src/base/memory/weak_ptr_unittest.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/memory/weak_ptr.h"
   6
   7 #include <string>
   8
   9 #include "base/bind.h"
  10 #include "base/debug/leak_annotations.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/message_loop/message_loop.h"
  13 #include "base/synchronization/waitable_event.h"
  14 #include "base/threading/thread.h"
  15 #include "testing/gtest/include/gtest/gtest.h"
  16
  17 namespace base {
  18 namespace {
  19
  20 template <class T>
  21 class OffThreadObjectCreator {
  22  public:
  23   static T* NewObject() {
  24     T* result;
  25     {
  26       Thread creator_thread("creator_thread");
  27       creator_thread.Start();
  28       creator_thread.message_loop()->PostTask(
  29           FROM_HERE,
  30           base::Bind(OffThreadObjectCreator::CreateObject, &result));
  31     }
  32     DCHECK(result);  // We synchronized on thread destruction above.
  33     return result;
  34   }
  35  private:
  36   static void CreateObject(T** result) {
  37     *result = new T;
  38   }
  39 };
  40
  41 struct Base {
  42   std::string member;
  43 };
  44 struct Derived : public Base {};
  45
  46 struct TargetBase {};
  47 struct Target : public TargetBase, public SupportsWeakPtr<Target> {
  48   virtual ~Target() {}
  49 };
  50 struct DerivedTarget : public Target {};
  51 struct Arrow {
  52   WeakPtr<Target> target;
  53 };
  54 struct TargetWithFactory : public Target {
  55   TargetWithFactory() : factory(this) {}
  56   WeakPtrFactory<Target> factory;
  57 };
  58
  59 // Helper class to create and destroy weak pointer copies
  60 // and delete objects on a background thread.
  61 class BackgroundThread : public Thread {
  62  public:
  63   BackgroundThread() : Thread("owner_thread") {}
  64
  65   virtual ~BackgroundThread() {
  66     Stop();
  67   }
  68
  69   void CreateArrowFromTarget(Arrow** arrow, Target* target) {
  70     WaitableEvent completion(true, false);
  71     message_loop()->PostTask(
  72         FROM_HERE,
  73         base::Bind(&BackgroundThread::DoCreateArrowFromTarget,
  74                    arrow, target, &completion));
  75     completion.Wait();
  76   }
  77
  78   void CreateArrowFromArrow(Arrow** arrow, const Arrow* other) {
  79     WaitableEvent completion(true, false);
  80     message_loop()->PostTask(
  81         FROM_HERE,
  82         base::Bind(&BackgroundThread::DoCreateArrowFromArrow,
  83                    arrow, other, &completion));
  84     completion.Wait();
  85   }
  86
  87   void DeleteTarget(Target* object) {
  88     WaitableEvent completion(true, false);
  89     message_loop()->PostTask(
  90         FROM_HERE,
  91         base::Bind(&BackgroundThread::DoDeleteTarget, object, &completion));
  92     completion.Wait();
  93   }
  94
  95   void CopyAndAssignArrow(Arrow* object) {
  96     WaitableEvent completion(true, false);
  97     message_loop()->PostTask(
  98         FROM_HERE,
  99         base::Bind(&BackgroundThread::DoCopyAndAssignArrow,
 100                    object, &completion));
 101     completion.Wait();
 102   }
 103
 104   void CopyAndAssignArrowBase(Arrow* object) {
 105     WaitableEvent completion(true, false);
 106     message_loop()->PostTask(
 107         FROM_HERE,
 108         base::Bind(&BackgroundThread::DoCopyAndAssignArrowBase,
 109                    object, &completion));
 110     completion.Wait();
 111   }
 112
 113   void DeleteArrow(Arrow* object) {
 114     WaitableEvent completion(true, false);
 115     message_loop()->PostTask(
 116         FROM_HERE,
 117         base::Bind(&BackgroundThread::DoDeleteArrow, object, &completion));
 118     completion.Wait();
 119   }
 120
 121   Target* DeRef(const Arrow* arrow) {
 122     WaitableEvent completion(true, false);
 123     Target* result = NULL;
 124     message_loop()->PostTask(
 125         FROM_HERE,
 126         base::Bind(&BackgroundThread::DoDeRef, arrow, &result, &completion));
 127     completion.Wait();
 128     return result;
 129   }
 130
 131  protected:
 132   static void DoCreateArrowFromArrow(Arrow** arrow,
 133                                      const Arrow* other,
 134                                      WaitableEvent* completion) {
 135     *arrow = new Arrow;
 136     **arrow = *other;
 137     completion->Signal();
 138   }
 139
 140   static void DoCreateArrowFromTarget(Arrow** arrow,
 141                                       Target* target,
 142                                       WaitableEvent* completion) {
 143     *arrow = new Arrow;
 144     (*arrow)->target = target->AsWeakPtr();
 145     completion->Signal();
 146   }
 147
 148   static void DoDeRef(const Arrow* arrow,
 149                       Target** result,
 150                       WaitableEvent* completion) {
 151     *result = arrow->target.get();
 152     completion->Signal();
 153   }
 154
 155   static void DoDeleteTarget(Target* object, WaitableEvent* completion) {
 156     delete object;
 157     completion->Signal();
 158   }
 159
 160   static void DoCopyAndAssignArrow(Arrow* object, WaitableEvent* completion) {
 161     // Copy constructor.
