c++ - /boost/lockfree/queue.hpp: error: static assertion failed: (boost::has_trivial_destructor<T>::value)

Question

I'm trying to substitute boost::lockfree::queue for std::queue in this file https://github.com/zaphoyd/websocketpp/blob/experimental/examples/broadcast_server/broadcast_server.cpp

I've added #include <boost/lockfree/queue.hpp>; changed line 130, std::queue<action> m_actions;, to boost::lockfree::queue<action> m_actions;; removed all lines having to do with locking; and changed line 103, m_actions.pop();, to m_actions.pop(a);.

I get these errors when I scons broadcast_server_lockfree in the project root after adding broadcast_server_lockfree = SConscript('#/broadcast_server_lockfree/SConscript',variant_dir = builddir + 'broadcast_server_lockfree',duplicate = 0) to the project root's SConstruct and using broadcast_server's SConstruct in the broadcast_server_lockfree directory:

root@server:~/websocketpp-experimental# scons broadcast_server_lockfree
scons: Reading SConscript files ...
C++11 build environment partially enabled
scons: done reading SConscript files.
scons: Building targets ...
scons: building associated VariantDir targets: build/release/broadcast_server_lockfree
g++ -o build/release/broadcast_server_lockfree/broadcast_server_lockfree.o -c -std=c++0x -Wall -Wcast-align -isystem /root/boost_1_53_0 -DNDEBUG -D_WEBSOCKETPP_CPP11_MEMORY_ -D_WEBSOCKETPP_CPP11_FUNCTIONAL_ -D_WEBSOCKETPP_CPP11_SYSTEM_ERROR_ -D_WEBSOCKETPP_CPP11_RANDOM_DEVICE_ -D_WEBSOCKETPP_NOEXCEPT_ -I. broadcast_server_lockfree/broadcast_server_lockfree.cpp
In file included from broadcast_server_lockfree/broadcast_server_lockfree.cpp:10:0:
/root/boost_1_53_0/boost/lockfree/queue.hpp: In instantiation of 'class boost::lockfree::queue<action>':
broadcast_server_lockfree/broadcast_server_lockfree.cpp:139:36:   required from here
/root/boost_1_53_0/boost/lockfree/queue.hpp:79:5: error: static assertion failed: (boost::has_trivial_destructor<T>::value)
/root/boost_1_53_0/boost/lockfree/queue.hpp:83:5: error: static assertion failed: (boost::has_trivial_assign<T>::value)
broadcast_server_lockfree/broadcast_server_lockfree.cpp: In member function 'void broadcast_server::process_messages()':
broadcast_server_lockfree/broadcast_server_lockfree.cpp:111:34: error: 'class boost::lockfree::queue<action>' has no member named 'front'
broadcast_server_lockfree/broadcast_server_lockfree.cpp:117:55: error: 'm_connection_lock' was not declared in this scope
broadcast_server_lockfree/broadcast_server_lockfree.cpp:120:55: error: 'm_connection_lock' was not declared in this scope
broadcast_server_lockfree/broadcast_server_lockfree.cpp:123:55: error: 'm_connection_lock' was not declared in this scope
In file included from broadcast_server_lockfree/broadcast_server_lockfree.cpp:10:0:
/root/boost_1_53_0/boost/lockfree/queue.hpp: In instantiation of 'boost::lockfree::queue<T, A0, A1, A2>::~queue() [with T = action; A0 = boost::parameter::void_; A1 = boost::parameter::void_; A2 = boost::parameter::void_]':
broadcast_server_lockfree/broadcast_server_lockfree.cpp:41:24:   required from here
/root/boost_1_53_0/boost/lockfree/queue.hpp:229:11: error: no matching function for call to 'action::action()'
/root/boost_1_53_0/boost/lockfree/queue.hpp:229:11: note: candidates are:
broadcast_server_lockfree/broadcast_server_lockfree.cpp:32:5: note: action::action(action_type, websocketpp::endpoint<websocketpp::connection<websocketpp::config::asio>, websocketpp::config::asio>::message_ptr)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:32:5: note:   candidate expects 2 arguments, 0 provided
broadcast_server_lockfree/broadcast_server_lockfree.cpp:31:5: note: action::action(action_type, websocketpp::connection_hdl)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:31:5: note:   candidate expects 2 arguments, 0 provided
broadcast_server_lockfree/broadcast_server_lockfree.cpp:30:8: note: action::action(const action&)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:30:8: note:   candidate expects 1 argument, 0 provided
In file included from broadcast_server_lockfree/broadcast_server_lockfree.cpp:10:0:
/root/boost_1_53_0/boost/lockfree/queue.hpp: In instantiation of 'boost::lockfree::queue<T, A0, A1, A2>::node::node(boost::lockfree::queue<T, A0, A1, A2>::node::handle_type) [with T = action; A0 = boost::parameter::void_; A1 = boost::parameter::void_; A2 = boost::parameter::void_; boost::lockfree::queue<T, A0, A1, A2>::node::handle_type = boost::lockfree::queue<action>::node*]':
/root/boost_1_53_0/boost/lockfree/detail/freelist.hpp:82:13:   required from 'T* boost::lockfree::detail::freelist_stack<T, Alloc>::construct(const ArgumentType&) [with bool ThreadSafe = true; bool Bounded = false; ArgumentType = boost::lockfree::queue<action>::node*; T = boost::lockfree::queue<action>::node; Alloc = std::allocator<boost::lockfree::queue<action>::node>]'
/root/boost_1_53_0/boost/lockfree/queue.hpp:126:75:   required from 'void boost::lockfree::queue<T, A0, A1, A2>::initialize() [with T = action; A0 = boost::parameter::void_; A1 = boost::parameter::void_; A2 = boost::parameter::void_]'
/root/boost_1_53_0/boost/lockfree/queue.hpp:166:9:   required from 'boost::lockfree::queue<T, A0, A1, A2>::queue() [with T = action; A0 = boost::parameter::void_; A1 = boost::parameter::void_; A2 = boost::parameter::void_]'
broadcast_server_lockfree/broadcast_server_lockfree.cpp:41:24:   required from here
/root/boost_1_53_0/boost/lockfree/queue.hpp:109:52: error: no matching function for call to 'action::action()'
/root/boost_1_53_0/boost/lockfree/queue.hpp:109:52: note: candidates are:
broadcast_server_lockfree/broadcast_server_lockfree.cpp:32:5: note: action::action(action_type, websocketpp::endpoint<websocketpp::connection<websocketpp::config::asio>, websocketpp::config::asio>::message_ptr)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:32:5: note:   candidate expects 2 arguments, 0 provided
broadcast_server_lockfree/broadcast_server_lockfree.cpp:31:5: note: action::action(action_type, websocketpp::connection_hdl)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:31:5: note:   candidate expects 2 arguments, 0 provided
broadcast_server_lockfree/broadcast_server_lockfree.cpp:30:8: note: action::action(const action&)
broadcast_server_lockfree/broadcast_server_lockfree.cpp:30:8: note:   candidate expects 1 argument, 0 provided
scons: *** [build/release/broadcast_server_lockfree/broadcast_server_lockfree.o] Error 1
scons: building terminated because of errors.

