June 2010 - Boost-users - lists.preview.boost.org

Using Boost Software License
by Paul Bilokon 14 Jun '10

14 Jun '10

Dear all, I have a question about using Boost Software License in my own software projects: http://www.boost.org/LICENSE_1_0.txt My understanding is that this is, indeed, allowed? Then there are two further questions (1) What if I were to use a copy of Boost Software License under a different name? With/without modification? The rationale here is that I think that the licenses may diverge in future versions. Would this be legal? (2) If my company is based in the United Kingdom, can I still use this software license? Many thanks, Paul

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How to find edge between two vertices of undirected graph?
by Eric Fowler 14 Jun '10

14 Jun '10

This should be easy .... typedef adjacency_list<vecS, vecS, undirectedS, POS<position_type>, LEN<position_type> > DG; typedef graph_traits<DG>::vertex_descriptor Vertex; typedef graph_traits<DG>::edge_descriptor Edge; ... Vertex b, d; ...populate b and .... bool bRet; Edge e; tie(e,bRet) = edge(b,d,*this); This earns me a lengthy error message from g++ (following). I notice that there is no function described for looking up an edge on an IncidenceGraph or an AdjacencyGraph ... hmm .... this puzzles me. What am I missing? Eric ../shuttle/trunk/DelaunayGraph.h:273: error: no matching function for call to ‘DelaunayGraph<int>::remove_edge(Edge&, DelaunayGraph<int>&)’ /usr/include/boost/graph/detail/adjacency_list.hpp:848: note: candidates are: void boost::undirected_graph_helper<Config>::remove_edge(typename Config::edge_descriptor) [with Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, POS<int>, LEN<int>, boost::no_property, boost::listS>, boost::vecS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_bundle_t, POS<int>, boost::no_property>, boost::property<boost::edge_bundle_t, LEN<int>, boost::no_property>, boost::no_property, boost::listS>::config] /usr/include/boost/graph/detail/adjacency_list.hpp:859: note: void boost::undirected_graph_helper<Config>::remove_edge(typename Config::out_edge_iterator) [with Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, POS<int>, LEN<int>, boost::no_property, boost::listS>, boost::vecS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_bundle_t, POS<int>, boost::no_property>, boost::property<boost::edge_bundle_t, LEN<int>, boost::no_property>, boost::no_property, boost::listS>::config] make: *** [MyDialog.o] Error 1

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asio HTTP Server 3 example memory leak
by xyz xyz 14 Jun '10

14 Jun '10

Hello, I've compiled (using MSVC 2008) the HTTP Server 3 example from asio library, and I noticed that if I enter the address in a browser and then repeatedly press F5, the memory usage for the server process keep increasing. Anyone know why this memory leak, or what is happening? Thanks.

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[MPI] recv throws exception: MPI_Unpack: MPI_ERR_TRUNCATE
by Riccardo Murri 14 Jun '10

14 Jun '10

Hello, I'm using Boost.MPI for a program that computes the rank of matrices. It currently works fine up to some matrix size; with larger matrices it throws an exception:: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::mpi::exception> >' what(): MPI_Unpack: MPI_ERR_TRUNCATE: message truncated I'm serializing a variable-length std::vector + some POD types; I guess the error comes from the resulting buffer exceeding some internal limit. Is this guess correct? How can I retrieve the max size of an MPI send buffer and fragment my mpi::send's? I'm using OpenMPI 1.4.1 (native Ubuntu 10.04 pkg). For reference, here's the serialization code:: class DenseRow : public Row { // ... std::vector<long long> storage; template<class Archive> inline void DenseRow::serialize(Archive& ar, const unsigned int version) { ar & boost::serialization::base_object<Row>(*this) & storage; }; // ... }; class Row { // ... int starting_column_; int ending_column_; long long leading_term_; template<class Archive> inline void Row::serialize(Archive& ar, const unsigned int version) { ar & starting_column_ & ending_column_ & leading_term_; }; }; Thank you for any suggestion. Best regards, Riccardo -- Riccardo Murri, Hadlaubstr. 150, 8006 Zürich (CH)

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help with thread::interrupt
by Conoscenza Silente 14 Jun '10

