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

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

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Statechart serialization
by mbrodeur65 04 Mar '15

04 Mar '15

Hi, I'm looking for a solution to serialize boost::statechart objects. I'm aware that this feature is on the statechart library todo list but was wondering if there are any workaround to achieve this with the latest boost release (1.34) ? thanks for your help ! mbrodeur65 -- View this message in context: http://www.nabble.com/Statechart-serialization-tf4131326.html#a11749139 Sent from the Boost - Users mailing list archive at Nabble.com.

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[Thread] Read-write locks
by lfrfly＠icqmail.com 18 Sep '14

18 Sep '14

I'm trying to create a standard read/write lock using Boost Threads, and I'm having a bit of difficulty mapping the Boost concepts onto the usual ones. A read/write lock should have several states: Locked for reading (multiple threads may lock at once), locked for writing (only one thread may lock, and no threads may be locked for reading at the same time), and unlocked. Ideally it would be nice if an RWL which is locked for reading may temporarily upgrade to locked for writing, then return to the locked for reading state. Boost supports several relevant notions of locking: shared locking, upgrade locking, and exclusive locking. This to me is a confusing distinction. In particular, a shared_mutex seems appropriate as the basis for a RWL, but is lock_upgrade() the equivalent of a write lock and lock_shared the equivalent of a read lock? This is unclear. If "upgrade locking" is not the same as "exclusive locking", then is an upgrade lock actually exclusive? Could someone please clarify this.

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[Statechart] How to decide between post_event and process_event atrun time ?
by Philippe DAVID 22 Jul '14

22 Jul '14

Hi, I have a method in which I want to post/process an event. The thing is, this method can be called from outside the state machine (so I need to call process_event), or indirectly by a reaction of the state machine (in this case I must call post_event since process_event is not reentrant). I don't want to write 2 distinct methods to do this (one that calls post, and the other process), I would much rather prefer adding a 'if' in my method that tells me if I have to call process_event or post_event (if I'm being called indirectly by the state machine or not). Is there a way to do this with statechart ? regards, Philippe

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[asio] resolver::cancel() problem
by Matthew Edwards 14 Mar '14

14 Mar '14

In my application (and a separate test program) it seems as though the cancel() function on the resolver does not work as intended. For async resolves, the cancel functionality should abort them immediately and pass an 'operation aborted' error code to the callback handler. In my tests, I will resolve an invalid domain (this causes the resolve to take a few seconds, to demonstrate the problem), sleep for 100ms, then call cancel on the resolver object. No cancelling actually occurs, and the callback is simply triggered after a few seconds with a "No host found" error code, not the expected operation aborted. Has anyone experienced this before, or know how I might be using the resolver incorrectly?

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Server failing when BOOST_ASIO_ENABLE_HANDLER_TRACKING is active
by Gonzalo Garramuno 22 Jan '14

22 Jan '14

Trying to track down when the socket closes on my program, I turned on asio debugging. Server fails when BOOST_ASIO_ENABLE_HANDLER_TRACKING is active. Its stack trace is: g Scanning dependencies of target mrViewer [ 9%] Building CXX object mrViewer/src/CMakeFiles/mrViewer.dir/core/mrvServer.o Linking CXX executable ../../../bin/mrViewer [100%] Built target mrViewer # gga@gga-laptop1 /media/Linux/code/applications/mrViewer # mar ene 01 10:04 [8] $ mrViewer /media/Linux/movies/Tangled.mov [opengl] Using hardware shader profile: NVidia NV30 [opengl] mrViewer supports YUV images through shaders. [psql] Connected to database 'assets2d_development'. The code: boost::asio::io_service io_service; tcp::endpoint listen_endpoint(tcp::v4(), s->port); server rp(io_service, listen_endpoint, s->ui); io_service.run(); fails with: @asio|1357088683.200673|0|socket@0x7f303d8d2d00.close Got signal 11, faulty address is 0x1, from 0x4d222a [bt] Execution path: [bt] mrViewer(_ZN5boost4asio6detail15task_io_service16shutdown_serviceEv+0x3a) [0x4d222a] [bt] mrViewer(_ZN5boost4asio6detail15task_io_service16shutdown_serviceEv+0x3a) [0x4d222a] [bt] mrViewer() [0x4dd2c9] [bt] mrViewer(_ZN3mrv13server_threadEPKNS_10ServerDataE+0x408) [0x4e0e58] [bt] /usr/lib/libboost_thread.so.1.48.0(+0xdda9) [0x7f304e191da9] [bt] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a) [0x7f304f7f0e9a] [bt] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f304da1ccbd] without the #define the code works reliably except sometimes the socket closes unexpectedly.

