root/base/observer_list_unittest.cc

DEFINITIONS

1. scaler_
2. Observe
3. doomed_
4. Observe
5. doomed_
6. Observe
7. adder
8. Observe
9. weak_factory_
10. ThreadMain
11. AddTask
12. Quit
13. Observe
14. TEST
15. TEST
16. TEST
17. TEST
18. AddFooToRemove
19. Observe
20. TEST
21. ThreadSafeObserverHarness
22. TEST
23. TEST
24. TEST
25. TEST
26. TEST
27. adder_
28. Observe
29. added
30. adder
31. TEST
32. TEST
33. Observe
34. TEST

// 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 "base/observer_list.h"
#include "base/observer_list_threadsafe.h"

#include <vector>

#include "base/compiler_specific.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/run_loop.h"
#include "base/threading/platform_thread.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {
namespace {

class Foo {
 public:
  virtual void Observe(int x) = 0;
  virtual ~Foo() {}
};

class Adder : public Foo {
 public:
  explicit Adder(int scaler) : total(0), scaler_(scaler) {}
  virtual void Observe(int x) OVERRIDE {
    total += x * scaler_;
  }
  virtual ~Adder() {}
  int total;

 private:
  int scaler_;
};

class Disrupter : public Foo {
 public:
  Disrupter(ObserverList<Foo>* list, Foo* doomed)
      : list_(list),
        doomed_(doomed) {
  }
  virtual ~Disrupter() {}
  virtual void Observe(int x) OVERRIDE {
    list_->RemoveObserver(doomed_);
  }

 private:
  ObserverList<Foo>* list_;
  Foo* doomed_;
};

class ThreadSafeDisrupter : public Foo {
 public:
  ThreadSafeDisrupter(ObserverListThreadSafe<Foo>* list, Foo* doomed)
      : list_(list),
        doomed_(doomed) {
  }
  virtual ~ThreadSafeDisrupter() {}
  virtual void Observe(int x) OVERRIDE {
    list_->RemoveObserver(doomed_);
  }

 private:
  ObserverListThreadSafe<Foo>* list_;
  Foo* doomed_;
};

template <typename ObserverListType>
class AddInObserve : public Foo {
 public:
  explicit AddInObserve(ObserverListType* observer_list)
      : added(false),
        observer_list(observer_list),
        adder(1) {
  }

  virtual void Observe(int x) OVERRIDE {
    if (!added) {
      added = true;
      observer_list->AddObserver(&adder);
    }
  }

  bool added;
  ObserverListType* observer_list;
  Adder adder;
};


static const int kThreadRunTime = 2000;  // ms to run the multi-threaded test.

// 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)
      : list_(list),
        loop_(NULL),
        in_list_(false),
        start_(Time::Now()),
        count_observes_(0),
        count_addtask_(0),
        do_notifies_(notify),
        weak_factory_(this) {
  }

  virtual ~AddRemoveThread() {
  }

  virtual void ThreadMain() OVERRIDE {
    loop_ = new MessageLoop();  // Fire up a message loop.
    loop_->PostTask(
        FROM_HERE,
        base::Bind(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
    loop_->Run();
    //LOG(ERROR) << "Loop 0x" << std::hex << loop_ << " done. " <<
    //    count_observes_ << ", " << count_addtask_;
    delete loop_;
    loop_ = reinterpret_cast<MessageLoop*>(0xdeadbeef);
    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(&Foo::Observe, 10);
    }

    loop_->PostTask(
        FROM_HERE,
        base::Bind(&AddRemoveThread::AddTask, weak_factory_.GetWeakPtr()));
  }

  void Quit() {
    loop_->PostTask(FROM_HERE, MessageLoop::QuitWhenIdleClosure());
  }

  virtual 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.

  base::WeakPtrFactory<AddRemoveThread> weak_factory_;
};

TEST(ObserverListTest, BasicTest) {
  ObserverList<Foo> observer_list;
  Adder a(1), b(-1), c(1), d(-1), e(-1);
  Disrupter evil(&observer_list, &c);

  observer_list.AddObserver(&a);
  observer_list.AddObserver(&b);

  FOR_EACH_OBSERVER(Foo, observer_list, Observe(10));

  observer_list.AddObserver(&evil);
  observer_list.AddObserver(&c);
  observer_list.AddObserver(&d);

  // Removing an observer not in the list should do nothing.
  observer_list.RemoveObserver(&e);

  FOR_EACH_OBSERVER(Foo, observer_list, Observe(10));

  EXPECT_EQ(20, a.total);
  EXPECT_EQ(-20, b.total);
  EXPECT_EQ(0, c.total);
  EXPECT_EQ(-10, d.total);
  EXPECT_EQ(0, e.total);
}

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);
  ThreadSafeDisrupter evil(observer_list.get(), &c);

  observer_list->AddObserver(&a);
  observer_list->AddObserver(&b);

  observer_list->Notify(&Foo::Observe, 10);
  RunLoop().RunUntilIdle();

  observer_list->AddObserver(&evil);
  observer_list->AddObserver(&c);
  observer_list->AddObserver(&d);

  observer_list->Notify(&Foo::Observe, 10);
  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(&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(&Foo::Observe, 10);
  RunLoop().RunUntilIdle();

  EXPECT_EQ(10, a.total);
  EXPECT_EQ(0, b.total);
}

TEST(ObserverListThreadSafeTest, WithoutMessageLoop) {
  scoped_refptr<ObserverListThreadSafe<Foo> > observer_list(
      new ObserverListThreadSafe<Foo>);

  Adder a(1), b(1), c(1);

  // No MessageLoop, so these should not be added.
  observer_list->AddObserver(&a);
  observer_list->AddObserver(&b);

