iox2::legacy::StaticLifetimeGuard< T > Class Template Reference

Manages a static instance of type T in a way so that each existing StaticLifetimeGuard prevents the destruction of the instance. More...

#include <static_lifetime_guard.hpp>

Public Member Functions
	StaticLifetimeGuard () noexcept
	StaticLifetimeGuard (const StaticLifetimeGuard &) noexcept
	StaticLifetimeGuard (StaticLifetimeGuard &&) noexcept
	~StaticLifetimeGuard () noexcept
StaticLifetimeGuard &	operator= (const StaticLifetimeGuard &) noexcept=default
StaticLifetimeGuard &	operator= (StaticLifetimeGuard &&) noexcept=default

Static Public Member Functions
template<typename... Args>
static T &	instance (Args &&... args) noexcept
	Construct the instance to be guarded with constructor arguments.
static uint64_t	count ()
	Get the current count value.

Static Protected Member Functions
static uint64_t	setCount (uint64_t count)
	Set the instance life time count.

Detailed Description

template<typename T>
class iox2::legacy::StaticLifetimeGuard< T >

Manages a static instance of type T in a way so that each existing StaticLifetimeGuard prevents the destruction of the instance.

1. instance() creates a static guard itself and hence has static lifetime
2. Any static StaticLifetimeGuard G created before that prolongs the lifetime of the instance at least until G is destroyed
3. The instance is lazily constructed, i.e. only when first used. Hence there can be guards without any instance existing. These guards still protect the instance from destruction if it is ever constructed.
4. If and once the instance is constructed, it will be destructed only after main exits (static destruction).
5. Guards can be used in static variables to control destruction order of static (singleton) instances if a specific order of destruction is required.

   Template Parameters

   T	the type of the instance to be guarded

   Note

   all public functions are thread-safe

   // instance will be destroyed after guard
   // (or later if there are guards preceding guard in construction order)
    
   static StaticLifetimeGuard<T> guard;
   static T& instance = StaticLifetimeGuard<T>::instance();

Definition at line 49 of file static_lifetime_guard.hpp.

Constructor & Destructor Documentation

StaticLifetimeGuard() [1/3]

template<typename T >

iox2::legacy::StaticLifetimeGuard< T >::StaticLifetimeGuard ( )

noexcept

StaticLifetimeGuard() [2/3]

template<typename T >

iox2::legacy::StaticLifetimeGuard< T >::StaticLifetimeGuard ( const StaticLifetimeGuard< T > &  )

noexcept

StaticLifetimeGuard() [3/3]

template<typename T >

iox2::legacy::StaticLifetimeGuard< T >::StaticLifetimeGuard ( StaticLifetimeGuard< T > &&  )

noexcept

~StaticLifetimeGuard()

template<typename T >

iox2::legacy::StaticLifetimeGuard< T >::~StaticLifetimeGuard ( )

noexcept

Member Function Documentation

count()

template<typename T >

static uint64_t iox2::legacy::StaticLifetimeGuard< T >::count ( )

static

Get the current count value.

Returns

current count value

References iox2::legacy::always_false_v.

instance()

template<typename T >

template<typename... Args>

static T & iox2::legacy::StaticLifetimeGuard< T >::instance ( Args &&...  args )

staticnoexcept

Construct the instance to be guarded with constructor arguments.

Parameters

args	constructor arguments

Returns

reference to the constructed instance or the existing instance if it already exists

Note

creates an implicit static StaticLifetimeGuard to ensure the instance is destroyed in the static destruction phase

operator=() [1/2]

template<typename T >

StaticLifetimeGuard & iox2::legacy::StaticLifetimeGuard< T >::operator= ( const StaticLifetimeGuard< T > &  )

defaultnoexcept

operator=() [2/2]

template<typename T >

StaticLifetimeGuard & iox2::legacy::StaticLifetimeGuard< T >::operator= ( StaticLifetimeGuard< T > &&  )

defaultnoexcept

setCount()

template<typename T >

static uint64_t iox2::legacy::StaticLifetimeGuard< T >::setCount ( uint64_t  count )

staticprotected

Set the instance life time count.

Parameters

count

value to be set

Returns

previous count value

Note

This can be used to additionally extend or shorten the instance lifetime, This has to be done carefully, to ensure destruction or prevent early destruction. It is useful for testing purposes.

Only to be used for testing.

Attention

setCount is only supposed to be used while no guards are created concurrently as it will influence the guard mechanism. The instance is destroyed once the counter reaches zero upon destruction of a guard, i.e. changing the counter may lead to the instance never being destroyed or being destroyed before the last guard.

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

• iox2/legacy/static_lifetime_guard.hpp