 162     Arrow a = *object;
 163     // Assignment operator.
 164     *object = a;
 165     completion->Signal();
 166   }
 167
 168   static void DoCopyAndAssignArrowBase(
 169       Arrow* object,
 170       WaitableEvent* completion) {
 171     // Copy constructor.
 172     WeakPtr<TargetBase> b = object->target;
 173     // Assignment operator.
 174     WeakPtr<TargetBase> c;
 175     c = object->target;
 176     completion->Signal();
 177   }
 178
 179   static void DoDeleteArrow(Arrow* object, WaitableEvent* completion) {
 180     delete object;
 181     completion->Signal();
 182   }
 183 };
 184
 185 }  // namespace
 186
 187 TEST(WeakPtrFactoryTest, Basic) {
 188   int data;
 189   WeakPtrFactory<int> factory(&data);
 190   WeakPtr<int> ptr = factory.GetWeakPtr();
 191   EXPECT_EQ(&data, ptr.get());
 192 }
 193
 194 TEST(WeakPtrFactoryTest, Comparison) {
 195   int data;
 196   WeakPtrFactory<int> factory(&data);
 197   WeakPtr<int> ptr = factory.GetWeakPtr();
 198   WeakPtr<int> ptr2 = ptr;
 199   EXPECT_EQ(ptr.get(), ptr2.get());
 200 }
 201
 202 TEST(WeakPtrFactoryTest, OutOfScope) {
 203   WeakPtr<int> ptr;
 204   EXPECT_EQ(NULL, ptr.get());
 205   {
 206     int data;
 207     WeakPtrFactory<int> factory(&data);
 208     ptr = factory.GetWeakPtr();
 209   }
 210   EXPECT_EQ(NULL, ptr.get());
 211 }
 212
 213 TEST(WeakPtrFactoryTest, Multiple) {
 214   WeakPtr<int> a, b;
 215   {
 216     int data;
 217     WeakPtrFactory<int> factory(&data);
 218     a = factory.GetWeakPtr();
 219     b = factory.GetWeakPtr();
 220     EXPECT_EQ(&data, a.get());
 221     EXPECT_EQ(&data, b.get());
 222   }
 223   EXPECT_EQ(NULL, a.get());
 224   EXPECT_EQ(NULL, b.get());
 225 }
 226
 227 TEST(WeakPtrFactoryTest, MultipleStaged) {
 228   WeakPtr<int> a;
 229   {
 230     int data;
 231     WeakPtrFactory<int> factory(&data);
 232     a = factory.GetWeakPtr();
 233     {
 234       WeakPtr<int> b = factory.GetWeakPtr();
 235     }
 236     EXPECT_TRUE(NULL != a.get());
 237   }
 238   EXPECT_EQ(NULL, a.get());
 239 }
 240
 241 TEST(WeakPtrFactoryTest, Dereference) {
 242   Base data;
 243   data.member = "123456";
 244   WeakPtrFactory<Base> factory(&data);
 245   WeakPtr<Base> ptr = factory.GetWeakPtr();
 246   EXPECT_EQ(&data, ptr.get());
 247   EXPECT_EQ(data.member, (*ptr).member);
 248   EXPECT_EQ(data.member, ptr->member);
 249 }
 250
 251 TEST(WeakPtrFactoryTest, UpCast) {
 252   Derived data;
 253   WeakPtrFactory<Derived> factory(&data);
 254   WeakPtr<Base> ptr = factory.GetWeakPtr();
 255   ptr = factory.GetWeakPtr();
 256   EXPECT_EQ(ptr.get(), &data);
 257 }
 258
 259 TEST(WeakPtrTest, SupportsWeakPtr) {
 260   Target target;
 261   WeakPtr<Target> ptr = target.AsWeakPtr();
 262   EXPECT_EQ(&target, ptr.get());
 263 }
 264
 265 TEST(WeakPtrTest, DerivedTarget) {
 266   DerivedTarget target;
 267   WeakPtr<DerivedTarget> ptr = AsWeakPtr(&target);
 268   EXPECT_EQ(&target, ptr.get());
 269 }
 270
 271 TEST(WeakPtrTest, InvalidateWeakPtrs) {
 272   int data;
 273   WeakPtrFactory<int> factory(&data);
 274   WeakPtr<int> ptr = factory.GetWeakPtr();
 275   EXPECT_EQ(&data, ptr.get());
 276   EXPECT_TRUE(factory.HasWeakPtrs());
 277   factory.InvalidateWeakPtrs();
 278   EXPECT_EQ(NULL, ptr.get());
