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