Guarded pointer. More...

#include <cds/gc/dhp.h>

Public Types
typedef GuardedType	guarded_type
	Guarded type.

typedef ValueType	value_type
	Value type.

typedef std::conditional< std::is_same< Cast, void >::value, trivial_cast, Cast >::type	value_cast
	Functor for casting `guarded_type` to `value_type`.

Public Member Functions
	guarded_ptr () noexcept
	Creates empty guarded pointer.

	guarded_ptr (guarded_ptr &&gp) noexcept
	Move ctor.

template<typename GT , typename VT , typename C >
	guarded_ptr (guarded_ptr< GT, VT, C > &&gp) noexcept
	Move ctor.

	guarded_ptr (Guard &&g) noexcept
	Ctor from `Guard`.

	guarded_ptr (guarded_ptr const &gp)=delete
	The guarded pointer is not copy-constructible.

	~guarded_ptr () noexcept
	Clears the guarded pointer. More...

guarded_ptr &	operator= (guarded_ptr &&gp) noexcept
	Move-assignment operator.

guarded_ptr &	operator= (Guard &&g) noexcept
	Move-assignment from `Guard`.

guarded_ptr &	operator= (guarded_ptr const &gp)=delete
	The guarded pointer is not copy-assignable.

value_type *	operator-> () const noexcept
	Returns a pointer to guarded value.

value_type &	operator* () noexcept
	Returns a reference to guarded value.

value_type const &	operator* () const noexcept
	Returns const reference to guarded value.

bool	empty () const noexcept
	Checks if the guarded pointer is `nullptr`.

	operator bool () const noexcept
	`bool` operator returns `!empty()`

void	release () noexcept
	Clears guarded pointer. More...

Detailed Description

template<typename GuardedType, typename ValueType = GuardedType, typename Cast = void>
class cds::gc::DHP::guarded_ptr< GuardedType, ValueType, Cast >

Guarded pointer.

A guarded pointer is a pair of a pointer and GC's guard. Usually, it is used for returning a pointer to the item from an lock-free container. The guard prevents the pointer to be early disposed (freed) by GC. After destructing guarded_ptr object the pointer can be disposed (freed) automatically at any time.

Template arguments:

GuardedType - a type which the guard stores
ValueType - a value type
Cast - a functor for converting GuardedType* to ValueType*. Default is void (no casting).

For intrusive containers, GuardedType is the same as ValueType and no casting is needed. In such case the guarded_ptr is:

typedef cds::gc::DHP::guarded_ptr< foo > intrusive_guarded_ptr;

For standard (non-intrusive) containers GuardedType is not the same as ValueType and casting is needed. For example:

struct foo {
    int const   key;
    std::string value;
};
struct value_accessor {
    std::string* operator()( foo* pFoo ) const
    {
        return &(pFoo->value);
    }
};
// Guarded ptr
typedef cds::gc::DHP::guarded_ptr< Foo, std::string, value_accessor > nonintrusive_guarded_ptr;

You don't need use this class directly. All set/map container classes from libcds declare the typedef for guarded_ptr with appropriate casting functor.

Constructor & Destructor Documentation

◆ ~guarded_ptr()

template<typename GuardedType , typename ValueType = GuardedType, typename Cast = void>

cds::gc::DHP::guarded_ptr< GuardedType, ValueType, Cast >::~guarded_ptr ( )

inlinenoexcept

Clears the guarded pointer.

release is called if guarded pointer is not empty

Member Function Documentation

◆ release()

template<typename GuardedType , typename ValueType = GuardedType, typename Cast = void>

void cds::gc::DHP::guarded_ptr< GuardedType, ValueType, Cast >::release ( )

inlinenoexcept

Clears guarded pointer.

If the guarded pointer has been released, the pointer can be disposed (freed) at any time. Dereferncing the guarded pointer after release() is dangerous.

The documentation for this class was generated from the following file:

cds/gc/dhp.h

Public Types