I know next to nothing about c++, and searches on the error have yielded nothing (since I have no idea what I'm reading).

Here's the boost::lockfree::queue example if it helps. http://boost-sandbox.sourceforge.net/doc/html/lockfree/examples.html

Please show me how to correct this.

action

struct action {
    action(action_type t, connection_hdl h) : type(t), hdl(h) {}
    action(action_type t, server::message_ptr m) : type(t), msg(m) {}

    action_type type;
    websocketpp::connection_hdl hdl;
    server::message_ptr msg;
};

Answer 1

From the docs:

T must have a copy constructor, a trivial assignment operator, and a trivial destructor.

Thus your action class must look like the following:

class action
{
public:
    action(const action& rhs) { ... }
    //Implicitly defined destructor for itself and all member variables
    //Implicitly defined operator= for itself and all member variables

};

The static_asserts are complaining because your destructor and operator= are not implicitly defined by the compiler (or this is the case for at least one member variable of action).

Edit: I've had a quick look at the repo - I can't seem to find connection_hdl, and there is no message_ptr in template <typename endpoint> class server. Either way, one of websocketpp::connection_hdl hdl or server::message_ptr msg does not satisfy the above conditions. Just "dropping in" a lockfree queue instead of using a std::queue is likely a non-trivial task which will require a number of changes.