blob: 29c6021fdd0594d7db2f8471804f9d0f61b15d33 [file] [log] [blame]
// 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/observer_list_threadsafe.h"
#include <memory>
#include <vector>
#include "base/bind.h"
#include "base/compiler_specific.h"
#include "base/location.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/run_loop.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/waitable_event.h"
#include "base/task/post_task.h"
#include "base/task/task_scheduler/task_scheduler.h"
#include "base/test/scoped_task_environment.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_restrictions.h"
#include "build/build_config.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace base {
namespace {
constexpr int kThreadRunTime = 2000; // ms to run the multi-threaded test.
class Foo {
public:
virtual void Observe(int x) = 0;
virtual ~Foo() = default;
virtual int GetValue() const { return 0; }
};
class Adder : public Foo {
public:
explicit Adder(int scaler) : total(0), scaler_(scaler) {}
~Adder() override = default;
void Observe(int x) override { total += x * scaler_; }
int GetValue() const override { return total; }
int total;
private:
int scaler_;
};
class AddInObserve : public Foo {
public:
explicit AddInObserve(ObserverListThreadSafe<Foo>* observer_list)
: observer_list(observer_list), to_add_() {}
void SetToAdd(Foo* to_add) { to_add_ = to_add; }
void Observe(int x) override {
if (to_add_) {
observer_list->AddObserver(to_add_);
to_add_ = nullptr;
}
}
ObserverListThreadSafe<Foo>* observer_list;
Foo* to_add_;
};
// A thread for use in the ThreadSafeObserver test which will add and remove
// itself from the notification list repeatedly.
class AddRemoveThread : public PlatformThread::Delegate, public Foo {
public:
AddRemoveThread(ObserverListThreadSafe<Foo>* list,
bool notify,
WaitableEvent* ready)
: list_(list),
loop_(nullptr),
in_list_(false),
start_(Time::Now()),
count_observes_(0),
count_addtask_(0),
do_notifies_(notify),
ready_(ready),
weak_factory_(this) {}
~AddRemoveThread() override = default;
void ThreadMain() override {
loop_ = new MessageLoop(); // Fire up a message loop.
loop_->task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
ready_->Signal();
// After ready_ is signaled, loop_ is only accessed by the main test thread
// (i.e. not this thread) in particular by Quit() which causes Run() to
// return, and we "control" loop_ again.
RunLoop run_loop;
quit_loop_ = run_loop.QuitClosure();
run_loop.Run();
delete loop_;
#if !SB_IS(COMPILER_MSVC)
loop_ = reinterpret_cast<MessageLoop*>(0xdeadbeef);
#endif
delete this;
}
// This task just keeps posting to itself in an attempt to race with the
// notifier.
void AddTask() {
count_addtask_++;
if ((Time::Now() - start_).InMilliseconds() > kThreadRunTime) {
VLOG(1) << "DONE!";
return;
}
if (!in_list_) {
list_->AddObserver(this);
in_list_ = true;
}
if (do_notifies_) {
list_->Notify(FROM_HERE, &Foo::Observe, 10);
}
loop_->task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
}
// This function is only callable from the main thread.
void Quit() { std::move(quit_loop_).Run(); }
void Observe(int x) override {
count_observes_++;
// If we're getting called after we removed ourselves from the list, that is
// very bad!
DCHECK(in_list_);
// This callback should fire on the appropriate thread
EXPECT_EQ(loop_, MessageLoop::current());
list_->RemoveObserver(this);
in_list_ = false;
}
private:
ObserverListThreadSafe<Foo>* list_;
MessageLoop* loop_;
bool in_list_; // Are we currently registered for notifications.
// in_list_ is only used on |this| thread.
Time start_; // The time we started the test.
int count_observes_; // Number of times we observed.
int count_addtask_; // Number of times thread AddTask was called
bool do_notifies_; // Whether these threads should do notifications.
