mojo/system/simple_dispatcher_unittest.cc - chromium/src - Git at Google

 // Copyright 2013 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.

 // NOTE(vtl): Some of these tests are inherently flaky (e.g., if run on a
 // heavily-loaded system). Sorry. |kEpsilonMicros| may be increased to increase
 // tolerance and reduce observed flakiness.

 #include "mojo/system/simple_dispatcher.h"

 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/platform_thread.h"  // For |Sleep()|.
 #include "base/time/time.h"
 #include "mojo/system/test_utils.h"
 #include "mojo/system/waiter.h"
 #include "mojo/system/waiter_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"

 namespace mojo {
 namespace system {
 namespace {

 const int64_t kMicrosPerMs = 1000;
 const int64_t kEpsilonMicros = 30 * kMicrosPerMs;  // 30 ms.

 class MockSimpleDispatcher : public SimpleDispatcher {
  public:
   MockSimpleDispatcher()
       : satisfied_flags_(MOJO_WAIT_FLAG_NONE),
         satisfiable_flags_(MOJO_WAIT_FLAG_READABLE | MOJO_WAIT_FLAG_WRITABLE) {}

   void SetSatisfiedFlags(MojoWaitFlags new_satisfied_flags) {
     base::AutoLock locker(lock());

     // Any new flags that are set should be satisfiable.
     CHECK_EQ(new_satisfied_flags & ~satisfied_flags_,
              new_satisfied_flags & ~satisfied_flags_ & satisfiable_flags_);

     if (new_satisfied_flags == satisfied_flags_)
       return;

     satisfied_flags_ = new_satisfied_flags;
     StateChangedNoLock();
   }

   void SetSatisfiableFlags(MojoWaitFlags new_satisfiable_flags) {
     base::AutoLock locker(lock());

     if (new_satisfiable_flags == satisfiable_flags_)
       return;

     satisfiable_flags_ = new_satisfiable_flags;
     StateChangedNoLock();
   }

   virtual Type GetType() const OVERRIDE {
     return kTypeUnknown;
   }

  private:
   friend class base::RefCountedThreadSafe<MockSimpleDispatcher>;
   virtual ~MockSimpleDispatcher() {}

   virtual scoped_refptr<Dispatcher>
       CreateEquivalentDispatcherAndCloseImplNoLock() OVERRIDE {
     scoped_refptr<MockSimpleDispatcher> rv(new MockSimpleDispatcher());
     rv->satisfied_flags_ = satisfied_flags_;
     rv->satisfiable_flags_ = satisfiable_flags_;
     return scoped_refptr<Dispatcher>(rv.get());
   }

   // |SimpleDispatcher| implementation:
   virtual MojoWaitFlags SatisfiedFlagsNoLock() const OVERRIDE {
     lock().AssertAcquired();
     return satisfied_flags_;
   }

   virtual MojoWaitFlags SatisfiableFlagsNoLock() const OVERRIDE {
     lock().AssertAcquired();
     return satisfiable_flags_;
   }

   // Protected by |lock()|:
   MojoWaitFlags satisfied_flags_;
   MojoWaitFlags satisfiable_flags_;

   DISALLOW_COPY_AND_ASSIGN(MockSimpleDispatcher);
 };

 TEST(SimpleDispatcherTest, Basic) {
   test::Stopwatch stopwatch;
   int64_t elapsed_micros;

   scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
   Waiter w;

   // Try adding a readable waiter when already readable.
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS,
             d->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 0));
   // Shouldn't need to remove the waiter (it was not added).

