Nomenclature in Synchronized - prefer read to shared

[folly.git] / folly / Singleton.h

diff --git a/folly/Singleton.h b/folly/Singleton.h
index c5fe79db274c0d15ebcbebf3a7efea282229e2ff..0539e28055e294a05bbd18d167a69cbe071e5dc3 100644 (file)
--- a/folly/Singleton.h
+++ b/folly/Singleton.h
@@ -218,16 +218,20 @@ class TypeDescriptorHasher {
 // SingletonHolders.
 class SingletonHolderBase {
  public:
+  explicit SingletonHolderBase(TypeDescriptor typeDesc) : type_(typeDesc) {}
   virtual ~SingletonHolderBase() = default;
 
-  virtual TypeDescriptor type() = 0;
+  TypeDescriptor type() const {
+    return type_;
+  }
   virtual bool hasLiveInstance() = 0;
   virtual void createInstance() = 0;
   virtual bool creationStarted() = 0;
+  virtual void preDestroyInstance(ReadMostlyMainPtrDeleter<>&) = 0;
   virtual void destroyInstance() = 0;
 
- protected:
-  static constexpr std::chrono::seconds kDestroyWaitTime{5};
+ private:
+  TypeDescriptor type_;
 };
 
 // An actual instance of a singleton, tracking the instance itself,
@@ -249,10 +253,10 @@ struct SingletonHolder : public SingletonHolderBase {
 
   void registerSingleton(CreateFunc c, TeardownFunc t);
   void registerSingletonMock(CreateFunc c, TeardownFunc t);
-  virtual TypeDescriptor type() override;
   virtual bool hasLiveInstance() override;
   virtual void createInstance() override;
   virtual bool creationStarted() override;
+  virtual void preDestroyInstance(ReadMostlyMainPtrDeleter<>&) override;
   virtual void destroyInstance() override;
 
  private:
@@ -264,7 +268,6 @@ struct SingletonHolder : public SingletonHolderBase {
     Living,
   };
 
-  TypeDescriptor type_;
   SingletonVault& vault_;
 
   // mutex protects the entire entry during construction/destruction
@@ -282,6 +285,8 @@ struct SingletonHolder : public SingletonHolderBase {
   // holds a ReadMostlyMainPtr to singleton instance, set when state is changed
   // from Dead to Living. Reset when state is changed from Living to Dead.
   folly::ReadMostlyMainPtr<T> instance_;
+  // used to release all ReadMostlyMainPtrs at once
+  folly::ReadMostlySharedPtr<T> instance_copy_;
   // weak_ptr to the singleton instance, set when state is changed from Dead
   // to Living. We never write to this object after initialization, so it is
   // safe to read it from different threads w/o synchronization if we know
@@ -443,6 +448,10 @@ class SingletonVault {
     return *stackTraceGetterPtr;
   }
 
+  void setType(Type type) {
+    type_ = type;
+  }
+
  private:
   template <typename T>
   friend struct detail::SingletonHolder;