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[Filesystem] questions
by John Dlugosz 14 Jun '10

14 Jun '10

I'm trying to replace my use of native file-path manipulations with the Filesystem TR2 candidate library, in preparation to advocating the use of this library as proper style instead of home-grown wrappers everywhere. However, I still have questions on some of the things I ran into in this simple usage: 1) I call remove (p,ec); and get a compile-time error that no form takes two arguments. Looking in the header, that seems to be the case. The Filesystem Reference (<http://www.boost.org/doc/libs/1_43_0/libs/filesystem/doc/reference.html>) clearly shows an error code parameter. I understand this module is tracking the standardization process. So which is newer? Should I be anticipating the code change to match the docs, or vice versa? How do I find out if there was an error and report the details? Note that I want to consider the case of the file not existing in the first place as OK. 2) The documentation shows things like: template <class Path> bool remove(const Path& p, system::error_code & ec = singular ); * if ec != singular, then ec.clear(). I can't find any definition for 'singular'. What is it? Besides acting as a flag to know if the argument was defaulted, it seems like it's doing some kind of one-shot behavior? 3) The basic_path constructor that takes two InputIterators: what kind of iterator is that? It doesn't seem to want characters, but an iterator of parts like produced by the begin/end functions. But the iterator's underlying type is not defined, so you can't make your own collection of "parts". So why doesn't the constructor just take its own iterator type, but is a template? What else could you give it? The documentation is not clear. TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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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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