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Thread_group semantics
by Kenneth Adam Miller 14 Jan '14

14 Jan '14

When a thread_group is assigned a task using post, does that task get executed sequentially? Is there a list, so that, when too many posts are added to it, it keeps track of them?

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[program-options] Line width ignored on add()-ed options_description?
by Rhys Ulerich 13 Jan '14

13 Jan '14

I've got a "primary" options_description instance to which I add() other "secondary" options_description instances. I want operator<< to print the primary and all secondary instances with the primary instance's line width. I expect that this should happen automagically because, after construction, I cannot adjust the private m_line_length member of the secondary instances through any public means. However, it does not. A small re-create follows my signature. In my applications, I do not control the construction of the secondary instances and so I cannot adjust the secondary instance's construction-time width setting. Is this behavior a deliberate design decision? Some minor rework to options_description::print(...) within src/options_description.cpp would make it possible. Thanks, Rhys #include <iostream> #include <boost/program_options.hpp> int main() { static const char lengthy[] = "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 " "123456789 123456789 123456789 123456789 "; boost::program_options::options_description foo(255); // Linewidth 255 foo.add_options() ( "foo", lengthy ); boost::program_options::options_description bar; // Default line width bar.add_options() ( "bar", lengthy ); // foo should either dictate bar's line width, or... // I should be able to change it via a public interface... // ... but I seemingly cannot. foo.add(bar); // Option --foo has a nice long width, // but option --bar is truncated. std::cout << foo; }

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UDP bind problems
by ustulation 13 Jan '14

13 Jan '14

{Windows 7, MinGW 4.8, boost 1.55} I'm having some problems with UDP binds. I've a client that broadcasts datagrams for listeners listening on specific port and binds to a port itself if the listeners want to communicate something back. The port on which the client needs to bind is X and the servers are listening on Y. Problem: If I simulate a client-crash (eg., by causing segmentation fault by dereferencing a nullptr) after binding the UDP socket to the port, then once the client application is no longer running (no longer listed in Windows Task Manager) netstat -ano | find "X" still shows that someone is bound to port X and ip address of 0.0.0.0 (the client had specified the IP address as any address). The PID cannot be found in Windows Task Manager. However when I downloaded application TCPView I can see that a *<non-existent>* process is still bound to 50000. On starting the client (without making it crash this time) subsequently I get two behaviors: <1> On some machines the client is unable to bind to the socket again (although reuse_address option is set to true) and the error message is: An attempt was made to access a socket in a way forbidden by its access permissions. <2> On other machines the client binds successfully but the read handler is not called and the client does not receive any datagram on port X although the servers are unicasting to the client port X. Infact <2> is true even for launching multiple instances of the client on the same machine even if none of the clients were deliberately made to crash and exist as zombie processes. Only the 1st one gets datagrams. Here is how client socket is set up: if(!m_udpSocket.is_open()) { m_udpSocket.open(m_localEndpoint.protocol(), errorCode); //m_localEndpoint is address 0.0.0.0 and port X if(errorCode) { std::cerr << "Unable to open socket: " << errorCode.message() << std::endl; } else { m_udpSocket.set_option(boost::asio::socket_base::reuse_address(true), errorCode); if(errorCode) { std::cerr << "Reuse address option set failure. " << errorCode.message() << std::endl; } m_udpSocket.set_option(boost::asio::socket_base::broadcast(true), errorCode); if(errorCode) { std::cerr << "Socket cannot send broadcast. " << errorCode.message() << std::endl; } else { m_udpSocket.bind(m_localEndpoint, errorCode); if(errorCode) { std::cerr << "Socket cannot bind...!! " << errorCode.message() << std::endl; } } } } Can you explain why do I get <1> and <2> and what can I do to avoid them and make socket bind even if there is some other process bound to that socket? I need to support Windows, Linux and MAC -- View this message in context: http://boost.2283326.n4.nabble.com/UDP-bind-problems-tp4657731.html Sent from the Boost - Users mailing list archive at Nabble.com.

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Fast IPC between Linux and Windows on the same host
by U.Mutlu 13 Jan '14

13 Jan '14

Hi, what is the fastest cross-platform IPC mechanism between Linux and Windows on the same physical host? Additional info: Host OS is Linux (Debian), Windows XP is hosted in VirtualBox. Of course TCP/IP sockets is a possibility, but I need something much faster. My preference would be to use shared memory, but is it possible in such an heterogene environment? And: can Boost.Interprocess be used for this scenario? Thx -- U.Mutlu DACOS Notdienstanlagen GmbH, Germany

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using iterator_range with wchar_t
by Sean Farrow 13 Jan '14

