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[Thread] Using thread accross libraries
by Sébastien Gallou 28 Nov '13

28 Nov '13

Hi all, first, thanks for this great library. I'm using Boost::thread and experiencing a problem when trying to interrupt thread executed in a dynamic library (DLL, under Windows). I reproduced it in a minimal example, that I join to this post (I don't know if attachment is authorized so I also put it on my GDrive<https://drive.google.com/file/d/0B3dXqBwTbfcAQ1E0MDRfU0hxNVE/edit?usp=shari…>, and copy the code at the end of this mail). In this code, I start a thread in the main, calling a function "doWork" of a plugin, dynamically loaded. The doWork just do some sleep and wait for boost::thread_interrupted exception. The problem is that the exception is never received when the main call interrupt on the thread. If the doWork code is in the main application, all works well. Trying to debug into Boost, I'm seeing that in the interruptible_wait function, the test "if(detail::get_current_thread_data() && detail::get_current_thread_data()->interruption_enabled)" doesn't give the same result if code is in DLL (test result is false) or in the main (true). What is the reason of this behaviour ? Thanks for your help, Sébastien Gallou Here is the code : *TestBoostThread.cpp :* IPlugin* Plugin; void doWork(){ try { Plugin->doWork(); } catch (boost::thread_interrupted&) { // End-of-thread exception was not catch by plugin, // it's a developer's error, we have to report it std::cout << "Plugin didn't catch boost::thread_interrupted."; }} int main(int argc, char* argv[]){ HMODULE libraryHandle = LoadLibrary(L"Dll.dll"); boost::function<IPlugin* ()> construct = (IPlugin* (*)(void))GetProcAddress(libraryHandle, "construct"); Plugin=construct(); boost::shared_ptr<boost::thread> thread = boost::shared_ptr<boost::thread>(new boost::thread(doWork)); Sleep(1500); thread->interrupt(); thread->join(); FreeLibrary(libraryHandle); return 0;} *Dll.cpp :* class MyPlugin : public IPlugin{ virtual ~MyPlugin(){} virtual void doWork() { try { while(1) { std::cout << "MyPlugin is running..."; // Give a chance to exit plugin thread boost::this_thread::sleep(boost::posix_time::milliseconds(1000)); }; } catch (boost::thread_interrupted&) { std::cout << "MyPlugin is stopped..."; } }}; extern "C" __declspec(dllexport) IPlugin* construct(){ return new MyPlugin;}

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Hash collision for pairs of int
by Saurabh T 27 Nov '13

27 Nov '13

Hi, I'm experiencing a lot of collisions using the hash_combine function in functional/hash/hash.hpp for integer-pairs-as-keys when there are few unique ints in each of the pair's positions (put together the keys themselves are unique of course). I've uploaded a simple enough test case here: http://www.speedyshare.com/Wcem6/hash.cc.gz. If there's a more preferred way to upload, let me know and I'll reupload. With 400K pairs, this returns only 86K unique indices and has a max of 18 collisions in size_t. Am I doing something really wrong here? Thank you. saurabh

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[Graph] filters and subgraphs?
by The Maschine 27 Nov '13

