| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // UNSUPPORTED: c++98, c++03 |
| // UNSUPPORTED: libcxxabi-no-threads, libcxxabi-no-exceptions |
| |
| #define TESTING_CXA_GUARD |
| #include "../src/cxa_guard_impl.h" |
| #include <unordered_map> |
| #include <thread> |
| #include <atomic> |
| #include <array> |
| #include <cassert> |
| #include <memory> |
| #include <vector> |
| |
| |
| using namespace __cxxabiv1; |
| |
| // Misc test configuration. It's used to tune the flakyness of the test. |
| // ThreadsPerTest - The number of threads used |
| constexpr int ThreadsPerTest = 10; |
| // The number of instances of a test to run concurrently. |
| constexpr int ConcurrentRunsPerTest = 10; |
| // The number of times to rerun each test. |
| constexpr int TestSamples = 50; |
| |
| |
| |
| void BusyWait() { |
| std::this_thread::yield(); |
| } |
| |
| void YieldAfterBarrier() { |
| std::this_thread::sleep_for(std::chrono::nanoseconds(10)); |
| std::this_thread::yield(); |
| } |
| |
| struct Barrier { |
| explicit Barrier(int n) : m_threads(n), m_remaining(n) { } |
| Barrier(Barrier const&) = delete; |
| Barrier& operator=(Barrier const&) = delete; |
| |
| void arrive_and_wait() const { |
| --m_remaining; |
| while (m_remaining.load()) { |
| BusyWait(); |
| } |
| } |
| |
| void arrive_and_drop() const { |
| --m_remaining; |
| } |
| |
| void wait_for_threads(int n) const { |
| while ((m_threads - m_remaining.load()) < n) { |
| std::this_thread::yield(); |
| } |
| } |
| |
| private: |
| const int m_threads; |
| mutable std::atomic<int> m_remaining; |
| }; |
| |
| |
| enum class InitResult { |
| COMPLETE, |
| PERFORMED, |
| WAITED, |
| ABORTED |
| }; |
| constexpr InitResult COMPLETE = InitResult::COMPLETE; |
| constexpr InitResult PERFORMED = InitResult::PERFORMED; |
| constexpr InitResult WAITED = InitResult::WAITED; |
| constexpr InitResult ABORTED = InitResult::ABORTED; |
| |
| |
| template <class Impl, class GuardType, class Init> |
| InitResult check_guard(GuardType *g, Init init) { |
| uint8_t *first_byte = reinterpret_cast<uint8_t*>(g); |
| if (std::__libcpp_atomic_load(first_byte, std::_AO_Acquire) == 0) { |
| Impl impl(g); |
| if (impl.cxa_guard_acquire() == INIT_IS_PENDING) { |
| #ifndef LIBCXXABI_HAS_NO_EXCEPTIONS |
| try { |
| #endif |
| init(); |
| impl.cxa_guard_release(); |
| return PERFORMED; |
| #ifndef LIBCXXABI_HAS_NO_EXCEPTIONS |
| } catch (...) { |
| impl.cxa_guard_abort(); |
| return ABORTED; |
| } |
| #endif |
| } |
| return WAITED; |
| } |
| return COMPLETE; |
| } |
| |
| |
| template <class GuardType, class Impl> |
| struct FunctionLocalStatic { |
| FunctionLocalStatic() {} |
| FunctionLocalStatic(FunctionLocalStatic const&) = delete; |
| |
| template <class InitFunc> |
| InitResult access(InitFunc&& init) { |
| auto res = check_guard<Impl>(&guard_object, init); |
| ++result_counts[static_cast<int>(res)]; |
| return res; |
| } |
| |
| template <class InitFn> |
| struct AccessCallback { |
| void operator()() const { this_obj->access(init); } |
| |
| FunctionLocalStatic *this_obj; |
| InitFn init; |
| }; |
| |
| template <class InitFn, class Callback = AccessCallback< InitFn > > |
| Callback access_callback(InitFn init) { |
| return Callback{this, init}; |
| } |
| |
| int get_count(InitResult I) const { |
| return result_counts[static_cast<int>(I)].load(); |
| } |
| |
| int num_completed() const { |
