December 2013 - Boost-users

[Asio] io_service(std::size_t concurrency_hint) constructor
by maks 16 Dec '13

16 Dec '13

Hello All In what cases using "io_service(std::size_t concurrency_hint)" ctor is more effective? 1. Use multiple threads - multiple io_service 2. Use multiple threads on one io_service object Thanks.

2 1

Delegating to boost::function with arbitrary signature
by Alexander Lamaison 16 Dec '13

16 Dec '13

I've asked this question on Stack Overflow but not found a solution yet: http://stackoverflow.com/q/20578575/67013. It's Boost.Function/MPL-related so I'll ask here too. I'm trying to create something like a `boost::function`, but with an extra 'smart handle' tucked inside, which controls the lifetime of a resource the functions needs to execute correctly. If I didn't need the function signature to be completely generic, this would be easy. I would just create a functor with the correct signature, and keep a `boost::function` and the handle as members. However, I do need generic signatures. The code below is as close as I've got but gets a compile error, presumably, because I'm not able to unpack a list of arguments like this: template<typename Signature> class library_function { public: library_function( library_handle handle, boost::function<result_type(arg1_type, arg2_type)> function) : m_handle(handle), m_function(function) {} typename result_type operator()(arg1_type arg1, arg2_type arg2) { return m_function(arg1, arg2); } // I don't think I can declare the 'params' like this ... typename boost::function_types::result_type<Signature>::type operator()( boost::function_types::parameter_types<Signature> params) { return m_function(params); // ... nor unpack them like this } private: boost::function<Signature> m_function; library_handle m_library; }; I think `params` is an MPL list, so what I've actually done is declare a call operator with a single MPL-list parameter. My MPL-foo is not good. Is there a way to convert the list to a legal definition of multiple function paramters? A suggested solution on SO is to use `boost::bind`, but I still don't see how to bind an arbitrary number of arguments. All advice greatly appreciated. Alex -- Swish - Easy SFTP for Windows Explorer (http://www.swish-sftp.org)

4 9

[asio][openssl]Boost SSL with Visual Studio 2012 and OpenSSL
by lx 16 Dec '13

16 Dec '13

hello: I use : windows 7 64bit, vs 2012 , boost 1.5.4 , Win64OpenSSL_Light-1_0_1e. the codes is: ######################## #include <boost/asio.hpp> #include <boost/asio/ssl.hpp> ######################## When I complie it, the wrong messages is: ########################################## 1>gtest.obj : error LNK2019: unresolved external symbol _CRYPTO_cleanup_all_ex_data referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _CRYPTO_num_locks referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _CRYPTO_set_locking_callback referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _CRYPTO_set_id_callback referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _CONF_modules_unload referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _OPENSSL_add_all_algorithms_noconf referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _EVP_cleanup referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _SSL_load_error_strings referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _SSL_library_init referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::do_init(void)" (??0do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _ERR_reason_error_string referenced in function "public: virtual class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall boost::asio::error::detail::ssl_category::message(int)const " (?message@ssl_category@detail@error@asio@boost@@UBE?AV?$basic_string@DU ?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z) 1>gtest.obj : error LNK2019: unresolved external symbol _ERR_free_strings referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _ERR_remove_state referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>gtest.obj : error LNK2019: unresolved external symbol _ENGINE_cleanup referenced in function "public: __thiscall boost::asio::ssl::detail::openssl_init_base::do_init::~do_init(void)" (??1do_init@openssl_init_base@detail@ssl@asio@boost@@QAE@XZ) 1>D:\program\gdnscenter-1.12.2\src\Debug\gtest.exe : fatal error LNK1120: 13 unresolved externals ========== Build: 0 succeeded, 1 failed, 3 up-to-date, 0 skipped ========== ########################################## the simiar question in stackoverflow : http://stackoverflow.com/questions/9357751/boost-ssl-with-visual-studio-201… . I use the openssl win64. So, Maybe a bug in asio? Thank you.

2 1

Crash in VS2013, bug in compiler, boost or my code ? (flyweight, variant and initializer list)
by Olivier Tristan 16 Dec '13

16 Dec '13

Hello Boost users, Using the following sample code I have some crash in VS2013 but it works fine in LLVM on OSX Is this is a mistake on my side or an issue elsewhere ? #include <string> #include <cstdint> #include <vector> #include <boost/flyweight/flyweight.hpp> #include <boost/flyweight/no_tracking.hpp> #include <boost/flyweight/static_holder.hpp> #include <boost/flyweight/set_factory.hpp> #include <boost/flyweight/simple_locking.hpp> #include <boost/variant.hpp> typedef boost::flyweights::flyweight< std::string, boost::flyweights::no_tracking, boost::flyweights::set_factory<>, boost::flyweights::static_holder, boost::flyweights::simple_locking > string_flyweight; typedef boost::variant< bool, double, string_flyweight > Variant; int main(void) { std::vector<Variant> v = { 1., true, string_flyweight("toto") }; return 0; } Thanks, -- Olivier TRISTAN uvi.net

5 8

library choice
by Mihir Thakkar 15 Dec '13

15 Dec '13

I am new to boost. I would like to contribute to development. I looked through the libraries and got confused from where to start understanding and reading such a large codebase. Is it that all the libraries are independent of each other and I've to look at only those which I want to work with? Please guide me on how to begin understanding. Thanks! :)

