May 2014 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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[Range, Phoenix] What am I missing...
by Robert Jones 25 Apr '17

25 Apr '17

Hi Folks Can anyone explain the output of this program... #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int f( int i ) { return i * 2; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1; copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } Which is... 8 6 4 2 1768406272 1768406272 1768406272 1768406272 I'm using Gcc 4.6.2 & Boost 1.53 Thx All.

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[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

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Re: [Boost-users] lexical_cast between double and string slow in Visual Studio 2013
by David Roberts 07 May '15

07 May '15

> That issue is unknown. I'd really appreciate the investigation. I have done some more investigation, and there are two factors that only cause the slowness when they both occur together. > Try excluding the lexical_cast from test, I have a feeling that this is only MSVC related issue: > > #include <sstream> > #include <string> > > int main (int, char **) > { > for (double count = 0.0; count < 1000000.0; count += 1.41) > { > std::stringstream ss; > ss << count; > std::string result = std::move(ss.str()); > ss.str(std::string()); > > ss << result; > ss >> count; > } > > return 0; > } > Running your test program does not exhibit the problem. It runs in around 3 seconds on my machine when built with either Visual Studio 2010 or Visual Studio 2013. However, changing it very slightly to match more closely what lexical_cast does internally does recreate the problem: #include <sstream> #include <string> int main (int, char **) { for (double count = 0.0; count < 1000000.0; count += 1.41) { std::stringstream ss; ss.unsetf(std::ios::skipws); ss.precision(17); ss << count; std::string result = std::move(ss.str()); ss.str(std::string()); ss << result; ss >> count; } return 0; } The effect of setting the precision to 17 is that lots of 9s appear in the string representations. (The number 17 is what boost::detail::lcast_get_precision(double*) chooses.) Without the precision call the contents of the string called result start off like this: 0 1.41 2.82 4.23 5.64 7.05 8.46 9.87 11.28 12.69 With precision set to 17 they start off like this: 0 1.4099999999999999 2.8199999999999998 4.2299999999999995 5.6399999999999997 7.0499999999999998 8.4599999999999991 9.8699999999999992 11.279999999999999 12.69 This happens for both Visual Studio 2010 and Visual Studio 2013. Then the next difference is that Visual Studio 2013 spends a lot longer handling all the extra 9s. Changing the program so that the double is converted to a string using std::stringstream without a precision call and then back to double using lexical_cast takes about 3 seconds for both Visual Studio 2010 and Visual Studio 2013. It is the combination of having all the extra 9s to parse and using Visual Studio 2013 that makes the test using lexical_cast to go both ways slow. Both Visual Studio 2010 and Visual Studio 2013 do the conversion by calling std::num_get<char,std::istreambuf_iterator<char,std::char_traits<char> > >::do_get() which then calls a function called _Stodx() which is implemented in xstod.c. This function is very different for the two versions. In Visual Studio 2010 it's a relatively thin wrapper around the C function strtod(). In Visual Studio 2013 _Stodx() has got a completely new implementation that's generated by #including xxstod.h with some macros defined. The original C function strtod() is much faster than the new _Stodx() when there are lots of 9s at the end of the strings being parsed. This modification to the program: #include <sstream> #include <string> #include <stdlib.h> int main (int, char **) { for (double count = 0.0; count < 1000000.0; count += 1.41) { std::stringstream ss; ss.unsetf(std::ios::skipws); ss.precision(17); ss << count; std::string result = std::move(ss.str()); ss.str(std::string()); ss << result; char *endptr; count = strtod(ss.str().c_str(), &endptr); } return 0; } has a runtime of about 3 seconds even though it's got to cope with all the 9s. I guess only someone from Microsoft or Dinkumware could comment on why _Stodx() was reimplemented. But the other thing is that by setting precision to 17 lexical_cast is bloating the string representations of the doubles with lots of 9s in both Visual Studio 2010 and Visual Studio 2013. Setting precision to 15 instead prevents this, and makes the original test run faster even with Visual Studio 2013 (about 4 seconds rather than 10). Regards, David

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Statechart serialization
by mbrodeur65 04 Mar '15

04 Mar '15

Hi, I'm looking for a solution to serialize boost::statechart objects. I'm aware that this feature is on the statechart library todo list but was wondering if there are any workaround to achieve this with the latest boost release (1.34) ? thanks for your help ! mbrodeur65 -- View this message in context: http://www.nabble.com/Statechart-serialization-tf4131326.html#a11749139 Sent from the Boost - Users mailing list archive at Nabble.com.

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NT² 3.0 and Boost.SIMD - Stable release
by Joel Falcou 21 Nov '14

21 Nov '14

The first stable release of the 3.x series of MetaScale’s open-source software is available: NT² 3.0. It also includes its spin-off project, Boost.SIMD (not yet a Boost library). Many Issues have been closed since last beta. The main focus of this release cycle was to fix performances issues and to stabilize some parts of the API. Next step will be to separate NT2 and Boost.SIMD into separate repositories, thus making one more step toward Boost.SIMD submission into review. [ http://www.metascale.org/nt%C2%B2-3-0-and-boost-simd ] *Changes & Bug Fixes:* - Major performance improvements in both libraries - Added experimental support for the HPX runtime for parallelization on shared memory systems - Optimizations of many elemental functions, in particuler log/ex, frexp/ldexp and cbrt - More advanced shuffle pattern recognition for SIMD - Fixed issues with Visual Studio 2013 - More functions are force-inlined to ensure good performance - New functions for conversion between types and mixing of vectors of different sizes - Demo applications usable as benchmarks - Better handling of errors when an unsupported function is called - New API for custom memory allocators Full changelog is available at https://github.com/MetaScale/nt2/releases/tag/3.0.0. *How to get it ?* - Source and binary packages can be downloaded here: http://nt2.metascale.org/downloads - The release is also available on Github : https://github.com/MetaScale/nt2/releases - The main master branch is still under development : https://github.com/MetaScale/nt2