WaitableEvent* ready_;
base::OnceClosure quit_loop_;
base::WeakPtrFactory<AddRemoveThread> weak_factory_;
};
} // namespace
TEST(ObserverListThreadSafeTest, BasicTest) {
MessageLoop loop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1);
Adder b(-1);
Adder c(1);
Adder d(-1);
observer_list->AddObserver(&a);
observer_list->AddObserver(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
observer_list->AddObserver(&c);
observer_list->AddObserver(&d);
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
observer_list->RemoveObserver(&c);
RunLoop().RunUntilIdle();
EXPECT_EQ(20, a.total);
EXPECT_EQ(-20, b.total);
EXPECT_EQ(0, c.total);
EXPECT_EQ(-10, d.total);
}
TEST(ObserverListThreadSafeTest, RemoveObserver) {
MessageLoop loop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1), b(1);
// A workaround for the compiler bug. See http://crbug.com/121960.
EXPECT_NE(&a, &b);
// Should do nothing.
observer_list->RemoveObserver(&a);
observer_list->RemoveObserver(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
EXPECT_EQ(0, a.total);
EXPECT_EQ(0, b.total);
observer_list->AddObserver(&a);
// Should also do nothing.
observer_list->RemoveObserver(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
EXPECT_EQ(10, a.total);
EXPECT_EQ(0, b.total);
}
TEST(ObserverListThreadSafeTest, WithoutSequence) {
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1), b(1), c(1);
// No sequence, so these should not be added.
observer_list->AddObserver(&a);
observer_list->AddObserver(&b);
{
// Add c when there's a sequence.
MessageLoop loop;
observer_list->AddObserver(&c);
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
EXPECT_EQ(0, a.total);
EXPECT_EQ(0, b.total);
EXPECT_EQ(10, c.total);
// Now add a when there's a sequence.
observer_list->AddObserver(&a);
// Remove c when there's a sequence.
observer_list->RemoveObserver(&c);
// Notify again.
observer_list->Notify(FROM_HERE, &Foo::Observe, 20);
RunLoop().RunUntilIdle();
EXPECT_EQ(20, a.total);
EXPECT_EQ(0, b.total);
EXPECT_EQ(10, c.total);
}
// Removing should always succeed with or without a sequence.
observer_list->RemoveObserver(&a);
// Notifying should not fail but should also be a no-op.
MessageLoop loop;
observer_list->AddObserver(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 30);
RunLoop().RunUntilIdle();
EXPECT_EQ(20, a.total);
EXPECT_EQ(30, b.total);
EXPECT_EQ(10, c.total);
}
class FooRemover : public Foo {
public:
explicit FooRemover(ObserverListThreadSafe<Foo>* list) : list_(list) {}
~FooRemover() override = default;
void AddFooToRemove(Foo* foo) { foos_.push_back(foo); }
void Observe(int x) override {
std::vector<Foo*> tmp;
tmp.swap(foos_);
for (auto it = tmp.begin(); it != tmp.end(); ++it) {
list_->RemoveObserver(*it);
}
}
private:
const scoped_refptr<ObserverListThreadSafe<Foo>> list_;
std::vector<Foo*> foos_;
};
TEST(ObserverListThreadSafeTest, RemoveMultipleObservers) {
MessageLoop loop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
FooRemover a(observer_list.get());
Adder b(1);
observer_list->AddObserver(&a);
observer_list->AddObserver(&b);
a.AddFooToRemove(&a);
a.AddFooToRemove(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
RunLoop().RunUntilIdle();
}
// A test driver for a multi-threaded notification loop. Runs a number of
// observer threads, each of which constantly adds/removes itself from the
// observer list. Optionally, if cross_thread_notifies is set to true, the
// observer threads will also trigger notifications to all observers.
