rocksdb/util/stop_watch.h

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// 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/env.h"
#include "util/statistics.h"
namespace rocksdb {
// Auto-scoped.
// Records the measure time into the corresponding histogram if statistics
// is not nullptr. It is also saved into *elapsed if the pointer is not nullptr.
class StopWatch {
public:
StopWatch(Env * const env, Statistics* statistics,
const uint32_t hist_type,
uint64_t* elapsed = nullptr)
: env_(env),
statistics_(statistics),
hist_type_(hist_type),
elapsed_(elapsed),
stats_enabled_(statistics && statistics->HistEnabledForType(hist_type)),
start_time_((stats_enabled_ || elapsed != nullptr) ?
env->NowMicros() : 0) {
}
~StopWatch() {
if (elapsed_) {
*elapsed_ = env_->NowMicros() - start_time_;
}
if (stats_enabled_) {
statistics_->measureTime(hist_type_,
(elapsed_ != nullptr) ? *elapsed_ :
(env_->NowMicros() - start_time_));
}
}
private:
Env* const env_;
Statistics* statistics_;
const uint32_t hist_type_;
uint64_t* elapsed_;
bool stats_enabled_;
const uint64_t start_time_;
};
// a nano second precision stopwatch
class StopWatchNano {
public:
explicit StopWatchNano(Env* const env, bool auto_start = false)
: env_(env), start_(0) {
if (auto_start) {
Start();
}
}
void Start() { start_ = env_->NowNanos(); }
uint64_t ElapsedNanos(bool reset = false) {
auto now = env_->NowNanos();
auto elapsed = now - start_;
if (reset) {
start_ = now;
}
return elapsed;
}
private:
Env* const env_;
uint64_t start_;
};
} // namespace rocksdb