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[Thread] Read-write locks
by lfrfly＠icqmail.com 18 Sep '14

18 Sep '14

I'm trying to create a standard read/write lock using Boost Threads, and I'm having a bit of difficulty mapping the Boost concepts onto the usual ones. A read/write lock should have several states: Locked for reading (multiple threads may lock at once), locked for writing (only one thread may lock, and no threads may be locked for reading at the same time), and unlocked. Ideally it would be nice if an RWL which is locked for reading may temporarily upgrade to locked for writing, then return to the locked for reading state. Boost supports several relevant notions of locking: shared locking, upgrade locking, and exclusive locking. This to me is a confusing distinction. In particular, a shared_mutex seems appropriate as the basis for a RWL, but is lock_upgrade() the equivalent of a write lock and lock_shared the equivalent of a read lock? This is unclear. If "upgrade locking" is not the same as "exclusive locking", then is an upgrade lock actually exclusive? Could someone please clarify this.

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[Statechart] How to decide between post_event and process_event atrun time ?
by Philippe DAVID 22 Jul '14

22 Jul '14

Hi, I have a method in which I want to post/process an event. The thing is, this method can be called from outside the state machine (so I need to call process_event), or indirectly by a reaction of the state machine (in this case I must call post_event since process_event is not reentrant). I don't want to write 2 distinct methods to do this (one that calls post, and the other process), I would much rather prefer adding a 'if' in my method that tells me if I have to call process_event or post_event (if I'm being called indirectly by the state machine or not). Is there a way to do this with statechart ? regards, Philippe

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[Log] Extract severity value
by Olivier Tournaire 17 Jul '14

17 Jul '14

Hi all, I am trying to extract severity level from a log record, but i seems that I am doing it the wrong way. Here is the code I use: void LogDockWidget::receiveLog(boost::log::record_view const& rec, const std::string& log) { logging::value_ref< logging::trivial::severity_level > level = logging::extract< logging::trivial::severity_level >("Severity", rec); // ... } Here level.get() always returns "info". All my logs are done with the BOOST_LOG_TRIVIAL(...) macro. The formatter whereas displays correctly the severity level. Here is how it is defined: void LogDockWidget::init_logging() { boost::shared_ptr< logging::core > core = logging::core::get(); typedef sinks::synchronous_sink< QTextEditFormattedSinkBackend > sink_t; boost::shared_ptr< sink_t > sink(new sink_t); // ... logging::add_file_log( keywords::file_name = logFilename, keywords::auto_flush = true, keywords::format = ( BUILD_LOG_FORMATTER() ) ); sink->set_formatter( BUILD_LOG_FORMATTER() ); core->add_sink(sink); // Add attributes that we will use logging::add_common_attributes(); core->add_global_attribute( "ThreadID", attrs::current_thread_id()); } #define BUILD_LOG_FORMATTER() \ expr::stream \ << "[" << expr::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d %H:%M:%S") << "] " \ << expr::attr<unsigned int>("LineID") << " " \ << ": <" << logging::trivial::severity << "> " \ << " [" << expr::attr<attrs::current_thread_id::value_type>("ThreadID") << "] " \ << expr::if_(expr::has_attr(scope_attribute)) \ [ \ expr::stream << "[" << scope_attribute << "] " \ ] \ << expr::message Could you please let me know what I am doing wrong? Regards, Olivier

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[Graph] Newbie on A*
by Sensei 04 Jul '14