static void ThreadSafeObserverHarness(int num_threads,
bool cross_thread_notifies) {
MessageLoop loop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1);
Adder b(-1);
observer_list->AddObserver(&a);
observer_list->AddObserver(&b);
std::vector<AddRemoveThread*> threaded_observer;
std::vector<base::PlatformThreadHandle> threads(num_threads);
std::vector<std::unique_ptr<base::WaitableEvent>> ready;
threaded_observer.reserve(num_threads);
ready.reserve(num_threads);
for (int index = 0; index < num_threads; index++) {
ready.push_back(std::make_unique<WaitableEvent>(
WaitableEvent::ResetPolicy::MANUAL,
WaitableEvent::InitialState::NOT_SIGNALED));
threaded_observer.push_back(new AddRemoveThread(
observer_list.get(), cross_thread_notifies, ready.back().get()));
EXPECT_TRUE(
PlatformThread::Create(0, threaded_observer.back(), &threads[index]));
}
ASSERT_EQ(static_cast<size_t>(num_threads), threaded_observer.size());
ASSERT_EQ(static_cast<size_t>(num_threads), ready.size());
// This makes sure that threaded_observer has gotten to set loop_, so that we
// can call Quit() below safe-ish-ly.
for (int i = 0; i < num_threads; ++i)
ready[i]->Wait();
Time start = Time::Now();
while (true) {
if ((Time::Now() - start).InMilliseconds() > kThreadRunTime)
break;
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
}
for (int index = 0; index < num_threads; index++) {
threaded_observer[index]->Quit();
PlatformThread::Join(threads[index]);
}
}
#if defined(OS_FUCHSIA)
// TODO(crbug.com/738275): This is flaky on Fuchsia.
#define MAYBE_CrossThreadObserver DISABLED_CrossThreadObserver
#else
#define MAYBE_CrossThreadObserver CrossThreadObserver
#endif
TEST(ObserverListThreadSafeTest, MAYBE_CrossThreadObserver) {
// Use 7 observer threads. Notifications only come from the main thread.
ThreadSafeObserverHarness(7, false);
}
TEST(ObserverListThreadSafeTest, CrossThreadNotifications) {
// Use 3 observer threads. Notifications will fire from the main thread and
// all 3 observer threads.
ThreadSafeObserverHarness(3, true);
}
TEST(ObserverListThreadSafeTest, OutlivesMessageLoop) {
MessageLoop* loop = new MessageLoop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1);
observer_list->AddObserver(&a);
delete loop;
// Test passes if we don't crash here.
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
}
namespace {
class SequenceVerificationObserver : public Foo {
public:
explicit SequenceVerificationObserver(
scoped_refptr<SequencedTaskRunner> task_runner)
: task_runner_(std::move(task_runner)) {}
~SequenceVerificationObserver() override = default;
void Observe(int x) override {
called_on_valid_sequence_ = task_runner_->RunsTasksInCurrentSequence();
}
bool called_on_valid_sequence() const { return called_on_valid_sequence_; }
private:
const scoped_refptr<SequencedTaskRunner> task_runner_;
bool called_on_valid_sequence_ = false;
DISALLOW_COPY_AND_ASSIGN(SequenceVerificationObserver);
};
} // namespace
// Verify that observers are notified on the correct sequence.
TEST(ObserverListThreadSafeTest, NotificationOnValidSequence) {
test::ScopedTaskEnvironment scoped_task_environment;
auto task_runner_1 = CreateSequencedTaskRunnerWithTraits(TaskTraits());
auto task_runner_2 = CreateSequencedTaskRunnerWithTraits(TaskTraits());
auto observer_list = MakeRefCounted<ObserverListThreadSafe<Foo>>();
SequenceVerificationObserver observer_1(task_runner_1);
SequenceVerificationObserver observer_2(task_runner_2);
task_runner_1->PostTask(FROM_HERE,
BindOnce(&ObserverListThreadSafe<Foo>::AddObserver,
observer_list, Unretained(&observer_1)));
task_runner_2->PostTask(FROM_HERE,
BindOnce(&ObserverListThreadSafe<Foo>::AddObserver,
observer_list, Unretained(&observer_2)));
TaskScheduler::GetInstance()->FlushForTesting();
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
TaskScheduler::GetInstance()->FlushForTesting();
EXPECT_TRUE(observer_1.called_on_valid_sequence());
EXPECT_TRUE(observer_2.called_on_valid_sequence());
}
// Verify that when an observer is added to a NOTIFY_ALL ObserverListThreadSafe
// from a notification, it is itself notified.