| return get_count(COMPLETE) + get_count(PERFORMED) + get_count(WAITED); |
| } |
| |
| int num_waiting() const { |
| return waiting_threads.load(); |
| } |
| |
| private: |
| GuardType guard_object = {}; |
| std::atomic<int> waiting_threads{0}; |
| std::array<std::atomic<int>, 4> result_counts{}; |
| static_assert(static_cast<int>(ABORTED) == 3, "only 4 result kinds expected"); |
| }; |
| |
| struct ThreadGroup { |
| ThreadGroup() = default; |
| ThreadGroup(ThreadGroup const&) = delete; |
| |
| template <class ...Args> |
| void Create(Args&& ...args) { |
| threads.emplace_back(std::forward<Args>(args)...); |
| } |
| |
| template <class Callback> |
| void CreateThreadsWithBarrier(int N, Callback cb) { |
| auto start = std::make_shared<Barrier>(N + 1); |
| for (int I=0; I < N; ++I) { |
| Create([start, cb]() { |
| start->arrive_and_wait(); |
| cb(); |
| }); |
| } |
| start->arrive_and_wait(); |
| } |
| |
| void JoinAll() { |
| for (auto& t : threads) { |
| t.join(); |
| } |
| } |
| |
| private: |
| std::vector<std::thread> threads; |
| }; |
| |
| |
| template <class GuardType, class Impl> |
| void test_free_for_all(int num_waiters) { |
| FunctionLocalStatic<GuardType, Impl> test_obj; |
| |
| ThreadGroup threads; |
| |
| bool already_init = false; |
| threads.CreateThreadsWithBarrier(num_waiters, |
| test_obj.access_callback([&]() { |
| assert(!already_init); |
| already_init = true; |
| }) |
| ); |
| |
| // wait for the other threads to finish initialization. |
| threads.JoinAll(); |
| |
| assert(test_obj.get_count(PERFORMED) == 1); |
| assert(test_obj.get_count(COMPLETE) + test_obj.get_count(WAITED) == num_waiters - 1); |
| } |
| |
| template <class GuardType, class Impl> |
| void test_waiting_for_init(int num_waiters) { |
| FunctionLocalStatic<GuardType, Impl> test_obj; |
| |
| ThreadGroup threads; |
| |
| Barrier start_init(2); |
| threads.Create(test_obj.access_callback( |
| [&]() { |
| start_init.arrive_and_wait(); |
| // Take our sweet time completing the initialization... |
| // |
| // There's a race condition between the other threads reaching the |
| // start_init barrier, and them actually hitting the cxa guard. |
| // But we're trying to test the waiting logic, we want as many |
| // threads to enter the waiting loop as possible. |
| YieldAfterBarrier(); |
| } |
| )); |
| start_init.wait_for_threads(1); |
| |
| threads.CreateThreadsWithBarrier(num_waiters, |
| test_obj.access_callback([]() { assert(false); }) |
| ); |
| // unblock the initializing thread |
| start_init.arrive_and_drop(); |
| |
| // wait for the other threads to finish initialization. |
| threads.JoinAll(); |
| |
| assert(test_obj.get_count(PERFORMED) == 1); |
| assert(test_obj.get_count(ABORTED) == 0); |
| assert(test_obj.get_count(COMPLETE) + test_obj.get_count(WAITED) == num_waiters); |
| } |
| |
| |
| template <class GuardType, class Impl> |
| void test_aborted_init(int num_waiters) { |
| FunctionLocalStatic<GuardType, Impl> test_obj; |
| |
| Barrier start_init(2); |
| ThreadGroup threads; |
| threads.Create(test_obj.access_callback( |
| [&]() { |
| start_init.arrive_and_wait(); |
| YieldAfterBarrier(); |
| throw 42; |
| }) |
| ); |
| start_init.wait_for_threads(1); |
| |
| bool already_init = false; |
| threads.CreateThreadsWithBarrier(num_waiters, |
| test_obj.access_callback([&]() { |
| assert(!already_init); |
