// Exercise some basic codepaths ensuring registration order and
// destruction order happen as expected, that instances are created
// when expected, etc etc.
TEST(Singleton, BasicUsage) {
SingletonVault vault;
EXPECT_EQ(vault.registeredSingletonCount(), 0);
Singleton<Watchdog> watchdog_singleton(nullptr, nullptr, &vault);
EXPECT_EQ(vault.registeredSingletonCount(), 1);
Singleton<ChildWatchdog> child_watchdog_singleton(nullptr, nullptr, &vault);
EXPECT_EQ(vault.registeredSingletonCount(), 2);
vault.registrationComplete();
Watchdog* s1 = Singleton<Watchdog>::get(&vault);
EXPECT_NE(s1, nullptr);
Watchdog* s2 = Singleton<Watchdog>::get(&vault);
EXPECT_NE(s2, nullptr);
EXPECT_EQ(s1, s2);
auto s3 = Singleton<ChildWatchdog>::get(&vault);
EXPECT_NE(s3, nullptr);
EXPECT_NE(s2, s3);
EXPECT_EQ(vault.registeredSingletonCount(), 2);
EXPECT_EQ(vault.livingSingletonCount(), 2);
vault.destroyInstances();
EXPECT_EQ(vault.registeredSingletonCount(), 2);
EXPECT_EQ(vault.livingSingletonCount(), 0);
}
TEST(Singleton, SingletonConcurrency) {
SingletonVault vault;
Singleton<Slowpoke> slowpoke_singleton(nullptr, nullptr, &vault);
vault.registrationComplete();
std::mutex gatekeeper;
gatekeeper.lock();
auto func = [&vault, &gatekeeper]() {
gatekeeper.lock();
gatekeeper.unlock();
auto unused = Singleton<Slowpoke>::get(&vault);
};
EXPECT_EQ(vault.livingSingletonCount(), 0);
std::vector<std::thread> threads;
for (int i = 0; i < 100; ++i) {
threads.emplace_back(func);
}
// If circular dependency checks fail, the unlock would trigger a
// crash. Instead, it succeeds, and we have exactly one living
// singleton.
gatekeeper.unlock();
for (auto& t : threads) {
t.join();
}
EXPECT_EQ(vault.livingSingletonCount(), 1);
}
TEST(Singleton, SingletonDependencies) {
Singleton<NeededSingleton> needed_singleton(nullptr, nullptr, &needy_vault);
Singleton<NeedySingleton> needy_singleton(nullptr, nullptr, &needy_vault);
needy_vault.registrationComplete();
EXPECT_EQ(needy_vault.registeredSingletonCount(), 2);
EXPECT_EQ(needy_vault.livingSingletonCount(), 0);
auto needy = Singleton<NeedySingleton>::get(&needy_vault);
EXPECT_EQ(needy_vault.livingSingletonCount(), 2);
Singleton<SelfNeedySingleton> self_needy_singleton(
nullptr, nullptr, &self_needy_vault);
self_needy_vault.registrationComplete();
EXPECT_THROW([]() {
Singleton<SelfNeedySingleton>::get(&self_needy_vault);
}(),
std::out_of_range);
}
TEST(Singleton, SharedPtrUsage) {
SingletonVault vault;
EXPECT_EQ(vault.registeredSingletonCount(), 0);
Singleton<Watchdog> watchdog_singleton(nullptr, nullptr, &vault);
EXPECT_EQ(vault.registeredSingletonCount(), 1);
Singleton<ChildWatchdog> child_watchdog_singleton(nullptr, nullptr, &vault);
EXPECT_EQ(vault.registeredSingletonCount(), 2);
vault.registrationComplete();
Watchdog* s1 = Singleton<Watchdog>::get(&vault);
EXPECT_NE(s1, nullptr);
Watchdog* s2 = Singleton<Watchdog>::get(&vault);
EXPECT_NE(s2, nullptr);
EXPECT_EQ(s1, s2);
auto weak_s1 = Singleton<Watchdog>::get_weak(&vault);
auto shared_s1 = weak_s1.lock();
EXPECT_EQ(shared_s1.get(), s1);
EXPECT_EQ(shared_s1.use_count(), 2);
LOG(ERROR) << "The following log message regarding ref counts is expected";
vault.destroyInstances();
EXPECT_EQ(vault.registeredSingletonCount(), 2);
EXPECT_EQ(vault.livingSingletonCount(), 0);
EXPECT_EQ(shared_s1.use_count(), 1);
EXPECT_EQ(shared_s1.get(), s1);
auto locked_s1 = weak_s1.lock();
EXPECT_EQ(locked_s1.get(), s1);
EXPECT_EQ(shared_s1.use_count(), 2);
locked_s1.reset();
EXPECT_EQ(shared_s1.use_count(), 1);
// Track serial number rather than pointer since the memory could be
// re-used when we create new_s1.
auto old_serial = shared_s1->serial_number;
shared_s1.reset();
locked_s1 = weak_s1.lock();
EXPECT_TRUE(weak_s1.expired());
Watchdog* new_s1 = Singleton<Watchdog>::get(&vault);
EXPECT_NE(new_s1->serial_number, old_serial);
}
