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

[asio] Detecting tcp peer disconnection
by Igor R 28 Jan '10

28 Jan '10

Hello, This issue has previously been discussed in details, and IIRC, the conclusion was that the reliable method to detect peer disconnection is to try reading from the socket. Now I encountered strange situation: I connect tcp socket to some proprietry server, then pull out the ethernet cable from the server side. If async_read_some was in progress - nothing happens, no handler is called. If I start an additional async_read_some - nothing happens. I tried to set SO_KEEPALIVE option and waited - nothing happened. My machine runs WinXPSP3, so async_read_some is delegated to WSARecv(). I'd appreciate any idea on the subj. Thanks.

2 3

[boost-build] boost projects, like boost/python/boost_python
by Simon Pickles 28 Jan '10

28 Jan '10

Hello, Can anyone tell me how I find which jamfile is run when the line: <library>boost/python/boost_python is encountered by bjam? And are there equivalent 'shortcuts' to other boost libraries, particularly boost unit test framework? Many thanks Si

2 1

[String Algo] error in ireplace_first or ireplace_all with std::wstring under gcc 3.4.2 (MingW)
by Doug Swanson 28 Jan '10

28 Jan '10

I hope this is the appropriate place to post -- I apologize in advance if it is not! The following code compiles and runs without error under g++ in Windows, GCC 3.4.2 (MingW): <code> #include <cstdio> #include <string> #include <boost/algorithm/string.hpp> using namespace std; using namespace boost; int main( void ) { string test = "This is a test"; ireplace_first( test, "test", "success" ); printf( "%s\r\n", test.c_str() ); return 0; } </code> The output is correct: "This is a success". If I change the above code to use a std::wstring instead, it will compile, but it will crash on execution: <code> #include <cstdio> #include <string> #include <boost/algorithm/string.hpp> using namespace std; using namespace boost; int main( void ) { wstring test = L"This is a test"; ireplace_first( test, L"test", L"success" ); printf( "%ws\r\n", test.c_str() ); return 0; } </code> Setting a breakpoint on std::terminate() in gdb gives the following backtrace: Breakpoint 1, 0x00407ae6 in std::terminate() () (gdb) bt #0 0x00407ae6 in std::terminate() () #1 0x00404dc2 in __cxa_throw () #2 0x004021d2 in std::__throw_bad_cast() () #3 0x00434c69 in std::ctype<wchar_t> const& std::use_facet<std::ctype<wchar_t> >(std::locale const&) (__loc=@0x22fe8c) at C:/Applications/Dev-Cpp/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/bits/locale_facets.tcc:112 #4 0x0043415c in wchar_t std::toupper<wchar_t>(wchar_t, std::locale const&) ( __c=84, __loc=@0x22fe8c) at C:/Applications/Dev-Cpp/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/bits/locale_facets.h:4553 #5 0x0041648c in bool boost::algorithm::is_iequal::operator()<wchar_t, wchar_t> (wchar_t const&, wchar_t const&) const (this=0x22fe8c, Arg1=@0x3e3df4, Arg2=@0x43702e) at C:/Applications/Boost_new/boost/algorithm/string/compare.hpp:71 #6 0x004163fb in boost::iterator_range<__gnu_cxx::__normal_iterator<wchar_t*, std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> > > > boost::algorithm::detail::first_finderF<wchar_t const*, boost::algorithm::is_iequal>::operator()<__gnu_cxx::__normal_iterator<wchar_t*, std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> > > >(__gnu_cxx::__normal_iterator<wchar_t*, std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> > >, __gnu_cxx::__normal_iterator<wchar_t*, std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> > >) const (this=0x22fe80, Begin={_M_current = 0x3e3df4}, End={_M_current = 0x3e3e10}) at C:/Applications/Boost_new/boost/algorithm/string/detail/finder.hpp:76 #7 0x00413fe8 in void boost::algorithm::find_format<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, boost::algorithm::detail::first_finderF<wchar_t const*, boost::algorithm::is_iequal>, boost::algorithm::detail::const_formatF<boost::iterator_range<wchar_t const*> > >(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&, boost::algorithm::detail::first_finderF<wchar_t const*, boost::algorithm::is_iequal>, boost::algorithm::detail::const_formatF<boost::iterator_range<wchar_t const*> >) ( Input=@0x22ff50, Finder=@0x22fe80, Formatter={m_Format = {m_Begin = 0x43701e, m_End = 0x43702e, singular = false}}) at C:/Applications/Boost_new/boost/algorithm/string/find_format.hpp:146 #8 0x004141b5 in void boost::algorithm::ireplace_first<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, wchar_t[5], wchar_t[8]> (std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&, wchar_t[5] const&, wchar_t[8] const&, std::locale const&) (Input=@0x22ff50, Search=@0x43702e, Format=@0x43701e, Loc=@0x22ff40) at C:/Applications/Boost_new/boost/algorithm/string/replace.hpp:259 #9 0x004014e8 in main () at test.cpp:11 I am not competent enough with Boost to understand what the call stack is telling me, except that __throw_bad_cast( ) is the source of the crash. ireplace_all gives the same behavior as ireplace_first above. Furthermore, the problem does not arise if I use replace_first or replace_all instead of ireplace_first or ireplace_all. It compiles and runs correctly. Finally, the problem does not arise if I compile using MSVC 2008. It compiles and runs correctly. Does this indicate a problem with gcc (MingW) unicode support? Is there an easy way to circumvent it? Thank you very much for any suggestions!

