July 2013 - Boost-users - lists.preview.boost.org

[Boost.Log] compiling issue of trivial example under boost version 1.5.4
by Steven Sun 30 Jul '13

30 Jul '13

Hi All - I was trying to compile the boost log example code under boost_1_54_0/libs/log/example/trivial/. I basically want to have a simple logger with filter function. So the example code serves the purpose. I got the attached error message while trying to compile. I think my compile command is fine because if I comment out the section of " core::get()->set_filter ( trivial::severity >= trivial::info ); " it compiles and runs fine. Can someone please provide some insight of how to make the severity filter work? Best, -- Steven Sun ********************************************************* Eco-Tips: Please consider the environment before printing this email!

1 0

[datetime] to/from ISO
by Michael Powell 30 Jul '13

30 Jul '13

Hello, I have a cross platform date/time quirk I want to work out. I am using Boost DateTime Posix to_iso_string and from_iso_string to pass date/time fields over the wire. What I am finding is that C# .NET DateTime and/or Boost DateTime Posix ISO do not agree, at least where ISO format is concerned. So... Is it a Boost issue? Or a .NET issue? I'm not positive, but the ISO format goes something like this: "YYYY-mm-DDTHH:MM:SS" Whereas Boost interpretation of that is something like: "YYYYmmDDT..." Something else after 'T', not sure, is that seconds since the epoch? Something like that. Anyway. Parsing the tree is falling over on that interpretation. A workaround is to leave the field out (for now), but longer term I would like to preserve the time field in whatever date/time format will work and parse ubiquitously over the wire. Any recommendations? Thank you... Regards, Michael Powell

1 1

[Spirit][Math] karma: regression in 1.54 due to argument promotion in math?
by Igor R 30 Jul '13

30 Jul '13

Hello, The following code compiles with 1.53, but fails with 1.54 (FreeBSD 9.1, gcc4.2.1): #include <boost/spirit/include/karma.hpp> #include <string> #include <iterator> int main() { using namespace boost::spirit::karma; std::string result; std::back_insert_iterator sink(result); unsigned short a; generate(sink, auto_, a); } The error is: boost/boost/math/tools/promotion.hpp: In instantiation of 'boost::math::tools::promote_args<long double, float, float, float, float, float>': boost/boost/math/special_functions/sign.hpp:114: instantiated from 'int boost::math::signbit(T) [with T = long double]' boost/boost/spirit/home/support/detail/sign.hpp:47: instantiated from 'bool boost::spirit::detail::signbit(T) [with T = long double]' boost/boost/spirit/home/karma/numeric/detail/numeric_utils.hpp:130: instantiated from here boost/boost/math/tools/promotion.hpp:141: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' I.e., the compilation fails because FreeBSD doesn't supprt "long double" type. This happens now due to the following changes in boost/math/special_functions/sign.hpp : 123 template<class T> int (signbit)(T x) 124 { 125 typedef typename detail::fp_traits<T>::type traits; 126 typedef typename traits::method method; 127 - typedef typename boost::is_floating_point<T>::type fp_tag; 128 - return detail::signbit_impl(x, method()); 127 + // typedef typename boost::is_floating_point<T>::type fp_tag; 128 + typedef typename tools::promote_args<T>::type result_type; 129 + return detail::signbit_impl(static_cast<result_type>(x), method()); 130 } So, what would be the right way to reconcile karma and math? Thanks, Igor'.

2 2

interprocess file_lock timed_lock not returning false after timeout
by Claudio Bantaloukas 30 Jul '13