13 Jan '14

Hi All, I'm sorry if this has already been covered. I'm trying to use iterator_range with a wchar_t. My code is as follows: std::wstring buttonName =L"jar:file:/C:/Program%20Files/diseMP/4.5.6/O2-LIVE/lib/client/ClientResources.jar!/branding/default/buttons/FindButtonActive.png"; bool isGraphical =false; isGraphical =boost::algorithm::starts_with(buttonName, L"jar:file:/") && boost::algorithm::ends_with(buttonName, L".png"); boost::iterator_range<wchar_t> range =boost::algorithm::find_last(buttonName, L"/"); I'm getting the following errors: 1>------ Build started: Project: TestApp, Configuration: Debug Win32 ------ 1> TestApp.cpp 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(30): error C2039: 'value_type' : is not a member of 'boost::detail::iterator_traits<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1> c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(141) : see reference to class template instantiation 'boost::iterator_value<Iterator>' being compiled 1> with 1> [ 1> Iterator=wchar_t 1> ] 1> c:\work\panthion studios\o2\testapp\testapp.cpp(11) : see reference to class template instantiation 'boost::iterator_range<IteratorT>' being compiled 1> with 1> [ 1> IteratorT=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(30): error C2146: syntax error : missing ';' before identifier 'type' 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(30): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(30): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(141): error C2039: 'type' : is not a member of 'boost::iterator_value<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(49): error C2039: 'difference_type' : is not a member of 'boost::detail::iterator_traits<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1> c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(145) : see reference to class template instantiation 'boost::iterator_difference<Iterator>' being compiled 1> with 1> [ 1> Iterator=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(49): error C2146: syntax error : missing ';' before identifier 'type' 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(49): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(49): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(145): error C2039: 'type' : is not a member of 'boost::iterator_difference<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(36): error C2039: 'reference' : is not a member of 'boost::detail::iterator_traits<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1> c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(159) : see reference to class template instantiation 'boost::iterator_reference<Iterator>' being compiled 1> with 1> [ 1> Iterator=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(36): error C2146: syntax error : missing ';' before identifier 'type' 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(36): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\iterator\iterator_traits.hpp(36): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(159): error C2039: 'type' : is not a member of 'boost::iterator_reference<Iterator>' 1> with 1> [ 1> Iterator=wchar_t 1> ] 1>c:\program files (x86)\boost\boost\type_traits\is_abstract.hpp(72): error C2139: 'boost::iterator_range<IteratorT>' : an undefined class is not allowed as an argument to compiler intrinsic type trait '__is_abstract' 1> with 1> [ 1> IteratorT=wchar_t 1> ] 1> c:\program files (x86)\boost\boost\type_traits\is_abstract.hpp(144) : see reference to class template instantiation 'boost::detail::is_abstract_imp<T>' being compiled 1> with 1> [ 1> T=boost::iterator_range<wchar_t> 1> ] 1> c:\program files (x86)\boost\boost\mpl\aux_\preprocessed\plain\or.hpp(51) : see reference to class template instantiation 'boost::is_abstract<T>' being compiled 1> with 1> [ 1> T=boost::iterator_range<wchar_t> 1> ] 1> c:\program files (x86)\boost\boost\mpl\if.hpp(63) : see reference to class template instantiation 'boost::mpl::or_<T1,T2>' being compiled 1> with 1> [ 1> T1=boost::is_abstract<boost::iterator_range<wchar_t>>, 1> T2=boost::is_array<boost::iterator_range<wchar_t>> 1> ] 1> c:\program files (x86)\boost\boost\range\iterator_range_core.hpp(174) : see reference to class template instantiation 'boost::mpl::if_<T1,T2,T3>' being compiled 1> with 1> [ 1> T1=boost::mpl::or_<boost::is_abstract<boost::iterator_range<wchar_t>>,boost::is_array<boost::iterator_range<wchar_t>>>, 1> T2=boost::iterator_range<wchar_t>, 1> T3=boost::iterator_range<wchar_t> 1> ] ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Does anyone have any clues as to why this is happening or alternatively any working example? Help appreciated as always. Regards Sean.

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Boost.Fiber review January 6-15
by Nat Goodspeed 13 Jan '14

13 Jan '14

Hi all, The review of Boost.Fiber by Oliver Kowalke begins today, Monday January 6th, and closes Wednesday January 15th. ----------------------------------------------------- About the library: Boost.Fiber provides a framework for micro-/userland-threads (fibers) scheduled cooperatively. The API contains classes and functions to manage and synchronize fibers similar to Boost.Thread. Each fiber has its own stack. A fiber can save the current execution state, including all registers and CPU flags, the instruction pointer, and the stack pointer and later restore this state. The idea is to have multiple execution paths running on a single thread using a sort of cooperative scheduling (versus threads, which are preemptively scheduled). The running fiber decides explicitly when it should yield to allow another fiber to run (context switching). Boost.Fiber internally uses coroutines from Boost.Coroutine; the classes in this library manage, schedule and, when needed, synchronize those coroutines. A context switch between threads usually costs thousands of CPU cycles on x86, compared to a fiber switch with a few hundred cycles. A fiber can only run on a single thread at any point in time. docs: http://olk.github.io/libs/fiber/doc/html/ git: https://github.com/olk/boost-fiber src: http://ok73.ok.funpic.de/boost.fiber.zip The documentation has been moved to another site; see the link above. If you have already downloaded the source, please refresh it; Oliver has added some new material. --------------------------------------------------- Please always state in your review whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Nat Goodspeed Boost.Fiber Review Manager ________________________________

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[Log 2.0] rotating files size limiation
by Ovanes Markarian 13 Jan '14

