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weird bug, std::list nodes don't work properly with pool_allocator.
by Flogromp N. 14 Dec '07

14 Dec '07

/* The pool allocator is not being used properly, somehow, with std::list. When you go to purge the pool, it says nothing was purged, because nothing is even registered as being allocated in the pool. What is going on here? I have included copious debugging information. I've even provided a dummy modification of the boost::pool_allocator class to show what's going on. It's weird. If you change l_type to an std::vector, everything will work, and the output will be: purged? 1 This program outputs the following when l_type is std::list, debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::debug_pool_allocator() [with Tag = foo_tag, T = int, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::debug_pool_allocator(const debug_pool_allocator<Tag, U, UserAllocator, Mutex, NextSize>&) [with U = int, Tag = foo_tag, T = std::_List_node<int>, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] static T* debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::allocate(typename boost::pool<UserAllocator>::size_type) [with Tag = foo_tag, T = std::_List_node<int>, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] --- static T* debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::allocate(typename boost::pool<UserAllocator>::size_type) [with Tag = foo_tag, T = std::_List_node<int>, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] --- ... purged? 0 released? 0 This program outputs the following when l_type is std::vector, debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::debug_pool_allocator() [with Tag = foo_tag, T = int, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] static T* debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::allocate(typename boost::pool<UserAllocator>::size_type) [with Tag = foo_tag, T = int, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] --- static T* debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::allocate(typename boost::pool<UserAllocator>::size_type) [with Tag = foo_tag, T = int, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] static void debug_pool_allocator<Tag, T, UserAllocator, Mutex, NextSize>::deallocate(T*, typename boost::pool<UserAllocator>::size_type) [with Tag = foo_tag, T = int, UserAllocator = boost::default_user_allocator_new_delete, Mutex = boost::details::pool::default_mutex, unsigned int NextSize = 32u] --- ... purged? 1 released? 0 */ #include <iostream> using std::cout; using std::endl; #include <list> #include <vector> #include <boost/current_function.hpp> #include <boost/limits.hpp> // std::numeric_limits #include <new> // std::bad_alloc #include <boost/pool/poolfwd.hpp> #include <boost/pool/singleton_pool.hpp> #include <boost/pool/pool_alloc.hpp> #define DEBUG_FUNC cout << BOOST_CURRENT_FUNCTION << " " << endl template < class Tag, class T, class UserAllocator = boost::default_user_allocator_new_delete, class Mutex = boost::details::pool::default_mutex, unsigned NextSize = 32 > class debug_pool_allocator { public: typedef T value_type; typedef UserAllocator user_allocator; typedef Mutex mutex; static unsigned const next_size = NextSize; typedef value_type* pointer; typedef value_type const* const_pointer; typedef value_type& reference; typedef value_type const& const_reference; typedef typename boost::pool<UserAllocator>::size_type size_type; typedef typename boost::pool<UserAllocator>::difference_type difference_type; template <class U> struct rebind { typedef debug_pool_allocator<Tag, U, UserAllocator, Mutex, NextSize> other; }; debug_pool_allocator() { DEBUG_FUNC; } // default copy constructor // default assignment operator // not explicit, mimicking std::allocator [20.4.1] template <class U> debug_pool_allocator( debug_pool_allocator<Tag, U, UserAllocator, Mutex, NextSize> const& ) { DEBUG_FUNC; } // default destructor static pointer address(reference r) { DEBUG_FUNC; return &r; } static const_pointer address(const_reference s) { DEBUG_FUNC; return &s; } static size_type max_size() { DEBUG_FUNC; return (std::numeric_limits<size_type>::max)(); } static void construct(pointer const ptr, value_type const& t) { DEBUG_FUNC; new(ptr) T(t); } static void destroy(pointer const ptr) { DEBUG_FUNC; ptr->~T(); } bool operator==(debug_pool_allocator const&) const { DEBUG_FUNC; return true; } bool operator!=(debug_pool_allocator const&) const { DEBUG_FUNC; return false; } static pointer allocate(size_type const n) { DEBUG_FUNC; const pointer ret = static_cast<pointer>( boost::singleton_pool< Tag, sizeof(T), UserAllocator, Mutex, NextSize >::ordered_malloc(n) ) ; if (ret == 0) throw std::bad_alloc(); return ret; } static pointer allocate(size_type const n, void const* const) { DEBUG_FUNC; return allocate(n); } static void deallocate(pointer const ptr, size_type const n) { DEBUG_FUNC; boost::singleton_pool< Tag, sizeof(T), UserAllocator, Mutex, NextSize >::ordered_free(ptr, n); } }; // --- struct foo_tag {}; // IF YOU CHANGE THIS TO std::vector, IT WILL DEALLOCATE PROPERLY! typedef std::list< int, debug_pool_allocator<foo_tag, int> > l_type; int main() { bool success = false; l_type* l = new l_type; for (int i=0; i<2; ++i) { l->push_back(444); cout << "---" << endl; } cout << "..." << endl; success = boost::singleton_pool<foo_tag, sizeof(int)>::purge_memory(); cout << "purged? " << success << endl; success = boost::singleton_pool<foo_tag, sizeof(int)>::release_memory(); cout << "released? " << success << endl; }