| already_init = true; |
| }) |
| ); |
| // unblock the initializing thread |
| start_init.arrive_and_drop(); |
| |
| // wait for the other threads to finish initialization. |
| threads.JoinAll(); |
| |
| assert(test_obj.get_count(ABORTED) == 1); |
| assert(test_obj.get_count(PERFORMED) == 1); |
| assert(test_obj.get_count(WAITED) + test_obj.get_count(COMPLETE) == num_waiters - 1); |
| } |
| |
| |
| template <class GuardType, class Impl> |
| void test_completed_init(int num_waiters) { |
| |
| FunctionLocalStatic<GuardType, Impl> test_obj; |
| |
| test_obj.access([]() {}); // initialize the object |
| assert(test_obj.num_waiting() == 0); |
| assert(test_obj.num_completed() == 1); |
| assert(test_obj.get_count(PERFORMED) == 1); |
| |
| ThreadGroup threads; |
| threads.CreateThreadsWithBarrier(num_waiters, |
| test_obj.access_callback([]() { assert(false); }) |
| ); |
| // wait for the other threads to finish initialization. |
| threads.JoinAll(); |
| |
| assert(test_obj.get_count(ABORTED) == 0); |
| assert(test_obj.get_count(PERFORMED) == 1); |
| assert(test_obj.get_count(WAITED) == 0); |
| assert(test_obj.get_count(COMPLETE) == num_waiters); |
| } |
| |
| template <class Impl> |
| void test_impl() { |
| using TestFn = void(*)(int); |
| TestFn TestList[] = { |
| test_free_for_all<uint32_t, Impl>, |
| test_free_for_all<uint32_t, Impl>, |
| test_waiting_for_init<uint32_t, Impl>, |
| test_waiting_for_init<uint64_t, Impl>, |
| test_aborted_init<uint32_t, Impl>, |
| test_aborted_init<uint64_t, Impl>, |
| test_completed_init<uint32_t, Impl>, |
| test_completed_init<uint64_t, Impl> |
| }; |
| |
| for (auto test_func : TestList) { |
| ThreadGroup test_threads; |
| test_threads.CreateThreadsWithBarrier(ConcurrentRunsPerTest, [=]() { |
| for (int I = 0; I < TestSamples; ++I) { |
| test_func(ThreadsPerTest); |
| } |
| }); |
| test_threads.JoinAll(); |
| } |
| } |
| |
| void test_all_impls() { |
| using MutexImpl = SelectImplementation<Implementation::GlobalLock>::type; |
| |
| // Attempt to test the Futex based implementation if it's supported on the |
| // target platform. |
| using RealFutexImpl = SelectImplementation<Implementation::Futex>::type; |
| using FutexImpl = typename std::conditional< |
| PlatformSupportsFutex(), |
| RealFutexImpl, |
| MutexImpl |
| >::type; |
| |
| test_impl<MutexImpl>(); |
| if (PlatformSupportsFutex()) |
| test_impl<FutexImpl>(); |
| } |
| |
| // A dummy |
| template <bool Dummy = true> |
| void test_futex_syscall() { |
| if (!PlatformSupportsFutex()) |
| return; |
| int lock1 = 0; |
| int lock2 = 0; |
| int lock3 = 0; |
| std::thread waiter1([&]() { |
| int expect = 0; |
| PlatformFutexWait(&lock1, expect); |
| assert(lock1 == 1); |
| }); |
| std::thread waiter2([&]() { |
| int expect = 0; |
| PlatformFutexWait(&lock2, expect); |
| assert(lock2 == 2); |
| }); |
| std::thread waiter3([&]() { |
| int expect = 42; // not the value |
| PlatformFutexWait(&lock3, expect); // doesn't block |
| }); |
| std::thread waker([&]() { |
| lock1 = 1; |
| PlatformFutexWake(&lock1); |
| lock2 = 2; |
| PlatformFutexWake(&lock2); |
| }); |
| waiter1.join(); |
| waiter2.join(); |
| waiter3.join(); |
| waker.join(); |
| } |
| |
| int main() { |
| // Test each multi-threaded implementation with real threads. |
| test_all_impls(); |
| // Test the basic sanity of the futex syscall wrappers. |
| test_futex_syscall(); |
| } |