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[thread] set thread affinity
by James C. Sutherland 08 Jul '11

08 Jul '11

Is it possible to set thread affinity through boost::thread? I suspect that I am losing performance in my application because the OS is migrating threads and causing cache thrashing... James

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ct_if.hpp
by Simon Knapp 08 Jul '11

08 Jul '11

Hi List, I was looking at the file boost/pending/detail/property.hpp and noted that boost::ct_if was used therein. I think this must have come from boost/pending/ct_if.hpp (but that header is not included?), which no longer exists in boost version 1.46.1. This is the only reference to boost::ct_if I can find within the boost distribution. I was wondering if this is just old code that is not used anywhere (any more), or if I am missing something?

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[Graph] Assertion in two_bit_color_map
by Maxime van Noppen 07 Jul '11

07 Jul '11

Hi, I'm getting an assertion failure that I don't understand. /usr/include/boost/graph/two_bit_color_map.hpp:86: void boost::put(const boost::two_bit_color_map<IndexMap>&, typename boost::property_traits<PropMap>::key_type, boost::two_bit_color_type) [with IndexMap = boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_bundle_t, trade_graph::vertex, boost::no_property>, long unsigned int>, typename boost::property_traits<PropMap>::key_type = long unsigned int]: Assertion `(std::size_t)i < pm.n' failed. It's triggered by a call to dijkstra. I've attached the relevant part of the backtrace to this mail. There's a lot of code involved and can't reproduce a minimal test-case. Here's the call to dijkstra: cost_map_t cmap(boost::num_vertices(cg)); predecessor_map_t pmap(boost::num_vertices(cg)); boost::dijkstra_shortest_paths(cg, src_rp->position(), boost::predecessor_map(&pmap[0]). distance_map(&cmap[0]).weight_map( make_function_property_map<edge_t> (boost::bind(&transaction::edge_cost_, this, _1, boost::ref(g), quantity, src, dst)))); Any idea greatly appreciated, thanks! -- Maxime

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Storing vertex descriptors when removing a vertex
by Orianne Siret 07 Jul '11

07 Jul '11

Hi all, I am using the boost graph library for my project and encountered a small problem I don't know how to solve. I had to keep in an extern storage some of the vertex_descriptor in order to have access to their adjacent vertices and their properties. But as it is written in the boost documentation, when I remove a vertex, the vertex_descriptors change and I am not able to keep the right ones in my storage. Is there something else apart from vertex_descriptor that won't change but from which I could also access adjacent vertices and properties ? Thank you in advance for your help. Orianne

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More Boostcon videos available
by Marshall Clow 07 Jul '11

07 Jul '11

Monday: Micheal Wong - C++0x Progress and status http://blip.tv/boostcon/c-0x-progress-and-status-5349952 Ruediger Berlich - Distributed parametric optimization with the Geneva library http://blip.tv/boostcon/distributed-parametric-optimization-with-the-geneva… Tuesday: Joel Falcou - Automatic Hybrid MPI+OpenMP Code Generation http://blip.tv/boostcon/automatic-hybrid-mpi-openmp-code-generation-5349961 Sebastian Schaetz - Mastering the Cell Broadband Engine architecture through a Boost based parallel communication library http://blip.tv/boostcon/mastering-the-cell-broadband-engine-architecture-th… Beman Daves -- The proposed Boost B-tree library http://blip.tv/boostcon/the-proposed-boost-b-tree-library-5349968 Boris Kolpackov - Parsing C++ with GCC plugi http://blip.tv/boostcon/parsing-c-with-gcc-plugins-5349971 More next week.... -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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xml_oarchive to a iostream
by Sillence, Martin (GE Oil & Gas) 07 Jul '11

07 Jul '11

Hi, Am I missing something or is there no way to serialise to a network stream? Using the blocking method for sending and receiving I have a boost::asio::ip::tcp::iostream and need a boost::archive::xml_oarchive to serialise to/from unfortunately I can't work out how to create a xml_oarchive from the network iostream. I see from the examples most people are serialising to a buffer and then sending that but it would be much neater to be able to use a stream directly. Am I missing something or is this a gap? Thanks, M

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Threads and virtual functions
by Geoffrey 07 Jul '11

07 Jul '11

Hello, here is a simplified code I wrote: class A{ public: A(); ~A(); void Run(); void ThreadA(); virtual void HandleSomething(); }; void A::HandleSomething() { } void A::ThreadA() { if(condition) { HandleSomething(); } } void A::Run() { boost::thread thread(&A::ThreadA,this); } This is my base class. As you can see the thread calls the virtual function when the condition becomes true. I use the virtual function in my derived class so everytime the condition becomes true the function HandleSomething() should do something. So far, so good but when I try to change some variables in the derived class the program crashes without any warning or error message. I use the latest Ubuntu version with GCC 4.5.3 and boost 1.46.1.

