base/lazy_instance_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/at_exit.h"
   6 #include "base/atomic_sequence_num.h"
   7 #include "base/lazy_instance.h"
   8 #include "base/memory/aligned_memory.h"
   9 #include "base/threading/simple_thread.h"
  10 #include "testing/gtest/include/gtest/gtest.h"
  11
  12 namespace {
  13
  14 base::StaticAtomicSequenceNumber constructed_seq_;
  15 base::StaticAtomicSequenceNumber destructed_seq_;
  16
  17 class ConstructAndDestructLogger {
  18  public:
  19   ConstructAndDestructLogger() {
  20     constructed_seq_.GetNext();
  21   }
  22   ~ConstructAndDestructLogger() {
  23     destructed_seq_.GetNext();
  24   }
  25 };
  26
  27 class SlowConstructor {
  28  public:
  29   SlowConstructor() : some_int_(0) {
  30     // Sleep for 1 second to try to cause a race.
  31     base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(1));
  32     ++constructed;
  33     some_int_ = 12;
  34   }
  35   int some_int() const { return some_int_; }
  36
  37   static int constructed;
  38  private:
  39   int some_int_;
  40 };
  41
  42 int SlowConstructor::constructed = 0;
  43
  44 class SlowDelegate : public base::DelegateSimpleThread::Delegate {
  45  public:
  46   explicit SlowDelegate(base::LazyInstance<SlowConstructor>* lazy)
  47       : lazy_(lazy) {}
  48
  49   virtual void Run() override {
  50     EXPECT_EQ(12, lazy_->Get().some_int());
  51     EXPECT_EQ(12, lazy_->Pointer()->some_int());
  52   }
  53
  54  private:
  55   base::LazyInstance<SlowConstructor>* lazy_;
  56 };
  57
  58 }  // namespace
  59
  60 static base::LazyInstance<ConstructAndDestructLogger> lazy_logger =
  61     LAZY_INSTANCE_INITIALIZER;
  62
  63 TEST(LazyInstanceTest, Basic) {
  64   {
  65     base::ShadowingAtExitManager shadow;
  66
  67     EXPECT_EQ(0, constructed_seq_.GetNext());
  68     EXPECT_EQ(0, destructed_seq_.GetNext());
  69
  70     lazy_logger.Get();
  71     EXPECT_EQ(2, constructed_seq_.GetNext());
  72     EXPECT_EQ(1, destructed_seq_.GetNext());
  73
  74     lazy_logger.Pointer();
  75     EXPECT_EQ(3, constructed_seq_.GetNext());
  76     EXPECT_EQ(2, destructed_seq_.GetNext());
  77   }
  78   EXPECT_EQ(4, constructed_seq_.GetNext());
  79   EXPECT_EQ(4, destructed_seq_.GetNext());
  80 }
  81
  82 static base::LazyInstance<SlowConstructor> lazy_slow =
  83     LAZY_INSTANCE_INITIALIZER;
  84
  85 TEST(LazyInstanceTest, ConstructorThreadSafety) {
  86   {
  87     base::ShadowingAtExitManager shadow;
  88
  89     SlowDelegate delegate(&lazy_slow);
  90     EXPECT_EQ(0, SlowConstructor::constructed);
  91
  92     base::DelegateSimpleThreadPool pool("lazy_instance_cons", 5);
  93     pool.AddWork(&delegate, 20);
  94     EXPECT_EQ(0, SlowConstructor::constructed);
  95
  96     pool.Start();
  97     pool.JoinAll();
  98     EXPECT_EQ(1, SlowConstructor::constructed);
  99   }
 100 }
 101
 102 namespace {
 103
 104 // DeleteLogger is an object which sets a flag when it's destroyed.
 105 // It accepts a bool* and sets the bool to true when the dtor runs.
 106 class DeleteLogger {
 107  public:
 108   DeleteLogger() : deleted_(NULL) {}
 109   ~DeleteLogger() { *deleted_ = true; }
 110
 111   void SetDeletedPtr(bool* deleted) {
 112     deleted_ = deleted;
 113   }
 114
 115  private:
 116   bool* deleted_;
 117 };
 118
 119 }  // anonymous namespace
 120
 121 TEST(LazyInstanceTest, LeakyLazyInstance) {
 122   // Check that using a plain LazyInstance causes the dtor to run
 123   // when the AtExitManager finishes.
 124   bool deleted1 = false;
 125   {
 126     base::ShadowingAtExitManager shadow;
 127     static base::LazyInstance<DeleteLogger> test = LAZY_INSTANCE_INITIALIZER;
 128     test.Get().SetDeletedPtr(&deleted1);
 129   }
 130   EXPECT_TRUE(deleted1);
 131
 132   // Check that using a *leaky* LazyInstance makes the dtor not run
 133   // when the AtExitManager finishes.
 134   bool deleted2 = false;
 135   {
 136     base::ShadowingAtExitManager shadow;
 137     static base::LazyInstance<DeleteLogger>::Leaky
 138         test = LAZY_INSTANCE_INITIALIZER;
 139     test.Get().SetDeletedPtr(&deleted2);
 140   }
 141   EXPECT_FALSE(deleted2);
 142 }
 143
 144 namespace {
 145
 146 template <size_t alignment>
 147 class AlignedData {
 148  public:
 149   AlignedData() {}
 150   ~AlignedData() {}
 151   base::AlignedMemory<alignment, alignment> data_;
 152 };
 153
 154 }  // anonymous namespace
 155
 156 #define EXPECT_ALIGNED(ptr, align) \
 157     EXPECT_EQ(0u, reinterpret_cast<uintptr_t>(ptr) & (align - 1))
 158
 159 TEST(LazyInstanceTest, Alignment) {
 160   using base::LazyInstance;
 161
 162   // Create some static instances with increasing sizes and alignment
 163   // requirements. By ordering this way, the linker will need to do some work to
 164   // ensure proper alignment of the static data.
 165   static LazyInstance<AlignedData<4> > align4 = LAZY_INSTANCE_INITIALIZER;
 166   static LazyInstance<AlignedData<32> > align32 = LAZY_INSTANCE_INITIALIZER;
 167   static LazyInstance<AlignedData<4096> > align4096 = LAZY_INSTANCE_INITIALIZER;
 168
 169   EXPECT_ALIGNED(align4.Pointer(), 4);
 170   EXPECT_ALIGNED(align32.Pointer(), 32);
 171   EXPECT_ALIGNED(align4096.Pointer(), 4096);
 172 }