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[Interprocess]: using condition variables with readers-writer lock (named_sharable_mutex)
by Chris Evans 21 Sep '16

21 Sep '16

Hi, I am trying to use condition variables to signify updated data in a managed_shared_memory segment. I have one "writer" and multiple "readers" of the shared state, so I am using a readers-writer lock as follows: using SharedMutex = bi::named_sharable_mutex; using ReadLock = bi::sharable_lock<SharedMutex>; using WriteLock = bi::scoped_lock<SharedMutex>; using NewEntryCondition = bi::named_condition_any; // With a "writer" block as follows: { WriteLock w_lock( sh_mut_ ); // Update the shared memory object sh_cond_.notify_all(); } // And a "reader" block as follows (many processes call the following simultaneously): { ReadLock r_lock( sh_mut_ ); sh_cond_.wait( r_lock, []() { std::cout << "checking predicate..." << std::endl; // predicate logic goes here... }); // Access object in shared memory here } Unfortunately, although the code compiles, the reader processes are never awakened from wait() and block forever. According to the following thread from 2011: http://lists.boost.org/boost-users/2011/02/66053.php "POSIX does not support condition variables with read-write locks (although I think Windows Vista does) so Interprocess does not offer any support for this." At the time, it appears named_condition_any didn't yet exist. Has the status of this changed in the last 5 years? Is there a suggested way of implementing readers-writer locks with condition variables using boost::interprocess? Thanks! -- Chris Evans Systems Engineer Azure Summit Technology, Inc. 3050 Chain Bridge Road, Suite 600 Fairfax, VA 22030

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[compute] extending meta_kernel functionality
by Oswin Krause 20 Sep '16

20 Sep '16

Hi, I am trying to use boost.compute to extend my linear algebra library to GPUs. so far it helped me a lot with vectors as i can directly use the iterator interface. Matrices are harder. for matrices i need to overload the operator matrix(i,j)-> return the element (i,j). For this i have to return an expression which then offers operator<< with meta_kernel, for example template<class T, class IndexExpr1, class IndexExpr2> inline meta_kernel& operator<<(boost::compute::detail::meta_kernel &kernel, const matrix_element_expr<T, IndexExpr1, IndexExpr2> &expr) { return kernel << kernel.get_buffer_identifier<T>(expr.m_buffer, expr.m_address_space) << '[' << expr.m_expr1 <<"*" <<expr.m_stride1<<"+"<<expr.m_expr2<< "*"<<expr.m_stride2 << ']'; } Unfortunately all of this is in namespace boost::compute::detail, making it a no-go area. Therefore two questions: 1. How stable is i?/can meta_kernel be moved into a normal namespace? 2. Is there a different way to achieve this? (Note that the code above is only an example. I could hack it in this case using the return type of buffer_iterator but not in all cases unfortunately...)

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boost::context "main" stack
by Michael Steinberg 20 Sep '16

20 Sep '16

Hello, is there some way to temporarily run a function on the main stack? I played around a bit, but failed ultimately since the first stub function to be called is getting a "null" context which I assume to be only a valid "return-context". We're facing a problem where a dialog run modally inside a context runs webkit, which triggers garbage collection, which fails miserably since it assumes we're on the "native" stack. If it were possible to run something "on-top" of the main stack, this could maybe be circumvented. Thank you, Michael

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Insertion/Use of boost::multi_index
by Ram 19 Sep '16

19 Sep '16

Hi All , I have created a boost::multi_index container for my use and it compiles successfully. I would like to add my pointer objects to it. boost::multi_index does not seem to have an insert method defined which just takes one arguement which is what I would like the container to store. Maybe I didnt understand how boost::multi_index is meant to be used. Can you please explain to me how to insert an object which I wish the store in the container defined? How is it intended to be used? The container I defined is , typedef boost::multi_index_ClassX< ClassX*, boost::multi_index::indexed_by< boost::multi_index::hashed_unique< boost::multi_index::const_mem_fun<ParentOfClassX, Int64, &ParentOfClassX::getKey1>, boost::multi_index::const_mem_fun<ParentOfClassX, Int64, &ParentOfClassX::getKey2>, > > > MultiIndexedClassX; I would like to do an equivalent of, MultiIndexedClassX sample; ClassX a; sample.insert(&a); <- Since I am interested in storing a *X and I would like it to be indexed by various parameters of X. Also please let me know how to, 1. Insert *X into the container 2. Look up by a) Value of ParentOfClassX::Key1 b) Value of ParentOfClassX::Key2 Please also let me know if I have some basic understanding wrong since I am getting confused a lot in trying to use boost::multi_index. Thanks in advance, Ram