04 Jul '14

Dear all, I am fiddling with the A* example on cities in order to learn how to use the A* search. Obviously, I cannot make it work :) The main goal is this, but I'm way too far from this: make A* fail when the path is longer, **not costlier**, than a constant. But right now I'd just like to have A* working on a graph. :) In order to see the different results, I've paired it with a Dijkstra search, and my A* heuristics is quite simple: constant. Dijkstra works fine, but A* stops at the first node, and the target isn't reached (but a path is available). What am I doing wrong? Forgive me if I'm making a stupid mistake bu I'm completely a newbie! If you need the graph, here's the link: https://dl.dropboxusercontent.com/u/15635416/g.txt Thanks! #include <cstdio> #include <cstdlib> #include <iostream> #include <utility> #include <algorithm> #include <numeric> #include <deque> #include <unordered_set> #include <vector> #include <fstream> #include <list> #include <boost/graph/graph_traits.hpp> #include <boost/graph/compressed_sparse_row_graph.hpp> #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/graph/breadth_first_search.hpp> #include <boost/graph/depth_first_search.hpp> #include <boost/pending/indirect_cmp.hpp> #include <boost/range/irange.hpp> #include <boost/property_map/property_map.hpp> #include <boost/graph/astar_search.hpp> // Properties: weights are int typedef boost::property<boost::edge_weight_t, int> edge_weight; // The graph itself as a compressed sparse row matrix typedef boost::compressed_sparse_row_graph<boost::bidirectionalS, boost::no_property, edge_weight> boost_graph; // Vertex iterator typedef boost::graph_traits<boost_graph>::vertex_iterator vertex_iterator; // Edge iterator typedef boost::graph_traits<boost_graph>::edge_iterator edge_iterator; // Adjacent nodes iterator typedef boost::graph_traits<boost_graph>::adjacency_iterator adjacency_iterator; typedef boost::graph_traits<boost_graph>::out_edge_iterator outward_iterator; typedef boost::graph_traits<boost_graph>::in_edge_iterator inward_iterator; // Property maps typedef boost::property_map<boost_graph, boost::vertex_index_t>::type index_map; //typedef boost::property_map<boost_graph, boost::vertex_name_t> name_map; // Property iterators typedef boost::iterator_property_map<std::size_t*, index_map, std::size_t, std::size_t&> predecessor_map; typedef boost::iterator_property_map<std::size_t*, index_map, std::size_t, std::size_t&> distance_map; bool isValid(std::size_t index) { return (index >= 0) && (index <= 12); } // **************************************************************************** // A* heuristics template <class graph_type> class astar_heuristic : public boost::astar_heuristic<graph_type, std::size_t> { public: typedef typename boost::graph_traits<graph_type>::vertex_descriptor vertex_type; astar_heuristic(vertex_type goal) : goal_(goal) { }; std::size_t operator()(vertex_type u) { return 3; } private: vertex_type goal_; }; // Class to be used to terminate the A* algorithm class exit_astar { public: exit_astar(bool found) { }; }; // A* visitor that terminates when we find the goal template <class vertex_type> class astar_visitor : public boost::default_astar_visitor { public: astar_visitor(vertex_type goal) : goal_(goal) { }; template <class Graph> void examine_vertex(vertex_type u, Graph& g) { //std::cout << "EXAM: " << u << std::endl; if (u == goal_) throw exit_astar(true); } private: vertex_type goal_; }; // **************************************************************************** int main(int argc, const char * argv[]) { std::vector<std::pair<std::size_t, std::size_t>> graph_edges; std::vector<int> edge_weight; int n_nodes; int read_a, read_b, read_w; n_nodes = -1; std::ifstream igraph("/Users/senseiwa/Documents/Projects/scratch/tbb/g.txt"); while(igraph >> read_a >> read_b >> read_w) { if (read_a > n_nodes) n_nodes = read_a; if (read_b > n_nodes) n_nodes = read_b; read_a--; read_b--; graph_edges.push_back(std::make_pair(read_a, read_b)); edge_weight.push_back(read_w); } std::cout << "+++ READ # NODES: " << n_nodes << std::endl; // Create the graph boost_graph graph(boost::edges_are_unsorted_multi_pass, graph_edges.begin(), graph_edges.end(), edge_weight.data(), n_nodes); std::cout << "Graph statistics: " << std::endl; std::cout << "Nodes: " << boost::num_vertices(graph) << std::endl; std::cout << "Edges: " << graph_edges.size() << std::endl; edge_iterator ei, ee; std::size_t source_node = std::stoul(argv[1]); std::size_t destination_node = std::stoul(argv[2]); std::cout << ">> SOURCE NODE " << source_node << std::endl; std::cout << "Degrees in/out: " << source_node << std::endl; std::cout << boost::in_degree(boost::vertex(source_node, graph), graph) << std::endl; std::cout << boost::out_degree(boost::vertex(source_node, graph), graph) << std::endl; std::cout << "Degrees in/out: " << destination_node << std::endl; std::cout << boost::in_degree(boost::vertex(destination_node, graph), graph) << std::endl; std::cout << boost::out_degree(boost::vertex(destination_node, graph), graph) << std::endl; std::vector<std::size_t> preds(boost::num_vertices(graph)); std::vector<std::size_t> dists(boost::num_vertices(graph)); index_map idx_map = boost::get(boost::vertex_index, graph); predecessor_map pred_map(preds.data(), idx_map); distance_map dist_map(dists.data(), idx_map); boost::dijkstra_shortest_paths(graph, source_node, boost::distance_map(dist_map).predecessor_map(pred_map)); typedef std::vector<boost_graph::edge_descriptor> path_type; path_type spath; std::cout << ">> SOURCE NODE " << source_node << std::endl; std::cout << ">> DESTINATION NODE " << destination_node << std::endl; // ******* DIJKSTRA ******************************************************** std::size_t v = destination_node; // We want to start at the destination and work our way back to the source for(std::size_t u = pred_map[v]; // Start by setting 'u' to the destintaion node's predecessor u != v; // Keep tracking the path until we get to the source v = u, u = pred_map[v]) // Set the current vertex to the current predecessor, and the predecessor to one level up { std::pair<boost_graph::edge_descriptor, bool> edgePair = boost::edge(u, v, graph); boost_graph::edge_descriptor edge = edgePair.first; spath.push_back(edge); } // Write shortest path int totalDistance = 0; for(path_type::reverse_iterator pathIterator = spath.rbegin(); pathIterator != spath.rend(); ++pathIterator) { std::cout << boost::source(*pathIterator, graph) << " - " << boost::target(*pathIterator, graph) << " = " << boost::get(boost::edge_weight, graph, *pathIterator) << std::endl; totalDistance += boost::get(boost::edge_weight, graph, *pathIterator); } std::cout << "Shortest Dijkstra path from " << source_node << " to " << destination_node << " cost " << totalDistance << std::endl; // ******* A* ************************************************************** // A* search predecessor and cost std::vector<std::size_t> p(boost::num_vertices(graph)); std::vector<std::size_t> d(boost::num_vertices(graph)); try { // A* parameter interface astar_search(graph, source_node, astar_heuristic<boost_graph>(destination_node), boost::predecessor_map(&p[0]).distance_map(&d[0]).visitor(astar_visitor<std::size_t>(destination_node))); } catch(exit_astar fg) { std::list<std::size_t> shortest_path; for(std::size_t v = source_node; ; v = p[v]) { shortest_path.push_front(v); if(p[v] == v) break; } auto spi = shortest_path.begin(); std::cout << "node " << source_node << std::endl; for(++spi; spi != shortest_path.end(); ++spi) std::cout << "node " << *spi << std::endl; std::cout << "Shortest A* path from " << source_node << " to " << destination_node << " cost " << d[destination_node] << std::endl; std::cout << shortest_path.size() << std::endl; return 0; } std::cout << "Didn't find a path from " << source_node << "to" << destination_node << "!" << std::endl; return 0; } +++ READ # NODES: 200 Graph statistics: Nodes: 200 Edges: 4000 >> SOURCE NODE 1 Degrees in/out: 1 0 35 Degrees in/out: 192 39 1 >> SOURCE NODE 1 >> DESTINATION NODE 192 1 - 47 = 2 47 - 91 = 3 91 - 120 = 1 120 - 175 = 1 175 - 192 = 10 Shortest Dijkstra path from 1 to 192 cost 17 node 1 Shortest A* path from 1 to 192 cost 17 1

