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boost::bind
by simone pilozzi 28 Apr '11

28 Apr '11

Dear Users, I am using bind to calculate the transform of an initial vector in its element by element power (to a given exponent). I used this syntax std::transform(values.begin(), values.end(), values.begin(),boost::bind(pow,_1,exponent)); but the compiler complains for with error C2780 : expects 2 arguments 3 provided... Do you have any solution/explanation? Thanks in adavnce!

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[iostream] gzip filter buggy on windows
by Bo Jensen 28 Apr '11

28 Apr '11

In my quest of making gzip work for my application on windows, I found the following bug : int main(int argc, char *argv[]) { std::ofstream strm("test.gz"); boost::iostreams::filtering_ostream sink; /* Push gzip compressor */ sink.push(boost::iostreams::gzip_compressor()); /* Push file writer */ sink.push(strm); #if 0 /* This does not work */ sink <<" OBJ N"<< std::endl; #else /* This works */ sink <<" OBJ N"<< std::endl; #endif } The first string results in a invalid gzip file i.e invalid compressed data--length error. I am aware this might be a bug in zib lib. It works on without any problems on linux. Does anyone use gzip on windows on a regular basis ?

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Request for conditional index feature in boost multi-index
by Gokulakannan Somasundaram 28 Apr '11

28 Apr '11

Hi, First of all thanks for the great library, which had reduced our development time by a lot. In boost multi-index, we currently have almost all the indexing concepts integrated. Hence i am requesting for a new feature called conditional indexes, where in an index/view inside multi-index will only index a portion of the entries inside the entire multi-index(Say something that satisfies a functor). This is in resemblance to the partial indexes in Postgresql. I feel that would provide elegant solutions to lot of issues without forming round about solutions. For example i have a requirement where in there are two sets of data with the same search criteria, but different eviction criteria Say i have two sets of data with same search condition, but one set needs a MRU(Most Recently Used) list of 100 and the other set requires a MRU of 200. Say the entry is like this class Student { int student_no; char sex; std::string address; }; The search criteria is student_no, but for sex='m', we need MRU of 200 and for sex='f', we need a MRU of 100. Now i have a solution where in i introduce a new ordered index to maintain ordering. For example the IndexSpecifierList will be something like this typedef multi_index_container< Student, indexed_by< ordered_unique< member<Student, int, &Student::student_no> >, ordered_unique< composite_key< member<Student, char, &Student::sex>, member<Student, int, &Student::sex_specific_student_counter> > > > > student_set Here i have to introduce a new counter called sex_specific_student_counter, and during the eviction time, i need a logn search. Insertion also involves a extra logn complexity. Now instead if i have two sequenced indexes (like mentioned in the MRU example) in the place of second ordered index, but both with a condition on indexing only a few items, this would have looked more elegant and with better performance. Thanks in advance, Gokul.

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stop thread before socket destructor
by Gianni Ambrosio 28 Apr '11

28 Apr '11

Hi All, I modified a boost example to implement a tcp server that's able to accept clients on a thread. Unfortunately I get the following message: "The I/O operation has been aborted because of either a thread exit or an application request". I realized that the problem is related to the fact the server destructor is called before the handle_accept occurs. Now, how could I stop the thread in the server destructor so that the handle_accept is not called anymore? Here is the test code I used: typedef boost::shared_ptr<boost::asio::ip::tcp::socket> tcp_socket_ptr; class stream_handler { public: stream_handler() : acceptor_(io_service_) { boost::asio::ip::tcp::endpoint endpoint = boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 32123); acceptor_.open(endpoint.protocol()); acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true)); acceptor_.bind(endpoint); acceptor_.listen(); new_socket = tcp_socket_ptr(new boost::asio::ip::tcp::socket(io_service_)); acceptor_.async_accept(*new_socket, boost::bind(&stream_handler::handle_accept, this, boost::asio::placeholders::error)); thread_ = boost::thread(boost::bind(&boost::asio::io_service::run, &io_service_)); } ~stream_handler() { acceptor_.close(); } void handle_accept(const boost::system::error_code& err) { if (err) { std::cout << err.message() << std::endl; } else { new_socket = tcp_socket_ptr(new boost::asio::ip::tcp::socket(io_service_)); acceptor_.async_accept(*new_socket, boost::bind(&stream_handler::handle_accept, this, boost::asio::placeholders::error)); } } private: io_service io_service_; tcp::acceptor acceptor_; boost::thread thread_; tcp_socket_ptr new_socket; }; int _tmain(int argc, _TCHAR* argv[]) { stream_handler sh; return 0; } Regards Gianni

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mpi skeleton/content does not work with stl complex
by Tobias Stollenwerk 27 Apr '11

