July 2015 - Boost-users - lists.boost.org

Re: [Boost-users] Subject:[atomic] why atomic<>::store method can not support memory_order_consum memory_order_acquire and memory_order_acq_rel
by Isaac To 23 Jul '15

23 Jul '15

On Thu, Jul 23, 2015 at 12:00 AM, "class7class(a)163.com" <class7class(a)163.com > wrote: > I found the the store() method can not support several memory_orders > metioned in the subject , and the other methods can not support all > memory_orders,such as: > 1.the load method can not support memory_order_release and > memory_order_acq_rel > 2. the compare_exchange_strong method can not support > memory_order_release and memory_order_acq_rel > 3. the compare_exchange_weak method can not support memory_order_release > and memory_order_acq_rel > > I really want to know the reason that why the methods of atomic can not > support all memory_orders. > > If I need the methods of the atomic<> support all memory_orders,how can i > do? > You are asking into the area of C++ where the fewest people in the world understand, namely relaxed atomics. Before I tell my limited understanding of the issue, I have an advice: - Use mutexes like boost::mutex to ensure all your accesses to variables shared among threads are not accessed concurrently, and you'll be fine. If your circumstance forces you to ignore the above advice (like me, e.g., when you cannot afford the scheduling overheads of mutexes), here is yet another advice which may save your life: - Make all your variables that can be accessed concurrently from multiple threads (with at least one thread writing) atomic. (This makes your program "data race free".) - Always use the default memory_order_seq_cst memory ordering for accesses to your atomics, never use anything else. If your circumstance forces you to ignore the above advices (unlike me, I just learn them because I haven't heard about the second advice before; you'll have to be writing for old ARM (i.e., ones without the LDA and STL instructions) or POWER for you to have a real reason to use relaxed atomics, I write for neither), here is what I have learnt. tl;dr The boost atomic doesn't support all memory ordering because the C++11 standard doesn't support all of them. The C++ standard doesn't support all memory ordering because not all make sense in the "memory model" supported by C++. It is not likely to change in the near future, i.e., unless some genius devises some novel memory model which changes the status quo. Here "memory model" means what "loads" from memory is allowed to return. Because of compiler and hardware optimization, writes (including atomic writes) to memory locations may be reordered, so the load doesn't always return "the last value stored". Special hardware instructions are necessary to ensure a particular ordering that the programmer needs. The easiest way to understand a program is that "All memory operations by all threads looks as if they are done one after another, interleaving among threads". But it proves to be too tricky for hardware to provide any reasonable performance for this model. The C++ memory model without relaxed atomics is essentially "All *atomic* memory operations by all threads looks as if they are done one after another, interleaving among threads. All other memory operations of each thread looks as if they are completely done between adjacent atomic memory operations. But the programmer guarantees not to write a data race. The compiler uses this assumption in all its work, and your program can break in all mysterious ways if you break this rule." This is essentially the illusion provided by sequential consistency. Everybody should want it. Except some don't, because in some architectures it is essentially impossible to provide sequential consistency efficiently. To do sequential consistency, one has to ensure that (1) the compiler doesn't reorder the statements written by the programmer, which is controllable by compiler writer; and (2) the hardware doesn't reorder the instructions generated by the compiler, which is damn hard. It usually means the compiler must insert memory fences before and after memory accesses (i.e., tell the CPU "don't return to me until everything I do up to this point are visible by all other CPUs" or "don't return to me until everything other CPUs do up to this point are visible by me"), which is very slow. It is particularly bad because for these architectures, fences must be inserted not just for atomic stores, but for the supposedly fast atomic loads as well. (Recent architectures do better because they link the requirement into the accesses of the particular memory location: the "particular memory location" here limits the scope where the "fences" have to do, and this makes a big difference in performance.) That's why relaxed atomics (i.e., memory_order_acq, etc) exists in the standard. They allow those architectures to perform better than using full sequential consistency in some common cases. Because different architectures require different sort of fences, it doesn't make sense for these to mean "insert a fence after the load". Instead, the C++ standard uses a more programmer centric view when defining relaxed memory ordering: - If a thread X stores a value with release semantics into an atomic variable, and another thread Y loads this value with acquire semantics from that same atomic variable, then everything done by thread X before this releasing store are guaranteed to be visible to thread Y after this acquiring load. There is no other semantics attached to the acquire and release. This is why acquiring stores and releasing loads are meaningless: they are not assigned any semantics. But the deeper reason for the lack is that the computer industry cannot find a way to give additional guarantee without incurring hefty performance overheads. And at the same time, sequentially consistent atomics are not so expensive in the new architectures. As for what to do if you want more than the above release-acquire guarantee: Simple, just use sequentially consistent atomic operations. Regards, Isaac