   // Wait (forever) for writable when already writable.
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 1));
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
   stopwatch.Start();
   EXPECT_EQ(1, w.Wait(MOJO_DEADLINE_INDEFINITE));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for zero time for writable when already writable.
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 2));
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
   stopwatch.Start();
   EXPECT_EQ(2, w.Wait(0));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for non-zero, finite time for writable when already writable.
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 3));
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
   stopwatch.Start();
   EXPECT_EQ(3, w.Wait(2 * kEpsilonMicros));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for zero time for writable when not writable (will time out).
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 4));
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(0));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for non-zero, finite time for writable when not writable (will time
   // out).
   w.Init();
   d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 4));
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(2 * kEpsilonMicros));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
   EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
   d->RemoveWaiter(&w);

   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
 }

 TEST(SimpleDispatcherTest, BasicUnsatisfiable) {
   test::Stopwatch stopwatch;
   int64_t elapsed_micros;

   scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
   Waiter w;

   // Try adding a writable waiter when it can never be writable.
   w.Init();
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
   d->SetSatisfiedFlags(0);
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
             d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 5));
   // Shouldn't need to remove the waiter (it was not added).

   // Wait (forever) for writable and then it becomes never writable.
   w.Init();
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE | MOJO_WAIT_FLAG_WRITABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 6));
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(MOJO_DEADLINE_INDEFINITE));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for zero time for writable and then it becomes never writable.
   w.Init();
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE | MOJO_WAIT_FLAG_WRITABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 6));
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(0));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   // Wait for non-zero, finite time for writable and then it becomes never
   // writable.
   w.Init();
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE | MOJO_WAIT_FLAG_WRITABLE);
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 7));
   d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(2 * kEpsilonMicros));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   d->RemoveWaiter(&w);

   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
 }

 TEST(SimpleDispatcherTest, BasicClosed) {
   test::Stopwatch stopwatch;
   int64_t elapsed_micros;

   scoped_refptr<MockSimpleDispatcher> d;
   Waiter w;

   // Try adding a writable waiter when the dispatcher has been closed.
   d = new MockSimpleDispatcher();
   w.Init();
   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
             d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 8));
   // Shouldn't need to remove the waiter (it was not added).

   // Wait (forever) for writable and then the dispatcher is closed.
   d = new MockSimpleDispatcher();
   w.Init();
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 9));
   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(MOJO_DEADLINE_INDEFINITE));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   // Don't need to remove waiters from closed dispatchers.

   // Wait for zero time for writable and then the dispatcher is closed.
   d = new MockSimpleDispatcher();
   w.Init();
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 10));
   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(0));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   // Don't need to remove waiters from closed dispatchers.

   // Wait for non-zero, finite time for writable and then the dispatcher is
   // closed.
   d = new MockSimpleDispatcher();
   w.Init();
   EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 11));
   EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   stopwatch.Start();
   EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(2 * kEpsilonMicros));
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_LT(elapsed_micros, kEpsilonMicros);
   // Don't need to remove waiters from closed dispatchers.
 }

 TEST(SimpleDispatcherTest, BasicThreaded) {
   test::Stopwatch stopwatch;
   bool did_wait;
   MojoResult result;
   int64_t elapsed_micros;

   // Wait for readable (already readable).
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     {
       d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
       test::WaiterThread thread(d,
                                 MOJO_WAIT_FLAG_READABLE,
                                 MOJO_DEADLINE_INDEFINITE,
                                 0,
                                 &did_wait, &result);
       stopwatch.Start();
       thread.Start();
     }  // Joins the thread.
     // If we closed earlier, then probably we'd get a |MOJO_RESULT_CANCELLED|.
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_FALSE(did_wait);
   EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS, result);
   EXPECT_LT(elapsed_micros, kEpsilonMicros);

   // Wait for readable and becomes readable after some time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     test::WaiterThread thread(d,
                               MOJO_WAIT_FLAG_READABLE,
                               MOJO_DEADLINE_INDEFINITE,
                               1,
                               &did_wait, &result);
     stopwatch.Start();
     thread.Start();
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the thread.
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_TRUE(did_wait);
   EXPECT_EQ(1, result);
   EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
   EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