27 Apr '11

Hello all, It seems that sending stl complex data via the skeleton/content mechanism does not work. Here is a simple code that shows th problem: #include <boost/mpi.hpp> #include <boost/serialization/complex.hpp> #include <boost/serialization/vector.hpp> #include <iostream> namespace mpi = boost::mpi; using namespace std; int main(int argc, char* argv[]) { mpi::environment env(argc, argv); mpi::communicator world; int NN=world.size(); int myid=world.rank(); if (myid == 0) { int N = 10; vector <complex<double> > l(N); for (int p=1; p!=NN; p++) { int taskid=1; world.send(p, 0, taskid); world.send(p, 1, mpi::skeleton(l)); } mpi::content c = mpi::get_content(l); for (int n = 0; n!=l.size() ; n++) { l[n]=complex<double>(1.0,1.0); } for (int p=1; p!=NN; p++) { world.send(p, 1, c); } } else { vector <complex<double> > l; mpi::content c; world.recv(0, 1, mpi::skeleton(l)); c = mpi::get_content(l); world.recv(0, 1, c); for (int n=0; n!=l.size(); n++) { cout << l[n] << " "; } cout << endl; } } The entries of the vector l are not (1.0,1.0) but they seem to be uninitialized. This only occurs if one uses complex data types AND the skeleton/content mechanism. Does anyone know, if this is a build in problem, or if I am doing something wrong? Thanks in advance, Tobias

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questions on the BFS example of Parallel BGL
by Da Zheng 27 Apr '11

27 Apr '11

Hello, I'm testing PBGL on my cluster. I have 4 nodes and each node has a dual-core processor. I changed the BFS example a little bit. The code generates a graph with RMAT, and it does BFS 10 times, starting from different nodes. I first run the program in a sequential mode, and the graph has 1,000,000 vertices. Then I run it in the cluster. The result is shown below, but I don't see much speedup. The running time is reduced from 14 seconds to 9.5 seconds. Can the result be right? I see very good speedup in the PBGL document. Another problem is that BFS starting from some vertices only needs very little time. I can imagine that it traverses only very few vertices. Is there any way I can count how many vertices are visited from the specific root vertex? My code is also shown below. Thanks, Da [zhengda@amdahl36 pbgl]$ ./bfs ~/bfs.out 1000000 generate graph takes 162.336 seconds to generate graph start BFS random v: 1395111516 takes 14.3496 seconds for BFS search random v: 488302563 takes 0.029389 seconds for BFS search random v: 72509101 takes 14.1103 seconds for BFS search random v: 1835953408 takes 0.028544 seconds for BFS search random v: 951813172 takes 14.7907 seconds for BFS search random v: 1708481694 takes 14.2254 seconds for BFS search random v: 305355333 takes 14.1587 seconds for BFS search random v: 1627009882 takes 0.02749 seconds for BFS search random v: 1769559585 takes 0.027495 seconds for BFS search random v: 101184463 takes 0.02756 seconds for BFS search [zhengda@amdahl36 pbgl]$ mpirun -np 8 --hostfile ~/.mpi_hostfile ./bfs ~/bfs.out 1000000 generate graph generate graph generate graph generate graph generate graph generate graph generate graph generate graph takes 136.623 seconds to generate graph start BFS random v: 1395111516 takes 9.6362 seconds for BFS search random v: 488302563 takes 0.017129 seconds for BFS search random v: 72509101 takes 9.49864 seconds for BFS search random v: 1835953408 takes 0.031777 seconds for BFS search random v: 951813172 takes 9.53063 seconds for BFS search random v: 1708481694 takes 9.45427 seconds for BFS search random v: 305355333 takes 9.58886 seconds for BFS search random v: 1627009882 takes 0.018723 seconds for BFS search random v: 1769559585 takes 0.020844 seconds for BFS search random v: 101184463 takes 0.016004 seconds for BFS search boost::minstd_rand gen; std::cout << "generate graph" << std::endl; struct timeval start_time; struct timeval end_time; gettimeofday (&start_time, NULL); Graph g(RMATGen(gen, nvertices, 16 * nvertices, 0.57, 0.19, 0.19, 0.05), RMATGen(), nvertices); gettimeofday (&end_time, NULL); if (process_id(process_group(g)) == 0) { std::cout << "takes " << (end_time.tv_sec - start_time.tv_sec) + ((double) end_time.tv_usec - start_time.tv_usec) / 1000000 << " seconds to generate graph" << std::endl; std::cout << "start BFS" << std::endl; } for (int i = 0; i < 10; i++) { int rv = gen(); if (process_id(process_group(g)) == 0) { std::cout << "random v: " << rv << std::endl; } graph_traits<Graph>::vertex_descriptor start = vertex(rv % nvertices, g); // Compute BFS levels from vertex 0 property_map<Graph, vertex_distance_t>::type distance = get(vertex_distance, g); put(distance, start, 0); gettimeofday (&start_time, NULL); breadth_first_search (g, start, visitor(make_bfs_visitor(record_distances(distance, on_tree_edge())))); gettimeofday (&end_time, NULL); if (process_id(process_group(g)) == 0) { std::cout << "takes " << (end_time.tv_sec - start_time.tv_sec) + ((double) end_time.tv_usec - start_time.tv_usec) / 1000000 << " seconds for BFS search" << std::endl; } }

