时间戳

首页 > 解决方案 > 将变量的引用发送到线程 C++

multithreading - 将变量的引用发送到线程 C++

问题描述

当我尝试发送对两个这样的向量的引用时：

void listenMsg(int socket, vector<string>&vector, vector<int>&size){
/../
}

void letsGo(int socket){
    vector<string> v;
    vector<int> size;
    thread(listenMsg, socket, ref(v), ref(size)). detach();
}

编译器给我一个错误：

/home/volenko/CLionProjects/tcp_second_try/main.cpp:258:51: error: ‘vector’ is not a type
 void listenMsg(int socket, vector<string>&vector, vector<int>&size){
                                                   ^~~~~~
/home/volenko/CLionProjects/tcp_second_try/main.cpp:258:57: error: expected ‘,’ or ‘...’ before ‘&lt;’ token
 void listenMsg(int socket, vector<string>&vector, vector<int>&size){
                                                         ^
In file included from /home/volenko/CLionProjects/tcp_second_try/main.cpp:12:0:
/usr/include/c++/7/thread: In instantiation of ‘struct std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >’:
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(int, std::vector<std::__cxx11::basic_string<char> >&, int); _Args = {int&, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > >}]’
/home/volenko/CLionProjects/tcp_second_try/main.cpp:455:47:   required from here
/usr/include/c++/7/thread:240:2: error: no matching function for call to ‘std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >::_M_invoke(std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >::_Indices)’
  operator()()
  ^~~~~~~~
/usr/include/c++/7/thread:231:4: note: candidate: template<long unsigned int ..._Ind> decltype (std::__invoke((_S_declval<_Ind>)()...)) std::thread::_Invoker<_Tuple>::_M_invoke(std::_Index_tuple<_Ind ...>) [with long unsigned int ..._Ind = {_Ind ...}; _Tuple = std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > >]
    _M_invoke(_Index_tuple<_Ind...>)
    ^~~~~~~~~
/usr/include/c++/7/thread:231:4: note:   template argument deduction/substitution failed:
/usr/include/c++/7/thread: In substitution of ‘template<long unsigned int ..._Ind> decltype (std::__invoke(_S_declval<_Ind>()...)) std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >::_M_invoke<_Ind ...>(std::_Index_tuple<_Ind1 ...>) [with long unsigned int ..._Ind = {0, 1, 2, 3}]’:
/usr/include/c++/7/thread:240:2:   required from ‘struct std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >’
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(int, std::vector<std::__cxx11::basic_string<char> >&, int); _Args = {int&, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > >}]’
/home/volenko/CLionProjects/tcp_second_try/main.cpp:455:47:   required from here
/usr/include/c++/7/thread:233:29: error: no matching function for call to ‘__invoke(std::__tuple_element_t<0, std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >, std::__tuple_element_t<1, std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >, std::__tuple_element_t<2, std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >, std::__tuple_element_t<3, std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >)’
    -> decltype(std::__invoke(_S_declval<_Ind>()...))
                ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/7/tuple:41:0,
                 from /usr/include/c++/7/bits/unique_ptr.h:37,
                 from /usr/include/c++/7/memory:80,
                 from /usr/include/c++/7/thread:39,
                 from /home/volenko/CLionProjects/tcp_second_try/main.cpp:12:
/usr/include/c++/7/bits/invoke.h:89:5: note: candidate: template<class _Callable, class ... _Args> constexpr typename std::__invoke_result<_Functor, _ArgTypes>::type std::__invoke(_Callable&&, _Args&& ...)
     __invoke(_Callable&& __fn, _Args&&... __args)
     ^~~~~~~~
/usr/include/c++/7/bits/invoke.h:89:5: note:   template argument deduction/substitution failed:
/usr/include/c++/7/bits/invoke.h: In substitution of ‘template<class _Callable, class ... _Args> constexpr typename std::__invoke_result<_Functor, _ArgTypes>::type std::__invoke(_Callable&&, _Args&& ...) [with _Callable = void (*)(int, std::vector<std::__cxx11::basic_string<char> >&, int); _Args = {int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > >}]’:
/usr/include/c++/7/thread:233:29:   required by substitution of ‘template<long unsigned int ..._Ind> decltype (std::__invoke(_S_declval<_Ind>()...)) std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >::_M_invoke<_Ind ...>(std::_Index_tuple<_Ind1 ...>) [with long unsigned int ..._Ind = {0, 1, 2, 3}]’
/usr/include/c++/7/thread:240:2:   required from ‘struct std::thread::_Invoker<std::tuple<void (*)(int, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > > >’
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(int, std::vector<std::__cxx11::basic_string<char> >&, int); _Args = {int&, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > >}]’
/home/volenko/CLionProjects/tcp_second_try/main.cpp:455:47:   required from here
/usr/include/c++/7/bits/invoke.h:89:5: error: no type named ‘type’ in ‘struct std::__invoke_result<void (*)(int, std::vector<std::__cxx11::basic_string<char> >&, int), int, std::reference_wrapper<std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::reference_wrapper<std::vector<int, std::allocator<int> > > >’

但是当我像这样交换它们时：

void listenMsg(int socket, vector<int>&size, vector<string>&vector){
/../
}

void letsGo(int socket){
    vector<string> v;
    vector<int> size;
    thread(listenMsg, socket, ref(size), ref(v)). detach();
}

编译器什么也没说。我担心我无法注意到的某种泄漏甚至更严重的问题。有人可以解释发生了什么吗？

编译：

g++ -Wall -g -std=c++17 -pthread main.cpp

标签： multithreadingvectorreference

解决方案

我不知道在这两种情况下为什么会出现或没有出现编译时错误，但vandsize是函数中的局部变量letsGo()。他们将在返回后立即销毁letsGo()。这将与您的listenMsg()线程开始运行的时间大致相同。

推荐阅读