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Why does async_connect() call listen()?
by Soren Dreijer 01 Jul '14

01 Jul '14

Hi there, By coincidence, I ended up looking at a stack trace where my application calls async_connect() on a asio::ip::tcp::socket. Two things took me by surprise: 1. Asio calls listen() under the hood. Why does it do that when I'm just trying to make an outbound TCP connection? 2. If the listen() call above is indeed required, why does it happen on the same thread where I call async_connect()? I thought the point of the method was to defer the work to the reactor? (For what it's worth, I've had a case on a customer's machine where the call to listen() would hang for 30 seconds before returning -- probably because of a bad firewall -- causing my entire app to hang since the code assumes async_connect() is indeed async.) I've included the full stack trace below. Thanks, Soren 0:000> k ChildEBP RetAddr 0117db50 0f681c65 WS2_32!listen 0117db70 0f691013 EvoClr!boost::asio::detail::socket_ops::listen+0x35 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_ops.ipp @ 658] 0117dbd8 0f690e9f EvoClr!boost::asio::detail::socket_select_interrupter::open_descriptors+0x163 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_select_interrupter.ipp @ 78] 0117dbe4 0f690cc0 EvoClr!boost::asio::detail::socket_select_interrupter::socket_select_interrupter+0xf [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\socket_select_interrupter.ipp @ 42] 0117dc1c 0f690c1e EvoClr!boost::asio::detail::select_reactor::select_reactor+0x70 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\select_reactor.ipp @ 48] 0117dc44 0f17837e EvoClr!boost::asio::detail::service_registry::create<boost::asio::detail::select_reactor>+0x4e [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.hpp @ 81] 0117dc80 0f6909e9 EvoClr!boost::asio::detail::service_registry::do_use_service+0x9e [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.ipp @ 123] 0117dca0 0f6908ee EvoClr!boost::asio::detail::service_registry::use_service<boost::asio::detail::select_reactor>+0x39 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\service_registry.hpp @ 49] 0117dca8 0f68fab0 EvoClr!boost::asio::use_service<boost::asio::detail::select_reactor>+0xe [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\impl\io_service.hpp @ 34] 0117dcbc 0f68f731 EvoClr!boost::asio::detail::win_iocp_socket_service_base::get_reactor+0x30 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\win_iocp_socket_service_base.ipp @ 620] 0117dce4 0f68f6f1 EvoClr!boost::asio::detail::win_iocp_socket_service_base::start_connect_op+0x11 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\impl\win_iocp_socket_service_base.ipp @ 550] 0117dd28 0f68ed22 EvoClr!boost::asio::detail::win_iocp_socket_service<boost::asio::ip::tcp>::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0xc1 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\detail\win_iocp_socket_service.hpp @ 515] 0117dd68 0f68c41a EvoClr!boost::asio::stream_socket_service<boost::asio::ip::tcp>::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0x52 [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\stream_socket_service.hpp @ 234] 0117ddec 0f68a32e EvoClr!boost::asio::basic_socket<boost::asio::ip::tcp,boost::asio::stream_socket_service<boost::asio::ip::tcp> >::async_connect<boost::_bi::bind_t<void,boost::_mfi::mf1<void,Swift::BoostConnection,boost::system::error_code const &>,boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Swift::BoostConnection> >,boost::arg<1> > > >+0x11a [c:\private\src\vendor\boost_1_55_0_sdk\include\boost\asio\basic_socket.hpp @ 779] 0117de9c 0f210146 EvoClr!Swift::BoostConnection::connect+0x11e [c:\private\src\vendor\swift\swiften\network\boostconnection.cpp @ 70]

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Autobahn for C++: RPC and PubSub
by Tobias Oberstein 24 Jun '14

24 Jun '14

Hi, I'm happy to anounce Autobahn|Cpp - another subproject of Autobahn (http://autobahn.ws) this time for C++ 11 / Boost. Autobahn|Cpp allows remote procedure calls and publish & subscribe messaging for C++ application components and uses boost::future, continuations and Boost/ASIO as underlying network library. Here is how app code looks like: https://github.com/tavendo/AutobahnCpp/blob/master/README.md#show-me-some-c… Using Autobahn|Cpp, you can e.g. call your C++ code from JavaScript running in a browser. And much more. This is an early alpha version, things aren't fully hashed out, but there are a couple of examples included here: https://github.com/tavendo/AutobahnCpp/blob/master/README.md#examples Cheers, /Tobias

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[Python]compiling python library
by Miklós Tóth 19 Jun '14

19 Jun '14

Hi All, I want to embed python in my c++ code using boost.python library. As far as I understand I need python headers and libs. So my python27.lib is "incompatible". I want to compile it from code but I failed with mingw32. Could you give me some advice, or links to achieve my goal? I'm using gcc4.6.3 and qt 4.8.2 and boost 1.49 on windows 7. Thanks, Miklós