2 1

Re: [Boost-users] [date_time][serialization] Fast persistence ofboost::date_time::ptime
by pete＠pcbartlett.com 28 Jan '10

28 Jan '10

On Thu 28/01/10 13:20 , Jeff Garland <azswdude(a)gmail.com> wrote: > Igor R wrote: > >> However on this glance this doesn’t seem possible > non-intrusively. Perhaps > >> I’ve missed something, perhaps there’s a third way > – I would be grateful if > >> any could share any ideas. > > > > Yes, it was already discussed here: > > > http://groups.google.com/group/boost-list/browse_thread/thread/d799ca831185 > 01e4/04b184b4c7af8c0b?show_docid=04b184b4c7af8c0b> > > I believe nothing changed since then. > There's not a direct way to get at the internal representation of a > ptime, > which varies based on how the library is compiled (64 or 96 bits > depending on > settings -- the thread above isn't completely accurate on this > point). If > it's critically important, of course, you could modify the source > directly to > fit your particular setup and provide the internal representation > for your app > to serialize (add a to_int64 for example). As a general rule, > however, it's > unwise to store these values as integers since future versions of > the library > might, for example, expand the epoch range and hence these > serialized values > wouldn't be compatible -- that, and the aforementioned fact that the > internal > size isn't fixed are a couple of the reasons there isn't direct > access. > Jeff Thank you both for your helpful replies (and for the helpful library!) They are good reasons. The Boost.Serialization library has it versioning mechanisms so it would be possible for a more intrusive set of load/save functions to be future- and config-proof as well as being fast. However whilst that would suit me, it has its costs - I am sure many like the readability of the current archives and I am sure the maintainer likes that the serialization functions only need to use public members of the date_time classes!

1 0

bjam --address-model=64 doesn't work anymore?
by Daher 28 Jan '10

28 Jan '10

Using msvc100 building with: bjam --address-model=64 and unable to link output libs in my project. msvc saying its X86 and not X64 am i missing something?

2 2

C++ and quality of software
by Peter Foelsche 28 Jan '10

28 Jan '10

I was thinking. There should be some C++ software quality assurance institution. They would give a stamp of approval to software written in C++. Criteria would be: a.. no usage fixed-sized buffers b.. no usage of functions from the c library, which do not check for correct type, like *printf(), *scanf(). c.. no dangling resources, no resource leaks in any case d.. usage of C++ Exception Handling for reporting errors (all fallible OS-calls are wrapped into C++, this can be checked by denying read/write permissions on some object, the software is trying to read/write to) e.. clean design -- e.g. no protocols (no protocols is my way of saying, that all methods of classes can be used and make sense to be used, as soon as this object exists) What do you think? I also published this on my blog: http://foelsche.spaces.live.com/blog/cns!2BFA22F3AB9E833!921.entry

15 31

[date_time][serialization] Fast persistence of boost::date_time::ptime
by Pete Bartlett 28 Jan '10

