PerformanceTests/StitchMarker/folly/folly/Singleton-inl.h - WebKit - Git at Google

 /*
  * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 namespace folly {

 namespace detail {

 template <typename T>
 template <typename Tag, typename VaultTag>
 SingletonHolder<T>& SingletonHolder<T>::singleton() {
   /* library-local */ static auto entry =
       createGlobal<SingletonHolder<T>, std::pair<Tag, VaultTag>>([]() {
         return new SingletonHolder<T>({typeid(T), typeid(Tag)},
                                       *SingletonVault::singleton<VaultTag>());
       });
   return *entry;
 }

 [[noreturn]] void singletonWarnDoubleRegistrationAndAbort(
     const TypeDescriptor& type);

 template <typename T>
 void SingletonHolder<T>::registerSingleton(CreateFunc c, TeardownFunc t) {
   std::lock_guard<std::mutex> entry_lock(mutex_);

   if (state_ != SingletonHolderState::NotRegistered) {
     /* Possible causes:
      *
      * You have two instances of the same
      * folly::Singleton<Class>. Probably because you define the
      * singleton in a header included in multiple places? In general,
      * folly::Singleton shouldn't be in the header, only off in some
      * anonymous namespace in a cpp file. Code needing the singleton
      * will find it when that code references folly::Singleton<Class>.
      *
      * Alternatively, you could have 2 singletons with the same type
      * defined with a different name in a .cpp (source) file. For
      * example:
      *
      * Singleton<int> a([] { return new int(3); });
      * Singleton<int> b([] { return new int(4); });
      *
      */
     singletonWarnDoubleRegistrationAndAbort(type());
   }

   create_ = std::move(c);
   teardown_ = std::move(t);

   state_ = SingletonHolderState::Dead;
 }

 template <typename T>
 void SingletonHolder<T>::registerSingletonMock(CreateFunc c, TeardownFunc t) {
   if (state_ == SingletonHolderState::NotRegistered) {
     LOG(FATAL) << "Registering mock before singleton was registered: "
                << type().name();
   }
   if (state_ == SingletonHolderState::Living) {
     destroyInstance();
   }

   {
     auto creationOrder = vault_.creationOrder_.wlock();

     auto it = std::find(creationOrder->begin(), creationOrder->end(), type());
     if (it != creationOrder->end()) {
       creationOrder->erase(it);
     }
   }

   std::lock_guard<std::mutex> entry_lock(mutex_);

   create_ = std::move(c);
   teardown_ = std::move(t);
 }

 template <typename T>
 T* SingletonHolder<T>::get() {
   if (LIKELY(state_.load(std::memory_order_acquire) ==
              SingletonHolderState::Living)) {
     return instance_ptr_;
   }
   createInstance();

   if (instance_weak_.expired()) {
     throw std::runtime_error(
         "Raw pointer to a singleton requested after its destruction."
         " Singleton type is: " +
         type().name());
   }

   return instance_ptr_;
 }

 template <typename T>
 std::weak_ptr<T> SingletonHolder<T>::get_weak() {
   if (UNLIKELY(state_.load(std::memory_order_acquire) !=
                SingletonHolderState::Living)) {
     createInstance();
   }

   return instance_weak_;
 }

 template <typename T>
 std::shared_ptr<T> SingletonHolder<T>::try_get() {
   if (UNLIKELY(state_.load(std::memory_order_acquire) !=
                SingletonHolderState::Living)) {
     createInstance();
   }

   return instance_weak_.lock();
 }

 template <typename T>
 folly::ReadMostlySharedPtr<T> SingletonHolder<T>::try_get_fast() {
   if (UNLIKELY(state_.load(std::memory_order_acquire) !=
                SingletonHolderState::Living)) {
     createInstance();
   }

   return instance_weak_fast_.lock();
 }

 template <typename T>
 bool SingletonHolder<T>::hasLiveInstance() {
   return !instance_weak_.expired();
 }

 template <typename T>
 void SingletonHolder<T>::preDestroyInstance(
     ReadMostlyMainPtrDeleter<>& deleter) {
   instance_copy_ = instance_;
   deleter.add(std::move(instance_));
 }