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Sanity check please?: Boost 1_55_0 and building VS2012 static libs?
by g4＠novadsp.com 04 Jun '14

04 Jun '14

Revisiting Boost after a long absence. Any thoughts on the following problem(s)? W7x64 with VS2008,2010,2012 and 2013 installed. VS2012 preferred for regular use. Built with boostrap and b2 b2 -link=static -runtime-link=static -toolset=msvc-11.0. I compile a debug test app with /MTd and attempt to link with libboost_system-vc110-mt-gd-1_55.lib which is the only library close to matching the ABI tag specified here : http://www.boost.org/doc/libs/1_55_0/more/getting_started/windows.html#id46 Ensuing link errors are: 1>libboost_system-vc110-mt-gd-1_55.lib(error_code.obj) : error LNK2038: mismatch detected for '_ITERATOR_DEBUG_LEVEL': value '2' doesn't match value '0' in tcpproxy_server.obj 1>libboost_system-vc110-mt-gd-1_55.lib(error_code.obj) : error LNK2038: mismatch detected for 'RuntimeLibrary': value 'MDd_DynamicDebug' doesn't match value 'MT_StaticRelease' in tcpproxy_server.obj 1>LINK : warning LNK4098: defaultlib 'MSVCRTD' conflicts with use of other libs; use /NODEFAULTLIB:library Many thanks.

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Re: [Boost-users] [serialization] deserialized instance empty even though proper serialize methods called
by Hickman, Steve (AdvTech) 31 May '14

31 May '14

From: Robert Ramey [mailto:robertmacleranramey@gmail.com] Sent: Friday, May 30, 2014 3:43 PM To: boostusers(a)googlegroups.com Cc: robertmacleranramey(a)gmail.com; boost-users(a)lists.boost.org; boost-users(a)lists.boost.org; Hickman, Steve (AdvTech) Subject: Re: [Boost-users] [serialization] deserialized instance empty even though proper serialize methods called On Friday, May 30, 2014 2:37:00 PM UTC-7, Hickman, Steve (AdvTech) wrote: I corrected the problem with the DLL import. That had no discernible effect. lol - you didn't tell me there was a problem with DLL import. The issue here was link warnings due to the fact that I was importing back into the DLL exported interfaces. I fixed this by changing how my DLL import macros in my header files expand for the library being built. When used in the library, they expand to nothing, otherwise they expand to “__declspec(dllimport)”. The actual function definitions in the .cpp files always expand to “__declspec(dllexport)” when the library is built as a DLL. It does not throw an unregistered_cast() exception (which it seems like it should). Consider filing a trac item for this. Done this strongly suggests a problem with EXPORT ing the derived class. Note that that each DLL contains it's own casting table. Of hand I don't remember which EXPORT s get added to which table. Certainly the EXPORT IMPLEMENT should be the *cpp file which is part of the DLL. It is One way to test this would be to verify that the static library build/test works. This always has only one table so such problem wouldn't come up. Building/linking my library statically does solve the problem. And it works for the application I need to use it for, so I’m going with that approach for now. . But it still leaves open the question of why we're getting to this point. There are two approaches to a problem like this: a) Just "make it work" by adding stuff until it seems to work. This is the approach favored by management. Given my current time constraints, using a static library works and will be my approach until I see it break. b) Get to the bottom of it and fix it once it once an for all - and add notes/comments and/or tests to make sure the bugger stays dead. This is the approach favored by (unemployed) programmers. And since I’m trying to avoid unemployment, I’ll have to delay this for now. The former seems to work - but the problem keeps sucking up time in the future. The latter is tedious and frustrating - but this keeps one from getting stuck in a dead end job constantly fixing the same problems. Robert Ramey --- Steve H.

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[boost.msm] BOOST_MSM_EUML_DECLARE_STATE_MACHINE with state base class
by Stefan Näwe 31 May '14

31 May '14

Hi there, I use MSM from boost 1.49 with VC9 on Windows XP. I want to use the eUML front end. My states shall use a polymorphic base class and are defined like this: // State base class struct Worker { virtual void work() = 0; }; // a state struct Running_ : msmf::state<Worker>, euml_state<Running_> { void work() { ... } } const Running; My transition table is defined with BOOST_MSM_EUML_TRANSITION_TABLE() My state machine is defined like this: BOOST_MSM_EUML_DECLARE_STATE_MACHINE(( trans_table, init_ << AnyState, no_action, // fsm_entry no_action, // fsm_exit attributes_ << one_attr << another_attr, configure_ << no_configure_, Log_No_Transition, Log_Exception), MyFSM_fe) struct FSM : msmb::state_machine<MyFSM_fe> {}; All OK until here. But now I want to add the state base class to the above invocation of BOOST_MSM_EUML_DECLARE_STATE_MACHINE to be able to say : fsm.get_state_by_id(fsm.current_state()[0])->work() at any given time. BOOST_MSM_EUML_DECLARE_STATE_MACHINE(( trans_table, init_ << Running, no_action, // fsm_entry no_action, // fsm_exit attributes_ << one_attr << another_attr, configure_ << no_configure_, Log_No_Transition, Log_Exception, Worker), MyFSM_fe) But this gives me a compile error: C2275: 'Worker' : illegal use of this type as an expression. Is there any way to achieve what I need ? Can I somehow _NOT_ use the macro and create the same state machine (i.e. with attributes!) ? Thanks for any help! Stefan -- ---------------------------------------------------------------- /dev/random says: A Bugless Program is an Abstract Theoretical Concept. python -c "print '73746566616e2e6e616577654061746c61732d656c656b74726f6e696b2e636f6d'.decode('hex')" GPG Key fingerprint = 2DF5 E01B 09C3 7501 BCA9 9666 829B 49C5 9221 27AF

