src/base/singleton_test.cc

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#include <stdlib.h>
#include "base/singleton.h"
#include "base/thread.h"
#include "base/util.h"
#include "testing/base/public/gunit.h"

namespace mozc {
namespace {

static int g_counter = 0;

class TestInstance {
 public:
  TestInstance() {
    ++g_counter;
  }
};

class ThreadInstance {
 public:
  ThreadInstance() {
    // Wait two secs to test the singleton
    // can safely block the initialization procedure.
    Util::Sleep(2000);   // wait 2sec
    ++g_counter;
  }
};

class ThreadTest : public Thread {
 public:
  void Run() {
    instance_ = Singleton<ThreadInstance>::get();
  }

  ThreadInstance *get() {
    return instance_;
  }

  ThreadTest() : instance_(NULL) {}

 private:
  ThreadInstance *instance_;
};
}  // namespace

// Cannot have a testcase for Singleton::SingletonFinalizer,
// since it affects other tests using Singleton objects.
TEST(SingletonTest, BasicTest) {
  g_counter = 0;
  TestInstance *t1 = Singleton<TestInstance>::get();
  TestInstance *t2 = Singleton<TestInstance>::get();
  TestInstance *t3 = Singleton<TestInstance>::get();
  EXPECT_EQ(t1, t2);
  EXPECT_EQ(t2, t3);
  EXPECT_EQ(1, g_counter);
}

TEST(SingletonTest, ThreadTest) {
  // call Singelton::get() at the same time from
  // different threds. Make sure that get() returns
  // the same instance

  g_counter = 0;

  ThreadTest test1;
  ThreadTest test2;
  ThreadTest test3;

  // Create the ThreadInstance simultaneously.
  test1.Start();
  test2.Start();
  test3.Start();

  test1.Join();
  test2.Join();
  test3.Join();

  EXPECT_EQ(1, g_counter);

  // three instances must be the same.
  EXPECT_EQ(test1.get(), test2.get());
  EXPECT_EQ(test2.get(), test3.get());
}
}  // namespace mozc