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[Interprocess] Named objects with 'Managed External Buffer' (newbie)
by Jorge Bellon 25 Apr '14

25 Apr '14

Good afternoon, First, I apologize if I'm asking something obvious or outside the acceptable topics. I'm starting to use Boost so I'm quite newbie. I'm interested in using the managed_external_buffer in order to perform buffer copies into a created buffer that was created previously. Therefore, I will be storing mostly raw data into that buffer. Basically, I'm trying to do the following: Suppose a program uses the following int array: int numbers[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; Eventually, I have to copy a chunk of that array into a pre-allocated buffer (i.e. the managed_external_buffer). Let the chunk be defined with: typedef struct { void* addr; size_t size; } chunk_t; However, these chunks can overlap, so I will sometimes merge two overlapping chunks into a bigger one. Example: // Chunk 1 chunk1_addr = (void*)&numbers[3]; chunk1_size = 3 * sizeof(int); // Chunk 2 chunk2_addr = (void*) &numbers[4]; chunk2_size = 4 * sizeof(int); The desired result is a single chunk containing {3, 4, 5, 6, 7}. The proposed problem is the merge, but how to find those chunks in the managed_external_buffer, so my question is the following: - Would it be possible to use named objects with another data type other than CharType and use managed_external_buffer::find to look for them? The thing is I could generate a hash or a numerical ID to identify the chunk. Generating a string using that number could be done but it would not be efficient. Otherwise, I guess I would have to keep a map (or other collection) with the <chunk ID, chunk pointer> pairs, define the managed_external_buffer with boost::interprocess::null_index (since I won't be using named objects) and use it through allocate and deallocate. Is this correct? Thanks in advance, Jorge WARNING / LEGAL TEXT: This message is intended only for the use of the individual or entity to which it is addressed and may contain information which is privileged, confidential, proprietary, or exempt from disclosure under applicable law. If you are not the intended recipient or the person responsible for delivering the message to the intended recipient, you are strictly prohibited from disclosing, distributing, copying, or in any way using this message. If you have received this communication in error, please notify the sender and destroy and delete any copies you may have received. http://www.bsc.es/disclaimer

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[msm] compilation warning with boost-1.55.0
by samriti katoch 24 Apr '14

24 Apr '14

Hi, With boost-1.55.0 I see this warning from msm code: In file included from /build/boost/fusion/include/make_map.hpp:10, from /build/boost/msm/front/euml/common.hpp:40, from /build/boost/msm/front/euml/operator.hpp:15, from /build/abc.cc:15: cc1plus: warnings being treated as errors /build/boost/msm/back/fold_to_list.hpp:35: warning: 'boost::msm::back::states_' defined but not used What is a good way to remove this warning? Thanks! Samriti

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Free Workshop: Test-Driven Development in C++ (Salt Lake City, UT)
by legalize+jeeves＠mail.xmission.com 24 Apr '14

24 Apr '14

[Please do not mail me a copy of your followup] This will be a practice run of my presentation for C++ Now! 2014. Workshop announcement: <http://bit.ly/RQgOtQ> Excerpt from the announcement: Test-Driven Development in C++, Wednesday, April 30, 2014 Have you heard about that new thing the kids are doing called test-driven development and wondered what it's all about? Is it about testing? Is it about design? Is it good or is it bad? Come join me for an evening workshop where I will show you what it's all about and you'll have a chance to try it out for yourself on a problem large enough to be interesting, but small enough that you can make progress on it during the workshop. The workshop will use the Boost.Test and Turtle libraries. Thanks to Fusion-io for the meeting facilities, WiFi access, food (pizza from The Pie) and refreshments. -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

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circular buffer in a multithreaded program
by Sebastian Gesemann 24 Apr '14

24 Apr '14

Hello! I had some troubles with using boost::circular_buffer in a multithreaded application and I'm not really sure whether I actually ran into a bug or wether I expected just too much that wasn't promised in the thread-safety section. Anyhow, I wanted to share my story and a theory of what possibly went wrong. Maybe this posting even contains some ideas of how circular_buffer could be made a little more thread-safe without ading any mutex- or atomics-based synchronization. What I tried to do: I tried to grant one thread write access to a sub-range in a circular_buffer while another thread had read-access to a non-overlapping sub-range. At no time any capacity change was needed. Occasionally, in a reader thread I would "consume" some of the values that were already "committed" by a writer and make more room for the writer to store new data by - locking a mutex - calling cb.erase_first(n); - calling cb.resize(cb.capacity()); - notify writer that there is new free space to write stuff into - unlocking the mutex As for iterator invalidation, erase_first just invalidates iterators to the elements being removed. And resize in this case just increases the size again to the capacity which should not invalidate any iterators If I understand correctly. But the program did not work. The first thing that came to my attention was that the checked iterators of circular_buffer don't support this kind of multithreading as they register and unregister themselves into a linked list without any synchronization. But even after disabling the checked iterators via BOOST_CB_DISABLE_DEBUG, the program still did not work. I could not figure out why (with enough certainty) and eventually replaced circular_buffer with a custom vector-based data structure. My guess is that the iterators of a circular_buffer somehow depend on some part of the state of the buffer that is modifed by erase_first. Then, I would have a data race. But such a dependency does not really have to be there. In my own implementation, an iterator is "self-sufficient" in the sense that it does not need to access any of the buffer's state (indices, counters and whatnot) to access the right elements. And this way, erasing some unneeded elements from the buffer while some other thread still works on other values in the buffer via iterators does not cause a data race. In my opinion, it's reasonable to expect something like this to work using a circular_buffer. Maybe someone knows more about how circular_buffer iterators are implemented and/or wants to improve the circular_buffer implementation w.r.t. thread-safety to support this kind of use. Since I switched to a custom data structure that is able to deal with this situation, I did not investiage this issue with circular_buffer any further. I already lost about a day because of this. I hope, this is of interest to somebody who wants to avoid exessive copying in the standard "producer-consumer / bounded-buffer pattern". Cheers! Sebastian