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Directed graph, incoming edges
by Jeremy Murphy 31 May '14

31 May '14

Just wondering what people generally do when they want to model a directed graph but they also want efficient access to the incoming edges of a vertex? Make a bidirectional graph and store directionality as a property of an edge? Thanks, cheers. Jeremy

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Re: [Boost-users] [serialization] deserialized instance empty even though proper serialize methods called
by Hickman, Steve (AdvTech) 30 May '14

30 May '14

I corrected the problem with the DLL import. That had no discernible effect. FWIW, I also note at this point that I have set all serializable classes to BOOST_CLASS_IMPLEMENTATION(fully_qualified_classname,boost::serialization::object_serializable); because I don’t save any of the archives. Since I’m only using this for immediate “over the wire” communication, I don’t need backwards compatibility. On the tracking bug: It would also be interesting to run your own test with the default tracking behavior to see if the symptom disappears. I set up to run with default tracking behavior. This had no discernible effect on stopping pointer_tweak (line 527 in iserializer.hpp) from nullifying the pointer to the deserialized instance. I didn’t look to see if it had an impact on the tracking flag (not certain how I would know since now tracking *should* be on) In the .cpp files of all serialized classes. This shouldn’t matter because I never read references to prior instances As far as we know. I never reference prior instances because, at least for the tests I’m running, the data structures don’t contain pointers. They do contain members that are also defined in the library. These members are never, at least in the tests I’m running, handled via pointers. In addition, I using this facility to serialize data that I send “over the wire” one data structure at a time. In each case I open a new archive to serialize one data structure instance, then extract the buffer created and close the archive. Similarly, on the receiving side, I open an archive for each structure I deserialize, do the deserialization, then close the archive (in both cases the archive stack variables go out of scope). It may be that on the receive side that there is some static data in the serialization library that thinks it needs to turn serialization on – I don’t know. I haven’t dug into that. Using/not using tracking is subservient to actually getting the deserialized data, so I’ll leave it with the default behavior for now. There remains the core problem that the call to pointer_tweak on line 527 of iserailzer.hpp causes the t pointer (the one containing the deserialized data) to be nullified. Digging into pointer_tweak, it appears that the problem lies in void_upcast(lines 314-334) in void_cast.cpp. While it receives the appropriate type information for both the base and derived class, it cannot find any info in the void_caster_register (which has size zero) to tell it how to convert one to the other, so it returns null. (line 333). It does not throw an unregistered_cast() exception (which it seems like it should). Could the problem lie in that because this is a DLL, its singletons (like void_caster_registry) are singletons across all EXEs that use that DLL ? Microsoft doc seems to indicate that isn’t the case (see http://msdn.microsoft.com/en-us/library/h90dkhs0(v=vs.90).aspx ) by default at least. If there is a problem here, I could envision the following scenario: In my case, both the serializing and deserializing EXEs are running in parallel, so they could be affecting any static data in the DLL. In particular, they both could be updating and clearing the void_caster_registry. If void_caster::recursive_unregister() has been called by the serializing EXE, it may not contain anything that is now needed by the deserializing EXE. Does that make sense? Is that possible? Regardless of what is causing the problem, should this be solvable by adding the explicit // method 2 : explicitly register base/derived relationship boost::serialization::void_cast_register<derived, base>( static_cast<derived *>=NULL), static_cast<base *>(NULL) to all my serialize methods? It doesn’t fix it for me(I added the appropriate calls as the first statement after a logging statement in all the serialize methods). Furthermore, the void_cast_registry still has size 0. --- Steve H.

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date_time: nth friday of month
by MM 30 May '14

30 May '14

Hello, Is there an object that encodes "second friday of month", rather than "second friday of april"? Then you would pass to it month + year to get a date? If not, how would I implement such a type? Extend nth_day_of_the_week_in_month? Thanks,

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how to correctly compile and use math module (for gmp) (b1.55 win32)
by eaj68 30 May '14