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Help Required, trouble while using boost::multi_index
by Ram 19 Sep '16

19 Sep '16

Hi, I am trying to create a ClassX using "boost::multi_index" and I was successfully able to create a ClassX like, typedef boost::multi_index_ClassX< ClassX*, boost::multi_index::indexed_by< boost::multi_index::hashed_unique< boost::multi_index::const_mem_fun<ParentOfClassX, Int64, &ParentOfClassX::getKey1>, boost::multi_index::const_mem_fun<ParentOfClassX, Int64, &ParentOfClassX::getKey2>, > > > MultiIndexedClassX; This compiles perfectly with no problems. I am writing the code and compiling with Visual Studio 2005 and have included, #include <boost/multi_index_container.hpp> #include "boost/multi_index/hashed_index_fwd.hpp" #include <boost/multi_index/mem_fun.hpp> and have defined namespaces, using namespace boost::multi_index; using boost::multi_index::multi_index_container; using boost::multi_index::hashed_unique; using boost::multi_index::indexed_by; But when I create an object of that type like, MultiIndexedClassX sample; I get a big list compilation errors like, *c:\code\common\lib\boost\boost\multi_index\detail\node_type.hpp(44) : error C2903: 'node_class' : symbol is neither a class template nor a function template* * c:\code\common\lib\boost\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(49) : see reference to class template instantiation 'boost::multi_index::detail::index_node_applier::apply<IndexSpecifierIterator,Super>' being compiled* * with* * [* * IndexSpecifierIterator=boost::mpl::v_iter<boost::mpl::vector1<boost::multi_index::hashed_unique<boost::multi_index::const_mem_fun<ParentOfClassX,GKey,ParentOfClassX::getKey1>,boost::multi_index::const_mem_fun<ParentOfClassX,Vs64,ParentOfClassX::getKey2>>>,0>,* * Super=boost::multi_index::detail::index_node_base<ClassX *,std::allocator<ClassX *>>* * ]* * c:\code\common\lib\boost\boost\mpl\aux_\preprocessed\plain\bind.hpp(207) : see reference to class template instantiation 'boost::mpl::apply_wrap2<F,T1,T2>' being compiled* * with* * [* * F=boost::multi_index::detail::index_node_applier,* * T1=boost::mpl::v_iter<boost::mpl::vector1<boost::multi_index::hashed_unique<boost::multi_index::const_mem_fun<ParentOfClassX,GKey,ParentOfClassX::getKey1>,boost::multi_index::const_mem_fun<ParentOfClassX,Vs64,ParentOfClassX::getKey2>>>,0>,* * T2=boost::multi_index::detail::index_node_base<ClassX *,std::allocator<ClassX *>>* * ]* * c:\code\common\lib\boost\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(49) : see reference to class template instantiation 'boost::mpl::bind2<F,T1,T2>::apply<U1,U2>' being compiled* * with* * [* * F=boost::multi_index::detail::index_node_applier,* * T1=boost::mpl::_2,* * T2=boost::mpl::_1,* * U1=boost::multi_index::detail::index_node_base<ClassX *,std::allocator<ClassX *>>,* * U2=boost::mpl::v_iter<boost::mpl::vector1<boost::multi_index::hashed_unique<boost::multi_index::const_mem_fun<ParentOfClassX,GKey,ParentOfClassX::getKey1>,boost::multi_index::const_mem_fun<ParentOfClassX,Vs64,ParentOfClassX::getKey2>>>,0>* * ]* * c:\code\common\lib\boost\boost\mpl\aux_\preprocessed\plain\apply.hpp(63) : see reference to class template instantiation 'boost::mpl::apply_wrap2<F,T1,T2>' being compiled* * with* * [* * F=boost::mpl::bind2<boost::multi_index::detail::index_node_applier,boost::mpl::_2,boost::mpl::_1>,* * T1=boost::multi_index::detail::index_node_base<ClassX *,std::allocator<ClassX *>>,* * T2=boost::mpl::v_iter<boost::mpl::vector1<boost::multi_index::hashed_unique<boost::multi_index::const_mem_fun<ParentOfClassX,GKey,ParentOfClassX::getKey1>,boost::multi_index::const_mem_fun<ParentOfClassX,Vs64,ParentOfClassX::getKey2>>>,0>* * ]* * c:\code\common\lib\boost\boost\mpl\aux_\preprocessed\plain\reverse_iter_fold_impl.hpp(58) : see reference to class template instantiation 'boost::mpl::apply2<F,T1,T2>' being compiled* * with* * [* * F=boost::mpl::bind2<boost::multi_index::detail::index_node_applier,boost::mpl::_2,boost::mpl::_1>,* * T1=boost::multi_index::detail::index_node_base<ClassX *,std::allocator<ClassX *>>,* * T2=boost::mpl::v_iter<boost::mpl::vector1<boost::multi_index::hashed_unique<boost::multi_index::const_mem_fun<ParentOfClassX,GKey,ParentOfClassX::getKey1>,boost::multi_index::const_mem_fun<ParentOfClassX,Vs64,ParentOfClassX::getKey2>>>,0>* * ]* Thanks, Ram