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Memory leak in boost::filesystems::parent_path()?
by B.W.H. van Beest 24 Apr '14

24 Apr '14

Hi, The following minimal program (only 7 lines) causes valgrind to report 2 errors, in line6: Some somebody point me to why it is wrong? a.cpp: 1 #include <boost/filesystem.hpp> 2 3 int main( int, char** ) 4 { 5 boost::filesystem::path path0( "/a/b/c" ); 6 boost::filesystem::path path1 = path0.parent_path(); 7 } Compiling and running with valgrind: g++ -g -lboost_system -lboost_filesystem a.cpp -o a.exe valgrind ./a.exe This gives the following output. Note the errors. ==13303== Memcheck, a memory error detector ==13303== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al. ==13303== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info ==13303== Command: ./a.exe ==13303== ==13303== Invalid read of size 8 ==13303== at 0x5B0A5C8: wcscmp (in /lib64/libc-2.18.so) ==13303== by 0x52CA5C4: std::moneypunct<wchar_t, false>::~moneypunct() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52CA638: std::moneypunct<wchar_t, false>::~moneypunct() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C1304: std::locale::_Impl::~_Impl() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C143C: std::locale::~locale() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x5AA775E: __cxa_finalize (in /lib64/libc-2.18.so) ==13303== by 0x503DD72: ??? (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x400EE69: _dl_fini (in /lib64/ld-2.18.so) ==13303== by 0x5AA73D8: __run_exit_handlers (in /lib64/libc-2.18.so) ==13303== by 0x5AA7424: exit (in /lib64/libc-2.18.so) ==13303== by 0x5A90BEB: (below main) (in /lib64/libc-2.18.so) ==13303== Address 0x604c038 is 0 bytes after a block of size 8 alloc'd ==13303== at 0x4C284B7: operator new[](unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==13303== by 0x52CBC81: std::moneypunct<wchar_t, false>::_M_initialize_moneypunct(__locale_struct*, char const*) (in /usr/lib64/libstdc++.so.6 .0.18) ==13303== by 0x52C3807: std::locale::_Impl::_Impl(char const*, unsigned long) (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C42D1: std::locale::locale(char const*) (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x50451B1: boost::filesystem::path::codecvt() (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x5046C7E: boost::filesystem::path::parent_path() const (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x401843: main (a.cpp:6) ==13303== ==13303== Invalid read of size 8 ==13303== at 0x5B0A5C8: wcscmp (in /lib64/libc-2.18.so) ==13303== by 0x52CA4D4: std::moneypunct<wchar_t, true>::~moneypunct() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52CA548: std::moneypunct<wchar_t, true>::~moneypunct() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C1304: std::locale::_Impl::~_Impl() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C143C: std::locale::~locale() (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x5AA775E: __cxa_finalize (in /lib64/libc-2.18.so) ==13303== by 0x503DD72: ??? (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x400EE69: _dl_fini (in /lib64/ld-2.18.so) ==13303== by 0x5AA73D8: __run_exit_handlers (in /lib64/libc-2.18.so) ==13303== by 0x5AA7424: exit (in /lib64/libc-2.18.so) ==13303== by 0x5A90BEB: (below main) (in /lib64/libc-2.18.so) ==13303== Address 0x604c268 is 0 bytes after a block of size 8 alloc'd ==13303== at 0x4C284B7: operator new[](unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==13303== by 0x52CB6B1: std::moneypunct<wchar_t, true>::_M_initialize_moneypunct(__locale_struct*, char const*) (in /usr/lib64/libstdc++.so.6. 0.18) ==13303== by 0x52C3854: std::locale::_Impl::_Impl(char const*, unsigned long) (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x52C42D1: std::locale::locale(char const*) (in /usr/lib64/libstdc++.so.6.0.18) ==13303== by 0x50451B1: boost::filesystem::path::codecvt() (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x5046C7E: boost::filesystem::path::parent_path() const (in /usr/lib64/libboost_filesystem.so.1.53.0) ==13303== by 0x401843: main (a.cpp:6) ==13303== ==13303== ==13303== HEAP SUMMARY: ==13303== in use at exit: 0 bytes in 0 blocks ==13303== total heap usage: 483 allocs, 483 frees, 34,115 bytes allocated ==13303== ==13303== All heap blocks were freed -- no leaks are possible ==13303== ==13303== For counts of detected and suppressed errors, rerun with: -v ==13303== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 2 from 2)