TEST(ObserverListThreadSafeTest, AddObserverFromNotificationNotifyAll) {
test::ScopedTaskEnvironment scoped_task_environment;
auto observer_list = MakeRefCounted<ObserverListThreadSafe<Foo>>();
Adder observer_added_from_notification(1);
AddInObserve initial_observer(observer_list.get());
initial_observer.SetToAdd(&observer_added_from_notification);
observer_list->AddObserver(&initial_observer);
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
base::RunLoop().RunUntilIdle();
EXPECT_EQ(1, observer_added_from_notification.GetValue());
}
namespace {
class RemoveWhileNotificationIsRunningObserver : public Foo {
public:
RemoveWhileNotificationIsRunningObserver()
: notification_running_(WaitableEvent::ResetPolicy::AUTOMATIC,
WaitableEvent::InitialState::NOT_SIGNALED),
barrier_(WaitableEvent::ResetPolicy::AUTOMATIC,
WaitableEvent::InitialState::NOT_SIGNALED) {}
~RemoveWhileNotificationIsRunningObserver() override = default;
void Observe(int x) override {
notification_running_.Signal();
ScopedAllowBaseSyncPrimitivesForTesting allow_base_sync_primitives;
barrier_.Wait();
}
void WaitForNotificationRunning() { notification_running_.Wait(); }
void Unblock() { barrier_.Signal(); }
private:
WaitableEvent notification_running_;
WaitableEvent barrier_;
DISALLOW_COPY_AND_ASSIGN(RemoveWhileNotificationIsRunningObserver);
};
} // namespace
// Verify that there is no crash when an observer is removed while it is being
// notified.
TEST(ObserverListThreadSafeTest, RemoveWhileNotificationIsRunning) {
auto observer_list = MakeRefCounted<ObserverListThreadSafe<Foo>>();
RemoveWhileNotificationIsRunningObserver observer;
WaitableEvent task_running(WaitableEvent::ResetPolicy::AUTOMATIC,
WaitableEvent::InitialState::NOT_SIGNALED);
WaitableEvent barrier(WaitableEvent::ResetPolicy::AUTOMATIC,
WaitableEvent::InitialState::NOT_SIGNALED);
// This must be after the declaration of |barrier| so that tasks posted to
// TaskScheduler can safely use |barrier|.
test::ScopedTaskEnvironment scoped_task_environment;
CreateSequencedTaskRunnerWithTraits({MayBlock()})
->PostTask(FROM_HERE,
base::BindOnce(&ObserverListThreadSafe<Foo>::AddObserver,
observer_list, Unretained(&observer)));
TaskScheduler::GetInstance()->FlushForTesting();
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
observer.WaitForNotificationRunning();
observer_list->RemoveObserver(&observer);
observer.Unblock();
}
// Same as ObserverListTest.Existing, but for ObserverListThreadSafe
TEST(ObserverListThreadSafeTest, Existing) {
MessageLoop loop;
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>(ObserverListPolicy::EXISTING_ONLY));
Adder a(1);
AddInObserve b(observer_list.get());
Adder c(1);
b.SetToAdd(&c);
observer_list->AddObserver(&a);
observer_list->AddObserver(&b);
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
RunLoop().RunUntilIdle();
EXPECT_FALSE(b.to_add_);
// B's adder should not have been notified because it was added during
// notification.
EXPECT_EQ(0, c.total);
// Notify again to make sure b's adder is notified.
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
RunLoop().RunUntilIdle();
EXPECT_EQ(1, c.total);
}
} // namespace base