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Subject:[atomic] why atomic<>::store method can not support memory_order_consum memory_order_acquire and memory_order_acq_rel these memory_orders?
by class7class＠163.com 23 Jul '15

23 Jul '15

Hello ! I am a SE and I program based on boost library, I have one question to ask as below: When I use the atomic library included boost , I coded as following: atomic<bool> flag; //declare the var flag.store(true,boost::memory_order_acq_rel); // use store method to change the value of flag but BOOST_ASSERT failed,and I read the code of base_atomic<> template class,I found the the store() method can not support several memory_orders metioned in the subject , and the other methods can not support all memory_orders,such as: 1.the load method can not support memory_order_release and memory_order_acq_rel 2. the compare_exchange_strong method can not support memory_order_release and memory_order_acq_rel 3. the compare_exchange_weak method can not support memory_order_release and memory_order_acq_rel I really want to know the reason that why the methods of atomic can not support all memory_orders. If I need the methods of the atomic<> support all memory_orders,how can i do? thank you very much! class7class(a)163.com

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[Graph] Warning with boost 1.54, but not with 1.46.1 or 1.55
by Vicky Vergara 22 Jul '15

22 Jul '15

I have, with this code: 100: graph_traits<graph_t>::edge_iterator ei, eend; 101: for (tie(ei, eend) = boost::edges(graph); ei != eend; ei++) { I know this is not a major problem, as for the final release I will remove the -Wall flag from the compilation But then my question is why is the difference? Using boost 1.54 under Ubuntu 14.04 this warning shows on line 100 about variable ei /home/woodbri/work/pgrouting/src/apsp_johnson/src/apsp_johnson_boost_wrapper.cpp:100:40: warning: '*((void*)(& ei)+32).__gnu_cxx::__normal_iterator<boost::detail::stored_edge_property<long unsigned int, Edge>*, std::vector<boost::detail::stored_edge_property<long unsigned int, Edge>, std::allocator<boost::detail::stored_edge_property<long unsigned int, Edge> > > >:: _M_current' may be used uninitialized in this function [-Wmaybe-uninitialized] graph_traits<graph_t>::edge_iterator ei, eend; the complete code can be found : https://github.com/pgRouting/pgrouting/blob/develop/src/apsp_johnson/src/ap… in the cmake the compiler flags are set like this: set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -O2 -g -Wall -std=c++0x -frounding-math -Wno-deprecated") Complete setup can be found: https://github.com/pgRouting/pgrouting/blob/develop_2_1_0/CMakeLists.txt#L2… This is a test that has boost 1.46.1, no warning shows I also don't get a warning with boost 1.55 https://travis-ci.org/pgRouting/pgrouting/jobs/72064827#L1834 The complete conversation of the problem can be found here: https://github.com/pgRouting/pgrouting/issues/373#issuecomment-123749888

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Help with voronoi diagram
by rehouma 22 Jul '15

22 Jul '15

<http://boost.2283326.n4.nabble.com/file/n4678233/voronoi.png> I work on a project were I needed to generate the voronoi diagram (dashed lines = voronoi diagram). I used boost successfully. Now, I need to determine the coordinates of the output point e11 from the coordinates of the input point e1 and determine the coordinates of the other input point e12. Please help me, how can I do this. Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/Help-with-voronoi-diagram-tp4678233.html Sent from the Boost - Users mailing list archive at Nabble.com.

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enable_if error with Intel compiler 15.0.1
by Matthieu Brucher 21 Jul '15