   // Wait for readable and becomes never-readable after some time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     test::WaiterThread thread(d,
                               MOJO_WAIT_FLAG_READABLE,
                               MOJO_DEADLINE_INDEFINITE,
                               2,
                               &did_wait, &result);
     stopwatch.Start();
     thread.Start();
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     d->SetSatisfiableFlags(MOJO_WAIT_FLAG_NONE);
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the thread.
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_TRUE(did_wait);
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
   EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
   EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

   // Wait for readable and dispatcher gets closed.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     test::WaiterThread thread(d,
                               MOJO_WAIT_FLAG_READABLE,
                               MOJO_DEADLINE_INDEFINITE,
                               3,
                               &did_wait, &result);
     stopwatch.Start();
     thread.Start();
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the thread.
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_TRUE(did_wait);
   EXPECT_EQ(MOJO_RESULT_CANCELLED, result);
   EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
   EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

   // Wait for readable and times out.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     {
       test::WaiterThread thread(d,
                                 MOJO_WAIT_FLAG_READABLE,
                                 2 * kEpsilonMicros,
                                 4,
                                 &did_wait, &result);
       stopwatch.Start();
       thread.Start();
       base::PlatformThread::Sleep(
           base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
       // Not what we're waiting for.
       d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
     }  // Joins the thread (after its wait times out).
     // If we closed earlier, then probably we'd get a |MOJO_RESULT_CANCELLED|.
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }
   elapsed_micros = stopwatch.Elapsed();
   EXPECT_TRUE(did_wait);
   EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, result);
   EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
   EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
 }

 TEST(SimpleDispatcherTest, MultipleWaiters) {
   static const size_t kNumWaiters = 20;

   bool did_wait[kNumWaiters];
   MojoResult result[kNumWaiters];

   // All wait for readable and becomes readable after some time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     ScopedVector<test::WaiterThread> threads;
     for (size_t i = 0; i < kNumWaiters; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_READABLE,
                                                MOJO_DEADLINE_INDEFINITE,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the threads.
   for (size_t i = 0; i < kNumWaiters; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
   }

   // Some wait for readable, some for writable, and becomes readable after some
   // time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     ScopedVector<test::WaiterThread> threads;
     for (size_t i = 0; i < kNumWaiters / 2; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_READABLE,
                                                MOJO_DEADLINE_INDEFINITE,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_WRITABLE,
                                                MOJO_DEADLINE_INDEFINITE,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
     // This will wake up the ones waiting to write.
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the threads.
   for (size_t i = 0; i < kNumWaiters / 2; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
   }
   for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(MOJO_RESULT_CANCELLED, result[i]);
   }

   // Some wait for readable, some for writable, and becomes readable and
   // never-writable after some time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     ScopedVector<test::WaiterThread> threads;
     for (size_t i = 0; i < kNumWaiters / 2; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_READABLE,
                                                MOJO_DEADLINE_INDEFINITE,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_WRITABLE,
                                                MOJO_DEADLINE_INDEFINITE,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
     d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
     d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the threads.
   for (size_t i = 0; i < kNumWaiters / 2; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
   }
   for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result[i]);
   }

   // Some wait for readable, some for writable, and becomes readable after some
   // time.
   {
     scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
     ScopedVector<test::WaiterThread> threads;
     for (size_t i = 0; i < kNumWaiters / 2; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_READABLE,
                                                3 * kEpsilonMicros,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
       threads.push_back(new test::WaiterThread(d,
                                                MOJO_WAIT_FLAG_WRITABLE,
                                                1 * kEpsilonMicros,
                                                static_cast<MojoResult>(i),
                                                &did_wait[i], &result[i]));
       threads.back()->Start();
     }
     base::PlatformThread::Sleep(
         base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
     d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
     // All those waiting for writable should have timed out.
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }  // Joins the threads.
   for (size_t i = 0; i < kNumWaiters / 2; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
   }
   for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
     EXPECT_TRUE(did_wait[i]);
     EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, result[i]);
   }
 }

 // TODO(vtl): Stress test?