30 May '14

When compiling only regex module all works ok, but when I substitute 'math' for regex in command i get this: b2 -a --debug-configuration --prefix=C:\boost --address-model=32 --with math --layout=tagged toolset=gcc variant=release link=static threading=single runtime-link=static optimization=off notice: found boost-build.jam at C:/boost/boost-build.jam notice: loading Boost.Build from C:/boost/tools/build/v2 notice: Searching 'C:\WINDOWS' 'C:\Documents and Settings\Administrator' 'C:\Documents and Settings\Administrator' 'C:\boost\tools/build/v2' 'C:/boost/tools/build/v2/kernel' 'C:/boost/tools/build/v2/util' 'C:/boost/tools/build/v2/build' 'C:/boost/tools/build/v2/tools' 'C:/boost/tools/build/v2/contrib' 'C:/boost/tools/build/v2/.' for site-config configuration file 'site-config.jam'. notice: Loading site-config configuration file 'site-config.jam' from 'C:/boost/tools/build/v2'. notice: Searching 'C:\Documents and Settings\Administrator' 'C:\Documents and Settings\Administrator' 'C:\boost\tools/build/v2' 'C:/boost/tools/build/v2/kernel' 'C:/boost/tools/build/v2/util' 'C:/boost/tools/build/v2/build' 'C:/boost/tools/build/v2/tools' 'C:/boost/tools/build/v2/contrib' 'C:/boost/tools/build/v2/.' for user-config configuration file 'user-config.jam'. notice: Loading user-config configuration file 'user-config.jam' from 'C:/boost/tools/build/v2'. notice: Searching '.' for project-config configuration file 'project-config.jam'. notice: Loading project-config configuration file 'project-config.jam' from '.'. warning: toolset msvc initialization: can not find tool cl.exe warning: initialized from project-config.jam:3 notice: will use 'cl.exe' for msvc, condition <toolset>msvc notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>/<address-model>', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>/<address-model>32', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>x86/<address-model>', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>x86/<address-model>32', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>/<address-model>64', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>x86/<address-model>64', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>ia64/<address-model>', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>ia64/<address-model>64', setup: '' notice: [msvc-cfg] condition: '<toolset>msvc/<architecture>arm/<address-model>32', setup: '' notice: [cmdline-cfg] toolset gcc not previously configured; attempting to auto-configure now notice: will use 'g++' for gcc, condition <toolset>gcc-4.10.0-mingw notice: using gcc libraries :: <toolset>gcc-4.10.0-mingw :: C:\gcc/bin C:\gcc/lib C:\gcc/lib32 C:\gcc/lib64 warning: toolset gcc initialization: can not find tool C:/gcc/i686-pc-mingw32/bin/ar.exe warning: initialized from notice: using gcc archiver :: <toolset>gcc-4.10.0-mingw :: C:/gcc/i686-pc-mingw32/bin/ar.exe warning: toolset gcc initialization: can not find tool C:/gcc/i686-pc-mingw32/bin/ranlib.exe warning: initialized from notice: using gcc ranlib :: <toolset>gcc-4.10.0-mingw :: C:/gcc/i686-pc-mingw32/bin/ranlib.exe notice: using rc compiler :: <toolset>gcc-4.10.0-mingw :: C:\gcc\bin\windres.exe link.jam: No such file or directory notice: [zlib] Using pre-installed library notice: [zlib] Condition notice: iostreams: not using bzip2 compression notice: iostreams: not using bzip2 compression notice: [python-cfg] Configuring python... notice: [python-cfg] Registry indicates Python 2.6 installed at "C:\Python26\" notice: [python-cfg] Checking interpreter command "python"... notice: [python-cfg] running command 'python -c "from sys import *; print('version=%d.%d\nplatform=%s\nprefix=%s\nexec_prefix=%s\nexecutable=%s' % (version_info[0],version_info[1],platform,prefix,exec_prefix,executable))" 2>&1' notice: [python-cfg] ...does not invoke a working interpreter notice: [python-cfg] Checking interpreter command "C:\Python26\python"... notice: [python-cfg] running command 'C:\Python26\python -c "from sys import *; print('version=%d.%d\nplatform=%s\nprefix=%s\nexec_prefix=%s\nexecutable=%s' % (version_info[0],version_info[1],platform,prefix,exec_prefix,executable))" 2>&1' notice: [python-cfg] ...does not invoke a working interpreter notice: [python-cfg] No working Python interpreter found. notice: [python-cfg] falling back to "python" notice: [python-cfg] Details of this Python configuration: notice: [python-cfg] interpreter commanC: "python" notice: [python-cfg] include path: "Include" notice: [python-cfg] library path: "\libs" notice: [python-cfg] DLL search path: "<empty>" error: Unable to find file or target named error: 'libs/math/build//boost_math' error: referred to from project at error: '.' compiling all the modules without `--where` switch seems to work ok and produce these modules: libboost_atomic-mt-s.a libboost_chrono-mt-s.a libboost_chrono-s.a libboost_coroutine-s.a libboost_date_time-s.a libboost_exception-s.a libboost_filesystem-s.a libboost_graph-s.a libboost_iostreams-s.a libboost_locale-mt-s.a libboost_log_setup-s.a libboost_log-s.a libboost_math_c99f-s.a libboost_math_c99l-s.a libboost_math_c99-s.a libboost_math_tr1f-s.a libboost_math_tr1l-s.a libboost_math_tr1-s.a libboost_prg_exec_monitor-s.a libboost_program_options-s.a libboost_random-s.a libboost_regex-s.a libboost_serialization-s.a libboost_signals-s.a libboost_system-mt-s.a libboost_system-s.a libboost_test_exec_monitor-s.a libboost_thread-mt-s.a libboost_timer-s.a libboost_unit_test_framework-s.a libboost_wave-s.a libboost_wserialization-s.a but when I try to make an appication that uses gmp: (from : http://www.boost.org/doc/libs/1_53_0/libs/multiprecision/doc/html/boost_mul… ) that is only the include part to see it works: #include <iostream> #include <boost/multiprecision/gmp.hpp> int main() { return 0; } I get: In file included from C:\boost_gmp_test.cpp:2:0: c:\boost/boost/multiprecision/gmp.hpp:19:17: fatal error: gmp.h: No such file or directory #include <gmp.h> ^ compilation terminated. But I am sure that I have correctly installed boost ang GCC because regex module compiles and works without any issue. -- View this message in context: http://boost.2283326.n4.nabble.com/how-to-correctly-compile-and-use-math-mo… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [serialization] deserialized instance empty even though proper serialize methods called [Honeywell Internal]
by Hickman, Steve (AdvTech) 30 May '14