3 2

Boost Geometry - RTree with 1D Segments
by Adam Baxter 14 Dec '13

14 Dec '13

Hello all, I've been using boost::icl for interval searching. So far it's been working great. I am using it for closed interval searches for chemical masses. Unfortunately, I've reached a point where I've too much data, I think. The use of sets has started to kill my memory usage. I'd like to switch over to Boost::Geometry, but there's precious little about indexing 1D segments (I don't even mind 2D segments). Can someone point me in the right direction? Thanks! Adam

1 0

Threading question
by Davies, John 13 Dec '13

13 Dec '13

I have the following code and it terminates as expected. When I call the destructor it interrupts the thread. But if I change the this_thread::sleep to this_thread::yield the join() never happens and the program hangs. I must be misunderstanding yield. But I really don't want a sleep if possible. Thanks, John MessageQueueHandler::~MessageQueueHandler() { // Terminate the thread pMessageQueueInputThread->interrupt(); pMessageQueueInputThread->join(); delete pMessageQueueInputThread; } void MessageQueueHandler::MessageQueueInputThread() { unsigned int receivedSize; unsigned int priority; char buffer[queueMaximumMessageSize]; boost::this_thread::interruption_enabled(); try { while(1) { // Process all messages in the queue while(inputMessageQueue->try_receive(buffer, queueMaximumMessageSize, receivedSize, priority)) { BaseMessage * msg = reinterpret_cast<BaseMessage*>(buffer); callbackTable->DispatchMessage(msg); boost::this_thread::interruption_point(); } // Give other threads a chance to run // This is also an interruption point boost::this_thread::sleep(boost::posix_time::millisec(50)); <==Here } } catch(boost::thread_interrupted const&) { return; } } ___________________________________ John Davies Contractor Home Respiratory Care Philips Home Healthcare Solutions 1740 Golden Mile Highway Monroeville, PA 15146 Email: john.davies(a)philips.com Fax: 724-387-4109 ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

4 5

[Spirit/Qi/Phoenix] non compiling rules...
by Francois Mauger 12 Dec '13

12 Dec '13

Dear Boosters, The following code is one of my first attempts to use Spirit/Qi. For my education, I have tried 2 techniques to parse the simple "aaa=131;" string. The first one (Block A) compiles and seems to output the expected result. The second (B) does not compile with a huge massively templatized backtrace that I don't understand. What is the difference between using online rules and rule objects ? Is there a syntax error somewhere ? I'm afraid the documentation and example are rather terse about the syntax to be used here when coupling Qi and Phoenix... Many thanks for your help. best regards frc -- <pre> #include <iostream> #include <string> #include <vector> // - Boost/Spirit #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/include/phoenix_operator.hpp> int main( int argc_, char * argv_[]) { int error_code = EXIT_SUCCESS; using boost::spirit::qi::double_; using boost::spirit::qi::string; using boost::spirit::qi::lit; using boost::spirit::qi::lexeme; using boost::spirit::qi::phrase_parse; using boost::spirit::qi::_1; using boost::spirit::qi::as_string; using boost::spirit::ascii::space; using boost::spirit::ascii::char_; using boost::phoenix::ref; { // Block A /// This compiles: std::string s = "aaa=131;"; std::cout << "s: '" << s << "'" << std::endl; std::string::iterator strbegin = s.begin(); std::vector<char> vkey; std::vector<char> vvalue; bool r = phrase_parse( strbegin, s.end(), (+(char_ - '='))[boost::phoenix::ref(vkey) = boost::spirit::qi::_1 ] >> '=' >> *space >> lexeme[+(char_ - ';')][boost::phoenix::ref(vvalue) = boost::spirit::qi::_1 ], space ); if (r) { std::string key(vkey.begin(), vkey.end()); std::string value(vvalue.begin(), vvalue.end()); std::cout << "key : '" << key << "'" << std::endl; std::cout << "value : '" << value << "'" << std::endl; } } { /// Block B /// This doesn't: std::string s = "aaa=131;"; std::cout << "s: '" << s << "'" << std::endl; std::string::iterator strbegin = s.begin(); std::vector<char> vkey; std::vector<char> vvalue; boost::spirit::qi::rule<std::string::iterator> key_rule = +(char_ - '='); boost::spirit::qi::rule<std::string::iterator> value_rule = lexeme[+(char_ - ';')]; bool r = phrase_parse( strbegin, s.end(), key_rule[boost::phoenix::ref(vkey) = boost::spirit::qi::_1 ] >> '=' >> *space >> value_rule[boost::phoenix::ref(vvalue) = boost::spirit::qi::_1 ], space ); if (r) { std::string key(vkey.begin(), vkey.end()); std::string value(vvalue.begin(), vvalue.end()); std::cout << "key : '" << key << "'" << std::endl; std::cout << "value : '" << value << "'" << std::endl; } } return error_code; } </pre> -- François Mauger

3 4

version control choice
by Mihir Thakkar 12 Dec '13

12 Dec '13

Hey all, I am using Ubuntu and Git. Would it be alright if I work on Git? Is everything available on Git repository as well?

2 1

slow exception handling
by XIN LI 12 Dec '13

12 Dec '13

Hi, In my code, I add some protection to catch the exception from boost like "catch (boost::archive::archive_exception& ex)", strangely, it slow exception handling, causing one of our tests to go from around 30 seconds to greater than 5 minutes. I did profiling and found "linear_searc_fdes" spent too much time when process exception now. Does anyone have similar experience, why this happen, and how to fix the problem? Thanks a lot! Best wishes, Andy Li

3 4