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Interprocess file mapping - fixed addresses
by Steve 13 May '12

13 May '12

I hope someone on this list is sufficiently familiar with file_mapping, mapped_region and "Fixed Address Maping" to be able to offer advice. I have a very large file, and I want to map pairs of system-page-sized blocks from it into memory. The catch: I want to map non-consecutive blocks from the file into consecutive memory addresses. For example, with block 42 mapped to BASE_ADDRESS, I might want block 7 mapped to BASE_ADDRESS+PAGE_SIZE. Under Linux, using mmap() directly, I can use one of two approaches: 1. I can map two pages from the first file-block-start-location, then map one block from the second, using MAP_FIXED, at the address returned by the first mapping plus one page. 2. I could map two pages of /dev/zero - then map the first and second pages explicitly using MAP_FIXED into that address space - this copes with the case where the first block in memory is the last block of the file, but has an overhead. Both approaches seem to work, though I've not done extensive testing. I'd prefer to avoid using mmap directly - both to gain the advantages of a well-tested library using high-level C++ idioms - and to compile cross-platform... definitely targeting Linux and Windows - but maybe other platforms too. When I attempt to use the above strategy, I get a boost::interprocess_exception::library_error - though I'm not sure why. The following code fails on both Linux and Windows: -- size_t page_size=mapped_region::get_page_size(); file_mapping m("file.dat", read_write); mapped_region ra(m,read_write,0,2*page_size); uint8_t *base=reinterpret_cast<uint8_t*>(ra.get_address()); mapped_region rb(m,read_write,2*page_size,page_size,base+page_size); //FAILS -- whereas, the following appeared to work under Windows 7 (but not Linux) - perhaps by fluke of the way address space was allocated: -- size_t page_size=mapped_region::get_page_size(); file_mapping m("file.dat", read_write); mapped_region ra(m,read_write,0,page_size); // N.B. Map 1 page only uint8_t *base=reinterpret_cast<uint8_t*>(ra.get_address()); mapped_region rb(m,read_write,2*page_size,page_size,base+page_size); -- The documentation seems focused on MAP_FIXED being used to map specific data in a file into the same memory address on every invocation - with the obvious reference to validity of pointers referencing the mapped address space. Pointers are not a problem for me - my file contains no pointers - just a long stream of application-specific values. I only need to explicitly control two pages to be mapped into contiguous memory - I can be flexible about the mapped base address for the pair of pages - and it doesn't matter if different addresses are chosen on successive invocations.. as long as, in memory, the byte following the last byte of the first page is the first byte of the second page for an arbitrary pair of pages... irrespective of the locations of those pages in the file. Is this a use case that boost::interprocess intends to support? What is the most appropriate, robust, platform independent, way to reserve address space in order map into fixed addresses to ensure contiguous mappings? Do I need to mmap /dev/zero for POSIX systems - and use VirtualAlloc with MEM_RESERVE on Windows myself in order to use fixed-address memory mapping of files? Does boost offer anything to make this platform independent - or am I 'on my own'?

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NaN and lexical_cast
by Claude 13 May '12

13 May '12

Hi! It is possible to convert the "nan" string in a Non a Number floating point value using lexical_cast? -- View this message in context: http://boost.2283326.n4.nabble.com/NaN-and-lexical-cast-tp4630035.html Sent from the Boost - Users mailing list archive at Nabble.com.

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boost::asio::ip::tcp::resolver::query does not work in Ubuntu!!!
by mozdemir 13 May '12

13 May '12

Hi, I am a newbie with Asio library and i got into crashing problem with the following code: boost::system::error_code ec; boost::asio::ip::tcp::resolver resolver( m_hive->GetService() ); boost::asio::ip::tcp::resolver::query query( m_host, boost::lexical_cast< std::string >( m_port )); boost::asio::ip::tcp::resolver::iterator endpointIterator = resolver.resolve( query ); When i run this in windows, i do not have any isssue but in Ubuntu, it works and after some more resolution of query, it crashes. I did install Miredo to activate Ipv6 but it did not help. When the crash happens, i see this: 23:37.47 [dbg] [0x8ec0650] Exception: Host not found (authoritative) 23:37.47 [dbg] [0x8ec0650] Exception: Host not found (authoritative) terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::system::system_error> >' what(): Host not found (authoritative) Aborted (core dumped) Do you know what else is missing or what is wrong? Thanks a lot, mustafa -- View this message in context: http://boost.2283326.n4.nabble.com/boost-asio-ip-tcp-resolver-query-does-no… Sent from the Boost - Users mailing list archive at Nabble.com.