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[boost.test] How to register custom exception for auto test?
by Jörg Becker 13 Jan '14

13 Jan '14

Hi, I'm using the test library of boost 1.49.0 for my unit tests. It works fine so fare, but if my program throws an error, I get the default error message unknown location(0): fatal error in "excption1_test": unknown type, witch hides the original error message. I tried to register an error translator, but without success. Here is what I tried (modified test/test/custom_exception_test.cpp to use auto test with global fixture): #define BOOST_TEST_MODULE "boost test custom_exception_test" #include <boost/test/unit_test.hpp> #include <boost/test/unit_test_monitor.hpp> using namespace boost::unit_test; BOOST_AUTO_TEST_SUITE( custom_exception_testsuite ) struct my_exception1 { explicit my_exception1( int res_code ) : m_res_code( res_code ) {} int m_res_code; }; void throw_my_exception1() { throw my_exception1( 12 ); } void my_exception1_translator( my_exception1 ) { BOOST_TEST_MESSAGE( "Caught my_exception1" ); } class my_config { public: my_config () { unit_test_monitor.register_exception_translator<my_exception1>( &my_exception1_translator ); } }; BOOST_GLOBAL_FIXTURE( my_config ) BOOST_AUTO_TEST_CASE( excption1_test ) { throw_my_exception1(); } BOOST_AUTO_TEST_SUITE_END() Can anybody tell me what I'm missing? Thanks, Jörg

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using boost with net-snmp
by moshe levi 12 Sep '13

12 Sep '13

I wrote an example on how to integrate net-snmp with boost. please checkout http://blog-moshe.blogspot.co.il/

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[BGL] Having a cost function as weight map
by Maxime van Noppen 06 Sep '13

06 Sep '13

Hi, I can't find how to do this pretty basic thing : having a function instead of a field to compute the cost of edges for various path finding algorithms. I couldn't find the answer in the documentation and Google was of no help. Did I miss something obvious ? Example : ------------------- #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> struct my_edge { double cost() const { return cost_ * 2; } double cost_; }; struct my_node { }; int main() { typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, my_node, my_edge > graph_t; typedef boost::graph_traits<graph_t>::vertex_descriptor vertex_t; graph_t graph; vertex_t v /*= ... */; using boost::weight_map; // Works : boost::dijkstra_shortest_paths(graph, v, weight_map(boost::get(&my_edge::cost_, graph))); // Doesn't compile : //boost::dijkstra_shortest_paths(graph, v, // weight_map(boost::get(&my_edge::cost, graph))); } ------------------- Thanks ! -- Maxime

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Identify cycles in a undirected graph
by NsPx 20 Aug '13

20 Aug '13

Hi all, I use undirected_dfs to detect all cycles in a undirected graph. I detect a cycle with DFSVisitor.back_edge(e,g) but how can I get the list of vertices defining this cycle ? Thanks by advance

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Is boost::this_thread::sleep_for interruption point?
by Serg Gulko 23 May '13