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[review] Boost.Functional/Forward - result
by John Torjo 13 Dec '07

13 Dec '07

Hi all, I'm happy to announce that The Boost.Functional/Forward library has been accepted into Boost. Congrats to Tobias for a great lib! Summary: 5 reviews, all positive. Suggestions for improvement: - Automatically detect if the compiler supports variadic templates and rvalue references and use those instead. This can be a useful portability utility when such compilers become more common. - It should use compressed_pair to store the wrapped function object to take advantage of EBO. - more tweakable parameters for specific uses - like, arity 3 for function X, and arity 5 for function Y - Docs: add more material explaining the forwarding problem - Docs: should be explicitly specified that the wrapped function object must be result_of compatible - Docs: A discussion of the impact of the library on compile time (especially with high values of N) Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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[boost::logging] flushing rolling_file
by Benjamin de Dardel 13 Dec '07

13 Dec '07

Hi all, Does anybody use boost::logging ? I wonder if it's possible to flush logs in a rolling_file as in a standard file (flush_each_time) ? It would be nice ! Thanks, Benjamin

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Re: [Boost-users] [boost] [review] Gentle reminder - Fast track formal review of Boost.Functional/Factory will begin December 17
by John Torjo 13 Dec '07

13 Dec '07

Joel de Guzman wrote: > John Torjo wrote: > >> Hi all, >> >> This is a gentle reminder of the Boost.Functional/Factory review, about >> to start next Monday. >> >> >> Factories are callback mechanisms for constructors, so we provide two >> function objects, boost::value_factory and boost::factory, that >> encasulate object construction through direct application of the >> constructor or operator new, respectively. These templates make other >> facilities that operate on function objects (such as standard >> algorithms, Boost.Bind, Boost.Function, or Fusion functional adapters) >> applicable to constructors. >> >> Get it from here: >> http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… >> > > Link to docs please? Thanks! > > I've posted them temporarily on my site - http://www.torjo.com/tobias/ Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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Re: [Boost-users] BGL Max flow min cut
by Line B. Reinhardt 13 Dec '07

13 Dec '07

It is mostly the reverse edge I have problem with. My graph is not necessarily a complete graph and therefore in my graph an reverse edge does not always exist. However I would like to introduce just when running the algorithm. I think I will need two graphs but maybe have a map between the edges which are cooresponding in both graphs. Thanks for your answer. Best regards Line On Dec 10, 2007 7:37 AM, Line B. Reinhardt <lbr(a)ctt.dtu.dk> wrote: > Dear All > I would like some help with graph structure for the edmund_karp max flow min cut function. > I have a general graph in which I have many properties + edge and vertex. I sould like to run edmund karp on this graph however I have not been able to make the structure right for edmund karp and therefore I have made a second graph a flow graph. However I do not want to copy edges over every time I change something in the original graph. I was wundering if I could make it the same graph or just make the flow graph a filteret version of the original graph. > The graphs are defined as follows:: <snip> Hi Line, Can you explain what you mean by "have not been able to make the structure right"? Your original graph needs to have reversed edges (for every edge (u,v) in the graph, (v,u) needs to also be in the graph), but unless you're missing that, you should be able to avoid having to create a separate graph to pass in. If you are missing reversed edges, you won't be able to add them through a filtered graph - a filtered graph only lets you remove some set of vertices and/or edges from the graph. Regards, Aaron _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[review] Review of Unordered library started December 7 and still running!
by Ion Gaztañaga 13 Dec '07

