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Re: [Boost-users] Boost.Random multithreading
by Heiko Bauke 15 Nov '10

15 Nov '10

Dear Juan Antonio, On Sun, 14 Nov 2010 16:03:12 +0100 Juan Antonio Farré Basurte <jafb(a)tinet.org> wrote: > Are random number generators thread safe? Can I use a random number > generator by multiple threads without explicit locking? > > I guess the answer is no... Then I wonder if every thread could use a > different instance of the same random number generator without > interference between the different generators. you might consider to use the TRNG library [1] for multithreaded Monte Carlo. It is very similar to Boost random but has some special support for parallel random number generation. Read the TRNG documentation [2] for details. Regards, Heiko [1] http://trng.berlios.de/ [2] http://trng.berlios.de/trng.pdf -- -- Wer lügt, hat die Wahrheit immerhin gedacht. -- (Oliver Hassencamp, dt. Schriftsteller, 1921-1987) -- Number Crunch Blog @ http://numbercrunch.de -- Heiko Bauke @ http://www.mpi-hd.mpg.de/personalhomes/bauke

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[multi_index] How to use a class instead of a struct with the boost:multi_index_container? (addendum)
by jamaj 15 Nov '10

15 Nov '10

Hi All, Since I posted the previous message, I made some experiments. First, I changed the employee from struct to class: From struct employee { int id; std::string name; int age; employee(int id_,std::string name_,int age_):id(id_),name(name_),age(age_){} friend std::ostream& operator<<(std::ostream& os,const employee& e) { os<<e.id<<" "<<e.name<<" "<<e.age<<std::endl; return os; } }; to class employee { int id; std::string name; int age; employee(int id_,std::string name_,int age_):id(id_),name(name_),age(age_){} friend std::ostream& operator<<(std::ostream& os,const employee& e) { os<<e.id<<" "<<e.name<<" "<<e.age<<std::endl; return os; } }; I got some errors /home/jamaj/src/wxTestes/multiindexsample/main.cpp|31|error: ‘int employee::id’ is private /home/jamaj/src/wxTestes/multiindexsample/main.cpp|69|error: within this context| typedef multi_index_container< employee, indexed_by< ordered_unique< tag<id>, BOOST_MULTI_INDEX_MEMBER(employee,int,id)>, ordered_non_unique< tag<name>,BOOST_MULTI_INDEX_MEMBER(employee,std::string,name)>, ordered_non_unique< tag<age>, BOOST_MULTI_INDEX_MEMBER(employee,int,age)> > > employee_set; So, I had to change the scope of index class members to public, and it worked: class employee { public: int id; std::string name; int age; employee(int id_,std::string name_,int age_):id(id_),name(name_),age(age_){} friend std::ostream& operator<<(std::ostream& os,const employee& e) { os<<e.id<<" "<<e.name<<" "<<e.age<<std::endl; return os; } }; The question is: is there any other way to do it without exposing all class members? Thanks in advance. Best Regards. José Augusto Jr. jamaj

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[multi_index] How to use a class instead of a struct with the boost:multi_index_container?
by jamaj 14 Nov '10

14 Nov '10

Dear All, I want to use a class instead of a struct to create a multi_index container. But the example that comes with the documention (basic.cpp) uses a struct. Which changes (if there are any) must I make in order to use this container with a class of objects, instead of with structs? Thanks in advance. Best Regards, José Augusto Jr. (jamaj)

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Doubt about using boost:multiindex containers with classes
by José Augusto Jr. 14 Nov '10

14 Nov '10

Dear All, I've written a set of classes. Suppose I have a class called WorkCenter and another called Machine. I created a smart pointer to each Machine object. Each Workcenter has one or more Machines. I could create a vector of MachineSmartPointers. But I will need to search for Machines by some different index keys, like by the unique ID (an Int) or by Tag (a String). I could not find any example like that. In the Boost documentation the example is made with a struct. I know that a class, in C++, is very similar to a Struct. But I dont know how to write this code. Could someone give me a light on this? Thanks in advance. -- sds. Written by - Escrito por: José Augusto M. Andrade Jr. - JamaJ

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Re: [Boost-users] Boost.Random multithreading
by Steven Watanabe 14 Nov '10