13 Jan '14

Hello *, I am a bit stuck to implement a very simple scenario with boost log. I need to limit the size of entire rotation log. My current logger configuration looks like that: void setup_logging( channel_settings_t const& settings , std::string const& log_file , std::string const& log_level ) { config_logger_attributes(logging::core::get(), settings, log_level); using namespace logging::aux::default_attribute_names; //add logging to file (which implicitly deletes the default console logger) logging::add_file_log ( keywords::auto_flush = true, keywords::open_mode = std::ios::out | std::ios::app, keywords::file_name = log_file+"_%N.log", keywords::rotation_size = 50 * 1024, // Just for test limit to 50K keywords::format = //"%TimeStamp%: [%Channel%] |ThreadId| <%Severity%> %Message%" expr::format("%1% : [%2%] |%3%| <%4%> %5%") % expr::attr< boost::posix_time::ptime >(timestamp()) % expr::attr<std::string>(channel()) % expr::attr<attrs::current_thread_id::value_type>(thread_id()) % trivial::severity % expr::smessage )->locked_backend()->set_file_collector ( sinks::file::make_collector ( keywords::target = "logs" , keywords::max_size = 200 * 1024 // just for test limit to 200K ) ) ; } Unfortunately, I can't find what the target keyword means, despite the fact that it is a target directory. Target directory relating to smth or should there be a full path? Should this target directory exist? I did a test and rotating log files just grow upon the 200K limit. I just want to have let's say 3 or 4 last rotated log files, the rest should be removed? We already ran into the situation, where the logger used all disc space and the server crashed :( Any help if very appreciated! Thanks, Ovanes

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Does Boost.Test cover 'golden file approach'?
by Journeyer J. Joh 13 Jan '14

13 Jan '14

Hello, I know almost nothing about 'golden file approach'. http://weblogs.java.net/blog/alexeyp/archive/2007/02/testing_command.html >From this blog, you can find the term 'golden file approach'. I want to know if Boost.Test cover this kind of testing. Can I implement 'golden file approach' with Boost.Test? If so please provide me more information about it. Thank you very much. ---------------------------------------- Journeyer J. Joh o o s a p r o g r a m m e r a t g m a i l d o t c o m ----------------------------------------

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lockfree::queue restrictions and performance on linux
by Leon Mlakar 13 Jan '14

13 Jan '14

Hello, after quite a while I'm back to using Boost (and back to the list) and quite happy to see that it made significant progress since I last last used it. One of the libraries that got my attentions is lockfree, the lockfree::queue in particular, since it almost completely meets my needs. Except that I've been wondering why is it that it places the requirement for the trivial destructor on the items it stores? I mean, that really reduces its usability. Is this something inherent to its design? I guess that this has been discussed during the review but a quick digging through the archives didn't come up anything on this. The reason for asking is that I have forced the queue to accept std::shared_ptr and this seems to work almost fine, except that there seem to be an extra reference left to the item last popped, but that's something I can live with. Another thing was its performance - I ran a sort of quick benchmark (queue of shared_ptr's to item containing atomic<int> as a counter, items were popped from the queue and immediately pushed back after decrementing the counter) and its perfromance was next to stellar on OSX (with multiple consumers and producers something like forty times faster than std::queue with mutex) but very poor on Linux. While I can understand that locking runs fast on Linux due to its spinlock/futex implementation of mutexes, I have no explanation for the poor performance of lockless::queue (with two producer/consumer threads std::queue with mutex was about 15 times faster and about 20 times slower than when run on OSX on the similar hardware). Did anybody else observe the same poor performance behavior? I used Boost 1.54 and tested with both gcc 4.8 and clang 3.5 and got similar results with both. Regards, Leon

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[Boost::any] Memory management using dynamic libraries
by Eugenio Bargiacchi 12 Jan '14

12 Jan '14

I'm building a framework which needs to allow communication between shared libraries which are loaded at runtime. Each shared library provides its own implementation of an abstract interface contained in the framework (called Module), and all Modules are called sequentially multiple times doing the work they need to do. Since modules need to communicate with each other with custom data types, I though of using an std::unordered_map<std::string,boost::any> kept by the framework and shared with the Modules. The map is filled and read by the modules when their code is called through the Module interface which the framework knows (virtual functions). However after a bug I realized that each boost::any value is allocated by the modules, which is logical, since the framework itself has no knowledge of the types that will be stored in the map, and thus the code to allocate them must reside in the libraries themselves. I was wondering whether this could be a problem both during overwriting of a map value (since boost::any has to destroy its old contents) and during program shutdown. This could maybe be because modules use their own allocators. The problem that I had, for example, resulted in a segfault if I tried to unload the modules from memory before the destruction of the map (which is owned by the framework), during boost::any destruction. I assume this happened because the contents of boost::any were created in memory that was then unloaded during the unloading of the shared libraries, resulting in the segfault. And this yet does not take into account custom allocators! So I'm wondering what the best approach here would be. If I would need to keep track of the current "owner" of each single boost::any value allocated, and use it to manually destroy instances when required, or if there is a better way, maybe using some particular boost::any property. Many thanks in advance!

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