2 * Copyright 2014 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/experimental/Singleton.h>
25 constexpr std::chrono::seconds SingletonHolderBase::kDestroyWaitTime;
29 SingletonVault::~SingletonVault() { destroyInstances(); }
31 void SingletonVault::destroyInstances() {
32 RWSpinLock::WriteHolder state_wh(&stateMutex_);
34 if (state_ == SingletonVaultState::Quiescing) {
37 state_ = SingletonVaultState::Quiescing;
39 RWSpinLock::ReadHolder state_rh(std::move(state_wh));
42 RWSpinLock::ReadHolder rh(&mutex_);
44 CHECK_GE(singletons_.size(), creation_order_.size());
46 for (auto type_iter = creation_order_.rbegin();
47 type_iter != creation_order_.rend();
49 singletons_[*type_iter]->destroyInstance();
52 for (auto& singleton_type: creation_order_) {
53 auto singleton = singletons_[singleton_type];
54 if (!singleton->hasLiveInstance()) {
58 LOG(DFATAL) << "Singleton of type " << singleton->type().name() << " has "
59 << "a living reference after destroyInstances was finished;"
60 << "beware! It is very likely that this singleton instance "
66 RWSpinLock::WriteHolder wh(&mutex_);
67 creation_order_.clear();
71 void SingletonVault::reenableInstances() {
72 RWSpinLock::WriteHolder state_wh(&stateMutex_);
74 stateCheck(SingletonVaultState::Quiescing);
76 state_ = SingletonVaultState::Running;
79 void SingletonVault::scheduleDestroyInstances() {
80 RequestContext::getStaticContext();
82 class SingletonVaultDestructor {
84 ~SingletonVaultDestructor() {
85 SingletonVault::singleton()->destroyInstances();
89 // Here we intialize a singleton, which calls destroyInstances in its
90 // destructor. Because of singleton destruction order - it will be destroyed
91 // before all the singletons, which were initialized before it and after all
92 // the singletons initialized after it.
93 static SingletonVaultDestructor singletonVaultDestructor;