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[chrono] Intel Composer XE 2011 unable to compile chrono library
by Edward Rankin 06 Jul '11

06 Jul '11

Hi, The purpose of this email is to get some insight on the problem we faced when trying to compile chrono from the 1.47 Beta 1 package. I have tried both the latest released compiler (2011 Update 4) and the current SP1 beta. There is no issue with VS 2010 SP1's compiler. It was first surfaced here: http://comments.gmane.org/gmane.comp.lib.boost.user/68421. The error received can be seen below: < snip > chrono.cpp .\boost/chrono/duration.hpp(94): error: expected an expression && (boost::is_convertible<Rep2, ^ .\boost/chrono/duration.hpp(124): error: expected an expression && (boost::is_convertible<Rep, ^ < snip > After some discussion with Vicente and some testing by me, it turns out that Intel was not happy with the first operand of the && operator in the following snippet of code: template <class Duration, class Rep2, bool = ( (boost::is_convertible<typename Duration::rep, typename common_type<typename Duration::rep, Rep2>::type>::value) && (boost::is_convertible<Rep2, typename common_type<typename Duration::rep, Rep2>::type>::value) ) > struct duration_divide_imp { }; If we place an additional parenthesis around that first operand like this: template <class Duration, class Rep2, bool = ( ( (boost::is_convertible<typename Duration::rep, typename common_type<typename Duration::rep, Rep2>::type>::value) ) && (boost::is_convertible<Rep2, typename common_type<typename Duration::rep, Rep2>::type>::value) ) > struct duration_divide_imp { }; It will happily compile. It is rather bizarre that this is necessary, which leads Vicente and I to believe that there is a bug in the Intel Compiler. What do you guys think? I have also posted to the Intel forums, the thread can be seen here: http://software.intel.com/en-us/forums/showthread.php?t=84061 Regards, Edward

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[units] combined systems and prefixes and output
by alfC 06 Jul '11

06 Jul '11

Hi, After some effort I managed to add a new system to boost units (namely "atomic"). The system works so far until I start using si prefixes in combination and printing int main(){ clog << 4.*atomic::hbar << endl; // output: 4 hbar clog << 4.*(si::femto*si::second) << endl; // output: 4 fs clog << 4.*(atomic::hbar/si::second) << endl; // output: 4 s^-1 hbar auto a = atomic::hbar/(si::femto*si::second); // ok clog << a << endl; // output: P(s^-1 hbar) auto b = 4.*atomic::hbar/(si::femto*si::second); // ok clog << b << endl; // error!!!! why? return 0; } As you see all lines work as expected except for the last line. Is there a workaround? do I need to define prefixes specific for the other system of units? The error message boils down to: usr/include/boost/units/detail/linear_algebra.hpp:197:48: error: no type named ‘item’ in ‘struct boost::units::list<boost::units::list<boost::units::static_rational<0l, 1l>, boost::units::list<boost::units::static_rational<1l>, boost::units::dimensionless_type> >, boost::units::dimensionless_type>::next’ also I defined hbar as struct reduced_planck_constant_base_unit : base_unit< reduced_planck_constant_base_unit, action_dimension, 3 >{ static string name(){return ("reduced Planck constant");} static string symbol() {return ("hbar");} }; static const action hbar;

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accumulators doc typo?
by Olaf Peter 06 Jul '11

06 Jul '11

Hi, at http://www.boost.org/doc/libs/1_46_1/doc/html/accumulators/user_s_guide.html in the example of section 'Droppable Accumulators' one can read // This will display "6 2 3" std::cout << sum(acc) << ' ' << count(acc) << ' ' << mean(acc); The text below says 'Note that at the point at which mean is dropped, sum is 3, count is 2, and therefore mean is 1.5'. After calculating my result is also 1.5 - the comment in the example isn't correct, isn't it? Probably the typo is in the upcoming release 1.47 too. Regards, Olaf

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