14 Nov '10

AMDG On 11/14/2010 7:03 AM, Juan Antonio Farré Basurte wrote: > Are random number generators thread safe? Can I use a random number > generator by multiple threads without explicit locking? No. > I guess the answer is no... Then I wonder if every thread could use a > different instance of the same random number generator without interference > between the different generators. > > I guess the answer is yes for pseudorandom generators. But what about > real random generators? If I have different instances of one, they all have > to access the same source of randomness (maybe hardware). Will they > synchronize transparently? random_device reads from /dev/urandom. I assume that this is safe. In Christ, Steven Watanabe

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boost::asio::buffer exception
by Lloyd Kanakkassery 14 Nov '10

14 Nov '10

Hi, I want to write some data using boost::asio::write(). write() has two arguments, one is the stream to which the data to be written and the other is the data buffer. The data buffer can be created using boost::asio::buffer() function. When I use it this way it works. Then, I have tried to wrap boost::asio::bufffer() in my custom function like this boost::asio::const_buffers_1 MyBuffer(string msg) { return boost::asio::const_buffers_1(boost::asio::const_buffer(msg.c_str(),msg.length())); } The I use this in my asio::write() as booost::asio::write(mySocket, MyBuffer("hai")); This program compiles and runs but it throws an exception called "The system detected an invalid pointer address in attempting to use a pointer argument in a call". I understand that, it is associated with the MyBuffer() function. I have checked it with the buffer() function available in "buffer.hpp". Both are written in the same way, but my function is throwing exception. Could you give some hint? Thanks and Regards, Lloyd

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[fusion] named parameter technique with fusion::map
by alfC 13 Nov '10

13 Nov '10

Hi, After I discovered Boost.Fusion I realize that I can define proper named functions with Boost.Fusion. Named in the sense of instrospection (not in the sense of default user parameters). It was something that is easy to achieve but it was very verbose. I simplified a little bit the syntax but at the end I got stuck just before achieving something useful with this ideas. I need a little help towards the end. using namespace boost::fusion; double H(double p, double q){ // original function for reference return p*p + q*q; } struct p{}; struct q{}; double H(map<pair<p, double>, pair<q, double> > const& args){ return H(at_key(args), at_key<q>(args)); } int main(){ cout << H( map<pair<p, double>, pair<q, double> >( make_pair(1.), make_pair<q>(2.) ) ); return 0; } One question: Why I can not interchange the order of p and q in the last call, after all it is a map at the library could in principle differentiate the pairs? making it possible to call an unordered named parameter. e.g. cout << H( map<pair<p, double>, pair<q, double> >( make_pair<q>(2.), // was p make_pair(1.) // was q ) ); Is it possible to interchange the order to give more flexibility to the user? After a little playing I gladly found that the make_pair is not stricly necesary cout << H( map<pair<p, double>, pair<q, double> >(1.,2.) ); which is a nice improvement. It seems that still there is some redundancy, so I tried cout << H(make_map<p, q>(1.,2.)); and worked! On the side of the function definition I can have an alternative syntax which may be shorter but more difficult to interpret: double H(result_of::make_map<p, q, double, double>::type const& args) { ... } although it is not a great improvement. Second question: Does it occur to anyone how simplify things further? This is nice because *in principle* I can distinguish between the two parameters (strictly speaking is all one big parameter) at compile time via templates. Third question: I say in principle because I am stuck here. For example how can I implement a named parameter bind? It seems to me that I am close to achieving this but I don't know exactly how. What I want is some kind of "bind<H, q>(3.0)" which is a function object that effectively evaluates to H( pvalue, 3.0) or to H(make_map(pvariable), 3.0) when calling bind<H, q>(3.0)(pvalue) or bind<H, q>(3.0)(make_map(pvalue)). Note that the most general case is something that defines partial parameters by a map //if H had four parameters: auto b = my::bind<H, set<q1, q2> >( make_map<q1, q2>(3.0, 4.0) ) ; // or my::make_bind<H>( make_map<q1, q2>(3.0, 4.0) ) // and then use it as b(make_map<p1, p2>(5.0,6.0)); I think this seems to be promising although I need a little push to finish the technique I hope it is useful for someone (if I am not reinventing the wheel) and that we can round up the idea. or just wanted to know some opinions. Thank you, Alfredo (Note, named parameter boost library is not the proper way to go here because the of the level of instrospection I need in the functions, and because the use of named parameters is not to omit passing parameters but to recognize 'externally' certain parameters).

