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// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/compiler_specific.h"
#include "base/synchronization/lock.h"
#include "base/threading/platform_thread.h"
#include "base/time/time.h"
#include "base/timer/lap_timer.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "testing/perf/perf_result_reporter.h"
namespace base {
namespace {
constexpr int kWarmupRuns = 1;
constexpr TimeDelta kTimeLimit = TimeDelta::FromSeconds(1);
constexpr int kTimeCheckInterval = 100000;
constexpr char kMetricPrefixLock[] = "Lock.";
constexpr char kMetricLockUnlockThroughput[] = "lock_unlock_throughput";
constexpr char kStoryBaseline[] = "baseline_story";
constexpr char kStoryWithCompetingThread[] = "with_competing_thread";
perf_test::PerfResultReporter SetUpReporter(const std::string& story_name) {
perf_test::PerfResultReporter reporter(kMetricPrefixLock, story_name);
reporter.RegisterImportantMetric(kMetricLockUnlockThroughput, "runs/s");
return reporter;
}
class Spin : public PlatformThread::Delegate {
public:
Spin(Lock* lock, uint32_t* data)
: lock_(lock), data_(data), should_stop_(false) {}
~Spin() override = default;
void ThreadMain() override {
// Local variable to avoid "cache line ping-pong" from influencing the
// results.
uint32_t count = 0;
while (!should_stop_.load(std::memory_order_relaxed)) {
lock_->Acquire();
count++;
lock_->Release();
}
lock_->Acquire();
(*data_) += count;
lock_->Release();
}
// Called from another thread to stop the loop.
void Stop() { should_stop_ = true; }
private:
Lock* lock_;
uint32_t* data_ GUARDED_BY(lock_);
std::atomic<bool> should_stop_;
};
} // namespace
TEST(LockPerfTest, Simple) {
LapTimer timer(kWarmupRuns, kTimeLimit, kTimeCheckInterval);
uint32_t data = 0;
Lock lock;
do {
lock.Acquire();
data += 1;
lock.Release();
timer.NextLap();
} while (!timer.HasTimeLimitExpired());
ALLOW_UNUSED_LOCAL(data);
auto reporter = SetUpReporter(kStoryBaseline);
reporter.AddResult(kMetricLockUnlockThroughput, timer.LapsPerSecond());
}
TEST(LockPerfTest, WithCompetingThread) {
LapTimer timer(kWarmupRuns, kTimeLimit, kTimeCheckInterval);
uint32_t data = 0;
Lock lock;
// Starts a competing thread executing the same loop as this thread.
Spin thread_main(&lock, &data);
PlatformThreadHandle thread_handle;
ASSERT_TRUE(PlatformThread::Create(0, &thread_main, &thread_handle));
do {
lock.Acquire();
data += 1;
lock.Release();
timer.NextLap();
} while (!timer.HasTimeLimitExpired());
thread_main.Stop();
PlatformThread::Join(thread_handle);
auto reporter = SetUpReporter(kStoryWithCompetingThread);
reporter.AddResult(kMetricLockUnlockThroughput, timer.LapsPerSecond());
}
} // namespace base
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