 template <typename T>
 void SingletonHolder<T>::destroyInstance() {
   state_ = SingletonHolderState::Dead;
   instance_.reset();
   instance_copy_.reset();
   if (destroy_baton_) {
     constexpr std::chrono::seconds kDestroyWaitTime{5};
     auto last_reference_released = destroy_baton_->timed_wait(
         std::chrono::steady_clock::now() + kDestroyWaitTime);
     if (last_reference_released) {
       teardown_(instance_ptr_);
     } else {
       print_destructor_stack_trace_->store(true);
       LOG(ERROR) << "Singleton of type " << type().name() << " has a "
                  << "living reference at destroyInstances time; beware! Raw "
                  << "pointer is " << instance_ptr_ << ". It is very likely "
                  << "that some other singleton is holding a shared_ptr to it. "
                  << "This singleton will be leaked (even if a shared_ptr to it "
                  << "is eventually released)."
                  << "Make sure dependencies between these singletons are "
                  << "properly defined.";
     }
   }
 }

 template <typename T>
 SingletonHolder<T>::SingletonHolder(
     TypeDescriptor typeDesc,
     SingletonVault& vault)
     : SingletonHolderBase(typeDesc), vault_(vault) {}

 template <typename T>
 bool SingletonHolder<T>::creationStarted() {
   // If alive, then creation was of course started.
   // This is flipped after creating_thread_ was set, and before it was reset.
   if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
     return true;
   }

   // Not yet built.  Is it currently in progress?
   if (creating_thread_.load(std::memory_order_acquire) != std::thread::id()) {
     return true;
   }

   return false;
 }

 template <typename T>
 void SingletonHolder<T>::createInstance() {
   if (creating_thread_.load(std::memory_order_acquire) ==
         std::this_thread::get_id()) {
     LOG(FATAL) << "circular singleton dependency: " << type().name();
   }

   std::lock_guard<std::mutex> entry_lock(mutex_);
   if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
     return;
   }
   if (state_.load(std::memory_order_acquire) ==
         SingletonHolderState::NotRegistered) {
     auto ptr = SingletonVault::stackTraceGetter().load();
     LOG(FATAL) << "Creating instance for unregistered singleton: "
                << type().name() << "\n"
                << "Stacktrace:"
                << "\n"
                << (ptr ? (*ptr)() : "(not available)");
   }

   if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
     return;
   }

   SCOPE_EXIT {
     // Clean up creator thread when complete, and also, in case of errors here,
     // so that subsequent attempts don't think this is still in the process of
     // being built.
     creating_thread_.store(std::thread::id(), std::memory_order_release);
   };

   creating_thread_.store(std::this_thread::get_id(), std::memory_order_release);

   auto state = vault_.state_.rlock();
   if (vault_.type_ != SingletonVault::Type::Relaxed &&
       !state->registrationComplete) {
     auto stack_trace_getter = SingletonVault::stackTraceGetter().load();
     auto stack_trace = stack_trace_getter ? stack_trace_getter() : "";
     if (!stack_trace.empty()) {
       stack_trace = "Stack trace:\n" + stack_trace;
     }

     LOG(FATAL) << "Singleton " << type().name() << " requested before "
                << "registrationComplete() call.\n"
                << "This usually means that either main() never called "
                << "folly::init, or singleton was requested before main() "
                << "(which is not allowed).\n"
                << stack_trace;
   }
   if (state->state == SingletonVault::SingletonVaultState::Quiescing) {
     return;
   }

   auto destroy_baton = std::make_shared<folly::Baton<>>();
   auto print_destructor_stack_trace =
     std::make_shared<std::atomic<bool>>(false);

   // Can't use make_shared -- no support for a custom deleter, sadly.
   std::shared_ptr<T> instance(
       create_(),
       [ destroy_baton, print_destructor_stack_trace, type = type() ](
           T*) mutable {
         destroy_baton->post();
         if (print_destructor_stack_trace->load()) {
           std::string output = "Singleton " + type.name() + " was released.\n";

           auto stack_trace_getter = SingletonVault::stackTraceGetter().load();
           auto stack_trace = stack_trace_getter ? stack_trace_getter() : "";
           if (stack_trace.empty()) {
             output += "Failed to get release stack trace.";
           } else {
             output += "Release stack trace:\n";
             output += stack_trace;
           }

           LOG(ERROR) << output;
         }
       });

   // We should schedule destroyInstances() only after the singleton was
   // created. This will ensure it will be destroyed before singletons,
   // not managed by folly::Singleton, which were initialized in its
   // constructor
   SingletonVault::scheduleDestroyInstances();

   instance_weak_ = instance;
   instance_ptr_ = instance.get();
   instance_.reset(std::move(instance));
   instance_weak_fast_ = instance_;

   destroy_baton_ = std::move(destroy_baton);
   print_destructor_stack_trace_ = std::move(print_destructor_stack_trace);

