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

Problem finally found!
by Gonzalo Garramuno 06 Jan '13

06 Jan '13

My problem was that acceptor_ was called twice and two sessions were created. The first session was used properly while the second session missed the socket setup. class server { public: server(boost::asio::io_service& io_service, const tcp::endpoint& listen_endpoint, mrv::ViewerUI* v) : io_service_(io_service), acceptor_(io_service, listen_endpoint), ui_( v ) { start_accept(); } void start_accept() { tcp_session_ptr new_session( boost::make_shared<tcp_session>( boost::ref( io_service_ ), boost::ref(ui_) ) ); std::cerr << "******** TCP SESSION " << new_session << std::endl; acceptor_.async_accept(new_session->socket(), boost::bind(&server::handle_accept, this, new_session, _1)); } void handle_accept(tcp_session_ptr session, const boost::system::error_code& ec) { if (!ec) { session->start(); } start_accept(); // BAD } Changed to: void handle_accept(tcp_session_ptr session, const boost::system::error_code& ec) { if (!ec) { session->start(); } else { start_accept(); } } I still don't know why this is so and the problem is not fully resolved, as only the server change in the timeline works only once, but at least the server now works.

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[interprocess] (OS X) waiting on condition variable = CPU 100% + fans running loud
by Francisco Lopes 06 Jan '13

06 Jan '13

Hi, I was implementing a kind of server using shared memory. The server should keep idle, waiting for a request and I do this by waiting on a condition variable, of course. I then noticed my fans running high when I let the server waiting a little longer while testing and discovered this happens simply because of some busy loop implementation for condition waiting. Is there any reason for that? Given the interprocess library age, no way for implementing a non-busy interprocess condition variable waiting is available? https://svn.boost.org/trac/boost/ticket/6108 Regards, Francisco Lopes

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MPL vs. Proto for EDSL dev?
by Chris Russell 05 Jan '13

05 Jan '13

Hello, all. I'm reading the MPL book (again) and tinkering with some ideas for a new library for building complex FSM hierarchies [1]. I've got a minimal runtime library written that codifies the important concepts but now want to try to make it a native C++ EDSL and am wondering if it makes more sense to concentrate on MPL, Proto (or both)? For pure education on the subject of C++ template metaprogramming the MPL and the amazing Abrahams/Gurtovoy book seems like the right starting place but would appreciate any advice you folks are willing to share with me. Thanks, Chris [1] I am aware of other FSM libs (e.g. StateChart, MSM) and likely some of what I'm planning is redundant. That's okay: my goal is to gain deeper understanding of C++ template metaprogramming by working through a non-trivial problem.

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boost-mpi assertion during recv fails
by Kyle Joseph Berger 04 Jan '13

04 Jan '13

Hello, I am using boost-mpi and I am getting an error that I am having a hard time figuring out. I am using a recv call and an assertion in the boost code fails: void boost::mpi::binary_buffer_iprimitive::load_impl(void *, int): Assertion `position+l<=static_cast<int>(buffer_.size())' This is from the file binary_bffer_iprimitive.hpp located in boost/mpi/detail/. This does not occur the first time I am receiving so I know it's not a general error with every send/recv call I make. I think this assertion is checking whether the buffer is large enough to accommodate the data being received, but I'm not even sure about that. If that is the case, what could cause the buffer to not be large enough? Shouldn't that be taken care of by the underlying boost? Thanks, Kyle

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[Locale] Security bug announcement - UTF-8 validation
by Artyom Beilis 04 Jan '13

04 Jan '13

Hello, Boost.Locale library in Boost 1.48 to 1.52 including has a security flow. boost::locale::utf::utf_traits accepted some invalid UTF-8 sequences. Applications that used these functions for UTF-8 input validation could expose themself to security threats as invalid UTF-8 sequece would be considered as valid. This bug is fixed in upcoming Boost 1.53. For more details see: https://svn.boost.org/trac/boost/ticket/7743 Users who can't upgrade to the latest versions may apply the following patch to fix the problem. http://cppcms.com/files/locale/boost_locale_utf.patch Regards, Artyom Beilis -------------- CppCMS - C++ Web Framework: http://cppcms.com/ CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/

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How to convert shared_ptr to pointer?
by young 03 Jan '13

03 Jan '13

I have shared_ptr<int> variable. I need to pass a int* pointer to a function call. How to pass shared_ptr<int> as int *? -- View this message in context: http://boost.2283326.n4.nabble.com/How-to-convert-shared-ptr-to-pointer-tp4… Sent from the Boost - Users mailing list archive at Nabble.com.