 }  // namespace
 }  // namespace system
 }  // namespace mojo
	// Copyright 2013 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.

	// NOTE(vtl): Some of these tests are inherently flaky (e.g., if run on a
	// heavily-loaded system). Sorry. \|kEpsilonMicros\| may be increased to increase
	// tolerance and reduce observed flakiness.

	#include "mojo/system/simple_dispatcher.h"

	#include "base/basictypes.h"
	#include "base/logging.h"
	#include "base/memory/ref_counted.h"
	#include "base/memory/scoped_vector.h"
	#include "base/synchronization/lock.h"
	#include "base/threading/platform_thread.h" // For \|Sleep()\|.
	#include "base/time/time.h"
	#include "mojo/system/test_utils.h"
	#include "mojo/system/waiter.h"
	#include "mojo/system/waiter_test_utils.h"
	#include "testing/gtest/include/gtest/gtest.h"

	namespace mojo {
	namespace system {
	namespace {

	const int64_t kMicrosPerMs = 1000;
	const int64_t kEpsilonMicros = 30 * kMicrosPerMs; // 30 ms.

	class MockSimpleDispatcher : public SimpleDispatcher {
	public:
	MockSimpleDispatcher()
	: satisfied_flags_(MOJO_WAIT_FLAG_NONE),
	satisfiable_flags_(MOJO_WAIT_FLAG_READABLE \| MOJO_WAIT_FLAG_WRITABLE) {}

	void SetSatisfiedFlags(MojoWaitFlags new_satisfied_flags) {
	base::AutoLock locker(lock());

	// Any new flags that are set should be satisfiable.
	CHECK_EQ(new_satisfied_flags & ~satisfied_flags_,
	new_satisfied_flags & ~satisfied_flags_ & satisfiable_flags_);

	if (new_satisfied_flags == satisfied_flags_)
	return;

	satisfied_flags_ = new_satisfied_flags;
	StateChangedNoLock();
	}

	void SetSatisfiableFlags(MojoWaitFlags new_satisfiable_flags) {
	base::AutoLock locker(lock());

	if (new_satisfiable_flags == satisfiable_flags_)
	return;

	satisfiable_flags_ = new_satisfiable_flags;
	StateChangedNoLock();
	}

	virtual Type GetType() const OVERRIDE {
	return kTypeUnknown;
	}

	private:
	friend class base::RefCountedThreadSafe<MockSimpleDispatcher>;
	virtual ~MockSimpleDispatcher() {}

	virtual scoped_refptr<Dispatcher>
	CreateEquivalentDispatcherAndCloseImplNoLock() OVERRIDE {
	scoped_refptr<MockSimpleDispatcher> rv(new MockSimpleDispatcher());
	rv->satisfied_flags_ = satisfied_flags_;
	rv->satisfiable_flags_ = satisfiable_flags_;
	return scoped_refptr<Dispatcher>(rv.get());
	}

	// \|SimpleDispatcher\| implementation:
	virtual MojoWaitFlags SatisfiedFlagsNoLock() const OVERRIDE {
	lock().AssertAcquired();
	return satisfied_flags_;
	}

	virtual MojoWaitFlags SatisfiableFlagsNoLock() const OVERRIDE {
	lock().AssertAcquired();
	return satisfiable_flags_;
	}

	// Protected by \|lock()\|:
	MojoWaitFlags satisfied_flags_;
	MojoWaitFlags satisfiable_flags_;

	DISALLOW_COPY_AND_ASSIGN(MockSimpleDispatcher);
	};

	TEST(SimpleDispatcherTest, Basic) {
	test::Stopwatch stopwatch;
	int64_t elapsed_micros;

	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	Waiter w;

	// Try adding a readable waiter when already readable.
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS,
	d->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 0));
	// Shouldn't need to remove the waiter (it was not added).

