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- // Copyright (c) 2012 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 <stddef.h>
- #include <memory>
- #include <utility>
- #include <vector>
- #include "base/at_exit.h"
- #include "base/atomic_sequence_num.h"
- #include "base/atomicops.h"
- #include "base/barrier_closure.h"
- #include "base/bind.h"
- #include "base/callback.h"
- #include "base/lazy_instance.h"
- #include "base/memory/aligned_memory.h"
- #include "base/memory/raw_ptr.h"
- #include "base/system/sys_info.h"
- #include "base/threading/platform_thread.h"
- #include "base/threading/simple_thread.h"
- #include "base/time/time.h"
- #include "build/build_config.h"
- #include "testing/gtest/include/gtest/gtest.h"
- namespace {
- base::AtomicSequenceNumber constructed_seq_;
- base::AtomicSequenceNumber destructed_seq_;
- class ConstructAndDestructLogger {
- public:
- ConstructAndDestructLogger() {
- constructed_seq_.GetNext();
- }
- ConstructAndDestructLogger(const ConstructAndDestructLogger&) = delete;
- ConstructAndDestructLogger& operator=(const ConstructAndDestructLogger&) =
- delete;
- ~ConstructAndDestructLogger() {
- destructed_seq_.GetNext();
- }
- };
- class SlowConstructor {
- public:
- SlowConstructor() : some_int_(0) {
- // Sleep for 1 second to try to cause a race.
- base::PlatformThread::Sleep(base::Seconds(1));
- ++constructed;
- some_int_ = 12;
- }
- SlowConstructor(const SlowConstructor&) = delete;
- SlowConstructor& operator=(const SlowConstructor&) = delete;
- int some_int() const { return some_int_; }
- static int constructed;
- private:
- int some_int_;
- };
- // static
- int SlowConstructor::constructed = 0;
- class SlowDelegate : public base::DelegateSimpleThread::Delegate {
- public:
- explicit SlowDelegate(
- base::LazyInstance<SlowConstructor>::DestructorAtExit* lazy)
- : lazy_(lazy) {}
- SlowDelegate(const SlowDelegate&) = delete;
- SlowDelegate& operator=(const SlowDelegate&) = delete;
- void Run() override {
- EXPECT_EQ(12, lazy_->Get().some_int());
- EXPECT_EQ(12, lazy_->Pointer()->some_int());
- }
- private:
- raw_ptr<base::LazyInstance<SlowConstructor>::DestructorAtExit> lazy_;
- };
- } // namespace
- base::LazyInstance<ConstructAndDestructLogger>::DestructorAtExit lazy_logger =
- LAZY_INSTANCE_INITIALIZER;
- TEST(LazyInstanceTest, Basic) {
- {
- base::ShadowingAtExitManager shadow;
- EXPECT_FALSE(lazy_logger.IsCreated());
- EXPECT_EQ(0, constructed_seq_.GetNext());
- EXPECT_EQ(0, destructed_seq_.GetNext());
- lazy_logger.Get();
- EXPECT_TRUE(lazy_logger.IsCreated());
- EXPECT_EQ(2, constructed_seq_.GetNext());
- EXPECT_EQ(1, destructed_seq_.GetNext());
- lazy_logger.Pointer();
- EXPECT_TRUE(lazy_logger.IsCreated());
- EXPECT_EQ(3, constructed_seq_.GetNext());
- EXPECT_EQ(2, destructed_seq_.GetNext());
- }
- EXPECT_FALSE(lazy_logger.IsCreated());
- EXPECT_EQ(4, constructed_seq_.GetNext());
- EXPECT_EQ(4, destructed_seq_.GetNext());
- }
- base::LazyInstance<SlowConstructor>::DestructorAtExit lazy_slow =
- LAZY_INSTANCE_INITIALIZER;
- TEST(LazyInstanceTest, ConstructorThreadSafety) {
- {
- base::ShadowingAtExitManager shadow;
- SlowDelegate delegate(&lazy_slow);
- EXPECT_EQ(0, SlowConstructor::constructed);
- base::DelegateSimpleThreadPool pool("lazy_instance_cons", 5);
- pool.AddWork(&delegate, 20);
- EXPECT_EQ(0, SlowConstructor::constructed);
- pool.Start();
- pool.JoinAll();
- EXPECT_EQ(1, SlowConstructor::constructed);
- }
- }
- namespace {
- // DeleteLogger is an object which sets a flag when it's destroyed.
- // It accepts a bool* and sets the bool to true when the dtor runs.
- class DeleteLogger {
- public:
- DeleteLogger() : deleted_(nullptr) {}
- ~DeleteLogger() { *deleted_ = true; }
- void SetDeletedPtr(bool* deleted) {
- deleted_ = deleted;
- }
- private:
- raw_ptr<bool> deleted_;
- };
- } // anonymous namespace
- TEST(LazyInstanceTest, LeakyLazyInstance) {
- // Check that using a plain LazyInstance causes the dtor to run
- // when the AtExitManager finishes.
- bool deleted1 = false;
- {
- base::ShadowingAtExitManager shadow;
- static base::LazyInstance<DeleteLogger>::DestructorAtExit test =
- LAZY_INSTANCE_INITIALIZER;
- test.Get().SetDeletedPtr(&deleted1);
- }
- EXPECT_TRUE(deleted1);
- // Check that using a *leaky* LazyInstance makes the dtor not run
- // when the AtExitManager finishes.
