr and overwrite is true, it will be
// added to *elapsed if overwrite is false.
class StopWatch {
 public:
  StopWatch(SystemClock* clock, Statistics* statistics,
            const uint32_t hist_type_1,
            const uint32_t hist_type_2 = Histograms::HISTOGRAM_ENUM_MAX,
            uint64_t* elapsed = nullptr, bool overwrite = true,
            bool delay_enabled = false)
      : clock_(clock),
        statistics_(statistics),
        hist_type_1_(statistics && statistics->HistEnabledForType(hist_type_1)
                         ? hist_type_1
                         : Histograms::HISTOGRAM_ENUM_MAX),
        hist_type_2_(statistics && statistics->HistEnabledForType(hist_type_2)
                         ? hist_type_2
                         : Histograms::HISTOGRAM_ENUM_MAX),
        elapsed_(elapsed),
        overwrite_(overwrite),
        stats_enabled_(statistics &&
                       statistics->get_stats_level() >
                           StatsLevel::kExceptTimers &&
                       (hist_type_1_ != Histograms::HISTOGRAM_ENUM_MAX ||
                        hist_type_2_ != Histograms::HISTOGRAM_ENUM_MAX)),
        delay_enabled_(delay_enabled),
        total_delay_(0),
        delay_start_time_(0),
        start_time_((stats_enabled_ || elapsed != nullptr) ? clock->NowMicros()
                                                           : 0) {}

  ~StopWatch() {
    if (elapsed_) {
      if (overwrite_) {
        *elapsed_ = clock_->NowMicros() - start_time_;
      } else {
        *elapsed_ += clock_->NowMicros() - start_time_;
      }
    }
    if (elapsed_ && delay_enabled_) {
      *elapsed_ -= total_delay_;
    }
    if (stats_enabled_) {
      const auto time = (elapsed_ != nullptr)
                            ? *elapsed_
                            : (clock_->NowMicros() - start_time_);
      if (hist_type_1_ != Histograms::HISTOGRAM_ENUM_MAX) {
        statistics_->reportTimeToHistogram(hist_type_1_, time);
      }
      if (hist_type_2_ != Histograms::HISTOGRAM_ENUM_MAX) {
        statistics_->reportTimeToHistogram(hist_type_2_, time);
      }
    }
  }

  void DelayStart() {
    // if delay_start_time_ is not 0, it means we are already tracking delay,
    // so delay_start_time_ should not be overwritten
    if (elapsed_ && delay_enabled_ && delay_start_time_ == 0) {
      delay_start_time_ = clock_->NowMicros();
    }
  }

  void DelayStop() {
    if (elapsed_ && delay_enabled_ && delay_start_time_ != 0) {
      total_delay_ += clock_->NowMicros() - delay_start_time_;
    }
    // reset to 0 means currently no delay is being tracked, so two consecutive
    // calls to DelayStop will not increase total_delay_
    delay_start_time_ = 0;
  }

  uint64_t GetDelay() const { return delay_enabled_ ? total_delay_ : 0; }

  uint64_t start_time() const { return start_time_; }

 private:
  SystemClock* clock_;
  Statistics* statistics_;
  const uint32_t hist_type_1_;
  const uint32_t hist_type_2_;
  uint64_t* elapsed_;
  bool overwrite_;
  bool stats_enabled_;
  bool delay_enabled_;
  uint64_t total_delay_;
  uint64_t delay_start_time_;
  const uint64_t start_time_;
};

// a nano second precision stopwatch
template <bool use_cpu_time = false>
class StopWatchNano {
 public:
  explicit StopWatchNano(SystemClock* clock, bool auto_start = false)
      : clock_(clock), start_(0) {
    if (auto_start) {
      Start();
    }
  }
  void Start() {
    assert(clock_);
    if constexpr (use_cpu_time) {
      start_ = clock_->CPUNanos();
    } else {
      start_ = clock_->NowNanos();
    }
  }
  uint64_t ElapsedNanos(bool reset = false) {
    assert(clock_);
    uint64_t now = 0;
    if constexpr (use_cpu_time) {
      now = clock_->CPUNanos();
    } else {
      now = clock_->NowNanos();
    }
    auto elapsed = now - start_;
    if (reset) {
      start_ = now;
    }
    return elapsed;
  }
  uint64_t ElapsedNanosSafe(bool reset = false) {
    return (clock_ != nullptr) ? ElapsedNanos(reset) : 0U;
  }
  bool IsStarted() { return start_ != 0; }
  uint64_t ElapsedMicros(bool reset = false) {
    return ElapsedNanos(reset) / 1000;
  }

 private:
  SystemClock* clock_;
  uint64_t start_;
};
}  // namespace ROCKSDB_NAMESPACE