27 Nov '13

Hi all, What Im trying to do is the get a filtered or subgraph that holds the properties of the original graph (vertex and edge bundles). Ill use the 'subgraph' in other algorithms but from time to time I'd like to be able to trace the original vertex_descriptor and push data back to the original graph. (that might be able to happen via the original_vertex_d below but lets see..) Below is an attempt to use graph filters to do it but for reasons that can be found in topics by others, I think this is not going to work. (filtered graph are too simple.. etc) Is it possible to use the 'distance map', that I use to produce a filtered graph, for producing a subgraph that all info from the original (minus the filtered vertexes that we dont want of course) data are there and can be also further used in algorithms? Thanks ///////////////////////////// struct VertexProperties { boost::graph_traits<unGraph>::vertex_descriptor original_vertex_d; // might be needed for the question above double m_bc; // for betweenness ..... .... }; struct EdgeProperties { double m_weight1; double m_weight2; }; typedef double Weight; typedef boost::property<boost::edge_weight_t, double> EdgeWeightProperty; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, VertexProperties, EdgeProperties> unGraph; typedef boost::graph_traits < unGraph >::vertex_descriptor Vertex; typedef boost::property_map < unGraph, boost::vertex_index_t >::type IndexMap; typedef boost::iterator_property_map < Vertex*, IndexMap, Vertex, Vertex& > PredecessorMap; typedef boost::iterator_property_map < Weight*, IndexMap, Weight, Weight& > DistanceMap; struct vertex_distance_filter { vertex_distance_filter() { } vertex_distance_filter(std::vector<Weight> distance_map, double radius) : m_dist_map(distance_map), m_radius(radius) { } bool operator()(const typename boost::graph_traits<unGraph>::vertex_descriptor& v) const { return m_radius > m_dist_map[v]; } double m_radius; std::vector<Weight> m_dist_map; }; ////// int i = 0; // simplified boost::graph_traits<unGraph>::vertex_descriptor s_vertex = boost::vertex(i, m_ugraph); // Filter std::vector<Vertex> predecessors(boost::num_vertices(m_ugraph)); std::vector<Weight> distances(boost::num_vertices(m_ugraph), std::numeric_limits<double>::max() ); IndexMap indexMap = boost::get(boost::vertex_index, m_ugraph); PredecessorMap predecessorMap(&predecessors[0], indexMap); DistanceMap distanceMap(&distances[0], indexMap); boost::dijkstra_shortest_paths(m_ugraph, s_vertex, boost::weight_map(boost::get(&EdgeProperties::m_weight1, m_ugraph)).predecessor_map(predecessorMap).distance_map(distanceMap)); vertex_distance_filter filter(distances, 400.0f); typedef boost::filtered_graph<unGraph, vertex_distance_filter> FilteredGraphType; FilteredGraphType filteredGraph(m_ugraph, filter); // Work on the filtered graph. Subgraph maybe??? std::vector< double > v_centrality_vec(boost::num_vertices(filteredGraph), 0.0); // different weight from above. here m_weight2 boost::brandes_betweenness_centrality(filteredGraph , boost::centrality_map(boost::make_iterator_property_map(v_centrality_vec.begin(),boost::get(boost::vertex_index, filteredGraph),double())).vertex_index_map(get(boost::vertex_index, m_ugraph)).weight_map(boost::get(&EdgeProperties::m_weight2, m_ugraph)) ); // here we start having problems... comments above boost::graph_traits<unGraph>::vertex_iterator vertex_iterator_begin, vertex_iterator_end; for ( boost::tie(vertex_iterator_begin, vertex_iterator_end) = vertices(filteredGraph); vertex_iterator_begin != vertex_iterator_end; ++vertex_iterator_begin) { // this is the original unfiltered graph!!!! m_ugraph[*vertex_iterator_begin].m_bc = v_centrality_vec[*vertex_iterator_begin]; }

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[log] switching from n loggers to 1
by Eric Prud'hommeaux 27 Nov '13

27 Nov '13

I'm updating an old library which sets up eight separate loggers with different channel labels: BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(DefaultLog, SWObjectsLogger); BOOST_LOG_INLINE_GLOBAL_LOGGER_CTOR_ARGS(RewriteLog, SWObjectsLogger, (channel = "Rewrite")); ... BOOST_LOG_SEV(L::RewriteLog::get(), L::info) << "foo->bar\n"; I'd like to update to 1.54 (or 1.55) and before I `perl -i` the heck out of it, I'm wondering what are the tradeoffs around using a single logger: BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(TheLogger, boost::log::sources::severity_channel_logger< severity_level >) ... BOOST_LOG_CHANNEL_SEV(L::TheLogger::get(), L:Rewrite, L::info) << "foo->bar"; I can guess that many loggers gives me more (future) versatility to log Rewrite stuff to a different stream and that these eight loggers come with some memory footprint. Is that about right? (Also, why does adding a template parameter for the channel BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(TheLogger, boost::log::sources::severity_channel_logger< severity_level >) barf with macro errors? expressions_channel_severity_filter.cpp:306:127: error: macro "BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT" passed 3 arguments, but takes just 2 expressions_channel_severity_filter.cpp:306:1: error: ‘BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT’ does not name a type? ) -- -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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[multiarray] How to make a generic one from an existing C multi-array.
by Mostafa 27 Nov '13

27 Nov '13

Given the following: template <typename T, std::size_t D1> void foo(T (&arr)[D1]) { typedef boost::multi_array_ref < typename boost::remove_all_extents<T>::type, boost::rank<T[D1]>::value > arr_type; // ? = ExtentList or extents_tuple. arr_type ma(arr, ?); } Are there any existing tools to create an ExtentList or extents_tuple obj from the type of arr? Thanks, Mostafa

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[graph] How to use default ColorMap when using depth_first_visit
by Laila, Akeel 26 Nov '13

