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rust-rocksdb/util/stop_watch.h

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// 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
class StopWatchNano {
public:
explicit StopWatchNano(SystemClock* clock, bool auto_start = false)
: clock_(clock), start_(0) {
if (auto_start) {
Start();
}
}
void Start() { start_ = clock_->NowNanos(); }
uint64_t ElapsedNanos(bool reset = false) {
auto 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; }
private:
SystemClock* clock_;
uint64_t start_;
};
} // namespace ROCKSDB_NAMESPACE