30 May '14

Classification: Honeywell Internal I should have been more explicit in my original post. All serialization/deserialization is being done with base class pointers. I have a set of tests where I discovered the problems of serializing/deserializing with different pointer types that you identify below - so I've avoided that. What you suggest for the test program is essentially what I've done in my tests. One thing I did find in review is that somehow the serialize methods were marked protected rather than private. Fixing that partially corrected the problem. Now the deserialization "sticks" for all of the base class objects deserialized through the base class pointer (the data is in the fields after exiting the serialize process). For derived class objects deserialized through a base class pointer, I'm using xml_archive and stepping through the code. Here's what I see: First, one thing I notice: It appears that the system thinks tracking is on (line 476 of basic_iarchive.cpp: tracking is true) even though I've consistently said BOOST_CLASS_TRACKING(fully_qualified_classname,boost::serialization::track_never); In the .cpp files of all serialized classes. This shouldn't matter because I never read references to prior instances, but it may indicate a problem. The correct constructors are called in load_construct_data and the correct serialize methods are called. Further, at the end of the derived class serializer, all the fields contain the correct data - so it is loading correctly from the archive. The deserialize works up through the return from line 516 of iserializer.hpp (call to ar.load_pointer()) (at the topmost level - I have no embedded pointers in the objects I'm using to test with). T continues to have the values loaded. The call on line 527 of iserializer.hpp to pointer_tweak() appears to be causing the problem. It returns a null pointer. This means that the second portion of the nvp at the top level is now a null pointer, and I've lost what was loaded. I should also note at this point that all of the relevant classes have virtual destructors. This is the only virtual method they have. Note that all of the methods on these classes are declared with the appropriate DLL import/export (since this is built as a DLL). I should also note that I was wrong from my final reply on my previous post that the warnings on locally defined symbol 'symbol' imported in function 'function' had disappeared. They only disappeared because I was inadvertently doing incremental links. My initial attempts to resolve this issue have not apparently been successful. While the Microsoft documentation indicates that the code will still work (but just run slower) in the presence of these warnings, is it possible that the downcast in pointer_tweak() is failing because of this? I am endeavoring to correct this, but I'm a bit surprised at how the Microsoft compiler appears to be unable to chain macro definitions. --- Steve H. From: Robert Ramey [mailto:robertmacleranramey@gmail.com] Sent: Thursday, May 29, 2014 2:03 PM To: boostusers(a)googlegroups.com Cc: robertmacleranramey(a)gmail.com; boost-users(a)lists.boost.org; boost-users(a)lists.boost.org; Hickman, Steve (AdvTech) Subject: Re: [Boost-users] [serialization] deserialized instance empty even though proper serialize methods called [Honeywell Internal] OK - this should work. But in a few rare cases it won't. Usually this due to a very unusual corner case. That case is were something isn's de-serialized exactly as it was serialized. a) serializing through a derived pointer de-serialization through a base class pointer fix - even though one knows the derived class when serializing, serialize through a pointer to the base class - effectively using an implicit cast b) some other bizarre cases I don't remember. make a pair of test program which tests your serialization. a) use xml_archives b) program A should invoke both e main(){ ... X xp1 = new X; oar << xp1; ... X xp2; iar >> xp2; assert(*xp1 == *xp2); } c) split b above into two programs Robert Ramey ============================================================================================================================================================================================================ This message classified as Honeywell Internal by Hickman, Steve (AdvTech) on Friday, May 30, 2014 at 7:33:06 AM. The above classification labels are in accordance with the Honeywell Corporate Classification Policy. The information contained in this electronic message is confidential and intended only for the use of the individual/entity named above, and the information may be privileged. If you, the reader of this message, are not the intended recipient or an employee or agent responsible to deliver this message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender and delete the original message. ============================================================================================================================================================================================================

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Fix for annoying bug / library maintenance
by Filip Konvička 30 May '14

30 May '14

Hi, https://svn.boost.org/trac/boost/ticket/4964 This is out there for years. To me this seems to be clearly explained and a fix is provided, but apparently all bugs assigned to 'bgubenko' aren't monitored (for years there has been no reaction). So is there a way of getting the fix ever applied? Or are such unmaintained libraries just doomed to eventually die, despite the efforts of the people reporting bugs and posting patches? Thanks, Filip

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[unordered] Merging unordered maps
by Pete bartlett 29 May '14

29 May '14

I have a performance hotspot when merging a few unordered_maps of the same type into a master unordered_map (also of the same type) Currently I am doing Foreach( auto const& submap ,submaps ) Master.insert( submap.begin() , submap.end() ); This seems to be somewhat wasteful because the insert is (I think) computing hashes that the submaps already "know". Can I improve on this - without changing Boost? - without changing the boost interface, but changing the implementation (eg specialising the insert for certain iterator types)? - some more intrusive change? If the second or third option, would the maintainer be willing to consider merging the change into Boost proper? Thanks, Pete

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[boost][metaprogramming] Looking for a good reference
by Kyle Ketterer 29 May '14

29 May '14

Hey all, I want to learn more about template (meta) programming. Including, type generators, adapters, etc. Looking for a good C++11 style reference. Any recommendations on books/material? Thanks

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naming a test
by Eric Prud'hommeaux 29 May '14

29 May '14

boost/libs/test/example/external_main_example_1.cpp provides an example of a dynamical test suite tree. The invocation of add( BOOST_TEST_CASE(boost::bind(&free_test_function, 1, 1))); results in unpleasant names like "boost::bind( &free_test_function, 1, 2 )" . I used the preprocessor output to override the 2nd arg to make_test_case with a name of my choosing: ts->add(boost::unit_test::make_test_case (boost::unit_test::callback0<> (boost::bind( &free_test_function, 1, 2)), boost::unit_test::const_string( minor, 1))); This works (pretty names and invocable with the logical run_test) but I have no particular confidence that this will survive version changes as well as would BOOST_TEST_CASE. Is there a better way to do this? (stand-alone example attached) -- -ericP office: +1.617.599.3509 mobile: +33.6.80.80.35.59 (eric(a)w3.org) Feel free to forward this message to any list for any purpose other than email address distribution. There are subtle nuances encoded in font variation and clever layout which can only be seen by printing this message on high-clay paper.

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