edm::AtomicPtrCache< T > Class Template Reference

#include "DataFormats/Common/interface/AtomicPtrCache.h"

Public Member Functions
	AtomicPtrCache ()
	AtomicPtrCache (T *)
	Takes exclusive ownership of the value. More...
	AtomicPtrCache (const AtomicPtrCache< T > &)
	Uses T's copy constructor to make a copy. More...
bool	isSet () const
T const *	load () const
T *	load ()
T const &	operator* () const
T &	operator* ()
T const *	operator-> () const
T *	operator-> ()
AtomicPtrCache &	operator= (const AtomicPtrCache< T > &)
T *	release ()
void	reset ()
	unsets the value and deletes the memory More...
bool	set (std::unique_ptr< T > iNewValue) const
	~AtomicPtrCache ()

Private Attributes
std::atomic< T * >	m_data

Detailed Description

template<typename T>
class edm::AtomicPtrCache< T >

Description: A thread safe cache managed by a pointer

Usage: Data products which need to cache results into non-trivial structures (e.g. an std::vector) can use this class to manage the cache in a thread-safe way. The thread-safety guarantee is only the standard C++, if calls are made to const functions simultaneously then everything is thread safe. Calling a non-const function while calling any other functions is not thread-safe.

This class also hides the std::atomic from ROOT so this class can safely be used in a stored class.

WARNING: member data which uses this class must be made transient in the classes_def.xml file!

Definition at line 38 of file AtomicPtrCache.h.

Constructor & Destructor Documentation

AtomicPtrCache() [1/3]

template<typename T >

edm::AtomicPtrCache< T >::AtomicPtrCache ( )

inline

Definition at line 78 of file AtomicPtrCache.h.

: m_data{nullptr} {}

AtomicPtrCache() [2/3]

template<typename T>

edm::AtomicPtrCache< T >::AtomicPtrCache ( T *  iValue )

inlineexplicit

Takes exclusive ownership of the value.

Definition at line 81 of file AtomicPtrCache.h.

: m_data{iValue} {}

AtomicPtrCache() [3/3]

template<typename T>

edm::AtomicPtrCache< T >::AtomicPtrCache ( const AtomicPtrCache< T > &  iOther )

inline

Uses T's copy constructor to make a copy.

Definition at line 84 of file AtomicPtrCache.h.

                                                                          : m_data{nullptr} {
    auto ptr = iOther.m_data.load(std::memory_order_acquire);
    if (ptr != nullptr) {
      m_data.store(new T{*ptr}, std::memory_order_release);
    }
  }

~AtomicPtrCache()

template<typename T >

edm::AtomicPtrCache< T >::~AtomicPtrCache ( )

inline

Definition at line 107 of file AtomicPtrCache.h.

                                            {
    delete m_data.load(std::memory_order_acquire);
  }

Member Function Documentation

isSet()

template<typename T >

bool edm::AtomicPtrCache< T >::isSet ( ) const

inline

Definition at line 122 of file AtomicPtrCache.h.

Referenced by HcalGeometry::fillDetIds(), and HcalGeometry::getHxSize().

                                             {
    return nullptr != m_data.load(std::memory_order_acquire);
  }

load() [1/2]

template<typename T >

T const * edm::AtomicPtrCache< T >::load ( ) const

inline

Definition at line 117 of file AtomicPtrCache.h.

Referenced by HcalGeometry::getValidDetIds(), edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::isSet(), edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::operator*(), edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::operator->(), and edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::~AtomicPtrCache().

                                                {
    return m_data.load(std::memory_order_acquire);
  }

load() [2/2]

template<typename T >

T * edm::AtomicPtrCache< T >::load ( )

inline

Definition at line 112 of file AtomicPtrCache.h.

                                    {
    return m_data.load(std::memory_order_acquire);
  }

operator*() [1/2]

template<typename T>

T const& edm::AtomicPtrCache< T >::operator* ( ) const

inline

Definition at line 53 of file AtomicPtrCache.h.

{ return *load(); }

operator*() [2/2]

template<typename T>

T& edm::AtomicPtrCache< T >::operator* ( )

inline

Definition at line 64 of file AtomicPtrCache.h.

{ return *load(); }

operator->() [1/2]

template<typename T>

T const* edm::AtomicPtrCache< T >::operator-> ( ) const

inline

Definition at line 52 of file AtomicPtrCache.h.

{ return load(); }

operator->() [2/2]

template<typename T>

T* edm::AtomicPtrCache< T >::operator-> ( )

inline

Definition at line 63 of file AtomicPtrCache.h.

{ return load(); }

operator=()

template<typename T>

AtomicPtrCache< T > & edm::AtomicPtrCache< T >::operator= ( const AtomicPtrCache< T > &  iOther )

inline

Definition at line 91 of file AtomicPtrCache.h.

                                                                                        {
    auto ptr = iOther.m_data.load(std::memory_order_acquire);
    if (ptr != nullptr) {
      auto ourPtr = m_data.load(std::memory_order_acquire);
      if (ourPtr != nullptr) {
        *ourPtr = *ptr;
      } else {
        m_data.store(new T{*ptr}, std::memory_order_release);
      }
    } else {
      delete m_data.exchange(nullptr, std::memory_order_acq_rel);
    }
    return *this;
  }

release()

template<typename T >

T * edm::AtomicPtrCache< T >::release ( )

inline

Definition at line 142 of file AtomicPtrCache.h.

Referenced by edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::set().

                                       {
    T* tmp = m_data.exchange(nullptr);
    return tmp;
  }

reset()

template<typename T >

void edm::AtomicPtrCache< T >::reset ( void  )

inline

unsets the value and deletes the memory

Definition at line 137 of file AtomicPtrCache.h.

Referenced by DTReadOutMapping::clear().

                                       {
    delete m_data.exchange(nullptr, std::memory_order_acq_rel);
  }

set()

template<typename T>

bool edm::AtomicPtrCache< T >::set ( std::unique_ptr< T >  iNewValue ) const

inline

returns true if actually was set. Will delete value held by iNewValue if not the first time set

Definition at line 127 of file AtomicPtrCache.h.

Referenced by DTReadOutMapping::cacheMap(), and HcalGeometry::fillDetIds().

                                                                     {
    bool retValue;
    T* expected = nullptr;
    if ((retValue = m_data.compare_exchange_strong(expected, iNewValue.get(), std::memory_order_acq_rel))) {
      iNewValue.release();
    }
    return retValue;
  }

Member Data Documentation

m_data

template<typename T>

std::atomic<T*> edm::AtomicPtrCache< T >::m_data

mutableprivate

Definition at line 75 of file AtomicPtrCache.h.

Referenced by edm::AtomicPtrCache< std::vector< reco::PFRecoTauChargedHadron > >::operator=().