	// Wait (forever) for writable when already writable.
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 1));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
	stopwatch.Start();
	EXPECT_EQ(1, w.Wait(MOJO_DEADLINE_INDEFINITE));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for zero time for writable when already writable.
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 2));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
	stopwatch.Start();
	EXPECT_EQ(2, w.Wait(0));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for non-zero, finite time for writable when already writable.
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 3));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
	stopwatch.Start();
	EXPECT_EQ(3, w.Wait(2 * kEpsilonMicros));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for zero time for writable when not writable (will time out).
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 4));
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(0));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for non-zero, finite time for writable when not writable (will time
	// out).
	w.Init();
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 4));
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(2 * kEpsilonMicros));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
	EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
	d->RemoveWaiter(&w);

	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	}

	TEST(SimpleDispatcherTest, BasicUnsatisfiable) {
	test::Stopwatch stopwatch;
	int64_t elapsed_micros;

	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	Waiter w;

	// Try adding a writable waiter when it can never be writable.
	w.Init();
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
	d->SetSatisfiedFlags(0);
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
	d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 5));
	// Shouldn't need to remove the waiter (it was not added).

	// Wait (forever) for writable and then it becomes never writable.
	w.Init();
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE \| MOJO_WAIT_FLAG_WRITABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 6));
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(MOJO_DEADLINE_INDEFINITE));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for zero time for writable and then it becomes never writable.
	w.Init();
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE \| MOJO_WAIT_FLAG_WRITABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 6));
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(0));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	// Wait for non-zero, finite time for writable and then it becomes never
	// writable.
	w.Init();
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE \| MOJO_WAIT_FLAG_WRITABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 7));
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, w.Wait(2 * kEpsilonMicros));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	d->RemoveWaiter(&w);

	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	}

	TEST(SimpleDispatcherTest, BasicClosed) {
	test::Stopwatch stopwatch;
	int64_t elapsed_micros;

	scoped_refptr<MockSimpleDispatcher> d;
	Waiter w;

	// Try adding a writable waiter when the dispatcher has been closed.
	d = new MockSimpleDispatcher();
	w.Init();
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
	d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 8));
	// Shouldn't need to remove the waiter (it was not added).

	// Wait (forever) for writable and then the dispatcher is closed.
	d = new MockSimpleDispatcher();
	w.Init();
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 9));
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(MOJO_DEADLINE_INDEFINITE));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	// Don't need to remove waiters from closed dispatchers.

	// Wait for zero time for writable and then the dispatcher is closed.
	d = new MockSimpleDispatcher();
	w.Init();
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 10));
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(0));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	// Don't need to remove waiters from closed dispatchers.

	// Wait for non-zero, finite time for writable and then the dispatcher is
	// closed.
	d = new MockSimpleDispatcher();
	w.Init();
	EXPECT_EQ(MOJO_RESULT_OK, d->AddWaiter(&w, MOJO_WAIT_FLAG_WRITABLE, 11));
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	stopwatch.Start();
	EXPECT_EQ(MOJO_RESULT_CANCELLED, w.Wait(2 * kEpsilonMicros));
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_LT(elapsed_micros, kEpsilonMicros);
	// Don't need to remove waiters from closed dispatchers.
	}

	TEST(SimpleDispatcherTest, BasicThreaded) {
	test::Stopwatch stopwatch;
	bool did_wait;
	MojoResult result;
	int64_t elapsed_micros;

	// Wait for readable (already readable).
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	{
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	test::WaiterThread thread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	0,
	&did_wait, &result);
	stopwatch.Start();
	thread.Start();
	} // Joins the thread.
	// If we closed earlier, then probably we'd get a \|MOJO_RESULT_CANCELLED\|.
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	}
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_FALSE(did_wait);
	EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS, result);
	EXPECT_LT(elapsed_micros, kEpsilonMicros);