  {
    // Add c when there's a loop.
    MessageLoop loop;
    observer_list->AddObserver(&c);

    observer_list->Notify(&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 loop.
    observer_list->AddObserver(&a);

    // Remove c when there's a loop.
    observer_list->RemoveObserver(&c);

    // Notify again.
    observer_list->Notify(&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 loop.
  observer_list->RemoveObserver(&a);

  // Notifying should not fail but should also be a no-op.
  MessageLoop loop;
  observer_list->AddObserver(&b);
  observer_list->Notify(&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) {}
  virtual ~FooRemover() {}

  void AddFooToRemove(Foo* foo) {
    foos_.push_back(foo);
  }

  virtual void Observe(int x) OVERRIDE {
    std::vector<Foo*> tmp;
    tmp.swap(foos_);
    for (std::vector<Foo*>::iterator 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(&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;

  const int kMaxThreads = 15;
  num_threads = num_threads > kMaxThreads ? kMaxThreads : num_threads;

  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);

  AddRemoveThread* threaded_observer[kMaxThreads];
  base::PlatformThreadHandle threads[kMaxThreads];
  for (int index = 0; index < num_threads; index++) {
    threaded_observer[index] = new AddRemoveThread(observer_list.get(), false);
    EXPECT_TRUE(PlatformThread::Create(0,
                threaded_observer[index], &threads[index]));
  }

  Time start = Time::Now();
  while (true) {
    if ((Time::Now() - start).InMilliseconds() > kThreadRunTime)
      break;

    observer_list->Notify(&Foo::Observe, 10);

    RunLoop().RunUntilIdle();
  }

  for (int index = 0; index < num_threads; index++) {
    threaded_observer[index]->Quit();
    PlatformThread::Join(threads[index]);
  }
}

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, 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(&Foo::Observe, 1);
}

TEST(ObserverListTest, Existing) {
  ObserverList<Foo> observer_list(ObserverList<Foo>::NOTIFY_EXISTING_ONLY);
  Adder a(1);
  AddInObserve<ObserverList<Foo> > b(&observer_list);

  observer_list.AddObserver(&a);
  observer_list.AddObserver(&b);

  FOR_EACH_OBSERVER(Foo, observer_list, Observe(1));

  EXPECT_TRUE(b.added);
  // B's adder should not have been notified because it was added during
  // notificaiton.
  EXPECT_EQ(0, b.adder.total);

  // Notify again to make sure b's adder is notified.
  FOR_EACH_OBSERVER(Foo, observer_list, Observe(1));
  EXPECT_EQ(1, b.adder.total);
}

// Same as above, but for ObserverListThreadSafe
TEST(ObserverListThreadSafeTest, Existing) {
  MessageLoop loop;
  scoped_refptr<ObserverListThreadSafe<Foo> > observer_list(
      new ObserverListThreadSafe<Foo>(ObserverList<Foo>::NOTIFY_EXISTING_ONLY));
  Adder a(1);
  AddInObserve<ObserverListThreadSafe<Foo> > b(observer_list.get());

  observer_list->AddObserver(&a);
  observer_list->AddObserver(&b);

  observer_list->Notify(&Foo::Observe, 1);
  RunLoop().RunUntilIdle();

  EXPECT_TRUE(b.added);
  // B's adder should not have been notified because it was added during
  // notificaiton.
  EXPECT_EQ(0, b.adder.total);

  // Notify again to make sure b's adder is notified.
  observer_list->Notify(&Foo::Observe, 1);
  RunLoop().RunUntilIdle();
  EXPECT_EQ(1, b.adder.total);
}

class AddInClearObserve : public Foo {
 public:
  explicit AddInClearObserve(ObserverList<Foo>* list)
      : list_(list), added_(false), adder_(1) {}

  virtual void Observe(int /* x */) OVERRIDE {
    list_->Clear();
    list_->AddObserver(&adder_);
    added_ = true;
  }

  bool added() const { return added_; }
  const Adder& adder() const { return adder_; }

 private:
  ObserverList<Foo>* const list_;

  bool added_;
  Adder adder_;
};

TEST(ObserverListTest, ClearNotifyAll) {
  ObserverList<Foo> observer_list;
  AddInClearObserve a(&observer_list);

  observer_list.AddObserver(&a);

  FOR_EACH_OBSERVER(Foo, observer_list, Observe(1));
  EXPECT_TRUE(a.added());
  EXPECT_EQ(1, a.adder().total)
      << "Adder should observe once and have sum of 1.";
}

TEST(ObserverListTest, ClearNotifyExistingOnly) {
  ObserverList<Foo> observer_list(ObserverList<Foo>::NOTIFY_EXISTING_ONLY);
  AddInClearObserve a(&observer_list);

  observer_list.AddObserver(&a);

  FOR_EACH_OBSERVER(Foo, observer_list, Observe(1));
  EXPECT_TRUE(a.added());
  EXPECT_EQ(0, a.adder().total)
      << "Adder should not observe, so sum should still be 0.";
}

class ListDestructor : public Foo {
 public:
  explicit ListDestructor(ObserverList<Foo>* list) : list_(list) {}
  virtual ~ListDestructor() {}

  virtual void Observe(int x) OVERRIDE {
    delete list_;
  }

 private:
  ObserverList<Foo>* list_;
};


TEST(ObserverListTest, IteratorOutlivesList) {
  ObserverList<Foo>* observer_list = new ObserverList<Foo>;
  ListDestructor a(observer_list);
  observer_list->AddObserver(&a);

  FOR_EACH_OBSERVER(Foo, *observer_list, Observe(0));
  // If this test fails, there'll be Valgrind errors when this function goes out
  // of scope.
}

}  // namespace
}  // namespace base