23 May '13

Hello! According to documentation(v 1.50.0) call boost::this_thread::sleep_for can be interrupted. For some reason this functionality not works for me. Here is code sample: //Simple thread function void Test::worker(int delay) { try { boost::this_thread::sleep_for(boost::chrono::milliseconds(delay)); cout << "Doing some work" << endl; } catch (boost::thread_interrupted const& e) { cout << "INTERRUPTED" << endl; } } //Far in the code boost::thread workerThread(boost::bind(&Test::worker, this, 1200)); boost::this_thread::sleep(boost::posix_time::milliseconds(30)); workerThread.interrupt(); boost::this_thread::sleep(boost::posix_time::milliseconds(1500)); I always getting 'Doing some work'... -- View this message in context: http://boost.2283326.n4.nabble.com/Is-boost-this-thread-sleep-for-interrupt… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [CMake] [boost][b2] Differenciate 32bit and 64 bit binaries when using CMake.
by Klaim - Joël Lamotte 16 Apr '13

16 Apr '13

Júlio Hoffimann said: > > I don't know if i understood correctly, but you can set the library > directory by hand, please refer to > /usr/share/cmake-<version>/Modules/FindBoost.cmake, in particular the > variable BOOST_LIBRARYDIR. On Thu, Oct 11, 2012 at 1:29 PM, Miller, Frank <FMiller(a)sjm.com> wrote: > A simple solution would be to install only the 64bit version of boost > into a new directory and change the environment variable to point there. > Then FindBoost will only be able to see the version you want. > Thanks, this will solve my immediate problem, but it don't solve it in general. (I will use it though, so thanks) I can't guarantee where the boost libraries are installed, that's why I use FindBoost. My current understanding is that boost don't have a specific default lib dir for different address models, which is the source of the problem as FindBoost script can't rely on a protocol to find these lib files. Am I correct? Joel Lamotte

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can't get first example in boost tutorial to work
by 7stud 11 Mar '13

11 Mar '13

I'm trying to install boost on mac osx 10.4.7. I followed the tutorial "Getting Started on Unix Variants" found here: http://www.boost.org/doc/libs/1_35_0/ more/getting_started/unix-variants.html Following the instructions in the tutorial, I installed boost in /usr/local as instructed, so my directory structure is: /usr/local/boost_1_34_1/boost But when I run the first example in the tutorial: #include <boost/lambda/lambda.hpp> #include <iostream> #include <iterator> #include <algorithm> int main() { using namespace boost::lambda; typedef std::istream_iterator<int> in; std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " ); } I get the error(among others): error: boost/lambda/lambda.hpp: No such file or directory If I change the include path to: #include </user/local/boost_1_34_1/boost/lambda/lambda.hpp> I get the error(among others): error: boost/lambda/core.hpp: No such file or directory But core.hpp is in the lambda directory: /usr/local/boost_1_34_1/boost/lambda$ ls algorithm.hpp control_structures.hpp lambda.hpp bind.hpp core.hpp loops.hpp casts.hpp detail numeric.hpp closures.hpp exceptions.hpp switch.hpp construct.hpp if.hpp I'm using the Xcode 2.4 IDE to run my C++ programs. I also tried to execute the program from the command line with the original include path: #include <boost/lambda/lambda.hpp> but I get the same error: ~/2testing/dir1$ g++ prog1.cpp prog1.cpp:1:35: error: boost/lambda/lambda.hpp: No such file or directory prog1.cpp: In function 'int main()': prog1.cpp:8: error: 'boost' has not been declared prog1.cpp:8: error: expected namespace-name before ';' token prog1.cpp:8: error: '<type error>' is not a namespace prog1.cpp:11: error: '_1' was not declared in this scope I get the same errors again with the full include path: #include </user/local/boost_1_34_1/boost/lambda/lambda.hpp> $ g++ prog1.cpp In file included from prog1.cpp:1: /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:14:33: error: boost/lambda/core.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:21:52: error: boost/lambda/detail/operator_actions.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:22:61: error: boost/lambda/detail/operator_lambda_func_base.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:23:63: error: boost/lambda/detail/operator_return_type_traits.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:26:45: error: boost/lambda/detail/operators.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:30:46: error: boost/lambda/detail/member_ptr.hpp: No such file or directory prog1.cpp: In function 'int main()': prog1.cpp:8: error: 'boost' has not been declared prog1.cpp:8: error: expected namespace-name before ';' token prog1.cpp:8: error: '<type error>' is not a namespace prog1.cpp:11: error: '_1' was not declared in this scope What path should I be using? Or, should I set an environment variable somewhere?