13 Dec '07

Hi all, The formal review of the Unordered library started December 7, we have a few nice reviews, but they are not enough. If you are interested in the library (and I *know* you are), please take some time to review it. This is the info you need to do a review: *Description*: An implementation of the unordered containers specified in TR1, with most of the changes from the recent draft standards. *Author*: Daniel James *Download*: http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… The documentation is in the zip file. I've put documentation online here: http://igaztanaga.drivehq.com/unordered http://tinyurl.com/yw8wjp What to include in Review Comments ================================== Your comments may be brief or lengthy, but basically the Review Manager needs your evaluation of the library. If you identify problems along the way, please note if they are minor, serious, or showstoppers. Here are some questions you might want to answer in your review: * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Ion Gaztañaga - Review Manager -

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a bug in lambda
by Guo Xu 12 Dec '07

12 Dec '07

i found that , when int a = 2, b = 0 the expression max( (_1 - _2 - 4)( a, b ) , 0 ); should return 0, but return -2, why ? is it a bug in lambda?

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[accumulators] Compilation Problem
by Olivier Tournaire 12 Dec '07

12 Dec '07

Hi all, I am trying to use boost::accumulators lib and I would appreciate some help. I do not know how to use the tag::density. How do I use : accumulator_set<double, tag::density > angular_acc; and set density::cache_size density::num_bins To have for example 10 subdivisions between -pi and pi ? Then, how do I extract the results of the accumulation ? Regards Olivier -- Le temps des cerises reviendra. Dans l'immédiat, c'est le temps des noyaux. Courage.

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Bug in filesystem library? (wpath, wdirectory_iterator)
by Olivier Delande 12 Dec '07

12 Dec '07

I noticed something which looks pretty much like a bug in the filesystem library. Both version 1.34.1 and CVS are affected under Linux. I do not know about other versions/platforms. If I compile and run the following code ----------------------------------- #include <boost/filesystem.hpp> #include <iostream> int main(int argc, char *argv[]) { boost::filesystem::wpath p(L"/"); boost::filesystem::wdirectory_iterator i(p); return 0; } ----------------------------------- then I get an exception: ----------------------------------- terminate called after throwing an instance of 'boost::filesystem::basic_filesystem_error<boost::filesystem::basic_path<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, boost::filesystem::wpath_traits> >' what(): boost::filesystem::wpath::to_external conversion error: Invalid argument Aborted ----------------------------------- However, the following alternate version (which uses char instead of wchar_t) works: ----------------------------------- #include <boost/filesystem.hpp> #include <iostream> int main(int argc, char *argv[]) { boost::filesystem::path p("/"); boost::filesystem::directory_iterator i(p); return 0; } ----------------------------------- Has anyone ever found a way to cope with that or filed a bug? Thanks -- Olivier

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maps and constructor
by Hicham Mouline 12 Dec '07

12 Dec '07

Hello, I am attempting to design a class: class C { std::map<double, const A> ma; std::map<double, const B> ma; . public: C(...); }; The keys in the 2 maps are always identical. So I could choose: std::map<double, const std::pair<A,B> > or std::map<double, const std::pair<A,B>* > (ps: AFAIK, using a const-ref for the pair is impossible, but possible with some boost classes) Q1: Is there a difference in memory usage, in access speed or in code readability between the top choice and bottom ones? Q2: Between the 2 bottom ones (storing the pair object in the map vs storing the ptr) Q3: For users of class C, what sort of constructors should I offer? C::C(const std::map<double, const std::pair<A,B>* >& ) Or, should I allow adding elements to the map after the object being constructed? C::add(double, const A&, const B&) Are there better ways with boost classes? Thank you for boost and your time, Rds,

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