- bool deleted2 = false;
- {
- base::ShadowingAtExitManager shadow;
- static base::LazyInstance<DeleteLogger>::Leaky
- test = LAZY_INSTANCE_INITIALIZER;
- test.Get().SetDeletedPtr(&deleted2);
- }
- EXPECT_FALSE(deleted2);
- }
- namespace {
- template <size_t alignment>
- class AlignedData {
- public:
- AlignedData() = default;
- ~AlignedData() = default;
- alignas(alignment) char data_[alignment];
- };
- } // namespace
- TEST(LazyInstanceTest, Alignment) {
- using base::LazyInstance;
- // Create some static instances with increasing sizes and alignment
- // requirements. By ordering this way, the linker will need to do some work to
- // ensure proper alignment of the static data.
- static LazyInstance<AlignedData<4>>::DestructorAtExit align4 =
- LAZY_INSTANCE_INITIALIZER;
- static LazyInstance<AlignedData<32>>::DestructorAtExit align32 =
- LAZY_INSTANCE_INITIALIZER;
- static LazyInstance<AlignedData<4096>>::DestructorAtExit align4096 =
- LAZY_INSTANCE_INITIALIZER;
- EXPECT_TRUE(base::IsAligned(align4.Pointer(), 4));
- EXPECT_TRUE(base::IsAligned(align32.Pointer(), 32));
- EXPECT_TRUE(base::IsAligned(align4096.Pointer(), 4096));
- }
- namespace {
- // A class whose constructor busy-loops until it is told to complete
- // construction.
- class BlockingConstructor {
- public:
- BlockingConstructor() {
- EXPECT_FALSE(WasConstructorCalled());
- base::subtle::NoBarrier_Store(&constructor_called_, 1);
- EXPECT_TRUE(WasConstructorCalled());
- while (!base::subtle::NoBarrier_Load(&complete_construction_))
- base::PlatformThread::YieldCurrentThread();
- done_construction_ = true;
- }
- BlockingConstructor(const BlockingConstructor&) = delete;
- BlockingConstructor& operator=(const BlockingConstructor&) = delete;
- ~BlockingConstructor() {
- // Restore static state for the next test.
- base::subtle::NoBarrier_Store(&constructor_called_, 0);
- base::subtle::NoBarrier_Store(&complete_construction_, 0);
- }
- // Returns true if BlockingConstructor() was entered.
- static bool WasConstructorCalled() {
- return base::subtle::NoBarrier_Load(&constructor_called_);
- }
- // Instructs BlockingConstructor() that it may now unblock its construction.
- static void CompleteConstructionNow() {
- base::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 base::subtle::Atomic32 constructor_called_;
- static base::subtle::Atomic32 complete_construction_;
- bool done_construction_ = false;
- };
- // A SimpleThread running at |thread_type| which invokes |before_get| (optional)
- // and then invokes Get() on the LazyInstance it's assigned.
- class BlockingConstructorThread : public base::SimpleThread {
- public:
- BlockingConstructorThread(
- base::ThreadType thread_type,
- base::LazyInstance<BlockingConstructor>::DestructorAtExit* lazy,
- base::OnceClosure before_get)
- : SimpleThread("BlockingConstructorThread", Options(thread_type)),
- lazy_(lazy),
- 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();
- EXPECT_TRUE(lazy_->Get().done_construction());
- }
- private:
- raw_ptr<base::LazyInstance<BlockingConstructor>::DestructorAtExit> lazy_;
- base::OnceClosure before_get_;
- };
- // static
- base::subtle::Atomic32 BlockingConstructor::constructor_called_ = 0;
- // static
- base::subtle::Atomic32 BlockingConstructor::complete_construction_ = 0;
- base::LazyInstance<BlockingConstructor>::DestructorAtExit lazy_blocking =
- LAZY_INSTANCE_INITIALIZER;
- } // namespace
- // Tests that if the thread assigned to construct the LazyInstance runs at
- // background priority : the foreground threads will yield to it enough for it
- // to eventually complete construction.
- // This is a regression test for https://crbug.com/797129.
- TEST(LazyInstanceTest, PriorityInversionAtInitializationResolves) {
- base::TimeTicks test_begin = base::TimeTicks::Now();
- // Construct BlockingConstructor from a background thread.
- BlockingConstructorThread background_getter(
- base::ThreadType::kBackground, &lazy_blocking, base::OnceClosure());
- background_getter.Start();
- while (!BlockingConstructor::WasConstructorCalled())
- base::PlatformThread::Sleep(base::Milliseconds(1));
- // Spin 4 foreground thread per core contending to get the already under
- // construction LazyInstance. When they are all running and poking at it :
- // allow the background thread to complete its work.
- const int kNumForegroundThreads = 4 * base::SysInfo::NumberOfProcessors();
- std::vector<std::unique_ptr<base::SimpleThread>> foreground_threads;
- base::RepeatingClosure foreground_thread_ready_callback =
- base::BarrierClosure(
- kNumForegroundThreads,
- base::BindOnce(&BlockingConstructor::CompleteConstructionNow));
- for (int i = 0; i < kNumForegroundThreads; ++i) {
- foreground_threads.push_back(std::make_unique<BlockingConstructorThread>(
- base::ThreadType::kDefault, &lazy_blocking,
- foreground_thread_ready_callback));
- foreground_threads.back()->Start();
- }
- // This test will hang if the foreground threads become stuck in
- // LazyInstance::Get() 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 r527445 but is expected to be fast (~30ms) with the fix).
- EXPECT_LT(base::TimeTicks::Now() - test_begin, base::Seconds(5));
- }
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