rocksdb/monitoring/perf_step_timer.h
Yanqin Jin 9fdc9fbeea Still use SystemClock* instead of shared_ptr in StepPerfTimer (#8006)
Summary:
This is likely a temp fix before we figure out a better way.

PerfStepTimer is used intensively in certain benchmarking/testings. https://github.com/facebook/rocksdb/issues/7858 stores a `shared_ptr` to system clock in PerfStepTimer which gets created each time a `PerfStepTimer` object is created. The atomic operations in `shared_ptr` may add overhead in CPU cycles. Therefore, we change it back to a raw `SystemClock*` for now.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8006

Test Plan: make check

Reviewed By: pdillinger

Differential Revision: D26703560

Pulled By: riversand963

fbshipit-source-id: 519d0769b28da2334bea7d86c848fcc26ee8a17f
2021-02-26 20:57:18 -08:00

80 lines
2 KiB
C++

// 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/perf_level_imp.h"
#include "monitoring/statistics.h"
#include "rocksdb/system_clock.h"
namespace ROCKSDB_NAMESPACE {
class PerfStepTimer {
public:
explicit PerfStepTimer(
uint64_t* metric, SystemClock* clock = nullptr, bool use_cpu_time = false,
PerfLevel enable_level = PerfLevel::kEnableTimeExceptForMutex,
Statistics* statistics = nullptr, uint32_t ticker_type = 0)
: perf_counter_enabled_(perf_level >= enable_level),
use_cpu_time_(use_cpu_time),
clock_((perf_counter_enabled_ || statistics != nullptr)
? (clock ? clock : SystemClock::Default().get())
: nullptr),
start_(0),
metric_(metric),
statistics_(statistics),
ticker_type_(ticker_type) {}
~PerfStepTimer() {
Stop();
}
void Start() {
if (perf_counter_enabled_ || statistics_ != nullptr) {
start_ = time_now();
}
}
void Measure() {
if (start_) {
uint64_t now = time_now();
*metric_ += now - start_;
start_ = now;
}
}
void Stop() {
if (start_) {
uint64_t duration = time_now() - start_;
if (perf_counter_enabled_) {
*metric_ += duration;
}
if (statistics_ != nullptr) {
RecordTick(statistics_, ticker_type_, duration);
}
start_ = 0;
}
}
private:
uint64_t time_now() {
if (!use_cpu_time_) {
return clock_->NowNanos();
} else {
return clock_->CPUNanos();
}
}
const bool perf_counter_enabled_;
const bool use_cpu_time_;
SystemClock* const clock_;
uint64_t start_;
uint64_t* metric_;
Statistics* statistics_;
uint32_t ticker_type_;
};
} // namespace ROCKSDB_NAMESPACE