14 Jun '10

Hi All I am playing with boost::thread and it is not clear how thread::interrupt actually works. If I understood clearly the thread will be interrupted the next time it enters one of the predefined *interruption points*<http://www.boost.org/doc/libs/1_43_0/doc/html/thread/thread_management.html…>; since thread::join is one interruption point, after I call tr.interrupt() I am expected that the thread will throw a boost::thread_interrupted exception once I call tr.join() right? . Below the sample code I am working now and I cannot get this behavior. Maybe I misunderstood the meaning of interrupt. If I uncomment the call to this_thread::sleep() I can see the thread_interrupted exception. Can you help me in understanding? Regards void f1_good(){ try{ int i = 0; while(true){ i++; // boost::this_thread::sleep( boost::posix_time::milliseconds( 0 ) ); // if I // uncomment this line calling interrupt will throw thread_interrupted } }catch(boost::thread_interrupted& ex ){ std::cout << "BREAK HERE!!" << std::endl; std::cout.flush(); } } int main( int argc, char** argv ){ boost::thread tr( f1 ); boost::this_thread::sleep( boost::posix_time::seconds( 3 ) ); std::cout << "calisl to INTER." << std::endl; std::cout.flush(); tr.interrupt(); std::cout << "PAUSE BEFORE JOIN." << std::endl; std::cout.flush(); boost::this_thread::sleep( boost::posix_time::seconds( 5 ) ); std::cout << "join" << std::endl; tr.join(); }

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[bind] & [function] How do I store member functions with generalised arguments for later invocation?
by Steve Lorimer 14 Jun '10

14 Jun '10

I am wanting to write library code that will allow a user to create an "event" which is associated with a thread, a class instance, and a member function of that class. The user can then "post" data (generalised number of arguments) - which results in the class instance's member function being called in the context of the associated thread. For example (pseudo code): event { thread* thr; class &that; mem_fun* fun; void post(); void post(a1); void post(a1, a2); void post(a1, a2, a3, ...etc); } mem_fun* fun stores a member function pointer which is of the form void class::fun(...0, 1 or more arguments...) Here is some example code which uses boost::bind to bind arguments to member functions and posts them to be called on another thread. However, it does not go far enough. #include <boost/function.hpp> > #include <boost/bind.hpp> > #include <boost/enable_shared_from_this.hpp> > #include <boost/thread/thread.hpp> > #include <boost/thread/mutex.hpp> > #include <boost/thread/condition.hpp> > #include <list> > #include <stdio.h> > > // cross-thread event queue. multiple threads can post jobs, one or many > threads can execute > // jobs. > class EventQueue > { > public: > typedef boost::function<void()> Job; > > // puts a jon into the queue > void post(Job job) > { > boost::mutex::scoped_lock lock(mtx_); > jobs_.push_back(job); > cnd_.notify_one(); > } > > // pulls one job from the queue, returns false when stopped > bool pull(Job* job) > { > boost::mutex::scoped_lock lock(mtx_); > for(;;) { // handle spurious wake-ups > while(!stop_ && jobs_.empty()) > cnd_.wait(lock); > if(!jobs_.empty() && 2 != stop_) { > job->swap(jobs_.front()); // move efficiently, avoiding > *job = jobs.front() > jobs_.pop_front(); > return true; > } > else if(stop_) { > return false; > } > } > } > > // make pull() return false > void stop(bool cancel_jobs) > { > boost::mutex::scoped_lock lock(mtx_); > stop_ = 1 + cancel_jobs; // 1 - complete jobs, 2 - cancel jobs > cnd_.notify_all(); > } > > EventQueue() : stop_() {} > ~EventQueue() { this->stop(true); } > > private: > boost::mutex mtx_; > boost::condition cnd_; > typedef std::list<Job> Jobs; > Jobs jobs_; > int stop_; > }; > > struct JobX > // micro-oprimization, embed the reference counter into the job to avoid an > extra memory > // allocation by boost::shared_ptr ctor > : boost::enable_shared_from_this<JobX> > { > void foo() > { > printf("%p foo()\n", this); > } > > void bar(int a) > { > printf("%p bar(%d)\n", this, a); > } > }; > > void anotherThread(EventQueue* queue) > { > EventQueue::Job job; > // wait and execute jobs till stopped > while(queue->pull(&job)) > job(); // execute the job > } > > int main() > { > EventQueue queue; > // start another thread and pass an argument > boost::thread another_thread(boost::bind(anotherThread, &queue)); > > // post jobs, allocate in this thread, deallocate in the other > boost::shared_ptr<JobX> job_0(new JobX); > queue.post(boost::bind(&JobX::foo, job_0)); > // post several jobs to the same object, deallocated when no longer in > use > boost::shared_ptr<JobX> job_1(new JobX); > queue.post(boost::bind(&JobX::foo, job_1)); > queue.post(boost::bind(&JobX::bar, job_1, 1)); // pass an extra arg 1 > queue.post(boost::bind(&JobX::bar, job_1, 2)); // pass an extra arg 2 > > // stop the queue and let it complete all jobs > queue.stop(false); > another_thread.join(); > } > And this is where I fall down. I am able to bind arguments to JobX::bar above, at the point at which I create my boost::function<void()>, but if I want to bind _1, _2 etc arguments for calling later, I'm not sure what to do. So my question is, how should I form class Event such that I can store member functions of the form void T::fn(), void T::fn(a1), void T::fn(a1, a2, etc...), and then allow a generalised form of post(), post(a1), post(a1, a2, etc...) to bind the arguments given in post to the callback and post it to the queue? I have some code below which clearly won't compile, but should illustrate to some degree what I'm looking for. template <typename T> class Event { EventQueue &queue_; // the event queue which will process the job boost::shared_ptr<T> that_; // the object whose mem_fun the event queue will call typedef boost::function<void (T*, void) > CB_0 ; // used for callbacks which are of the form void T::fn(); typedef boost::function<void (T*, _1) > CB_1 ; // used for callbacks which are of the form void T::fn(1 arg); typedef boost::function<void (T*, _1, _2) > CB_2 ; // used for callbacks which are of the form void T::fn(1 arg); CB_0 cb_0; CB_1 cb_1; CB_2 cb_2; public: Event(boost::shared_ptr<T> &that, CB &cb, EventQueue &queue) : that_(that), cb_(cb), queue_(queue) {} void post() { queue_.post(boost::bind(&cb_0, that)); template <typename arg_1> void post(arg_1 &arg1) { queue_.post(boost::bind(&cb_1, that)); template <typename arg_1, typename arg_2> void post(arg_1 &arg1, arg_2 &arg2) { queue_.post(boost::bind(&cb_2, that)); // TODO: args should be shared_ptr }; TIA Steve