30 Jul '13

Hi all! I think there are two issues, one is a documentation issue, the other might be a bug with boost::interprocess file_lock. The documentation issue is that it was not clear to me by reading the documentation on file_lock that it is a RAII-style class. By reading that it has process lifetime, I assumed that once acquired, the lock would be held even after the file_lock object is destroyed. Once I figured this out, I changed the file_lock to a static method variable and ran into the following issue. I have two processes that use the following class method that I wrote. They both try to acquire a lock on the same file and the lock must be held until the process exits. When I start the first process, it acquires the lock correctly. When I start up the second process, I would expect the following code to return false after 10 seconds //// static boost::interprocess::file_lock process_flock(processLockFile.string().c_str()); if (!process_flock.timed_lock(wait_until)){ //// However, when I read through the logs, I see that the process reaches the timed_lock call and gets stuck there. Can you please help me diagnose this? I'm attaching the entire method with log lines treated for brevity. Boost version is 1.53, running on Centos 6. Thanks! ------------------------8<-------------- ReturnStatus ProcessLocker::lockViaFile() { L_CONTEXT("ProcessLocker::lockViaFile()"); path lockDirectory(lockFileDirectoryName); if (!exists(lockDirectory)){ L_ERROR("missing lock directory"); return r_error; } if (!is_directory(lockDirectory)){ L_ERROR("lock path is not a directory"); return r_error; } path globalLockFile = lockDirectory / "general-locking.lock"; // make sure file exists boost::filesystem::ofstream globalfile(globalLockFile, std::ios::out); // we do nothing with it... globalfile.close(); std::string filename; // class member, this is the process identifier, and is the same between invocations filename.append(identifier); filename.append(".lock"); path processLockFile = lockDirectory / filename; // make sure file exists boost::filesystem::ofstream processfile(processLockFile, std::ios::out); // we do nothing with it... processfile.close(); try { ptime now(second_clock::local_time()); ptime wait_until = now +seconds(10); L_DEBUG("Waiting for global lock until " << wait_until); boost::interprocess::file_lock global_flock(globalLockFile.string().c_str()); if (!global_flock.timed_lock(wait_until)){ L_ERROR("Cannot create global lock"); return r_error; } try { L_DEBUG("Waiting for process lock until " << wait_until); static boost::interprocess::file_lock process_flock(processLockFile.string().c_str()); if (!process_flock.timed_lock(wait_until)){ global_flock.unlock(); // this point is never reached!? L_ERROR("Cannot create process lock"); return r_error; } global_flock.unlock(); L_DEBUG("Obtained process lock, freeing global lock"); return r_ok; } catch (std::exception& e){ global_flock.unlock(); L_ERROR("Cannot create process lock, freeing global lock"); return r_error; } } catch (std::exception& e){ L_ERROR("Cannot create global lock"); return r_error; } } -- Claudio Bantaloukas

1 1

serialization of standard unordered containers
by D. R. Evans 29 Jul '13

29 Jul '13

I have a several classes that currently use old-fashioned ("ordered") containers that would benefit greatly from using the C++11 unordered variants. But in the version of boost I'm currently using (1.49.0) serialization of those containers is not supported. So I have some questions: 1. Is serialization of standard unordered containers supported in version 1.54.0 of the boost libraries? 2a. If so, what was the earliest version of the boost libraries that supported serialization of standard unordered containers? 2b. If not, is there a timetable for when this might be added? (The documentation and comments I could find gave completely inconsistent answers on this issue, so I'd like a definitive answer before I go to the trouble of installing a more recent version of boost if that's not going to help.) Doc -- Web: http://www.sff.net/people/N7DR

7 15

[move] Where is it? when to use it?
by Michael Powell 29 Jul '13

29 Jul '13

Hello, Okay, this is kind of a Boost question, and kind of not. Kind of a C++ question, and kind of not. Depends where I can find a workable solution. First, I am using Sourcery CodeBench in a more recent (not the most recent) version. I believe it is one revision back from most recent. Targeting (Arch)Linux/ARM. I believe I answered my question from online references: http://en.cppreference.com/w/cpp/utility/move, which I've also confirmed is a C++0x experimental feature in the version of CodeBench I am using. It may be more or less up to date when I upgrade to the latest CodeBench. If the experimental doesn't work out, is there a Boost alternative? If so, where do I include it? Thank you... Regards, Michael Powell

2 1

[asio] reconnect without close the socket, is it possible?
by TONGARI J 28 Jul '13

28 Jul '13

Hi, I want to know if the connection is broken up at some point, can I reconnect without shutdown-close the socket. On Windows, I keep getting already_connected error when reconnecting but still fails to do other async read/write... Also, any way to test if the socket is connected? Thanks.