26 Nov '13

Hi, I'm looking to use depth_first_visit to traverse a labeled_graph, but the below code fails to compile due to the absence of ColorMap argument: depth_first_visit(dependencyGraph, targetDepVertex, visitor(cycleDetector)); error C2780: 'void boost::depth_first_visit(const IncidenceGraph &,graph_traits<G>::vertex_descriptor,DFSVisitor,ColorMap,TerminatorFunc)' : expects 5 arguments - 3 provided e:\TR\ToolsRelease\git\boost\1.54.0\src\boost/graph/depth_first_search.hpp:320:0 : see declaration of 'boost::depth_first_visit' error C2780: 'void boost::depth_first_visit(const IncidenceGraph &,graph_traits<G>::vertex_descriptor,DFSVisitor,ColorMap)' : expects 4 arguments - 3 provided e:\TR\ToolsRelease\git\boost\1.54.0\src\boost/graph/depth_first_search.hpp:309:0 : see declaration of 'boost::depth_first_visit' On the other hand, depth_first_search compile just fine: depth_first_search(dependencyGraph, visitor(cycleDetector)); I guess what it comes down to is that a default ColorMap is utilized by depth_first_search. Anyone know how I can access this same default ColorMap (which I can then feed to depth_first_visit()) FYI, my labeled_graph type is defined as follows: typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS , DependencyVertex, DependencyEdge> DependencyGraphInternalType; typedef boost::labeled_graph<DependencyGraphInternalType, string> DependencyGraphType; Thanks, Akeel Laila ________________________________ This email is non-binding, is subject to contract, and neither Kulicke & Soffa Industries Inc nor its subsidiaries shall have any obligation to you to consummate the transactions herein or to enter into any agreement, other than in accordance with the terms and conditions of a definitive agreement if and when negotiated, finalized and executed between the parties.

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how to learn Boost
by e.palmero＠googlemail.com 26 Nov '13

26 Nov '13

Dear Boost Developer: I am new to Boost and I would like to know any suggestion for books to get deeply inside the Boost libraries. Best Ernesto

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[multiprecision] FMA without expression templates?
by Francesco Biscani 26 Nov '13

26 Nov '13

Hello, I would like to start using the Boost multiprecision library in my code. For a series of reasons, I would like to disable the expression template support (I need the return type of a + b to be the type of a or b, and not an expression). My understanding after briefly venturing into the library code is that there is the concept of a multiply_add() function (e.g., in boost/multiprecision/detail/default_ops.hpp), but that such support is hidden behind the expression template magic and it is not exposed when ET is disabled. I tried to look into Boost math as well, where there is a fused multiply-add function, but it seems like it is built to support floating-point types and I need support for integral types (for the implementation of algebraic operations on polynomials with integer coefficients). Is my understanding correct or is there a way to use some kind of a multiply_accumulate function in multiprecision without using ET? Many thanks, Francesco.

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[random] infinite loop in uniform_real_distribution
by Jérémy Coulon 26 Nov '13

26 Nov '13

Hello, I'm using Boost 1.54. The following code hangs in infinite loop when generating a single floating point number : #include <boost/random.hpp> #include <iostream> #include <limits> int main() { boost::random::mt19937 rng; boost::random::uniform_real_distribution<float> distrib( -std::numeric_limits<float>::max(), std::numeric_limits<float>::max()); std::cout << distrib(rng) << std::endl; return 0; } I can reproduce the bug with both - Linux GCC 4.8 x86_64 and - Windows VisualStudio 2012 32bits It looks like this uniform distribution doesn't work if the range [min,max] is large. From uniform_real_distribution.hpp:61 T result = numerator / divisor * (max_value - min_value) + min_value; Here the operation (max_value - min_value) produces an overflow. Regards, Jeremy

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[Iostreams] Segmentation fault when stream is flushed or closed
by Steven Maenhout 26 Nov '13

26 Nov '13

Hello, I'm trying to open a boost::iostreams::stream in the constructor of a class and to close the stream in the destructor. This works fine but when I pass a reference to a std::stringstream in that same constructor I get a segmentation fault in the destructor when I flush or close the stream. This happens irrespective if the passed std::stringstream reference takes part in the boost::iostream::stream or not. I'm using gcc 4.6.3 with boost 1.53 on Linux x86_64. Below I provided a small example that exhibits this behaviour. Any ideas anyone? #include "test.h" int main(int argc, char **argv) { std::stringstream logStream; Test test(logStream); return 0; } where test.h contains: #include <fstream> #include <sstream> #include <boost/iostreams/stream.hpp> #include <boost/iostreams/tee.hpp> typedef boost::iostreams::tee_device<std::stringstream, std::ofstream> TeeDevice; typedef boost::iostreams::stream<TeeDevice> TeeStream; class Test { public: Test(const std::stringstream& logStream) { std::ofstream dummyFileHandle("/dev/null", std::ios_base::out | std::ios_base::app); std::stringstream logStream2; TeeDevice myTee (logStream2, dummyFileHandle); m_out.open(myTee); } virtual ~Test() { if(m_out.is_open()) { m_out.flush(); m_out.close(); } }; protected: TeeStream m_out; };

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