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Serializing a vector containing an unsupported data type
by Tim Burgess 13 May '12

13 May '12

Hi, I have a vector: Std::vector <std::pair< std::string, wxAny> > myParameters; I need to serialize this as part of the class it belongs to and I'm confused as to how to do it, given that the wxWidgets wxAny class isn't supported by Boost. A colleague suggested using lexical cast and I think I can see how this would help if I was just serializing an individual wxAny variable, but how would I cope with it within the vector? I'm serializing out to XML, if this is an issue. Can anybody help, please? Best wishes. Tim Burgess Raised Bar Ltd Phone: +44 (0)1827 719822 Don't forget to vote for improved access to music and music technology at <http://www.raisedbar.net/petition.htm> http://www.raisedbar.net/petition.htm

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[interprocess] interprocess_barrier missing
by Sebastian Messerschmidt 12 May '12

12 May '12

Hello, I just upgraded my boost version from 1.42 to 1.49. Unfortunately the interprocess_barrier is not longer part of the interprocess library. I've checked the SVN and the file /boost/interprocess/sync/interprocess_barrier has been removed in revision 76106. Is there a reason for the removal? Or can someone point me to replacement? Right now I can live without it, but in order to get some of my components working again, I need a shared memory barrier. Any hints? cheers Sebastian

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Boost libraries on MacOS X: libboost_foo.dylib vs libboost_foo-mt.dylib (+)
by Nick Zavaritsky 12 May '12

12 May '12

Hi all! Please enlighten me what is the difference between libboost_foo.dylib and libboost_foo-mt.dylib? I guess -mt naming convention originates from Windows which once had both signle- and multithreaded CRT (-mt). However there is neither a single-threaded CRT nor a single-threaded program on Mac, thanks to GCD. Is there any use for non-MT libboost_foo.dylib or not? And let me squeeze another vaguely related question in the same letter. Are Boost debug and normal library variants binary-compatible? The reason I am curious is because Mac dynamic library linker (dyld) has a promising feature to load a different library variant without program recompilation. This feature is activated through the environment variable DYLD_IMAGE_SUFFIX. Ex: setting DYLD_IMAGE_SUFFIX=_debug will result in dyld attempting to load libfoo_debug.dylib instead of libfoo.dylib. Thanks in advance.

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BGL: get(p, g, x) and get(get(p, g), x)
by Shaun Jackman 11 May '12

11 May '12

Hi, I’ve implemented a graph that’s quite similar to adjacency_list. get(get(vertex_index, g), u) works as expected, but get(vertex_index, g, u) does not work. Is their a default implementation in boost/graph somewhere that translates the latter call to the first, or does my graph have to implement the following function? template <typename Tag, typename Key> typename property_map_value<MyGraph, Tag>::type get(Tag tag, const MyGraph& g, Key key) { return get(get(tag, g), key); } When I include this implementation, the get(tag, g, u) call works as expected. Cheers, Shaun

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multiprecision (/sandbox/big_number/) - pow function
by Ryan Lichtenwalter 11 May '12