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Re: [Boost-users] Boost.Random Generator ignores seed
by Alex Hagen-Zanker 13 Nov '10

13 Nov '10

> I'm using mt19937 random number generator, belonging to Boost.Random >library, and it looks to ignore my call to seed. > I show relevant code. > > static mt19937 gen; > static MiniUni cien(1, 100); > static variate_generator d100(gen, cien); > > int main() { > { > struct timeval time; > gettimeofday( > gen.seed(time.tv_usec); > } > > And it generates the same sequence over and over. I've double-checked >that time.tv_usec really changes. Could it be that variate_generator d100(gen, cien) defaults to variate_generator<mt19937, MiniUni> d100(gen,cien) whereas you really need variate_generator<mt19937&, MiniUni> d100(gen,cien)? The constructor of the variate_generator now makes a copy of gen and changing the seed of gen afterwards does not affect the variate_generator. Solution: explicitly use variate_generator<mt19937&, MiniUni>(gen,cien). Kind regards, Alex

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Re: [Boost-users] Boost.Random Generator ignores seed
by alfC 13 Nov '10

13 Nov '10

On Nov 13, 2:09 pm, Juan Antonio Farré Basurte <j...(a)tinet.org> wrote: > Hello, > > I'm using mt19937 random number generator, belonging to Boost.Random > library, and it looks to ignore my call to seed. > I show relevant code. > > static mt19937 gen; > static MiniUni cien(1, 100); > static variate_generator d100(gen, cien); > > ..... > > int main() { > { > struct timeval time; > gettimeofday( > gen.seed(time.tv_usec); > } > > .... > > And it generates the same sequence over and over. I've double-checked > that time.tv_usec really changes. > Any help would be appreciated. > Thanks, Try with a negative seed. gen.seed( - time.tv_usec); -- Alfredo

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[serialization][thread] possible regressions? (was: [1.45.0] Beta 1 available from SourceForge)
by Eric Niebler 13 Nov '10

