std :: mapa de impulso :: mutex con un comportamiento extraño

tengo este código:std :: mapa de impulso :: mutex con un comportamiento extraño

//// 
// Default Namespaces 
/// 

using namespace std; 

typedef map <string, boost::shared_mutex> t_map_shared_mutex; 

int main(int argc, char** argv) { 

    t_map_shared_mutex list_lock; 

    boost::shared_mutex global_lock; 

    string   i = "ABC"; 

    boost::unique_lock <boost::shared_mutex> l_lock (global_lock); 

    boost::unique_lock <boost::shared_mutex> lock (list_lock[i]); 
     //Do Something with that lock 
    lock.unlock(); 

    l_lock.unlock(); 

}

Esto genera el siguiente error. Por lo que entiendo (y podría estar bastante equivocado aquí) g ++ me está diciendo que el mutex se está pasando como un valor constante ... Y no puedo ver por qué.

In file included from /usr/include/c++/4.4/utility:63, 
       from /usr/include/boost/config/no_tr1/utility.hpp:21, 
       from /usr/include/boost/config/select_stdlib_config.hpp:33, 
       from /usr/include/boost/config.hpp:40, 
       from /usr/include/boost/date_time/compiler_config.hpp:12, 
       from /usr/include/boost/date_time/posix_time/posix_time.hpp:14, 
       from prova.cpp:5: 
/usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _T2 = boost::shared_mutex]’: 
/usr/include/c++/4.4/bits/stl_map.h:450: instantiated from ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = boost::shared_mutex, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
prova.cpp:66: instantiated from here 
/usr/include/c++/4.4/bits/stl_pair.h:84: error: no matching function for call to ‘boost::shared_mutex::shared_mutex(const boost::shared_mutex&)’ 
/usr/include/boost/thread/pthread/shared_mutex.hpp:47: note: candidates are: boost::shared_mutex::shared_mutex() 
/usr/include/boost/thread/pthread/shared_mutex.hpp:21: note:     boost::shared_mutex::shared_mutex(boost::shared_mutex&) 
/usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _U2 = boost::shared_mutex, _T1 = const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _T2 = boost::shared_mutex]’: 
/usr/include/c++/4.4/ext/new_allocator.h:105: instantiated from ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex>]’ 
/usr/include/c++/4.4/bits/stl_tree.h:371: instantiated from ‘std::_Rb_tree_node<_Val>* std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_create_node(const _Val&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Val = std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex>, _KeyOfValue = std::_Select1st<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
/usr/include/c++/4.4/bits/stl_tree.h:881: instantiated from ‘std::_Rb_tree_iterator<_Val> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert_(const std::_Rb_tree_node_base*, const std::_Rb_tree_node_base*, const _Val&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Val = std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex>, _KeyOfValue = std::_Select1st<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
/usr/include/c++/4.4/bits/stl_tree.h:1215: instantiated from ‘std::_Rb_tree_iterator<_Val> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert_unique_(std::_Rb_tree_const_iterator<_Val>, const _Val&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Val = std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex>, _KeyOfValue = std::_Select1st<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
/usr/include/c++/4.4/bits/stl_map.h:540: instantiated from ‘typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator std::map<_Key, _Tp, _Compare, _Alloc>::insert(typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator, const std::pair<const _Key, _Tp>&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = boost::shared_mutex, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
/usr/include/c++/4.4/bits/stl_map.h:450: instantiated from ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = boost::shared_mutex, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_mutex> >]’ 
prova.cpp:66: instantiated from here 
/usr/include/c++/4.4/bits/stl_pair.h:101: error: no matching function for call to ‘boost::shared_mutex::shared_mutex(const boost::shared_mutex&)’ 
/usr/include/boost/thread/pthread/shared_mutex.hpp:47: note: candidates are: boost::shared_mutex::shared_mutex() 
/usr/include/boost/thread/pthread/shared_mutex.hpp:21: note:     boost::shared_mutex::shared_mutex(boost::shared_mutex&)

¿Cómo resolver eso?

Fuente

2011-08-30 St0rM

Los contenedores STL requieren un constructor de copia para el tipo de valor; ya que los mutexes no se pueden copiar, no puede ponerlos directamente en map. Debe usar un puntero a un mutex (quizás a través de std::unique_ptr o boost::ptr_map).

Fuente

2011-08-30 17:27:47 bdonlan

Tal vez mi habilidad con los mutex impulso no es tan fuerte .. . Cómo lo harías tú ? ¿Me puede dar un código? – St0rM

@ St0rM - Diría que es más su habilidad con los contenedores estándar que necesitan trabajo. Hay algunas situaciones en las que está bien colocar objetos directamente en un contenedor si sabe lo que está haciendo. Pero, en general, debería buscar ** colocar punteros a objetos en un contenedor ** (como un std :: map), ** no los objetos en sí mismos **. Los contenedores pueden copiar los objetos internamente como mejor les parezca, por lo que realmente no tiene control sobre cuándo se invocarán los constructores y los destructores. –

@TED: En realidad, no quiere decir en general, ¿verdad? Los punteros en contenedores generalmente no son correctos. – GManNickG

Me parece que std::map está tratando de llamar al constructor de copia de boost::shared_mutex pasándolo a un const boost::shared_mutex&, pero no hay tal constructor está disponible:

/usr/include/c++/4.4/bits/stl_pair.h:84: error: no matching function for call to ‘boost::shared_mutex::shared_mutex(const boost::shared_mutex&)’ 
/usr/include/boost/thread/pthread/shared_mutex.hpp:47: note: candidates are: boost::shared_mutex::shared_mutex() 
/usr/include/boost/thread/pthread/shared_mutex.hpp:21: note:     boost::shared_mutex::shared_mutex(boost::shared_mutex&)

Fuente

2011-08-30 17:29:46

std :: mapa de impulso :: mutex con un comportamiento extraño

Respuesta

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