11 May '12

I am using the multiprecision library from /sandbox/big_number compiling with boost 1.49.0. Specifically, I am using cpp_int. I can successfully compile and run the following example: #include <boost/multiprecision/cpp_int.hpp> using namespace boost::multiprecision; cpp_int u = 1; for(unsigned i = 1; i <= 100; ++i) u *= i; std::cout << u << std::endl; // prints 100! which I obtained from: https://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/… When I add the following code: cpp_int x; x = pow( u, 2 ); I receive the following compiler error (g++ 4.1.2): ./boost/boost/multiprecision/detail/functions/pow.hpp: In function ‘void boost::multiprecision::default_ops::eval_pow(T&, const T&, const U&) [with T = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, U = int]’: ./boost/boost/multiprecision/detail/default_ops.hpp:1250: instantiated from ‘void boost::multiprecision::detail::pow_funct<Backend>::operator()(Backend&, const Backend&, const Arithmetic&) const [with Arithmetic = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >]’ ./boost/boost/multiprecision/mp_number.hpp:1089: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign_function_2(const F&, const Exp1&, const Exp2&, const boost::multiprecision::detail::terminal&, const boost::multiprecision::detail::terminal&) [with F = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Exp1 = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::terminal, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, void, void>, Exp2 = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::terminal, int, void, void>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:1084: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign_function(const Exp&, const mpl_::int_<3>&) [with Exp = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::function, boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, int>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:973: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign(const Exp&, const boost::multiprecision::detail::function&) [with Exp = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::function, boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, int>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:570: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign(const boost::multiprecision::detail::mp_exp<tag, Arg1, Arg2, Arg3>&, const mpl_::true_&) [with tag = boost::multiprecision::detail::function, Arg1 = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Arg2 = boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, Arg3 = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:95: instantiated from ‘boost::multiprecision::mp_number<Backend, ExpressionTemplates>& boost::multiprecision::mp_number<Backend, ExpressionTemplates>::operator=(const boost::multiprecision::detail::mp_exp<tag, Arg1, Arg2, Arg3>&) [with tag = boost::multiprecision::detail::function, Arg1 = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Arg2 = boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, Arg3 = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ vcp_translator_test.cpp:24: instantiated from here ./boost/boost/multiprecision/detail/functions/pow.hpp:89: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ Different invocations of pow with the arbitrary precision argument as the base, exponent, or both yield different compiler errors, but all of them seem to be broken. Am I doing something wrong? Is there some other fast way to achieve exponentiation with this library? Thanks, Ryan

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Interval Timers - Boost 1.49.0
by asif saeed 11 May '12

11 May '12

Hi, >From 1.49.0 release notes: "ASIO : Added a new class template basic_waitable_timer based around the C++11 clock type requirements. It may be used with the clocks from the C++11 <chrono> library facility or, if those are not available, Boost.Chrono. The typedefs high_resolution_timer, steady_timer and system_timer may be used to create timer objects for the standard clock types". I haven't yet looked into these facilities much - I only want to know if I can use any one or more of these facilities to create a periodic interval timer that could call my callback after every, say, 10 milliseconds. Has this been incorporated? Someone in an earlier thread said that ASIO deadline timer could be used but that doesn't work if system clock gets modified by the code itself. I look forward to receiving your feedback on this. -Asif

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[BGL] remove all children of a given vertex in a directed graph
by NsPx 11 May '12

11 May '12

Hi all, I would like to delete a vertex and all its children vertices in a directed graph. For example, 0 <-- 1 1 <-- 2 1 <-- 3 3 <-- 5 0 <-- 4 Removing 1 will remove 2, 3, 5 too. I have read the doc which explains how to remove all vertices from a graph but for my case it's a little more complicated and I can't find a clean way to do it. Thanks by advance for helping me. Here is what I planned to do but it isn't working : ### typedef adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, vertex_info> Graph; typedef Graph::vertex_descriptor vertexGraph; Graph* myGraph; //given graph vertexGraph vpos; //given vertex vector<vertexGraph> vertsLvl, allChildren; vector<vertexGraph>::iterator it, ite; vertsLvl.push_back(vpos); while( !vertsLvl.empty() ) { vector<vertexGraph> tmp; // all children of the vertsLvl's vertices for( it=vertsLvl.begin(), ite=vertsLvl.end(); it!=ite; ++it) { vector<vertexGraph> children; this->getChildren(*it, children); allChildren.insert( allChildren.end(), children.begin(), children.end()); tmp.insert( tmp.end(), children.begin(), children.end()); // remove edges between vertices from vertsLvl and their children clear_in_edges(*it, *myGraph); } vertsLvl = tmp; } // remove all children and the given vertex : doesn't work for( it=allChildren.begin(), ite=allChildren.end(); it!=ite; ++it) { remove_vertex(*it, *myGraph); } ###

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