Allow intrusive_ptr<const T> for objects

This allows using ref-counted pointers to const objects. Adds a second typedef
so that T::ConstPtr can be used similar to how T::Ptr currently is.

Author: julianbrost

lib/base/object.cpp

@@ -201,14 +201,14 @@ Value icinga::GetPrototypeField(const Value& context, const String& field, bool
 }
 
 #ifdef I2_LEAK_DEBUG
-void icinga::TypeAddObject(Object *object)
+void icinga::TypeAddObject(const Object *object)
 {
 	std::unique_lock<std::mutex> lock(l_ObjectCountLock);
 	String typeName = Utility::GetTypeName(typeid(*object));
 	l_ObjectCounts[typeName]++;
 }
 
-void icinga::TypeRemoveObject(Object *object)
+void icinga::TypeRemoveObject(const Object *object)
 {
 	std::unique_lock<std::mutex> lock(l_ObjectCountLock);
 	String typeName = Utility::GetTypeName(typeid(*object));
@@ -239,7 +239,7 @@ INITIALIZE_ONCE([]() {
 });
 #endif /* I2_LEAK_DEBUG */
 
-void icinga::intrusive_ptr_add_ref(Object *object)
+void icinga::intrusive_ptr_add_ref(const Object *object)
 {
 #ifdef I2_LEAK_DEBUG
 	if (object->m_References.fetch_add(1) == 0u)
@@ -249,7 +249,7 @@ void icinga::intrusive_ptr_add_ref(Object *object)
 #endif /* I2_LEAK_DEBUG */
 }
 
-void icinga::intrusive_ptr_release(Object *object)
+void icinga::intrusive_ptr_release(const Object *object)
 {
 	auto previous (object->m_References.fetch_sub(1));
 

lib/base/object.hpp

@@ -31,7 +31,8 @@ class ValidationUtils;
 extern const Value Empty;
 
 #define DECLARE_PTR_TYPEDEFS(klass) \
-	typedef intrusive_ptr<klass> Ptr
+	typedef intrusive_ptr<klass> Ptr; \
+	typedef intrusive_ptr<const klass> ConstPtr
 
 #define IMPL_TYPE_LOOKUP_SUPER() 					\
 
@@ -192,7 +193,7 @@ class Object
 	Object(const Object& other) = delete;
 	Object& operator=(const Object& rhs) = delete;
 
-	std::atomic<uint_fast64_t> m_References;
+	mutable std::atomic<uint_fast64_t> m_References;
 	mutable std::recursive_mutex m_Mutex;
 
 #ifdef I2_DEBUG
@@ -202,17 +203,17 @@ class Object
 
 	friend struct ObjectLock;
 
-	friend void intrusive_ptr_add_ref(Object *object);
-	friend void intrusive_ptr_release(Object *object);
+	friend void intrusive_ptr_add_ref(const Object *object);
+	friend void intrusive_ptr_release(const Object *object);
 };
 
 Value GetPrototypeField(const Value& context, const String& field, bool not_found_error, const DebugInfo& debugInfo);
 
-void TypeAddObject(Object *object);
-void TypeRemoveObject(Object *object);
+void TypeAddObject(const Object *object);
+void TypeRemoveObject(const Object *object);
 
-void intrusive_ptr_add_ref(Object *object);
-void intrusive_ptr_release(Object *object);
+void intrusive_ptr_add_ref(const Object *object);
+void intrusive_ptr_release(const Object *object);
 
 template<typename T>
 class ObjectImpl

lib/base/shared-object.hpp

@@ -12,8 +12,8 @@ namespace icinga
 
 class SharedObject;
 
-inline void intrusive_ptr_add_ref(SharedObject *object);
-inline void intrusive_ptr_release(SharedObject *object);
+inline void intrusive_ptr_add_ref(const SharedObject *object);
+inline void intrusive_ptr_release(const SharedObject *object);
 
 /**
  * Seamless and polymorphistic base for any class to create shared pointers of.
@@ -23,8 +23,8 @@ inline void intrusive_ptr_release(SharedObject *object);
  */
 class SharedObject
 {
-	friend void intrusive_ptr_add_ref(SharedObject *object);
-	friend void intrusive_ptr_release(SharedObject *object);
+	friend void intrusive_ptr_add_ref(const SharedObject *object);
+	friend void intrusive_ptr_release(const SharedObject *object);
 
 protected:
 	inline SharedObject() : m_References(0)
@@ -38,15 +38,15 @@ class SharedObject
 	~SharedObject() = default;
 
 private:
-	Atomic<uint_fast64_t> m_References;
+	mutable Atomic<uint_fast64_t> m_References;
 };
 
-inline void intrusive_ptr_add_ref(SharedObject *object)
+inline void intrusive_ptr_add_ref(const SharedObject *object)
 {
 	object->m_References.fetch_add(1);
 }
 
-inline void intrusive_ptr_release(SharedObject *object)
+inline void intrusive_ptr_release(const SharedObject *object)
 {
 	if (object->m_References.fetch_sub(1) == 1u) {
 		delete object;

lib/base/shared.hpp

@@ -16,13 +16,13 @@ template<class T>
 class Shared;
 
 template<class T>
-inline void intrusive_ptr_add_ref(Shared<T> *object)
+inline void intrusive_ptr_add_ref(const Shared<T> *object)
 {
 	object->m_References.fetch_add(1);
 }
 
 template<class T>
-inline void intrusive_ptr_release(Shared<T> *object)
+inline void intrusive_ptr_release(const Shared<T> *object)
 {
 	if (object->m_References.fetch_sub(1) == 1u) {
 		delete object;
@@ -38,11 +38,12 @@ inline void intrusive_ptr_release(Shared<T> *object)
 template<class T>
 class Shared : public T
 {
-	friend void intrusive_ptr_add_ref<>(Shared<T> *object);
-	friend void intrusive_ptr_release<>(Shared<T> *object);
+	friend void intrusive_ptr_add_ref<>(const Shared<T> *object);
+	friend void intrusive_ptr_release<>(const Shared<T> *object);
 
 public:
 	typedef boost::intrusive_ptr<Shared> Ptr;
+	typedef boost::intrusive_ptr<const Shared> ConstPtr;
 
 	/**
 	 * Like std::make_shared, but for this class.
@@ -94,7 +95,7 @@ class Shared : public T
 	}
 
 private:
-	Atomic<uint_fast64_t> m_References;
+	mutable Atomic<uint_fast64_t> m_References;
 };
 
 }