 279   EXPECT_FALSE(factory.HasWeakPtrs());
 280 }
 281
 282 TEST(WeakPtrTest, HasWeakPtrs) {
 283   int data;
 284   WeakPtrFactory<int> factory(&data);
 285   {
 286     WeakPtr<int> ptr = factory.GetWeakPtr();
 287     EXPECT_TRUE(factory.HasWeakPtrs());
 288   }
 289   EXPECT_FALSE(factory.HasWeakPtrs());
 290 }
 291
 292 TEST(WeakPtrTest, ObjectAndWeakPtrOnDifferentThreads) {
 293   // Test that it is OK to create an object that supports WeakPtr on one thread,
 294   // but use it on another.  This tests that we do not trip runtime checks that
 295   // ensure that a WeakPtr is not used by multiple threads.
 296   scoped_ptr<Target> target(OffThreadObjectCreator<Target>::NewObject());
 297   WeakPtr<Target> weak_ptr = target->AsWeakPtr();
 298   EXPECT_EQ(target.get(), weak_ptr.get());
 299 }
 300
 301 TEST(WeakPtrTest, WeakPtrInitiateAndUseOnDifferentThreads) {
 302   // Test that it is OK to create an object that has a WeakPtr member on one
 303   // thread, but use it on another.  This tests that we do not trip runtime
 304   // checks that ensure that a WeakPtr is not used by multiple threads.
 305   scoped_ptr<Arrow> arrow(OffThreadObjectCreator<Arrow>::NewObject());
 306   Target target;
 307   arrow->target = target.AsWeakPtr();
 308   EXPECT_EQ(&target, arrow->target.get());
 309 }
 310
 311 TEST(WeakPtrTest, MoveOwnershipImplicitly) {
 312   // Move object ownership to another thread by releasing all weak pointers
 313   // on the original thread first, and then establish WeakPtr on a different
 314   // thread.
 315   BackgroundThread background;
 316   background.Start();
 317
 318   Target* target = new Target();
 319   {
 320     WeakPtr<Target> weak_ptr = target->AsWeakPtr();
 321     // Main thread deletes the WeakPtr, then the thread ownership of the
 322     // object can be implicitly moved.
 323   }
 324   Arrow* arrow;
 325
 326   // Background thread creates WeakPtr(and implicitly owns the object).
 327   background.CreateArrowFromTarget(&arrow, target);
 328   EXPECT_EQ(background.DeRef(arrow), target);
 329
 330   {
 331     // Main thread creates another WeakPtr, but this does not trigger implicitly
 332     // thread ownership move.
 333     Arrow arrow;
 334     arrow.target = target->AsWeakPtr();
 335
 336     // The new WeakPtr is owned by background thread.
 337     EXPECT_EQ(target, background.DeRef(&arrow));
 338   }
 339
 340   // Target can only be deleted on background thread.
 341   background.DeleteTarget(target);
 342   background.DeleteArrow(arrow);
 343 }
 344
 345 TEST(WeakPtrTest, MoveOwnershipOfUnreferencedObject) {
 346   BackgroundThread background;
 347   background.Start();
 348
 349   Arrow* arrow;
 350   {
 351     Target target;
 352     // Background thread creates WeakPtr.
 353     background.CreateArrowFromTarget(&arrow, &target);
 354
 355     // Bind to background thread.
 356     EXPECT_EQ(&target, background.DeRef(arrow));
 357
 358     // Release the only WeakPtr.
 359     arrow->target.reset();
 360
 361     // Now we should be able to create a new reference from this thread.
 362     arrow->target = target.AsWeakPtr();
 363
 364     // Re-bind to main thread.
 365     EXPECT_EQ(&target, arrow->target.get());
 366
 367     // And the main thread can now delete the target.