   // This has to be the last step, because once state is Living other threads
   // may access instance and instance_weak w/o synchronization.
   state_.store(SingletonHolderState::Living, std::memory_order_release);

   vault_.creationOrder_.wlock()->push_back(type());
 }

 }

 }
	/*
	* Copyright 2017 Facebook, Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	namespace folly {

	namespace detail {

	template <typename T>
	template <typename Tag, typename VaultTag>
	SingletonHolder<T>& SingletonHolder<T>::singleton() {
	/* library-local */ static auto entry =
	createGlobal<SingletonHolder<T>, std::pair<Tag, VaultTag>>([]() {
	return new SingletonHolder<T>({typeid(T), typeid(Tag)},
	*SingletonVault::singleton<VaultTag>());
	});
	return *entry;
	}

	[[noreturn]] void singletonWarnDoubleRegistrationAndAbort(
	const TypeDescriptor& type);

	template <typename T>
	void SingletonHolder<T>::registerSingleton(CreateFunc c, TeardownFunc t) {
	std::lock_guard<std::mutex> entry_lock(mutex_);

	if (state_ != SingletonHolderState::NotRegistered) {
	/* Possible causes:
	*
	* You have two instances of the same
	* folly::Singleton<Class>. Probably because you define the
	* singleton in a header included in multiple places? In general,
	* folly::Singleton shouldn't be in the header, only off in some
	* anonymous namespace in a cpp file. Code needing the singleton
	* will find it when that code references folly::Singleton<Class>.
	*
	* Alternatively, you could have 2 singletons with the same type
	* defined with a different name in a .cpp (source) file. For
	* example:
	*
	* Singleton<int> a([] { return new int(3); });
	* Singleton<int> b([] { return new int(4); });
	*
	*/
	singletonWarnDoubleRegistrationAndAbort(type());
	}

	create_ = std::move(c);
	teardown_ = std::move(t);

	state_ = SingletonHolderState::Dead;
	}

	template <typename T>
	void SingletonHolder<T>::registerSingletonMock(CreateFunc c, TeardownFunc t) {
	if (state_ == SingletonHolderState::NotRegistered) {
	LOG(FATAL) << "Registering mock before singleton was registered: "
	<< type().name();
	}
	if (state_ == SingletonHolderState::Living) {
	destroyInstance();
	}

	{
	auto creationOrder = vault_.creationOrder_.wlock();

	auto it = std::find(creationOrder->begin(), creationOrder->end(), type());
	if (it != creationOrder->end()) {
	creationOrder->erase(it);
	}
	}

	std::lock_guard<std::mutex> entry_lock(mutex_);

	create_ = std::move(c);
	teardown_ = std::move(t);
	}

	template <typename T>
	T* SingletonHolder<T>::get() {
	if (LIKELY(state_.load(std::memory_order_acquire) ==
	SingletonHolderState::Living)) {
	return instance_ptr_;
	}
	createInstance();

	if (instance_weak_.expired()) {
	throw std::runtime_error(
	"Raw pointer to a singleton requested after its destruction."
	" Singleton type is: " +
	type().name());
	}

	return instance_ptr_;
	}

	template <typename T>
	std::weak_ptr<T> SingletonHolder<T>::get_weak() {
	if (UNLIKELY(state_.load(std::memory_order_acquire) !=
	SingletonHolderState::Living)) {
	createInstance();
	}

	return instance_weak_;
	}

	template <typename T>
	std::shared_ptr<T> SingletonHolder<T>::try_get() {
	if (UNLIKELY(state_.load(std::memory_order_acquire) !=
	SingletonHolderState::Living)) {
	createInstance();
	}

	return instance_weak_.lock();
	}

	template <typename T>
	folly::ReadMostlySharedPtr<T> SingletonHolder<T>::try_get_fast() {
	if (UNLIKELY(state_.load(std::memory_order_acquire) !=
	SingletonHolderState::Living)) {
	createInstance();
	}

	return instance_weak_fast_.lock();
	}

	template <typename T>
	bool SingletonHolder<T>::hasLiveInstance() {
	return !instance_weak_.expired();
	}

	template <typename T>
	void SingletonHolder<T>::preDestroyInstance(
	ReadMostlyMainPtrDeleter<>& deleter) {
	instance_copy_ = instance_;
	deleter.add(std::move(instance_));
	}

	template <typename T>
	void SingletonHolder<T>::destroyInstance() {
	state_ = SingletonHolderState::Dead;
	instance_.reset();
	instance_copy_.reset();
	if (destroy_baton_) {
	constexpr std::chrono::seconds kDestroyWaitTime{5};
	auto last_reference_released = destroy_baton_->timed_wait(
	std::chrono::steady_clock::now() + kDestroyWaitTime);
	if (last_reference_released) {
	teardown_(instance_ptr_);
	} else {
	print_destructor_stack_trace_->store(true);
	LOG(ERROR) << "Singleton of type " << type().name() << " has a "
	<< "living reference at destroyInstances time; beware! Raw "
	<< "pointer is " << instance_ptr_ << ". It is very likely "
	<< "that some other singleton is holding a shared_ptr to it. "
	<< "This singleton will be leaked (even if a shared_ptr to it "
	<< "is eventually released)."
	<< "Make sure dependencies between these singletons are "
	<< "properly defined.";
	}
	}
	}

