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/*
* Copyright 2014 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <memory>
#include <set>
#include <vector>
#include "webrtc/rtc_base/arraysize.h"
#include "webrtc/rtc_base/checks.h"
#include "webrtc/rtc_base/criticalsection.h"
#include "webrtc/rtc_base/event.h"
#include "webrtc/rtc_base/gunit.h"
#include "webrtc/rtc_base/platform_thread.h"
#include "webrtc/rtc_base/thread.h"
namespace rtc {
namespace {
const int kLongTime = 10000; // 10 seconds
const int kNumThreads = 16;
const int kOperationsToRun = 1000;
class UniqueValueVerifier {
public:
void Verify(const std::vector<int>& values) {
for (size_t i = 0; i < values.size(); ++i) {
std::pair<std::set<int>::iterator, bool> result =
all_values_.insert(values[i]);
// Each value should only be taken by one thread, so if this value
// has already been added, something went wrong.
EXPECT_TRUE(result.second)
<< " Thread=" << Thread::Current() << " value=" << values[i];
}
}
void Finalize() {}
private:
std::set<int> all_values_;
};
class CompareAndSwapVerifier {
public:
CompareAndSwapVerifier() : zero_count_(0) {}
void Verify(const std::vector<int>& values) {
for (auto v : values) {
if (v == 0) {
EXPECT_EQ(0, zero_count_) << "Thread=" << Thread::Current();
++zero_count_;
} else {
EXPECT_EQ(1, v) << " Thread=" << Thread::Current();
}
}
}
void Finalize() {
EXPECT_EQ(1, zero_count_);
}
private:
int zero_count_;
};
class RunnerBase : public MessageHandler {
public:
explicit RunnerBase(int value)
: threads_active_(0),
start_event_(true, false),
done_event_(true, false),
shared_value_(value) {}
bool Run() {
// Signal all threads to start.
start_event_.Set();
// Wait for all threads to finish.
return done_event_.Wait(kLongTime);
}
void SetExpectedThreadCount(int count) {
threads_active_ = count;
}
int shared_value() const { return shared_value_; }
protected:
// Derived classes must override OnMessage, and call BeforeStart and AfterEnd
// at the beginning and the end of OnMessage respectively.
void BeforeStart() {
ASSERT_TRUE(start_event_.Wait(kLongTime));
}
// Returns true if all threads have finished.
bool AfterEnd() {
if (AtomicOps::Decrement(&threads_active_) == 0) {
done_event_.Set();
return true;
}
return false;
}
int threads_active_;
Event start_event_;
Event done_event_;
int shared_value_;
};
class LOCKABLE CriticalSectionLock {
public:
void Lock() EXCLUSIVE_LOCK_FUNCTION() {
cs_.Enter();
}
void Unlock() UNLOCK_FUNCTION() {
cs_.Leave();
}
private:
CriticalSection cs_;
};
template <class Lock>
class LockRunner : public RunnerBase {
public:
LockRunner() : RunnerBase(0) {}
void OnMessage(Message* msg) override {
BeforeStart();
lock_.Lock();
EXPECT_EQ(0, shared_value_);
int old = shared_value_;
// Use a loop to increase the chance of race.
for (int i = 0; i < kOperationsToRun; ++i) {
++shared_value_;
}
EXPECT_EQ(old + kOperationsToRun, shared_value_);
shared_value_ = 0;
lock_.Unlock();
AfterEnd();
}
private:
Lock lock_;
};
template <class Op, class Verifier>
class AtomicOpRunner : public RunnerBase {
public:
explicit AtomicOpRunner(int initial_value) : RunnerBase(initial_value) {}
void OnMessage(Message* msg) override {
BeforeStart();
std::vector<int> values;
values.reserve(kOperationsToRun);
// Generate a bunch of values by updating shared_value_ atomically.
for (int i = 0; i < kOperationsToRun; ++i) {
values.push_back(Op::AtomicOp(&shared_value_));
}
{ // Add them all to the set.
CritScope cs(&all_values_crit_);
verifier_.Verify(values);
}
if (AfterEnd()) {
verifier_.Finalize();
}
}
private:
CriticalSection all_values_crit_;
Verifier verifier_;
};
struct IncrementOp {
static int AtomicOp(int* i) { return AtomicOps::Increment(i); }
};
struct DecrementOp {
static int AtomicOp(int* i) { return AtomicOps::Decrement(i); }
};
struct CompareAndSwapOp {
static int AtomicOp(int* i) { return AtomicOps::CompareAndSwap(i, 0, 1); }
};
void StartThreads(std::vector<std::unique_ptr<Thread>>* threads,
MessageHandler* handler) {
for (int i = 0; i < kNumThreads; ++i) {
std::unique_ptr<Thread> thread(Thread::Create());
thread->Start();
thread->Post(RTC_FROM_HERE, handler);
threads->push_back(std::move(thread));
}
}
} // namespace
TEST(AtomicOpsTest, Simple) {
int value = 0;
EXPECT_EQ(1, AtomicOps::Increment(&value));
EXPECT_EQ(1, value);
EXPECT_EQ(2, AtomicOps::Increment(&value));
EXPECT_EQ(2, value);
EXPECT_EQ(1, AtomicOps::Decrement(&value));
EXPECT_EQ(1, value);
EXPECT_EQ(0, AtomicOps::Decrement(&value));
EXPECT_EQ(0, value);
}
TEST(AtomicOpsTest, SimplePtr) {
class Foo {};
Foo* volatile foo = nullptr;
std::unique_ptr<Foo> a(new Foo());
std::unique_ptr<Foo> b(new Foo());
// Reading the initial value should work as expected.
EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == nullptr);
// Setting using compare and swap should work.
EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(
&foo, static_cast<Foo*>(nullptr), a.get()) == nullptr);
EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == a.get());
// Setting another value but with the wrong previous pointer should fail
// (remain a).
EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(
&foo, static_cast<Foo*>(nullptr), b.get()) == a.get());
EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == a.get());
// Replacing a with b should work.
EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(&foo, a.get(), b.get()) ==
a.get());
EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == b.get());
}
TEST(AtomicOpsTest, Increment) {
// Create and start lots of threads.
AtomicOpRunner<IncrementOp, UniqueValueVerifier> runner(0);
std::vector<std::unique_ptr<Thread>> threads;
StartThreads(&threads, &runner);
runner.SetExpectedThreadCount(kNumThreads);
// Release the hounds!
EXPECT_TRUE(runner.Run());
EXPECT_EQ(kOperationsToRun * kNumThreads, runner.shared_value());
}
TEST(AtomicOpsTest, Decrement) {
// Create and start lots of threads.
AtomicOpRunner<DecrementOp, UniqueValueVerifier> runner(
kOperationsToRun * kNumThreads);
std::vector<std::unique_ptr<Thread>> threads;
StartThreads(&threads, &runner);
runner.SetExpectedThreadCount(kNumThreads);
// Release the hounds!
EXPECT_TRUE(runner.Run());
EXPECT_EQ(0, runner.shared_value());
}
TEST(AtomicOpsTest, CompareAndSwap) {
// Create and start lots of threads.
AtomicOpRunner<CompareAndSwapOp, CompareAndSwapVerifier> runner(0);
std::vector<std::unique_ptr<Thread>> threads;
StartThreads(&threads, &runner);
runner.SetExpectedThreadCount(kNumThreads);
// Release the hounds!
EXPECT_TRUE(runner.Run());
EXPECT_EQ(1, runner.shared_value());
}
TEST(GlobalLockTest, Basic) {
// Create and start lots of threads.
LockRunner<GlobalLock> runner;
std::vector<std::unique_ptr<Thread>> threads;
StartThreads(&threads, &runner);
runner.SetExpectedThreadCount(kNumThreads);
// Release the hounds!
EXPECT_TRUE(runner.Run());
EXPECT_EQ(0, runner.shared_value());
}
TEST(CriticalSectionTest, Basic) {
// Create and start lots of threads.
LockRunner<CriticalSectionLock> runner;
std::vector<std::unique_ptr<Thread>> threads;
StartThreads(&threads, &runner);
runner.SetExpectedThreadCount(kNumThreads);
// Release the hounds!
EXPECT_TRUE(runner.Run());
EXPECT_EQ(0, runner.shared_value());
}
class PerfTestData {
public:
PerfTestData(int expected_count, Event* event)
: cache_line_barrier_1_(), cache_line_barrier_2_(),
expected_count_(expected_count), event_(event) {
cache_line_barrier_1_[0]++; // Avoid 'is not used'.
cache_line_barrier_2_[0]++; // Avoid 'is not used'.
}
~PerfTestData() {}
void AddToCounter(int add) {
rtc::CritScope cs(&lock_);
my_counter_ += add;
if (my_counter_ == expected_count_)
event_->Set();
}
int64_t total() const {
// Assume that only one thread is running now.
return my_counter_;
}
private:
uint8_t cache_line_barrier_1_[64];
CriticalSection lock_;
uint8_t cache_line_barrier_2_[64];
int64_t my_counter_ = 0;
const int expected_count_;
Event* const event_;
};
class PerfTestThread {
public:
PerfTestThread() : thread_(&ThreadFunc, this, "CsPerf") {}
void Start(PerfTestData* data, int repeats, int id) {
RTC_DCHECK(!thread_.IsRunning());
RTC_DCHECK(!data_);
data_ = data;
repeats_ = repeats;
my_id_ = id;
thread_.Start();
}
void Stop() {
RTC_DCHECK(thread_.IsRunning());
RTC_DCHECK(data_);
thread_.Stop();
repeats_ = 0;
data_ = nullptr;
my_id_ = 0;
}
private:
static bool ThreadFunc(void* param) {
PerfTestThread* me = static_cast<PerfTestThread*>(param);
for (int i = 0; i < me->repeats_; ++i)
me->data_->AddToCounter(me->my_id_);
return false;
}
PlatformThread thread_;
PerfTestData* data_ = nullptr;
int repeats_ = 0;
int my_id_ = 0;
};
// Comparison of output of this test as tested on a MacBook Pro Retina, 15-inch,
// Mid 2014, 2,8 GHz Intel Core i7, 16 GB 1600 MHz DDR3,
// running OS X El Capitan, 10.11.2.
//
// Native mutex implementation:
// Approximate CPU usage:
// System: ~16%
// User mode: ~1.3%
// Idle: ~82%
// Unit test output:
// [ OK ] CriticalSectionTest.Performance (234545 ms)
//
// Special partially spin lock based implementation:
// Approximate CPU usage:
// System: ~75%
// User mode: ~16%
// Idle: ~8%
// Unit test output:
// [ OK ] CriticalSectionTest.Performance (2107 ms)
//
// The test is disabled by default to avoid unecessarily loading the bots.
TEST(CriticalSectionTest, DISABLED_Performance) {
PerfTestThread threads[8];
Event event(false, false);
static const int kThreadRepeats = 10000000;
static const int kExpectedCount = kThreadRepeats * arraysize(threads);
PerfTestData test_data(kExpectedCount, &event);
for (auto& t : threads)
t.Start(&test_data, kThreadRepeats, 1);
event.Wait(Event::kForever);
for (auto& t : threads)
t.Stop();
}
} // namespace rtc