/*
- * Copyright 2015 Facebook, Inc.
+ * 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.
template <typename T>
template <typename Tag, typename VaultTag>
SingletonHolder<T>& SingletonHolder<T>::singleton() {
- static auto entry = new SingletonHolder<T>(
- {typeid(T), typeid(Tag)},
- *SingletonVault::singleton<VaultTag>());
+ /* 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) {
- LOG(FATAL) << "Double registration of singleton: " << type_.name();
+ /* 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);
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();
+ detail::singletonWarnRegisterMockEarlyAndAbort(type());
+ }
+ 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);
+ }
}
- destroyInstance();
std::lock_guard<std::mutex> entry_lock(mutex_);
template <typename T>
T* SingletonHolder<T>::get() {
- if (LIKELY(state_ == SingletonHolderState::Living)) {
+ 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());
+ detail::singletonThrowGetInvokedAfterDestruction(type());
}
return instance_ptr_;
template <typename T>
std::weak_ptr<T> SingletonHolder<T>::get_weak() {
- if (UNLIKELY(state_ != SingletonHolderState::Living)) {
+ if (UNLIKELY(state_.load(std::memory_order_acquire) !=
+ SingletonHolderState::Living)) {
createInstance();
}
}
template <typename T>
-TypeDescriptor SingletonHolder<T>::type() {
- return type_;
+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>
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_) {
- auto wait_result = destroy_baton_->timed_wait(
- std::chrono::steady_clock::now() + kDestroyWaitTime);
- if (!wait_result) {
+ constexpr std::chrono::seconds kDestroyWaitTime{5};
+ auto last_reference_released =
+ destroy_baton_->try_wait_for(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. "
- << "Make sure dependencies between these singletons are "
- << "properly defined.";
+ detail::singletonWarnDestroyInstanceLeak(type(), instance_ptr_);
}
}
}
template <typename T>
-SingletonHolder<T>::SingletonHolder(TypeDescriptor type__,
- SingletonVault& vault) :
- type_(type__), vault_(vault) {
+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() {
- // There's no synchronization here, so we may not see the current value
- // for creating_thread if it was set by other thread, but we only care about
- // it if it was set by current thread anyways.
- if (creating_thread_ == std::this_thread::get_id()) {
- LOG(FATAL) << "circular singleton dependency: " << type_.name();
+ if (creating_thread_.load(std::memory_order_acquire) ==
+ std::this_thread::get_id()) {
+ detail::singletonWarnCreateCircularDependencyAndAbort(type());
}
std::lock_guard<std::mutex> entry_lock(mutex_);
- if (state_ == SingletonHolderState::Living) {
+ if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
return;
}
- if (state_ == 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::NotRegistered) {
+ detail::singletonWarnCreateUnregisteredAndAbort(type());
}
- if (state_ == SingletonHolderState::Living) {
+ if (state_.load(std::memory_order_acquire) == SingletonHolderState::Living) {
return;
}
// 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_ = std::thread::id();
+ creating_thread_.store(std::thread::id(), std::memory_order_release);
};
- creating_thread_ = std::this_thread::get_id();
+ creating_thread_.store(std::this_thread::get_id(), std::memory_order_release);
- RWSpinLock::ReadHolder rh(&vault_.stateMutex_);
- if (vault_.state_ == SingletonVault::SingletonVaultState::Quiescing) {
+ auto state = vault_.state_.rlock();
+ if (vault_.type_ != SingletonVault::Type::Relaxed &&
+ !state->registrationComplete) {
+ detail::singletonWarnCreateBeforeRegistrationCompleteAndAbort(type());
+ }
+ if (state->state == detail::SingletonVaultState::Type::Quiescing) {
return;
}
auto destroy_baton = std::make_shared<folly::Baton<>>();
auto print_destructor_stack_trace =
std::make_shared<std::atomic<bool>>(false);
- auto teardown = teardown_;
- auto type_name = type_.name();
// Can't use make_shared -- no support for a custom deleter, sadly.
- instance_ = std::shared_ptr<T>(
- create_(),
- [destroy_baton, print_destructor_stack_trace, teardown, type_name]
- (T* instance_ptr) mutable {
- teardown(instance_ptr);
- destroy_baton->post();
- if (print_destructor_stack_trace->load()) {
- std::string output = "Singleton " + type_name + " was destroyed.\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 destructor stack trace.";
- } else {
- output += "Destructor stack trace:\n";
- output += stack_trace;
+ 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()) {
+ detail::singletonPrintDestructionStackTrace(type);
}
-
- LOG(ERROR) << output;
- }
- });
+ });
// We should schedule destroyInstances() only after the singleton was
// created. This will ensure it will be destroyed before singletons,
// constructor
SingletonVault::scheduleDestroyInstances();
- instance_weak_ = instance_;
- instance_ptr_ = instance_.get();
+ 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);
+ state_.store(SingletonHolderState::Living, std::memory_order_release);
- {
- RWSpinLock::WriteHolder wh(&vault_.mutex_);
- vault_.creation_order_.push_back(type_);
- }
+ vault_.creationOrder_.wlock()->push_back(type());
}
-}
+} // namespace detail
-}
+} // namespace folly
projects / folly.git / blobdiff