 368   }
 369
 370   delete arrow;
 371 }
 372
 373 TEST(WeakPtrTest, MoveOwnershipAfterInvalidate) {
 374   BackgroundThread background;
 375   background.Start();
 376
 377   Arrow arrow;
 378   scoped_ptr<TargetWithFactory> target(new TargetWithFactory);
 379
 380   // Bind to main thread.
 381   arrow.target = target->factory.GetWeakPtr();
 382   EXPECT_EQ(target.get(), arrow.target.get());
 383
 384   target->factory.InvalidateWeakPtrs();
 385   EXPECT_EQ(NULL, arrow.target.get());
 386
 387   arrow.target = target->factory.GetWeakPtr();
 388   // Re-bind to background thread.
 389   EXPECT_EQ(target.get(), background.DeRef(&arrow));
 390
 391   // And the background thread can now delete the target.
 392   background.DeleteTarget(target.release());
 393 }
 394
 395 TEST(WeakPtrTest, MainThreadRefOutlivesBackgroundThreadRef) {
 396   // Originating thread has a WeakPtr that outlives others.
 397   // - Main thread creates a WeakPtr
 398   // - Background thread creates a WeakPtr copy from the one in main thread
 399   // - Destruct the WeakPtr on background thread
 400   // - Destruct the WeakPtr on main thread
 401   BackgroundThread background;
 402   background.Start();
 403
 404   Target target;
 405   Arrow arrow;
 406   arrow.target = target.AsWeakPtr();
 407
 408   Arrow* arrow_copy;
 409   background.CreateArrowFromArrow(&arrow_copy, &arrow);
 410   EXPECT_EQ(arrow_copy->target.get(), &target);
 411   background.DeleteArrow(arrow_copy);
 412 }
 413
 414 TEST(WeakPtrTest, BackgroundThreadRefOutlivesMainThreadRef) {
 415   // Originating thread drops all references before another thread.
 416   // - Main thread creates a WeakPtr and passes copy to background thread
 417   // - Destruct the pointer on main thread
 418   // - Destruct the pointer on background thread
 419   BackgroundThread background;
 420   background.Start();
 421
 422   Target target;
 423   Arrow* arrow_copy;
 424   {
 425     Arrow arrow;
 426     arrow.target = target.AsWeakPtr();
 427     background.CreateArrowFromArrow(&arrow_copy, &arrow);
 428   }
 429   EXPECT_EQ(arrow_copy->target.get(), &target);
 430   background.DeleteArrow(arrow_copy);
 431 }
 432
 433 TEST(WeakPtrTest, OwnerThreadDeletesObject) {
 434   // Originating thread invalidates WeakPtrs while its held by other thread.
 435   // - Main thread creates WeakPtr and passes Copy to background thread
 436   // - Object gets destroyed on main thread
 437   //   (invalidates WeakPtr on background thread)
 438   // - WeakPtr gets destroyed on Thread B
 439   BackgroundThread background;
 440   background.Start();
 441   Arrow* arrow_copy;
 442   {
 443     Target target;
 444     Arrow arrow;
 445     arrow.target = target.AsWeakPtr();
 446     background.CreateArrowFromArrow(&arrow_copy, &arrow);
 447   }
 448   EXPECT_EQ(NULL, arrow_copy->target.get());
 449   background.DeleteArrow(arrow_copy);
 450 }
 451
 452 TEST(WeakPtrTest, NonOwnerThreadCanCopyAndAssignWeakPtr) {
 453   // Main thread creates a Target object.
 454   Target target;
 455   // Main thread creates an arrow referencing the Target.
 456   Arrow *arrow = new Arrow();
 457   arrow->target = target.AsWeakPtr();
 458
 459   // Background can copy and assign arrow (as well as the WeakPtr inside).
 460   BackgroundThread background;
 461   background.Start();
 462   background.CopyAndAssignArrow(arrow);
 463   background.DeleteArrow(arrow);
 464 }
 465
 466 TEST(WeakPtrTest, NonOwnerThreadCanCopyAndAssignWeakPtrBase) {
 467   // Main thread creates a Target object.
 468   Target target;
 469   // Main thread creates an arrow referencing the Target.
 470   Arrow *arrow = new Arrow();
 471   arrow->target = target.AsWeakPtr();
 472
 473   // Background can copy and assign arrow's WeakPtr to a base class WeakPtr.
 474   BackgroundThread background;
 475   background.Start();
 476   background.CopyAndAssignArrowBase(arrow);
 477   background.DeleteArrow(arrow);
 478 }
 479
 480 TEST(WeakPtrTest, NonOwnerThreadCanDeleteWeakPtr) {
 481   // Main thread creates a Target object.
 482   Target target;
 483   // Main thread creates an arrow referencing the Target.
