blob: 63d26e451de5067c0d52b78ed21ec32fbeee12d3 [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/thread_pool/thread_pool.h"
#include "base/test/scoped_task_environment.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_restrictions.h"
#include "base/threading/thread_task_runner_handle.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 task for use in the ThreadSafeObserver test which will add and remove
// itself from the notification list repeatedly.
class AddRemoveThread : public Foo {
public:
AddRemoveThread(ObserverListThreadSafe<Foo>* list, bool notify)
: list_(list),
task_runner_(CreateSingleThreadTaskRunner(
TaskTraits(ThreadPool()),
SingleThreadTaskRunnerThreadMode::DEDICATED)),
in_list_(false),
start_(Time::Now()),
do_notifies_(notify) {
task_runner_->PostTask(
FROM_HERE,
base::BindOnce(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
}
~AddRemoveThread() override = default;
// This task just keeps posting to itself in an attempt to race with the
// notifier.
void 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);
}
ThreadTaskRunnerHandle::Get()->PostTask(
FROM_HERE,
base::BindOnce(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
}
void Observe(int x) override {
// If we're getting called after we removed ourselves from the list, that is
// very bad!
EXPECT_TRUE(in_list_);
// This callback should fire on the appropriate thread
EXPECT_TRUE(task_runner_->BelongsToCurrentThread());
list_->RemoveObserver(this);
in_list_ = false;
}
private:
ObserverListThreadSafe<Foo>* list_;
scoped_refptr<SingleThreadTaskRunner> task_runner_;
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.
bool do_notifies_; // Whether these threads should do notifications.
base::WeakPtrFactory<AddRemoveThread> weak_factory_{this};
};
} // namespace
TEST(ObserverListThreadSafeTest, BasicTest) {
test::TaskEnvironment task_environment;
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) {
test::TaskEnvironment task_environment;
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.
test::TaskEnvironment task_environment;
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.
test::TaskEnvironment task_environment;
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) {
list_->RemoveObserver(it);
}
}
private:
const scoped_refptr<ObserverListThreadSafe<Foo>> list_;
std::vector<Foo*> foos_;
};
TEST(ObserverListThreadSafeTest, RemoveMultipleObservers) {
test::TaskEnvironment task_environment;
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) {
test::TaskEnvironment task_environment;
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<std::unique_ptr<AddRemoveThread>> threaded_observer;
threaded_observer.reserve(num_threads);
for (int index = 0; index < num_threads; index++) {
threaded_observer.push_back(std::make_unique<AddRemoveThread>(
observer_list.get(), cross_thread_notifies));
}
ASSERT_EQ(static_cast<size_t>(num_threads), threaded_observer.size());
Time start = Time::Now();
while (true) {
if ((Time::Now() - start).InMilliseconds() > kThreadRunTime)
break;
observer_list->Notify(FROM_HERE, &Foo::Observe, 10);
RunLoop().RunUntilIdle();
}
task_environment.RunUntilIdle();
}
TEST(ObserverListThreadSafeTest, 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, OutlivesTaskEnvironment) {
Optional<test::TaskEnvironment> task_environment(in_place);
scoped_refptr<ObserverListThreadSafe<Foo>> observer_list(
new ObserverListThreadSafe<Foo>);
Adder a(1);
observer_list->AddObserver(&a);
task_environment.reset();
// 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::TaskEnvironment task_environment;
auto task_runner_1 = CreateSequencedTaskRunner(TaskTraits(ThreadPool()));
auto task_runner_2 = CreateSequencedTaskRunner(TaskTraits(ThreadPool()));
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)));
ThreadPoolInstance::Get()->FlushForTesting();
observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
ThreadPoolInstance::Get()->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::TaskEnvironment 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
// ThreadPool can safely use |barrier|.
test::TaskEnvironment task_environment;
CreateSequencedTaskRunner({ThreadPool(), MayBlock()})
->PostTask(FROM_HERE,
base::BindOnce(&ObserverListThreadSafe<Foo>::AddObserver,
observer_list, Unretained(&observer)));
ThreadPoolInstance::Get()->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) {
test::TaskEnvironment task_environment;
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