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Geometry buffer algorithm: complete or not?
by John Lilley 22 Feb '13

22 Feb '13

I was looking here: http://www.boost.org/doc/libs/1_52_0/libs/geometry/doc/html/geometry/refere… And saw this: "The current implemetation only enlarges a box, which is not defined by OGC. A next version of the library will contain a more complete implementation" It looks like Boost::Geometry is incapable of buffering an arbitrary polygon. But various forum discussions refer to the buffer() algorithm like it actually works for the general case. Which is correct? John Lilley

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chaining functions input output
by MM 19 Feb '13

19 Feb '13

Hello, i have these 2 functions provided to me and I wonder whether they can somehow be chained without using intermediary memory? http://codepad.org/tTwkUQhp Rds, MM

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A cool book for c++11 is Published now (Revised Edition)
by Algocoders . 04 Feb '13

04 Feb '13

Hi All, Revised edition of the book : "Foundation of Algorithms in C++11, Volume 1(Revised Edition): Using and Extending C++11, Boost And Beyond" : is available now. @Amazon: http://www.amazon.com/Foundation-Algorithms-Volume-Revised-Edition/dp/14819… @Pothi.com (Indian Edition): http://pothi.com/pothi/book/chandra-shekhar-kumar-foundation-algorithms-c11… This book is vital to understand and extend the C++11 Algorithms by carefully worked out synthesis of language and library features with an eye at future evolution with special emphasis to : - Template Alias - constexpr - copy_backward - requires - std::enable_if : SFINAE - Private Cast - Type Functions - Type Traits - Explicit Template Instantiations and Specializations - Trailing Return Type - auto type specifier - Intermediate Traits Idiom - Value Type Deduction Framework Table of Contents : http://algocoders.com/sites/default/files/toc_foa_revised.pdf Sample Chapter : http://algocoders.com/sites/default/files/chapter1_foa_revised.pdf For more details, please visit the link : http://www.algocoders.com/article/books Have Fun ! Cheers, Algocoders http://www.algocoders.com

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[asio] How to handle 'Bad file descriptor'
by Torsten＠Robitzki.de 03 Feb '13

03 Feb '13

Hello, I have problems to understand, what might causing a 'Bad file descriptor' exception to be thrown in my application. The exception is most likely thrown by a call to tcp::socket::close. From the logs I have, I'm quit certain, that the last function calls on a socket are: s.shutdown(tcp::socket::shutdown_receive); s.shutdown(tcp::socket::shutdown_send); s.close(); // first time to cancel outstanding handlers s.close(); // a second time, later in the d'tor I'm not sure, whether it's the first or the second call to close(), that causes the exception. But what does 'Bad file descriptor' mean in this context? Is the underlying socket is somehow broken/corrupted? If so, there must be a bug in my code. If not, is it save to simply ignore the error? The program is not single threaded, but there is only one boost::io_service object which is run by a single dedicated thread. Kind reagards Torsten P.S: if someone interested in the code: https://github.com/TorstenRobitzki/Sioux/blob/master/source/server/connecti…; it's open source

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[Graph] visitor dijkstra_shortest_paths
by The Maschine 31 Jan '13

31 Jan '13

Hi all, Can someone explain me why I get an error with the first one and not the second? 1) (error) boost::dijkstra_shortest_paths(m_ugraph,*vertex_iterator_begin, boost::distance_map(boost::make_iterator_property_map(dist_map.begin(), boost::get(boost::vertex_index, m_ugraph))), boost::visitor(dijkstra_vis( *vertex_iterator_begin, superStorage ) )); 2) (good) boost::dijkstra_shortest_paths(m_ugraph,*vertex_iterator_begin, boost::distance_map(boost:: make_iterator_property_map(dist_map.begin(), boost::get(boost::vertex_index, m_ugraph))).visitor(dijkstra_vis( *vertex_iterator_begin, superStorage )) ); Why I need to "." the visitor on the distance_map? BFS is ok with it: (good) boost::breadth_first_search(m_ugraph, *vertex_iterator_begin , boost ::visitor(bfs_vis( *vertex_iterator_begin, superStorage ) )); Best, Tasos

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[Fusion] Why restrict 'copy' to equal sizes?
by TONGARI 31 Jan '13

31 Jan '13

Hi, As the counterpart of STL copy, I expected the src just need to be <= dst, but it requires equal sizes in Fusion. What's the rationale? Is it OK to loosen the restriction? (it just compiles if I change '==' to '<=') Thanks.