	template <typename T>
	SingletonHolder<T>::SingletonHolder(
	TypeDescriptor typeDesc,
	SingletonVault& vault)
	: SingletonHolderBase(typeDesc), vault_(vault) {}

	template <typename T>
	bool SingletonHolder<T>::creationStarted() {
	// If alive, then creation was of course started.
	// This is flipped after creating_thread_ was set, and before it was reset.
	if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
	return true;
	}

	// Not yet built. Is it currently in progress?
	if (creating_thread_.load(std::memory_order_acquire) != std::thread::id()) {
	return true;
	}

	return false;
	}

	template <typename T>
	void SingletonHolder<T>::createInstance() {
	if (creating_thread_.load(std::memory_order_acquire) ==
	std::this_thread::get_id()) {
	LOG(FATAL) << "circular singleton dependency: " << type().name();
	}

	std::lock_guard<std::mutex> entry_lock(mutex_);
	if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
	return;
	}
	if (state_.load(std::memory_order_acquire) ==
	SingletonHolderState::NotRegistered) {
	auto ptr = SingletonVault::stackTraceGetter().load();
	LOG(FATAL) << "Creating instance for unregistered singleton: "
	<< type().name() << "\n"
	<< "Stacktrace:"
	<< "\n"
	<< (ptr ? (*ptr)() : "(not available)");
	}

	if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
	return;
	}

	SCOPE_EXIT {
	// Clean up creator thread when complete, and also, in case of errors here,
	// so that subsequent attempts don't think this is still in the process of
	// being built.
	creating_thread_.store(std::thread::id(), std::memory_order_release);
	};

	creating_thread_.store(std::this_thread::get_id(), std::memory_order_release);

	auto state = vault_.state_.rlock();
	if (vault_.type_ != SingletonVault::Type::Relaxed &&
	!state->registrationComplete) {
	auto stack_trace_getter = SingletonVault::stackTraceGetter().load();
	auto stack_trace = stack_trace_getter ? stack_trace_getter() : "";
	if (!stack_trace.empty()) {
	stack_trace = "Stack trace:\n" + stack_trace;
	}

	LOG(FATAL) << "Singleton " << type().name() << " requested before "
	<< "registrationComplete() call.\n"
	<< "This usually means that either main() never called "
	<< "folly::init, or singleton was requested before main() "
	<< "(which is not allowed).\n"
	<< stack_trace;
	}
	if (state->state == SingletonVault::SingletonVaultState::Quiescing) {
	return;
	}

	auto destroy_baton = std::make_shared<folly::Baton<>>();
	auto print_destructor_stack_trace =
	std::make_shared<std::atomic<bool>>(false);

	// Can't use make_shared -- no support for a custom deleter, sadly.
	std::shared_ptr<T> instance(
	create_(),
	[ destroy_baton, print_destructor_stack_trace, type = type() ](
	T*) mutable {
	destroy_baton->post();
	if (print_destructor_stack_trace->load()) {
	std::string output = "Singleton " + type.name() + " was released.\n";

	auto stack_trace_getter = SingletonVault::stackTraceGetter().load();
	auto stack_trace = stack_trace_getter ? stack_trace_getter() : "";
	if (stack_trace.empty()) {
	output += "Failed to get release stack trace.";
	} else {
	output += "Release stack trace:\n";
	output += stack_trace;
	}

	LOG(ERROR) << output;
	}
	});

	// We should schedule destroyInstances() only after the singleton was
	// created. This will ensure it will be destroyed before singletons,
	// not managed by folly::Singleton, which were initialized in its
	// constructor
	SingletonVault::scheduleDestroyInstances();

	instance_weak_ = instance;
	instance_ptr_ = instance.get();
	instance_.reset(std::move(instance));
	instance_weak_fast_ = instance_;

	destroy_baton_ = std::move(destroy_baton);
	print_destructor_stack_trace_ = std::move(print_destructor_stack_trace);

	// This has to be the last step, because once state is Living other threads
	// may access instance and instance_weak w/o synchronization.
	state_.store(SingletonHolderState::Living, std::memory_order_release);

	vault_.creationOrder_.wlock()->push_back(type());
	}

	}

	}