 484   Arrow* arrow = new Arrow();
 485   arrow->target = target.AsWeakPtr();
 486
 487   // Background can delete arrow (as well as the WeakPtr inside).
 488   BackgroundThread background;
 489   background.Start();
 490   background.DeleteArrow(arrow);
 491 }
 492
 493 #if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)) && GTEST_HAS_DEATH_TEST
 494
 495 TEST(WeakPtrDeathTest, WeakPtrCopyDoesNotChangeThreadBinding) {
 496   // The default style "fast" does not support multi-threaded tests
 497   // (introduces deadlock on Linux).
 498   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 499
 500   BackgroundThread background;
 501   background.Start();
 502
 503   // Main thread creates a Target object.
 504   Target target;
 505   // Main thread creates an arrow referencing the Target.
 506   Arrow arrow;
 507   arrow.target = target.AsWeakPtr();
 508
 509   // Background copies the WeakPtr.
 510   Arrow* arrow_copy;
 511   background.CreateArrowFromArrow(&arrow_copy, &arrow);
 512
 513   // The copy is still bound to main thread so I can deref.
 514   EXPECT_EQ(arrow.target.get(), arrow_copy->target.get());
 515
 516   // Although background thread created the copy, it can not deref the copied
 517   // WeakPtr.
 518   ASSERT_DEATH(background.DeRef(arrow_copy), "");
 519
 520   background.DeleteArrow(arrow_copy);
 521 }
 522
 523 TEST(WeakPtrDeathTest, NonOwnerThreadDereferencesWeakPtrAfterReference) {
 524   // The default style "fast" does not support multi-threaded tests
 525   // (introduces deadlock on Linux).
 526   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 527
 528   // Main thread creates a Target object.
 529   Target target;
 530
 531   // Main thread creates an arrow referencing the Target (so target's
 532   // thread ownership can not be implicitly moved).
 533   Arrow arrow;
 534   arrow.target = target.AsWeakPtr();
 535   arrow.target.get();
 536
 537   // Background thread tries to deref target, which violates thread ownership.
 538   BackgroundThread background;
 539   background.Start();
 540   ASSERT_DEATH(background.DeRef(&arrow), "");
 541 }
 542
 543 TEST(WeakPtrDeathTest, NonOwnerThreadDeletesWeakPtrAfterReference) {
 544   // The default style "fast" does not support multi-threaded tests
 545   // (introduces deadlock on Linux).
 546   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 547
 548   scoped_ptr<Target> target(new Target());
 549
 550   // Main thread creates an arrow referencing the Target.
 551   Arrow arrow;
 552   arrow.target = target->AsWeakPtr();
 553
 554   // Background thread tries to deref target, binding it to the thread.
 555   BackgroundThread background;
 556   background.Start();
 557   background.DeRef(&arrow);
 558
 559   // Main thread deletes Target, violating thread binding.
 560   ASSERT_DEATH(target.reset(), "");
 561
 562   // |target.reset()| died so |target| still holds the object, so we
 563   // must pass it to the background thread to teardown.
 564   background.DeleteTarget(target.release());
 565 }
 566
 567 TEST(WeakPtrDeathTest, NonOwnerThreadDeletesObjectAfterReference) {
 568   // The default style "fast" does not support multi-threaded tests
 569   // (introduces deadlock on Linux).
 570   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 571
 572   scoped_ptr<Target> target(new Target());
 573
 574   // Main thread creates an arrow referencing the Target, and references it, so
 575   // that it becomes bound to the thread.
 576   Arrow arrow;
 577   arrow.target = target->AsWeakPtr();
 578   arrow.target.get();
 579
 580   // Background thread tries to delete target, volating thread binding.
 581   BackgroundThread background;
 582   background.Start();
 583   ASSERT_DEATH(background.DeleteTarget(target.release()), "");
 584 }
 585
 586 TEST(WeakPtrDeathTest, NonOwnerThreadReferencesObjectAfterDeletion) {
 587   // The default style "fast" does not support multi-threaded tests
 588   // (introduces deadlock on Linux).
 589   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 590
 591   scoped_ptr<Target> target(new Target());
 592
 593   // Main thread creates an arrow referencing the Target.
 594   Arrow arrow;
 595   arrow.target = target->AsWeakPtr();
 596
 597   // Background thread tries to delete target, binding the object to the thread.
 598   BackgroundThread background;
 599   background.Start();
 600   background.DeleteTarget(target.release());
 601
 602   // Main thread attempts to dereference the target, violating thread binding.
 603   ASSERT_DEATH(arrow.target.get(), "");
 604 }
 605
 606 #endif
 607
 608 }  // namespace base