28 Jan '10

I am interested in serializing data structures like vector< pair< boost::date_time::ptime , double> > as quickly as possible. I see that ptime is a serializable object (in the Boost.Serialization sense) but on the surface this implementation looks slow - we first get a date and time_duration and then serialize the various components (mins,secs,subsecs) separately for the latter and construct a full ISO string for the date. Something faster is surely possible - digging into the implementation it looks like a (non-special) ptime is represented as boost::uint64_t so if we were privy to all implementation details we could use serialize that. However on this glance this doesn't seem possible non-intrusively. Perhaps I've missed something, perhaps there's a third way - I would be grateful if any could share any ideas. Thanks, Pete

3 2

passing socket descriptor to a function
by pedro chaparro 28 Jan '10

28 Jan '10

Hi, i have the code below, i want to separate the open socket code from the writting fucntions, i want to call a escribir() function from the main but i¡m not clear the value i have to pass the function, inthe way i have below it has not work. thanks #include <ctime> #include <iostream> #include <string> #include <boost/asio.hpp> using boost::asio::ip::tcp; void escribir( tcp::socket socket){ std::string message = "mensaje"; boost::system::error_code ignored_error; boost::asio::write(socket, boost::asio::buffer(message), boost::asio::transfer_all(), ignored_error); } int main() { int contador=0; try { boost::asio::io_service io_service; tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), 5544)); for (;;) { tcp::socket socket(io_service); acceptor.accept(socket); escribir(socket); } } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; } -- Ing Pedro Alonso Chaparro Valero Ciudad Politecnica de la Innovación iTEAM - Mobile Communications Group Polytechnic University of Valencia C\ Camino de Vera S/N, Edificio 8G 46022 Valencia, Spain

2 5

Re: [Boost-users] [interprocess] shared_memory_object constructor with create_only parameter
by Philipp Hamann 28 Jan '10

28 Jan '10

Hi all, I am sorry. I made a mistake. My first problem is solved. It is not a bug. > I have some problems using the shared_memory_object constructor with the > create_only parameter. > The goal is to allow only one process to write to the shared memory. So > I create a shared_memory_object with the create_only parameter. For the > first process this is successful (as I assumed), but for the second > process (same parameters) this is successful, too (not as I assumed). > The documentation of boost says that it should throw an exception, if > the shared memory is allready created. Is this a bug or a misuse or > understanding of the library? But the second problem concerning shared_memory_object::remove(const char* name) is still present. > I realized another problem. If I call the static function > shared_memory_object::remove(const char* name), the memory should be > removed only when no further process has access to the memory. This > seems also not to work. I did the following: > 1. create shared memory for writing. > 2. open shared memory for reading > 3. shared_memory_object::remove(const char* name) (from the reading > process) > 4. reopen the shared memory for reading -> exception: can not find the file Thanks for your help and apoligizes for bothering you with my first problem. Philipp

2 4

serialization: pointer reconstruction
by Noah Roberts 27 Jan '10

27 Jan '10

A while back I asked about saving a pointer to an item in another class that is stored as a direct instance variable (no pointer). Here's a brief illustration: struct A { }; struct B { A a; }; struct C { A * a; // points to a B::a. }; I have an idea how to store and restore these relationships but I'd like to see if there are any improvement ideas and/or direction to existing behavior I'm not seeing in the documentation. My idea is to first store B::a (which simply makes sense in my problem anyway) and when I do this to call some custom support functions to generate a unique ID for the object at that address and store it first, then the rest of the data in A. This would appear in A::serialize and the unique ID would be stored in the Archive (added behavior) as a map from address to uid. Then when storing C I would request the unique ID for the address the pointer stores and store it. On reading I read B::a first and it sort of reverses the process. The uid is read and then A::serialize stores the uid and 'this' in the archive map in a uid->address format. I then read the uid on reading C::a and request the address from the archive using that value. I've already subclassed the Archive in order to pass around other load information needed by classes that didn't have local copies, so that's the easy part (though it wasn't a straight forward operation). The question I have though is that since the pointer archiving already must use some similar type of API, can I use it instead of rolling my own and how would I do that?

2 3