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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include <benchmark/benchmark.h>
#include "mongo/util/clock_source.h"
#include "mongo/util/fast_clock_source_factory.h"
#include "mongo/util/processinfo.h"
#include "mongo/util/system_clock_source.h"
namespace mongo {
namespace {
/**
* Benchmark calls to the now() method of a clock source. With an argument of 0,
* tests the system clock source, and with larger values, uses the FastClockSource
* with a clock resolution of the specified number of milliseconds.
*
* All threads executing the benchmark use the same instance of the clock source,
* to allow benchmarking to identify synchronization costs inside the now() method.
*/
void BM_ClockNow(benchmark::State& state) {
static std::unique_ptr<ClockSource> clock;
if (state.thread_index == 0) {
if (state.range(0) > 0) {
clock = FastClockSourceFactory::create(Milliseconds{state.range(0)});
} else if (state.range(0) == 0) {
clock = std::make_unique<SystemClockSource>();
} else {
state.SkipWithError("poll period must be non-negative");
return;
}
}
for (auto keepRunning : state) {
benchmark::DoNotOptimize(clock->now());
}
if (state.thread_index == 0) {
clock.reset();
}
}
BENCHMARK(BM_ClockNow)
->ThreadRange(1, ProcessInfo::getNumAvailableCores())
->ArgName("poll period")
->Arg(0)
->Arg(1)
->Arg(10);
} // namespace
} // namespace mongo
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