13 Nov '10

I don't know whether this is a serialization issue or a thread issue. Robert, Anthony, can you two weigh in? Eric On 11/11/2010 6:32 AM, Ruediger Berlich wrote: > Hi again, > > here is an update: I have now also tested the behaviour below ("pure virtual > method called; terminate called without an active exception" -> related to > Boost.Serialization) with Boost 1.44 and see the same problem. This does not > happen with 1.43. > > Anyway, I thought it might be important to know that whatever causes this > wasn't introduced with 1.45 but 1.44 (and of course I might be doing > something wrong which only triggers now due to 1.44's changes in the > serialization library). > > Thanks and Best Regards, > Ruediger > > > Ruediger Berlich wrote: >> Dear all, >> here are a few experiences with the beta: >> >> Beman Dawes wrote: >> [...] >>> Please download the beta, give it a try, and report any problems you >>> encounter. >> >> Platform: >> ========= >> Kubuntu 10.10 64 bit, g++ 4.4.5 >> >> Compilation: >> ============ >> Runs mostly smoothely, albeit with many warnings of the type: >> >> [...] >> libs/program_options/src/parsers.cpp:233: instantiated from here >> ./boost/function/function_base.hpp:321: warning: dereferencing type-punned >> pointer will break strict-aliasing rules >> ./boost/function/function_base.hpp:325: warning: dereferencing type-punned >> pointer will break strict-aliasing rules >> [...] >> >> This is not a new situation and has been there with many prior versions. >> It happens in different components. >> >> Compiling a complex application >> =============================== >> (The Geneva library's trunk version, close to version 0.85, see >> http://launchpad.net/geneva ; depends on probably a dozen different boost >> libraries) >> >> In order to get it to compile I hat to make a single change: >> I had to add "#include <boost/serialization/nvp.hpp>" prior to the >> inclusion of the date_time libraries in a single file (out of some 65 >> headers, some of which also include date_time), or else I would get >> messages of the type >> >> /opt/boost145/include/boost/date_time/gregorian/greg_serialize.hpp: In >> function ‘void boost::serialization::save(Archive&, const >> boost::gregorian::date&, unsigned int)’: >> /opt/boost145/include/boost/date_time/gregorian/greg_serialize.hpp:58: >> error: there are no arguments to ‘make_nvp’ that depend on a template >> parameter, so a declaration of ‘make_nvp’ must be available >> >> I _do_ serialize date_time objects in my application. This is new with >> Boost 1.45 (compared with 1.43). >> >> Running the application >> ======================= >> >> When running the application in serial. multithreaded or networked mode >> (Geneva does distributed parametric optimization, but also allows >> multithreaded optimization and has a serial mode for debugging), I get the >> error: >> >> [...] >> 1000: 4.99999977648258e-05 >> End of optimization reached >> Done ... >> pure virtual method called >> terminate called without an active exception >> Aborted >> >> "Done" is printed at the end of main(), so there are only some singletons >> left to clean up, one of which stems from the Boost.Serialization library, >> AFAIK. >> >> Running the application in gdb yields: >> >> /********************************************************/ >> (gdb) up >> #1 0x00007ffff40726b0 in abort () at abort.c:92 >> 92 abort.c: No such file or directory. >> in abort.c >> (gdb) up >> #2 0x00007ffff49126bd in __gnu_cxx::__verbose_terminate_handler() () from >> /usr/lib/libstdc++.so.6 >> (gdb) up >> #3 0x00007ffff4910906 in ?? () from /usr/lib/libstdc++.so.6 >> (gdb) up >> #4 0x00007ffff4910933 in std::terminate() () from /usr/lib/libstdc++.so.6 >> (gdb) up >> #5 0x00007ffff491128f in __cxa_pure_virtual () from >> #/usr/lib/libstdc++.so.6 >> (gdb) up >> #6 0x00007ffff4fc1f16 in >> > boost::serialization::void_cast_detail::void_caster::operator<(boost::serialization::void_cast_detail::void_caster >> const&) const () from /opt/boost145/lib/libboost_serialization.so.1.45.0 >> (gdb) up >> #7 0x00007ffff4fc282d in >> > boost::serialization::void_cast_detail::void_caster::recursive_unregister() >> const >> () from /opt/boost145/lib/libboost_serialization.so.1.45.0 >> (gdb) up >> #8 0x00007ffff4fc2f27 in >> > boost::serialization::void_cast_detail::void_caster_shortcut::~void_caster_shortcut() >> () from /opt/boost145/lib/libboost_serialization.so.1.45.0 >> (gdb) up >> #9 0x00007ffff4fc289f in >> > boost::serialization::void_cast_detail::void_caster::recursive_unregister() >> const >> () from /opt/boost145/lib/libboost_serialization.so.1.45.0 >> (gdb) up >> #10 0x00007ffff72ad64f in >> > boost::serialization::void_cast_detail::void_caster_primitive<Gem::Geneva::GPersonalityTraits, >> Gem::Geneva::GObject>::~void_caster_primitive (this=0x7ffff7bb7e80, >> __in_chrg=<value optimized out>) at >> /opt/boost145/include/boost/serialization/void_cast.hpp:198 >> 198 recursive_unregister(); >> (gdb) up >> #11 0x00007ffff72ad7be in >> > boost::serialization::detail::singleton_wrapper<boost::serialization::void_cast_detail::void_caster_primitive<Gem::Geneva::GPersonalityTraits, >> Gem::Geneva::GObject> >::~singleton_wrapper ( >> this=0x7ffff7bb7e80, __in_chrg=<value optimized out>) >> at /opt/boost145/include/boost/serialization/singleton.hpp:111 >> 111 m_is_destroyed = true; >> (gdb) up >> #12 0x00007ffff40748c0 in __cxa_finalize (d=0x7ffff7baa2d0) at >> cxa_finalize.c:56 >> 56 cxa_finalize.c: No such file or directory. >> in cxa_finalize.c >> (gdb) up >> #13 0x00007ffff7016366 in __do_global_dtors_aux () >> from >> /home/rberlich/geneva-build/src/geneva/libgemfony-geneva.so.0.8.5rc0 >> (gdb) up >> #14 0x0000000000000000 in ?? () >> (gdb) up >> Initial frame selected; you cannot go up. >> /********************************************************/ >> >> Gem::Geneva::GPersonalityTraits is a purely virtual class, marked as such >> with the following code: >> "BOOST_SERIALIZATION_ASSUME_ABSTRACT(Gem::Geneva::GPersonalityTraits)" . >> GObject is the base class of all optimization-related classes. >> >> The exact same code compiles and runs fine with Boost 1.43, the last >> version I have been using excessively. I cannot really comment on Boost >> 1.44 , but would be happy to try if it helps. >> >> Note that the above problem does not seem to have any influence on the >> results of the program. The problems only appear at the very end of the >> execution, when various singletons get destroyed. >> >> Best Regards, >> Ruediger -- Eric Niebler BoostPro Computing http://www.boostpro.com

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