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converting bison to boost::spirit
by Littlefield, Tyler 27 Apr '11

27 Apr '11

Hello all: I have a server I am trying to rewrite, but it uses bison to generate the parser. I know near to nothing about either of these, and the examples kind of confuse me. Is there a way that I can somehow convert the bison to boost::spirit for parsing? Also: I'm kind of curious how one would go about making a parser with boost::spirit. So I define my tokens, (lets say I want to make a calculator as it's pretty simple). Then I would need to generate a tree, correct? My first thought was to just use the [] operator to pass in a function to receive the tokens, then push it to a vector, but that seems like it would be really slow when it comes to parsing the tokens. I also know of an abstract syntax tree, but I'm kind of confused how that works and how spirit would work with it. The calculator overloaded a lot of operators, but I sort of got lost down the line in terms of what was supposed to be happening. Anyone willing to explain this would be greatly appreciated. -- Thanks, Ty

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[units][uBlas] Problems using matrix operations with dimension constraints
by Ryan 27 Apr '11

27 Apr '11

I'm currently trying to use the uBlas library with the units library and I'm running into some problems. The matrix and vector classes I've instantiated with unit constraints don't seem to play well with uBlas methods. Has anyone found ways of using the two libraries together? I've included some lines of what I'm trying to do and would really appreciate some help. Ryan using namespace boost::numeric::ublas; using namespace boost::units; //Works fine. This is expected though since dimensionless quantity can accept //regular built in types. bounded_matrix<quantity<si::dimensionless, 3, 3> rotate = identity_matrix<double>(3); //How do I initialize a vector of dimension lengths with something like the zero_matrix? bounded_vector<quantity<si::length>, 3> diff = zero_matrix<double>(3) * si::meter; //??? //Lets pretend the diff variable has values in it. This line doesn't compile. //The compiler is saying it can't deduce the template argument. //What can I do to help the compiler out so I can get the correct result? bounded_vector<quantity<si::length>, 3> result = prod(rotate, diff);

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[Thread] Solution to conflict with MFC?
by Christian Larsen 27 Apr '11

27 Apr '11

Hello, I know this has been asked before, but I could not find a good solution. I'm experiencing problems with an application using both MFC and Boost.Thread. Specifically the assertion ASSERT(AfxGetModuleState() != AfxGetAppModuleState()); in AfxCoreInitModule() fails. I link Boost.Thread statically into a DLL in my project. From previous posts to this list and elsewhere, e.g. http://lists.boost.org/boost-users/2009/04/46929.php, I see that the issue is caused by setting _pRawDllMain in tss_pe.cpp. Commenting this line does "solve" the problem, but I would rather not have to hack the Boost source code this way. It seems there is a patch somewhere for this problem (referred to in http://lists.boost.org/boost-users/2009/04/47015.php) but it appears it never made it into the source. Is there any chance of this issue being solved in a better way? Best regards, Christian Larsen

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boost build problem?...
by Krzysztof 27 Apr '11

27 Apr '11

I wrote a few lines of code just for start with a library of boost (program_options). Before I did it I had built boost library as prescribed and *.a and *.so files were created in my /home/krzysztof/Documents/Projects/boost/lib directory. However, compilation fails because of undefined references of some external symbols which belongs to program_options library. Could anyone help me with it? Below, there is the code and g++ output. (Linux 64b, Qt Creator and Code::Blocks used as IDE) #include "boost/program_options.hpp" using namespace boost::program_options; using namespace std; int main(int argc, char *argv[]) { options_description opd; opd.add_options() ("help","Display help") ("input_file,if",value<string>(),"Specifies input file") ("fet_file",value<string>(),"definitions file") ("output_file,of",value<string>(),"file after edition"); } g++ -o fetxedit main.o -L/usr/lib -L/home/krzysztof/Documents/Projects/boost/lib -lQtCore -lpthread main.o: In function `main': /home/krzysztof/Documents/Projects/fetxedit-build-desktop/../fetxedit/main.cpp:8: undefined reference to `boost::program_options::options_description::m_default_line_length' /home/krzysztof/Documents/Projects/fetxedit-build-desktop/../fetxedit/main.cpp:8: undefined reference to `boost::program_options::options_description::m_default_line_length' /home/krzysztof/Documents/Projects/fetxedit-build-desktop/../fetxedit/main.cpp:8: undefined reference to `boost::program_options::options_description::options_description(unsigned int, unsigned int)' /home/krzysztof/Documents/Projects/fetxedit-build-desktop/../fetxedit/main.cpp:14: undefined reference to `boost::program_options::options_description::add_options()' /home/krzysztof/Documents/Projects/fetxedit-build-desktop/../fetxedit/main.cpp:14: undefined reference to `boost::program_options::options_description_easy_init::operator()(char const*, char const*)' ... and so on -- Regards Krzysztof Jasieński

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