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- // 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 <memory>
- #include <string>
- #include <utility>
- #include <vector>
- #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<CheckOnDestroy> 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<UncopyableUnmovable> default_constructed;
- EXPECT_EQ(1, default_constructed->value);
- static NoDestructor<UncopyableUnmovable> constructed_with_arg(-1);
- EXPECT_EQ(-1, constructed_with_arg->value);
- }
- TEST(NoDestructorTest, ForwardsArguments) {
- CopyOnly copy_only;
- MoveOnly move_only;
- static NoDestructor<ForwardingTestStruct> test_forwarding(
- copy_only, std::move(move_only));
- }
- TEST(NoDestructorTest, Accessors) {
- static NoDestructor<std::string> awesome("awesome");
- EXPECT_EQ("awesome", *awesome);
- EXPECT_EQ(0, awesome->compare("awesome"));
- EXPECT_EQ(0, awesome.get()->compare("awesome"));
- }
- TEST(NoDestructorTest, AllowForTriviallyDestructibleType) {
- static NoDestructor<bool, AllowForTriviallyDestructibleType>
- 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<std::vector<std::string>> 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<BlockingConstructor> 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<std::unique_ptr<SimpleThread>> 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<BlockingConstructorThread>(
- 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
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