21 Jul '15

Hi, I got this error on Linux with the Intel compiler: PATH/boost/boost_1_58_0/include/boost/core/enable_if.hpp(36): error: incomplete type is not allowed struct enable_if : public enable_if_c<Cond::value, T> {}; ^ detected during: instantiation of class "boost::enable_if<Cond, T> [with Cond=boost::mpl::and_<boost::fusion::traits::is_sequence<boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>>, boost::mpl::not_<boost::is_convertible<boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>, boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>>>, boost::mpl::bool_<true>, boost::mpl::bool_<true>, boost::mpl::bool_<true>>, T=void]" at line 92 of "PATH/boost/boost_1_58_0/include/boost/type_traits/is_convertible.hpp" instantiation of class "boost::detail::is_convertible_basic_impl<From, To, false> [with From=boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>, To=boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>]" at line 357 of "PATH/boost/boost_1_58_0/include/boost/type_traits/is_convertible.hpp" instantiation of class "boost::detail::is_convertible_impl<From, To> [with From=boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>, To=boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>]" at line 437 of "PATH/boost/boost_1_58_0/include/boost/type_traits/is_convertible.hpp" instantiation of class "boost::detail::is_convertible_impl_dispatch<From, To> [with From=boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>, To=boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>]" at line 482 of "PATH/boost/boost_1_58_0/include/boost/type_traits/is_convertible.hpp" instantiation of class "boost::is_convertible<From, To> [with From=boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>, boost::fusion::cons<boost::spirit::qi::action<boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type>>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>>>, boost::fusion::nil_>>, To=boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, true, false>]" at line 27 of "PATH/boost/boost_1_58_0/include/boost/mpl/aux_/nested_type_wknd.hpp" [ 26 instantiation contexts not shown ] instantiation of class "boost::proto::transform<PrimitiveTransform, X>::result<Sig> [with PrimitiveTransform=boost::proto::switch_<boost::spirit::meta_compiler<boost::spirit::qi::domain>::cases, boost::proto::tag_of<boost::proto::_> ()>, X=void, Sig=boost::spirit::meta_compiler<boost::spirit::qi::domain>::meta_grammar (boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::spirit::_1_type>, 2L>> &>, 2L> &, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::dereference, boost::proto::argsns_::list1<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char &>, 0L>, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>> &>, 2L> &>, 2L> &>, 1L> &>, 2L>, boost::mpl::void_, boost::spirit::unused_type)]" at line 206 of "PATH/boost/boost_1_58_0/include/boost/spirit/home/support/meta_compiler.hpp" instantiation of class "boost::spirit::result_of::compile<Domain, Expr, Modifiers, Enable> [with Domain=boost::spirit::qi::domain, Expr=boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::spirit::_1_type>, 2L>> &>, 2L> &, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::dereference, boost::proto::argsns_::list1<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char &>, 0L>, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>> &>, 2L> &>, 2L> &>, 1L> &>, 2L>, Modifiers=boost::spirit::unused_type, Enable=void]" at line 184 of "PATH/boost/boost_1_58_0/include/boost/spirit/home/qi/nonterminal/rule.hpp" instantiation of "void boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>::define<Auto,Expr>(boost::spirit::qi::rule<Iterator, T1, T2, T3, T4> &, const Expr &, boost::mpl::true_) [with Iterator=__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, T1=expr_node (), T2=boost::spirit::ascii::space_type, T3=boost::spirit::unused_type, T4=boost::spirit::unused_type, Auto=boost::mpl::false_, Expr=boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::spirit::_1_type>, 2L>> &>, 2L> &, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::dereference, boost::proto::argsns_::list1<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char &>, 0L>, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>> &>, 2L> &>, 2L> &>, 1L> &>, 2L>]" at line 221 of "PATH/boost/boost_1_58_0/include/boost/spirit/home/qi/nonterminal/rule.hpp" instantiation of "boost::spirit::qi::rule<Iterator, T1, T2, T3, T4> &boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>::operator=(const Expr &) [with Iterator=__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, T1=expr_node (), T2=boost::spirit::ascii::space_type, T3=boost::spirit::unused_type, T4=boost::spirit::unused_type, Expr=boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::spirit::_1_type>, 2L>> &>, 2L> &, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::dereference, boost::proto::argsns_::list1<const boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_right, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char &>, 0L>, const boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, boost::proto::argsns_::list2<boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, expr_node (), boost::spirit::ascii::space_type, boost::spirit::unused_type, boost::spirit::unused_type> &, const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::attribute<0>>, 0L>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list4<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<binary_op_phx>, 0L>, boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<const char *>, 0L>, boost::spirit::_val_type, boost::spirit::_1_type>, 4L>>>, 2L>> &>, 2L> &>, 2L> &>, 1L> &>, 2L>]" at line 82 of "test.cpp" instantiation of "Grammar<Iterator>::Grammar() [with Iterator=__gnu_cxx::__normal_iterator<const char *, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>]" at line 92 of "test.cpp" I can't make sense of this, as it works fine with gcc or Visual Studio. The original file is far bigger, but this is the smallest grammar I could make that displays this error... If someone knows... Matthieu -- Information System Engineer, Ph.D. Blog: http://matt.eifelle.com LinkedIn: http://www.linkedin.com/in/matthieubrucher Music band: http://liliejay.com/