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How to build boost out-of-tree?
by Keitel, Tino (ALC NetworX GmbH) 31 Jan '13

31 Jan '13

Hi, I want to build boost out-of-tree. Usually, this is done like this: $ mkdir /path/to/build $ cd /path/to/build $ /path/to/source/configure $ make The actual source is not modified, all output is written in the build directory. The best I could find was http://www.boost.org/doc/libs/1_52_0/more/getting_started/unix-variants.htm…, but the bootstrap.sh step will still modify the source directory. How can I do a real out-of-tree build of boost? Regards, Tino

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boost linkage problem
by Dave Dyer 30 Jan '13

30 Jan '13

I'm trying to construct a small library of wrappers for boost-using functions. In my test environment that links with this library (a windows executable) everything is fine. The working environment doesn't name any libraries explicitly. In another environment (the one I'm actually interested in) I get a large number of linkage errors, apparently seeking libstdc++ A small sample: 1>sharedmem-debug-x64.lib(sharedmemory.obj) : warning LNK4217: locally defined symbol ??1?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEAA@XZ (public: __cdecl std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::~basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(void)) imported in function "public: static bool __cdecl boost::interprocess::shared_memory_object::remove(char const *)" (?remove@shared_memory_object@interprocess@boost@@SA_NPEBD@Z) 1>sharedmem-debug-x64.lib(sharedmemory.obj) : warning LNK4217: locally defined symbol ?c_str@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QEBAPEBDXZ (public: char const * __cdecl std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::c_str(void)const ) imported in function "public: static bool __cdecl boost::interprocess::shared_memory_object::remove(charconst *)" (?remove@shared_memory_object@interprocess@boost@@SA_NPEBD@Z) The non-working link is a complex environment, but I'm stumped why it doesn't link, or how to get it to link.

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[phoenix] segmentation fault with valarray
by Philipp Schwaha 30 Jan '13

30 Jan '13

Hi all! I have worked with phoenix together with valarray and am currently stumbling over a case of segmentation fault. I construct the following phoenix expression boost::phoenix::at_c<0>(arg1) += boost::phoenix::at_c<1>(arg1) / val(mass) * arg2 I then feed a std::tuple<std::valarray<double>, std::valarray<double>> to it. It compiles nicely with gcc (4.6 & 4.7) using boost 1.52 as well as trunk. The resulting executable then proceeds to segfault, however. I have put together a small example (c++11) demonstrating my problem. The valarray's memory should already be reserved from original initialization. Performing the same operations manually with just the valarray not in phoenix seems to work fine. Am I missing something or doing something stupid here? thanks for any help! cheers Philipp

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[threadpool] from your experience, is it safe to use threadpool with recent boost release?
by Frédéric Bron 30 Jan '13

30 Jan '13

Dear community, I found the threadpool library very useful (http://threadpool.sourceforge.net/) Apparently, it was designed for boost 1.37.0 and seemed to target inclusion in boost but probably did never go to a review because its author had not enough time to meet all requirements for boost inclusion, in particular, documentation. However, it is ready to be used with boost as is can just be untared in the boost include directory. I have tried to use it with boost 1.51.0 and it seems to work nicely. Before using it for long term projects, I was wondering if some of you use this library with success together with a rather recent boost release? Do you experience any issue or everything is just fine. Any chance that the latest changes in the thread library (http://thread.gmane.org/gmane.comp.lib.boost.devel/237484) would impact threadpool? Regards, Frédéric

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hey
by Hossein Haeri 30 Jan '13

30 Jan '13

hey have a look http://www.com-im5.net/finance/ Hossein

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