CxxUtils::CachedValue< T > Class Template Reference

Cached value with atomic update. More...

#include <CachedValue.h>

Collaboration diagram for CxxUtils::CachedValue< T >:

Public Member Functions
	CachedValue ()
	Default constructor. Sets the value to invalid. More...
	CachedValue (const T &val)
	Constructor from a value. More...
	CachedValue (T &&val) noexcept
	Move constructor from a value. More...
	CachedValue (const CachedValue &other)
	Copy constructor. More...
	CachedValue (CachedValue &&other) noexcept
	Move constructor. More...
template<class U >
	CachedValue (const CachedValue< U > &other)
	Copy constructor from other type. More...
CachedValue &	operator= (const CachedValue &other)
	Assignment. More...
CachedValue &	operator= (CachedValue &&other) noexcept
	Move. More...
void	set (const T &val) const
	Set the value, assuming it is currently invalid. More...
void	set (T &&val) const noexcept
	Set the value by move, assuming it is currently invalid. More...
bool	isValid () const
	Test to see if the value is valid. More...
const T *	ptr () const
	Return a pointer to the cached value. More...
void	store (const T &val)
	Store a new value. More...
void	store (T &&val) noexcept
	Store a new value, by move. More...
void	reset ()
	Reset the value to invalid. More...

Private Attributes
T m_val	ATLAS_THREAD_SAFE
	The cached value. More...
std::atomic< CacheState >	m_cacheValid
	Transient. More...

Friends
template<class U >
class	CachedValue

Detailed Description

template<class T>
class CxxUtils::CachedValue< T >

Cached value with atomic update.

Hold a cache of some value. The cache may be set atomically through a const method. This can happen in multiple threads, but the value set should be the same in all threads. The value can be either valid or invalid; it can be set using the set() method. (The value can also be set using the non-const store() method; however, this is not atomic and should not be done while other threads may be accessing the value.) The validity of the value may be tested with isValid(), and ptr() will get back a pointer to the value. ptr() should not be called until isValid() has returned true or set() returned.

The state of the cached value is given by m_cacheState, which can have the values: INVALID: No value has been cached. VALID: The cached value is valid. UPDATING: Some thread is in the process of setting the value.

Definition at line 54 of file CachedValue.h.

Constructor & Destructor Documentation

CachedValue() [1/6]

template<class T >

CxxUtils::CachedValue< T >::CachedValue

(

)

Default constructor. Sets the value to invalid.

CachedValue() [2/6]

template<class T >

CxxUtils::CachedValue< T >::CachedValue

(

const T &

val

)

Constructor from a value.

CachedValue() [3/6]

template<class T >

CxxUtils::CachedValue< T >::CachedValue ( T &&  val )

noexcept

Move constructor from a value.

CachedValue() [4/6]

template<class T >

CxxUtils::CachedValue< T >::CachedValue

(

const CachedValue< T > &

other

)

Copy constructor.

CachedValue() [5/6]

template<class T >

CxxUtils::CachedValue< T >::CachedValue ( CachedValue< T > &&  other )

noexcept

Move constructor.

No concurrent operations on OTHER are possible.

CachedValue() [6/6]

template<class T >

template<class U >

CxxUtils::CachedValue< T >::CachedValue

(

const CachedValue< U > &

other

)

Copy constructor from other type.

Member Function Documentation

isValid()

template<class T >

bool CxxUtils::CachedValue< T >::isValid

(

)

const

Test to see if the value is valid.

May spin if another thread is currently updating the value.

operator=() [1/2]

template<class T >

CachedValue& CxxUtils::CachedValue< T >::operator= ( CachedValue< T > &&  other )

noexcept

Move.

No concurrent operations on OTHER are possible.

operator=() [2/2]

template<class T >

CachedValue& CxxUtils::CachedValue< T >::operator=

(

const CachedValue< T > &

other

)

Assignment.

ptr()

template<class T >

const T* CxxUtils::CachedValue< T >::ptr

(

)

const

Return a pointer to the cached value.

Should not be called unless isValid() has returned true or set() has returned.

reset()

template<class T >

void CxxUtils::CachedValue< T >::reset

(

)

Reset the value to invalid.

set() [1/2]

template<class T >

void CxxUtils::CachedValue< T >::set

(

const T &

val

)

const

Set the value, assuming it is currently invalid.

Otherwise, this method will do nothing. The value will be valid once this returns.

set() [2/2]

template<class T >

void CxxUtils::CachedValue< T >::set ( T &&  val ) const

noexcept

Set the value by move, assuming it is currently invalid.

Otherwise, this method will do nothing. The value will be valid once this returns.

store() [1/2]

template<class T >

void CxxUtils::CachedValue< T >::store

(

const T &

val

)

Store a new value.

store() [2/2]

template<class T >

void CxxUtils::CachedValue< T >::store ( T &&  val )

noexcept

Store a new value, by move.

Friends And Related Function Documentation

CachedValue

template<class T >

template<class U >

friend class CachedValue

friend

Definition at line 58 of file CachedValue.h.

Member Data Documentation

ATLAS_THREAD_SAFE

template<class T >

T m_val CxxUtils::CachedValue< T >::ATLAS_THREAD_SAFE

mutableprivate

The cached value.

Do not return a pointer to this to the user unless the state is VALID.

Definition at line 134 of file CachedValue.h.

m_cacheValid

template<class T >

std::atomic<CacheState> CxxUtils::CachedValue< T >::m_cacheValid

mutableprivate

Transient.

Current state of the cached value. INVALID — value has not been set. VALID — value has been set. UPDATING — value is in the process of being set by some thread.

Definition at line 140 of file CachedValue.h.

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

• CachedValue.h