	// Wait for readable and becomes readable after some time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	test::WaiterThread thread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	1,
	&did_wait, &result);
	stopwatch.Start();
	thread.Start();
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the thread.
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_TRUE(did_wait);
	EXPECT_EQ(1, result);
	EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
	EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

	// Wait for readable and becomes never-readable after some time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	test::WaiterThread thread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	2,
	&did_wait, &result);
	stopwatch.Start();
	thread.Start();
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_NONE);
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the thread.
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_TRUE(did_wait);
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
	EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
	EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

	// Wait for readable and dispatcher gets closed.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	test::WaiterThread thread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	3,
	&did_wait, &result);
	stopwatch.Start();
	thread.Start();
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the thread.
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_TRUE(did_wait);
	EXPECT_EQ(MOJO_RESULT_CANCELLED, result);
	EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
	EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);

	// Wait for readable and times out.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	{
	test::WaiterThread thread(d,
	MOJO_WAIT_FLAG_READABLE,
	2 * kEpsilonMicros,
	4,
	&did_wait, &result);
	stopwatch.Start();
	thread.Start();
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
	// Not what we're waiting for.
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_WRITABLE);
	} // Joins the thread (after its wait times out).
	// If we closed earlier, then probably we'd get a \|MOJO_RESULT_CANCELLED\|.
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	}
	elapsed_micros = stopwatch.Elapsed();
	EXPECT_TRUE(did_wait);
	EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, result);
	EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
	EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
	}

	TEST(SimpleDispatcherTest, MultipleWaiters) {
	static const size_t kNumWaiters = 20;

	bool did_wait[kNumWaiters];
	MojoResult result[kNumWaiters];

	// All wait for readable and becomes readable after some time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	ScopedVector<test::WaiterThread> threads;
	for (size_t i = 0; i < kNumWaiters; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the threads.
	for (size_t i = 0; i < kNumWaiters; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
	}

	// Some wait for readable, some for writable, and becomes readable after some
	// time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	ScopedVector<test::WaiterThread> threads;
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_WRITABLE,
	MOJO_DEADLINE_INDEFINITE,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	// This will wake up the ones waiting to write.
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the threads.
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(MOJO_RESULT_CANCELLED, result[i]);
	}

	// Some wait for readable, some for writable, and becomes readable and
	// never-writable after some time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	ScopedVector<test::WaiterThread> threads;
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_READABLE,
	MOJO_DEADLINE_INDEFINITE,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_WRITABLE,
	MOJO_DEADLINE_INDEFINITE,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
	d->SetSatisfiableFlags(MOJO_WAIT_FLAG_READABLE);
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(1 * kEpsilonMicros));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the threads.
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result[i]);
	}

	// Some wait for readable, some for writable, and becomes readable after some
	// time.
	{
	scoped_refptr<MockSimpleDispatcher> d(new MockSimpleDispatcher());
	ScopedVector<test::WaiterThread> threads;
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_READABLE,
	3 * kEpsilonMicros,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	threads.push_back(new test::WaiterThread(d,
	MOJO_WAIT_FLAG_WRITABLE,
	1 * kEpsilonMicros,
	static_cast<MojoResult>(i),
	&did_wait[i], &result[i]));
	threads.back()->Start();
	}
	base::PlatformThread::Sleep(
	base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
	d->SetSatisfiedFlags(MOJO_WAIT_FLAG_READABLE);
	// All those waiting for writable should have timed out.
	EXPECT_EQ(MOJO_RESULT_OK, d->Close());
	} // Joins the threads.
	for (size_t i = 0; i < kNumWaiters / 2; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(static_cast<MojoResult>(i), result[i]);
	}
	for (size_t i = kNumWaiters / 2; i < kNumWaiters; i++) {
	EXPECT_TRUE(did_wait[i]);
	EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, result[i]);
	}
	}

	// TODO(vtl): Stress test?

	} // namespace
	} // namespace system
	} // namespace mojo