2 3

Re: [Boost-users] serialization of standard unordered containers
by Brian Wood 28 Jul '13

28 Jul '13

niXman writes: > 2013/7/27 D. R. Evans: >> 1. Is serialization of standard unordered containers supported in version >>1.54.0 of the boost libraries? >No. > > Alternatively, look at the YAS: > https://github.com/niXman/yas The C++ Middleware Writer - http://webEbenezer.net has support for the standard unordered containers. -- Brian Wood Ebenezer Enterprises http://webEbenezer.net

1 0

find positions of punctuations with boost regex
by chenyong 27 Jul '13

27 Jul '13

I am trying to find ALL positions of punctuations in a textual string so that I can divide the text into sentence. How to do this with boost regex. Thanks Felix

2 1

[asio] Async (or sync) in threads
by Michael Powell 27 Jul '13

27 Jul '13

Hello, I am having a hard time getting my Asio usage off the ground. I started with what I thought was a nominal (knock on wood) asynchronous server, which runs in a worker thread, but was running into seg fault issues. In the interest of "simplifying" the issue, I decided to simplify to a "blocking" server, hopefully also hosted in a thread, but am also running into seg fault issues. First I am trying to capture the server instance in a lambda passing it to a thread as a runner. Then I am trying to capture a shared pointer to the server thinking there is some move semantic or something. Seg fault in either case. Most of the examples are one main being the sole main thread hosting the io_service. Would that this were the case with me. This has to be one worker among several other workers running in the same process. Wouldn't mind if there were a couple of ideas recommending what I might explore next. Thank you... In the diagnostic routine I've got wired up: boost::shared_ptr<dchem::asio::ip::tcp::server2> server_ = boost::make_shared<dchem::asio::ip::tcp::server2>(17017); boost::thread runner_([&server_]() { server_->start_server(); }); runner_.start_thread(); while (!timer_.has_elapsed_query_wait(wait_timeout_, elapsed_milliseconds_)) { //... } runner_.interrupt(); runner_.join(); And the server itself, header first: class server2 { public: /** * \brief Endpoint type definition. */ typedef boost::asio::ip::tcp::endpoint endpoint_type; /** * \brief Acceptor type definition. */ typedef boost::asio::ip::tcp::acceptor acceptor_type; /** * \brief Service type definition. */ typedef boost::asio::io_service service_type; /** * \brief Socket type definition. */ typedef boost::asio::ip::tcp::socket socket_type; /** * \brief Socket pointer type definition. */ typedef boost::shared_ptr<socket_type> socket_pointer; /** * \brief Port type definition. */ typedef unsigned int port_type; protected: /** * \brief Returns whether bytes are available. * \param s A socket reference. */ static bool are_bytes_readable(socket_type& s); /** * \brief Starts a new session. * \param s Starts running a new session. */ void session(socket_pointer s); public: /** * \brief Constructor * \param port A TCP port. */ server2(port_type port); /** * \brief Destructor */ virtual ~server2(); /** * \brief Starts the server. */ void start_server(); private: /** * \brief Service. */ service_type m_service; /** * \brief Port. */ port_type m_port; }; ///////////////////////////////////////////////////////////////////// server2::server2(port_type port) : m_service(), m_port(port) { } ///////////////////////////////////////////////////////////////////// server2::~server2() { } ///////////////////////////////////////////////////////////////////// bool server2::are_bytes_readable(socket_type& s) { boost::asio::socket_base::bytes_readable cmd_(true); s.io_control(cmd_); std::size_t cmd_result_ = cmd_.get(); return cmd_result_ > 0; } ///////////////////////////////////////////////////////////////////// void server2::start_server() { try { endpoint_type ep_(boost::asio::ip::tcp::v4(), m_port); acceptor_type a_(m_service, ep_); std::cout << "accepting connection" << std::endl; boost::system::error_code ec_; auto s_ = boost::make_shared<socket_type>(m_service); a_.accept((*s_), ec_); if (!ec_) return; std::cout << "starting session" << std::endl; session(s_); } catch (boost::thread_interrupted& tiex) { } catch (...) { } } ///////////////////////////////////////////////////////////////////// void server2::session(socket_pointer s) { auto& s_ = (*s); while (true) { { utils::sleep_for_milliseconds(100); threading::thread_interruption_disabler tid; std::cout << "are bytes readable" << std::endl; if (!are_bytes_readable(s_)) continue; std::cout << "reading some" << std::endl; boost::system::error_code ec_; std::vector<byte> buffer_; size_t length_ = s_.read_some(boost::asio::buffer(buffer_), ec_); //Connection reset cleanly by peer. if (ec_ == boost::asio::error::eof) break; else if (ec_) //Some other error. throw boost::system::system_error(ec_); boost::asio::write(s_, boost::asio::buffer(buffer_, length_)); } } } Regards, Michael Powell

2 9