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Re: [Boost-users] [IPC Named Mutex]
by Lorenzo Trivelli 21 Jul '15

21 Jul '15

Good evening, I've further investigated innto the possible solution I found out to get system boot time under win machines (even if my last post did not have so much success :-D ) After some tries, it seems that the boot time is not always the same, but they are different ALWAYS by 1 ms,Usually in my experience a machine does not boot every 1 ms (:-D) so a possible workaround would be: 1) compute boot time 2) try to open the shared folders with the given boot time 3) if fails, try to add or subtract one ms and repet step 2, if all of them failes then you are sure that id does not exist may it work or is it too cumbersome ? regards L. Trivelli

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asio: async_write handler not called in Linux but called in Windows
by Lloyd 21 Jul '15

21 Jul '15

Hi, I have an application that need to work on both Windows and Linux. We are using asio for network communication (boost 1.57). In this, once the connection is established with the server, the connection handler in client executes the following async calls... boost::asio::async_read_until(Socket, stream, string("\r\n"), boost::bind(&MyConnection::HandleRead, shared_from_this(), boost::asio::placeholders::error)); ... ... ... boost::asio::async_write(Socket,boost::asio::buffer(buff,len), boost::bind(&MyConnection::HandleWrite,shared_from_this(), boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); On Windows, the "HandleWrite" function is called as soon as the data is written. But on Linux this function never gets called!. In Linux and Windows HandleRead is getting called as expected. In bot the the case, the server receives the data properly. Is there any reason for this? Thanks, Lloyd

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Log: Filter expression in file stream init
by Florian Lindner 20 Jul '15

20 Jul '15

Hello, I have this piece of code: http://pastebin.com/iMyyaB6a It adds a file and a console log and reads in a file config: [Core] # Filter="%Severity% > 1" [Sinks.MyConsoleSink1] Destination=Console and prints some messages: using namespace boost::log::trivial; boost::log::sources::severity_logger<severity_level> lg; BOOST_LOG_SEV(lg, trace) << "A trace severity message"; BOOST_LOG_SEV(lg, debug) << "A debug severity message"; BOOST_LOG_SEV(lg, info) << "An informational severity message"; BOOST_LOG_SEV(lg, warning) << "A warning severity message"; BOOST_LOG_SEV(lg, error) << "An error severity message"; BOOST_LOG_SEV(lg, fatal) << "A fatal severity message"; It does exactly what I want, prints each message twice to the console. But when I uncomment the Filter expression it prints nothing. Why not? Severity > 1 means everything info and above, doesn't it? Thanks, Florian

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Test: Aborting at global fixture
by Florian Lindner 17 Jul '15

17 Jul '15

Hello, what is the canonical way of reporting an error that accours at the global fixture: #include <boost/test/unit_test.hpp> struct GlobalFixture { GlobalFixture() { std::cout << master.argc << std::endl; BOOST_FAIL("CRASH BOOM"); } ~GlobalFixture() { std::cout << "Global teardown\n"; } }; BOOST_GLOBAL_FIXTURE(GlobalFixture) Crashes with segfault. Thanks, Florian

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Boost.DLL formal review is ending soon - submit your reviews
by Vladimir Prus 17 Jul '15

17 Jul '15

Boosters, I wanted to remind that the formal review of Boost.DLL library by Antony Polukhin is nearing the end - the last day to submit reviews is Sunday. Of course, not much discussion is likely to happen on Sunday, so if you have any thoughts, sending them on Thursday or Friday will be much appreciated. Thanks in advance! The summary of the library features and review checklists are reproduced below. Boost.DLL is a C++98 library for comfortable work with DLL and DSO. Library provides a portable across platforms way to: - load libraries at runtime - import and export any native functions and variables - make alias names for C++ mangled functions and symbols - query libraries/objects and executables for sections and exported symbols - self loading and self querying - getting program and module location by exported symbol The documentation can be found at: http://apolukhin.github.io/Boost.DLL/index.html and the source can be obtained at: https://github.com/apolukhin/Boost.DLL Please post your reviews on the mailing list and if possible, answer the following questions: - Should the library be accepted? - How useful is it? - What's your evaluation of - Design - Implementation - Documentations - Tests - How much effort did you put into your evaluation? - Did you attempt to use the library? On what systems and compilers? Thanks, Volodya _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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