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[Polygon] Boolean (Clipping) performance
by kusogray 03 Jan '13

03 Jan '13

Hi there, I input 200,000 to both polygon set A and B, with each polygon contains 5~8 points then do the A^B; however, this instruction cost about *30 minutes.* my question is: I thought the O(n logn) algorithm with n ~ 1,000,000 just cost about at most 2 or 3 mins I checked the XOR AND OR result is correct, but the performance is weird, did I do anything wrong or misunderstanding? Thanks for reading this! -- View this message in context: http://boost.2283326.n4.nabble.com/Polygon-Boolean-Clipping-performance-tp4… Sent from the Boost - Users mailing list archive at Nabble.com.

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[system] local static and threading in C++03
by Felipe Magno de Almeida 02 Jan '13

02 Jan '13

Hello, Boost.System returns the system_category this way: BOOST_SYSTEM_DECL const error_category & system_category() { static const system_error_category system_category_const; return system_category_const; } But couldn't this make double construction/double free in C++03 systems if system_category is ran concurrently? Regards, -- Felipe Magno de Almeida

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[serialization] deserializing chunk by chunk
by Arash Abghari 02 Jan '13

02 Jan '13

Hi, I have an encrypted archive. I can decrypt the file chunk by chunk. I wonder if there is a way to deserialize each chunk on the fly. The main purpose is to reduce the memory footprint of the application since the archive can be a few hundred mega bytes. The problem as I mentioned is the file is encrypted and it has to be decrypted first in the memory and then deserialized. Thanks, Arash

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[filesystem] segfault in path::imbue after upgrade to boost 1.52
by Shawn Chidester 02 Jan '13

02 Jan '13

Just upgraded from boost 1.47 to 1.52 and I'm experiencing segmentation faults in boost::filesystem::path::imbue. This is on 64-bit Ubuntu 12.04 and 12.10. Compiling with g++-4.6 Here is a stack trace from valgrind: ==26893== Memcheck, a memory error detector ==26893== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al. ==26893== Using Valgrind-3.9.0.SVN and LibVEX; rerun with -h for copyright info ==26893== Command: bin/example ==26893== ==26893== Invalid read of size 4 ==26893== at 0x9843970: std::locale::locale(std::locale const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17) ==26893== by 0x69FAD0F: boost::filesystem::path::imbue(std::locale const&) (path.cpp:918) ==26893== by 0x69FAC76: boost::filesystem::path::codecvt() (path.cpp:911) ==26893== by 0x69F8546: boost::enable_if<boost::filesystem::path_traits::is_pathable<boost::decay<char*>::type>, boost::filesystem::path&>::type boost::filesystem::path::operator=<char*>(char* const&) (path.hpp:202) ==26893== by 0x69F4737: boost::filesystem::detail::current_path(boost::system::error_code*) (operations.cpp:1077) ==26893== by 0x5AB0D2C: boost::filesystem::current_path() (operations.hpp:429) ==26893== by 0x5AB0447: __static_initialization_and_destruction_0(int, int) (example.cpp:53) ==26893== by 0x5AB0BB5: _GLOBAL__sub_I_example.cpp (example.cpp:1192) ==26893== by 0x400F315: call_init.part.0 (dl-init.c:85) ==26893== by 0x400F3EE: _dl_init (dl-init.c:52) ==26893== by 0x40016F9: ??? (in /lib/x86_64-linux-gnu/ld-2.15.so) The stack trace looks the same in GDB. In case it's of any use here's what "path_locale" looks like at path.cpp:918 (gdb) frame #1 0x00007ffff561ed10 in boost::filesystem::path::imbue (loc=...) at boost/libs/filesystem/src/path.cpp:918 918 std::locale temp(path_locale); (gdb) print path_locale $1 = {_M_impl = 0x0} I'm guessing the crash has to do with path_locale being uninitialized, but I don't know what to do about it (if that is indeed the problem). If anyone can provide some insight (or better yet, a solution) I would be very grateful! Thanks, Shawn

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