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cmake + CUDA 6 + clang + boost errors on OS X Mavericks
by John Owens 24 Apr '14

24 Apr '14

Greetings, I’m using boost (1.55) (installed via macports) on: - OS X Mavericks - using clang (5.1, the Xcode default version, LLVM 3.4) - with CUDA 6 - and cmake (2.8.12.2). It has a large number of compile errors, shown here: http://pastebin.com/Qg2V0UwM that begin with: /opt/local/include/boost/type_traits/is_abstract.hpp(72): error: identifier "__is_abstract" is undefined I’d be delighted to have any advice on how to do cmake + CUDA 6 + clang + boost on OS X! JDO

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include error in OS X 10.9.2
by Freddy Martinez Garcia 22 Apr '14

22 Apr '14

Hi guys I’m trying to use mongodb in my develop. MongoDB use Boost library in its implementation… I had installed boost 1.55 with macport… the problem is when the mongo c++ driver import son files like: #include <boost/function.hpp> and this file does not exists in my system… How can I fix this in Mac ?? I’m new in os x, because in linux I don’t have this error… best regards freddy

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[Boost][Graph] vf2 implementation question
by Marc Viala 20 Apr '14

20 Apr '14

Hi, Recently,I tried to use Boost.Graph's VF2 implementation and after having played few days with this module, I was wondering if this implementation supports "adjacency_matrix" model as explained by the documentation (cf. http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/vf2_sub_graph_iso.html) To demonstrate my point, you will find hereafter an C++ example extracted from the Boost.Graph's documentation. If the macro "ADJACENCY_LIST_STRUCT" is commented out, this code can't be compiled w/ VS2012 aka VC11 because the static assertion @line 837 of "boost/graph/vf2_sub_graph_iso.hpp" is triggered. My questions are: - Does this VF2 implementation supports "adjacency_matrix" model? - Is there any patch for supporting this model of graph? FYI: If I comment two static assertations in file "boost/graph/vf2_sub_graph_iso.hpp", at line 837 and line 843, the code compiles and runs correctly for "adjacency_matrix" model. #include <boost/graph/adjacency_list.hpp> #include <boost/graph/adjacency_matrix.hpp> #include <boost/graph/vf2_sub_graph_iso.hpp> using namespace boost; //#define ADJACENCY_LIST_STRUCT int main() { #ifdef ADJACENCY_LIST_STRUCT typedef adjacency_list<vecS, vecS, undirectedS> graph_type; #else typedef adjacency_matrix<undirectedS> graph_type; #endif // Build graph1. const int num_vertices1 = 8; graph_type graph1(num_vertices1); add_edge(0, 6, graph1); add_edge(0, 7, graph1); add_edge(1, 5, graph1); add_edge(1, 7, graph1); add_edge(2, 4, graph1); add_edge(2, 5, graph1); add_edge(2, 6, graph1); add_edge(3, 4, graph1); // Build graph2. const int num_vertices2 = 9; graph_type graph2(num_vertices2); add_edge(0, 6, graph2); add_edge(0, 8, graph2); add_edge(1, 5, graph2); add_edge(1, 7, graph2); add_edge(2, 4, graph2); add_edge(2, 7, graph2); add_edge(2, 8, graph2); add_edge(3, 4, graph2); add_edge(3, 5, graph2); add_edge(3, 6, graph2); // Compute de subgraph isomorphing. vf2_print_callback<graph_type, graph_type> cb(graph1, graph2); vf2_subgraph_iso(graph1, graph2, cb); } Best regards, Marc

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[Iostream] how to build iostream with zlib on windows
by Pritesh Acharya 18 Apr '14

18 Apr '14

Boost version: 1.55.0 OS: Windows 8 IDE: Visual Studio 2010 Is there a good tutorial on building boost iostream with zlib on windows. I looked over reference manual but with no solution. I did download zlib dll and source code and made reference in visual studio. I have link error on gzip_decompressor();

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Using metric_tsp_approx with bundled properties
by Alexis Praga 18 Apr '14

18 Apr '14

Hi, I am trying to use metric_tsp_approx on a graph defined as : typedef adjacency_list<vecS, vecS, undirectedS, City, Road> Graph; City contains the vertex id and Road the edge weight. After reading the documentation, I arrived to : metric_tsp_approx(g_init, weight_map(get(&Road::length, g_init)). vertex_index_map(get(&City::id, g_init)), make_tsp_tour_visitor(back_inserter(c))); I have compilation errors however. The relevant part seems to be : /usr/include/boost/property_map/property_map.hpp:382:58: error: no type named ‘key_type’ in ‘struct boost::property_traits<boost::bgl_named_params<boost::bundle_property_map<boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, City, Road>, long unsigned int, City, int>, boost::vertex_index_t, boost::no_property> >’ Any help appreciated, thanks. -- Alexis Praga, PhD Student (CERFACS) GPG key : AD4A AF6D BB5C 042F 9422 1223 06E1 C1BF E287 65D0

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