blob: 89bdd5b40db7a1a0e412cc324b0d2da300577699 [file] [log] [blame]
// Copyright 2012 The Chromium Authors
// 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/functional/bind.h"
#include "base/functional/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));
}