// Copyright 2018 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/no_destructor.h" #include #include #include #include #include "base/atomicops.h" #include "base/barrier_closure.h" #include "base/bind.h" #include "base/check.h" #include "base/system/sys_info.h" #include "base/threading/platform_thread.h" #include "base/threading/simple_thread.h" #include "build/build_config.h" #include "testing/gtest/include/gtest/gtest.h" namespace base { namespace { struct CheckOnDestroy { ~CheckOnDestroy() { CHECK(false); } }; TEST(NoDestructorTest, SkipsDestructors) { NoDestructor destructor_should_not_run; } struct UncopyableUnmovable { UncopyableUnmovable() = default; explicit UncopyableUnmovable(int value) : value(value) {} UncopyableUnmovable(const UncopyableUnmovable&) = delete; UncopyableUnmovable& operator=(const UncopyableUnmovable&) = delete; int value = 1; std::string something_with_a_nontrivial_destructor; }; struct CopyOnly { CopyOnly() = default; CopyOnly(const CopyOnly&) = default; CopyOnly& operator=(const CopyOnly&) = default; CopyOnly(CopyOnly&&) = delete; CopyOnly& operator=(CopyOnly&&) = delete; }; struct MoveOnly { MoveOnly() = default; MoveOnly(const MoveOnly&) = delete; MoveOnly& operator=(const MoveOnly&) = delete; MoveOnly(MoveOnly&&) = default; MoveOnly& operator=(MoveOnly&&) = default; }; struct ForwardingTestStruct { ForwardingTestStruct(const CopyOnly&, MoveOnly&&) {} std::string something_with_a_nontrivial_destructor; }; TEST(NoDestructorTest, UncopyableUnmovable) { static NoDestructor default_constructed; EXPECT_EQ(1, default_constructed->value); static NoDestructor constructed_with_arg(-1); EXPECT_EQ(-1, constructed_with_arg->value); } TEST(NoDestructorTest, ForwardsArguments) { CopyOnly copy_only; MoveOnly move_only; static NoDestructor test_forwarding( copy_only, std::move(move_only)); } TEST(NoDestructorTest, Accessors) { static NoDestructor awesome("awesome"); EXPECT_EQ("awesome", *awesome); EXPECT_EQ(0, awesome->compare("awesome")); EXPECT_EQ(0, awesome.get()->compare("awesome")); } TEST(NoDestructorTest, AllowForTriviallyDestructibleType) { static NoDestructor trivially_destructible_type; } // Passing initializer list to a NoDestructor like in this test // is ambiguous in GCC. // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84849 #if !defined(COMPILER_GCC) && !defined(__clang__) TEST(NoDestructorTest, InitializerList) { static NoDestructor> vector({"a", "b", "c"}); } #endif } // namespace namespace { // A class whose constructor busy-loops until it is told to complete // construction. class BlockingConstructor { public: BlockingConstructor() { EXPECT_FALSE(WasConstructorCalled()); subtle::NoBarrier_Store(&constructor_called_, 1); EXPECT_TRUE(WasConstructorCalled()); while (!subtle::NoBarrier_Load(&complete_construction_)) PlatformThread::YieldCurrentThread(); done_construction_ = true; } BlockingConstructor(const BlockingConstructor&) = delete; BlockingConstructor& operator=(const BlockingConstructor&) = delete; ~BlockingConstructor() = delete; // Returns true if BlockingConstructor() was entered. static bool WasConstructorCalled() { return subtle::NoBarrier_Load(&constructor_called_); } // Instructs BlockingConstructor() that it may now unblock its construction. static void CompleteConstructionNow() { subtle::NoBarrier_Store(&complete_construction_, 1); } bool done_construction() const { return done_construction_; } private: // Use Atomic32 instead of AtomicFlag for them to be trivially initialized. static subtle::Atomic32 constructor_called_; static subtle::Atomic32 complete_construction_; bool done_construction_ = false; }; // static subtle::Atomic32 BlockingConstructor::constructor_called_ = 0; // static subtle::Atomic32 BlockingConstructor::complete_construction_ = 0; // A SimpleThread running at |thread_type| which invokes |before_get| (optional) // and then invokes thread-safe scoped-static-initializationconstruction on its // NoDestructor instance. class BlockingConstructorThread : public SimpleThread { public: BlockingConstructorThread(ThreadType thread_type, OnceClosure before_get) : SimpleThread("BlockingConstructorThread", Options(thread_type)), before_get_(std::move(before_get)) {} BlockingConstructorThread(const BlockingConstructorThread&) = delete; BlockingConstructorThread& operator=(const BlockingConstructorThread&) = delete; void Run() override { if (before_get_) std::move(before_get_).Run(); static NoDestructor instance; EXPECT_TRUE(instance->done_construction()); } private: OnceClosure before_get_; }; } // namespace // Tests that if the thread assigned to construct the local-static // initialization of the NoDestructor runs at background priority : the // foreground threads will yield to it enough for it to eventually complete // construction. While local-static thread-safe initialization isn't specific to // NoDestructor, it is tested here as NoDestructor is set to replace // LazyInstance and this is an important regression test for it // (https://crbug.com/797129). TEST(NoDestructorTest, PriorityInversionAtStaticInitializationResolves) { TimeTicks test_begin = TimeTicks::Now(); // Construct BlockingConstructor from a thread that is lower priority than the // other threads that will be constructed. This thread used to be BACKGROUND // priority but that caused it to be starved by other simultaneously running // test processes, leading to false-positive failures. BlockingConstructorThread background_getter(ThreadType::kDefault, OnceClosure()); background_getter.Start(); while (!BlockingConstructor::WasConstructorCalled()) PlatformThread::Sleep(Milliseconds(1)); // Spin 4 foreground thread per core contending to get the already under // construction NoDestructor. When they are all running and poking at it : // allow the background thread to complete its work. const int kNumForegroundThreads = 4 * SysInfo::NumberOfProcessors(); std::vector> foreground_threads; RepeatingClosure foreground_thread_ready_callback = BarrierClosure(kNumForegroundThreads, BindOnce(&BlockingConstructor::CompleteConstructionNow)); for (int i = 0; i < kNumForegroundThreads; ++i) { // Create threads that are higher priority than background_getter. See above // for why these particular priorities are chosen. foreground_threads.push_back(std::make_unique( ThreadType::kDisplayCritical, foreground_thread_ready_callback)); foreground_threads.back()->Start(); } // This test will hang if the foreground threads become stuck in // NoDestructor's construction per the background thread never being scheduled // to complete construction. for (auto& foreground_thread : foreground_threads) foreground_thread->Join(); background_getter.Join(); // Fail if this test takes more than 5 seconds (it takes 5-10 seconds on a // Z840 without https://crrev.com/527445 but is expected to be fast (~30ms) // with the fix). EXPECT_LT(TimeTicks::Now() - test_begin, Seconds(5)); } } // namespace base