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[units] initialization from zero magic
by alfC 14 Jun '10

14 Jun '10

Hi, I am curious. In Boost.Units it is not possible to *initialize* a quantity from a plain value, the closest thing to it is the ::from_value static member function. But ... What is the magic that makes this particular initialization compile? boost::units::quantity<si::length> L(0); //compiles and works as expected but *not* these ones: boost::units::quantity<si::length> L(1); //does not compile or boost::units::quantity<si::length> L(0.); //does not compile (gives a compile error, "no matching function for call to '...::quantity(int/double)') By the way, I think it is a great feature! I am interested to know how is this achieved. Thanks, Alfredo

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Serializing to .csv files
by Sean Farrow 14 Jun '10

14 Jun '10

Hi: Has anyone ever written extra classes to serialize c++ datatypes to .csv files using boost.Serialization. If so what is the best way of going about this? Cheers Sean

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boost MPI error
by Jack Bryan 13 Jun '10

13 Jun '10

Hi, all: I need to install boost library (/home/myname/boost_2010_6_8/boost_1_43_0). http://www.boost.org/doc/libs/1_43_0/more/getting_started/index.html It has MPI library : http://www.boost.org/doc/libs/1_42_0/doc/html/mpi.html After installing it, I compile some c++ program with calling for boost.MPI class, the compiler cannot find the header files in the program even though I have included the boost path in the compile command. example: ------------------------------------------------------------------------ #include </boost/mpi/environment.hpp> #include <boost/mpi/communicator.hpp> #include <iostream> namespace mpi = boost::mpi; int main(int argc, char* argv[]) { mpi::environment env(argc, argv); mpi::communicator world; std::cout << "I am process " << world.rank() << " of " << world.size() << "." << std::endl; return 0; } -------------------------------------------------------------------------- mpic++ -o testp2p test_p2p.cpp I/home/myname/boost_2010_6_8/boost_1_43_0 g++: I/home/myname/boost_2010_6_8/boost_1_43_0: No such file or directory test_p2p.cpp:7:38: error: /boost/mpi/environment.hpp: No such file or directory test_p2p.cpp:11:38: error: boost/mpi/communicator.hpp: No such file or directory Actually, I have installed these header files in the directory. I find a possible reason: When I built the package, it tells me that : ----------------------------------------------------------------- -bash-3.2$ ./bjam Building the Boost C++ Libraries. warning: Building Boost.Regex with the optional Unicode/ICU support disabled. note: Please refer to the Boost.Regex documentation for more information note: this is a strictly optional feature. warning: Graph library does not contain MPI-based parallel components. note: to enable them, add "using mpi ;" to your user-config.jam warning: skipping optional Message Passing Interface (MPI) library. note: to enable MPI support, add "using mpi ;" to user-config.jam. note: to suppress this message, pass "--without-mpi" to bjam. note: otherwise, you can safely ignore this message. Component configuration: - date_time : building - filesystem : building - graph : building - graph_parallel : building - iostreams : building - math : building - mpi : building - program_options : building - python : building - random : building - regex : building - serialization : building - signals : building - system : building - test : building - thread : building - wave : building ...patience... ...patience... ...patience... ...found 6754 targets... The Boost C++ Libraries were successfully built! The following directory should be added to compiler include paths: /lustre/jxding/boost_2010_6_8/boost_1_43_0 The following directory should be added to linker library paths: /lustre/jxding/boost_2010_6_8/boost_1_43_0/stage/lib ------------------------------------------------------------------------------------------ It seems that I need to specify I need to use mpi for the bjam builder. But, I have added "using mpi ;" and "using mpi : /opt/openmpi-gnu/bin/mpic++ ;" in the file /home/myname/boost_2010_6_8/boost_1_43_0/user-config.jam. I have also added it in the file /home/myname/boost_2010_6_8/boost_1_43_0/tools/build/v2/user-config.jam. But, I still got the same error. It seems that there is something wrong with the package ? or the compiler cannot understand the "using mpi ;" in the user-config.jam ? Any help is appreciated. Jack June 13 2010 _________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28…

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dynamic_properties and std::vector attributes
by Dominik Dahlem 13 Jun '10

13 Jun '10

Hi guys, the boost graph library has an example on using bundled properties. I would like to serialise the resulting graph into graphml. Using dynamic_properties for the std::vector attribute fails to compile with boost 1.41. Is there a way to get this example below to work? I would greatly appreciate it. Thanks, Dominik #include <vector> #include <string> #include <boost/graph/adjacency_list.hpp> #include <boost/property_map/dynamic_property_map.hpp> struct City { std::string name; int population; std::vector<int> zipcodes; }; struct Highway { std::string name; double miles; int speed_limit; int lanes; bool divided; }; int main() { typedef boost::adjacency_list< boost::listS, boost::vecS, boost::bidirectionalS, City, Highway> Graph; Graph g; Graph::vertex_descriptor v = *vertices(g).first; g[v].name = "Troy"; g[v].population = 49170; g[v].zipcodes.push_back(12180); Graph::edge_descriptor e = *out_edges(v, g).first; g[e].name = "I-87"; g[e].miles = 10; g[e].speed_limit = 65; g[e].lanes = 4; g[e].divided = true; boost::dynamic_properties dp; // dp.property("zip_codes", boost::get(&City::zipcodes, g)); dp.property("name", boost::get(&City::name, g)); return EXIT_SUCCESS; } -- Dominik Dahlem <Dominik.Dahlem(a)scss.tcd.ie> ------------------------------------------------------- Trinity College Dublin School of Computer Science and Statistics, Dublin 2, Ireland tel: (+353) 1-896 3789 fax: (+353) 1-677 2204 www: http://www.cs.tcd.ie/Dominik.Dahlem/ -------------------------------------------------------

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