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[Graph] Is there an active maintainer for Boost.Graph?
by Rohan Shah 19 Sep '16

19 Sep '16

Hi all. I'm wondering whether Boost.Graph currently has an active maintainer. I only ask because there is a fairly active github repository ( https://github.com/boostorg/graph) but it seems that important commits fail to make it into the main release on the website. For example, I would consider this (https://github.com/boostorg/graph/commit/ 8ece8fac15560cf38cf3ffbb1d56708ef8e586a2) commit to be fairly critical - Without it part of depth_first_search seems to be somewhat broken, and that's a core algorithm. And that commit is from 2014! A conversation on #boost IRC suggested I mention this problem here. Note: I am not volunteering myself to help fix this - I'm simply not qualified for it. Sorry.

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[boost] [bjam] combinations of options
by Lorenzo Caminiti 19 Sep '16

19 Sep '16

Hello all, When I use bjam the following will compile my code with combinations of MSVC, GCC, and CLang for both shared and static linking: $ bjam toolset=msvc,gcc,clang link=shared,static # (1) Is there a way to define a variant, target, or something else in the Jamfiles so that I can shortcut the above by typing just the variant target at the command line: $ bjam all_toolset_link_combinations # equivalent to (1) above I am asking this just for convenience because I have a feature like toolset but with 30+ values so it'd be nice to shortcut it to a single target on the bjam command line. Thank you. --Lorenzo

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[test] Init framework before dataset generation
by Florian Lindner 16 Sep '16

16 Sep '16

Hello, I try to use boost test with data test cases: std::vector<float> fibonacci() { std::cout << "Data Set" << std::endl; [...] } BOOST_DATA_TEST_CASE(datatest, boost::unit_test::data::make(fibonacci()), mapping) { std::cout << "Datatype" << typeid(mapping).name() << std::endl; } The problem of that is, that fibonacci is initialized before anything else. The order of initializations is: Data Set main init_unit_test Global Fixture That works fine here, but my fibonacci uses MPI which needs to initialized by MPI_Init. I want to do that initialization in the global fixture or int main or init_unit_tests, once for the entire test runner. Is there anything I can do about that and belay initialization of Data Set after one of the others? Thanks, Florian

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[release] Boost 1.62.0. Beta 2
by Rene Rivera 15 Sep '16

15 Sep '16

The packages for 1.62.0 beta 2 are now available: <https://sourceforge.net/projects/boost/files/boost/1.62.0.beta.2/> The SHA256 checksums are as follows: 95feae3620b3e604e93f14d97195fc04a4b67063692859af8df19657d41b82d5 boost_1_62_0_b2.7z 27bc9b328ff73d7dbf80cd9d4b5f79b0878221e5d8e4b6c47444b135edc1080a boost_1_62_0_b2.tar.bz2 3939d5efa683449e87b374d7e92e3eeb6490063ddb2877919f0fad26e3a0f53e boost_1_62_0_b2.tar.gz cff9ab5db0928244c4c836cf3da5140e6e93db7756e2791ba99a21104ad3aa72 boost_1_62_0_b2.zip As always, the release managers would appreciate it if you download the archive of your choice and give building and using it a try. Please report both success and failure, and anything else that is noteworthy. Thanks! -- The release managers -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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[Boost.Graph] Accessing underlying graph of a boost::reverse_graph
by Björn Pollex 13 Sep '16

13 Sep '16

Hello, I am currently trying to find out if there is a way to access the underlying graph of a boost::reverse_graph [1]. There does not seem to be support for this. I want to use this to generically define interior edge-properties for reversed graphs, if the underlying graph has them as well. Currently this does not work, because I cannot access the underlying graph object. Am I overlooking something? If not, where could I request to add this? Cheers, Björn Pollex [1]: http://www.boost.org/doc/libs/release/libs/graph/doc/reverse_graph.html

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