October 2007 - Boost-users - lists.boost.org

[thread] example to delegtate jobs to threads
by Torsten Mohr 07 Oct '07

07 Oct '07

Hi, i wrote a small test project that makes use of boost::thread to split jobs into parts that are delegated to threads. A class "Job" contains a state machine (IDLE, EXECUTING, ABORTED, ...). That class can be derived from and methods "execute" and "report" can be overwritten. A class JobProvider can be derived from to feed new data to a Job. A Template "Foreman" can then start several threads and delegate Jobs that get their data from "JobProvider" to the Jobs and they report when they are done. In the example, MyJobProvider provides numbers from 3 to 100. MyJob::execute calculates if these numbers are prime. MyJob::report prints out the numbers that are prime. All the methods "report" are protected, only one of them at a time is ever called, methods "execute" are run in parallel. The performance is poor, can anybody give me a hint why? Best regards, Torsten. ######## job.h: #ifndef JOB_H #define JOB_H 1 #include <boost/thread.hpp> extern boost::mutex io_mutex; #define QWE { boost::mutex::scoped_lock lck(io_mutex); printf("file %s line %i\n", __FILE__, __LINE__); } class Job { boost::mutex job_mutex; boost::mutex cond_mutex; boost::mutex* m_report_mutex; boost::condition* m_condition; boost::thread* thr; bool m_stopped; int m_state; void setState(int state); protected: bool is_stopped(void); public: enum { CMD_IDLE = 212, CMD_EXEC, CMD_KILL }; enum { STATE_IDLE = 37, STATE_EXEC_PREPARE, STATE_EXEC, STATE_EXEC_ABORTED, STATE_REPORT_PREPARE, STATE_REPORT, STATE_DEAD }; void set_foreman_data(boost::mutex* report_mutex, boost::condition* condition); void init(void); virtual void execute_handler(void); void report_handler(void); void fork(void); int getState(void); void doCommand(int command); virtual void execute(void); virtual void report(void); }; class JobProvider { public: bool provide(Job& j); }; #endif ######## job.cc: #include <boost/thread.hpp> #include <boost/bind.hpp> #include "job.h" int Job::getState(void) { boost::mutex::scoped_lock lock(job_mutex); return m_state; } void Job::setState(int state) { boost::mutex::scoped_lock lock(job_mutex); m_state = state; } void Job::doCommand(int cmd) { boost::mutex::scoped_lock lock(job_mutex); // sparse transitions if((m_state == STATE_EXEC || m_state == STATE_EXEC_PREPARE) && cmd == CMD_KILL) { m_state = STATE_EXEC_ABORTED; m_stopped = true; } else if(m_state == STATE_IDLE && cmd == CMD_EXEC) { m_state = STATE_EXEC_PREPARE; } else if(m_state == STATE_IDLE && cmd == CMD_KILL) { m_state = STATE_DEAD; m_stopped = true; } } bool Job::is_stopped(void) { boost::mutex::scoped_lock lock(job_mutex); return m_stopped; } void Job::execute_handler(void) { int state; do { state = getState(); switch(state) { case STATE_EXEC_PREPARE: execute(); state = getState(); if(state != STATE_EXEC_ABORTED) { boost::mutex::scoped_lock lock(*m_report_mutex); report(); m_condition->notify_one(); setState(STATE_IDLE); } break; case STATE_DEAD: case STATE_EXEC_ABORTED: return; } } while(1); } void Job::init(void) { m_state = STATE_IDLE; } void Job::fork(void) { thr = new boost::thread(boost::bind(execute_handler, this)); } void Job::report_handler(void) { boost::mutex::scoped_lock lock(*m_report_mutex); report(); } void Job::set_foreman_data(boost::mutex* report_mutex, boost::condition* condition) { m_report_mutex = report_mutex; m_condition = condition; } void Job::execute(void) { } void Job::report(void) { } ######## foreman.h: #ifndef FOREMAN_H #define FOREMAN_H 1 #include <boost/thread.hpp> #include <boost/bind.hpp> #include "job.h" template<class JOBB, class JOBB_PROVIDER> class Foreman { JOBB* jb; JOBB_PROVIDER* m_provider; int m_threads; bool m_finished; boost::mutex report_mutex; boost::mutex m_cond_mutex; boost::condition m_condition; boost::thread* me; void handler(void); public: Foreman(int threads, JOBB_PROVIDER* provider); ~Foreman(); void spawn(void); void cleanup(void); void abort(void); bool is_finished(void); }; template<class JOBB, class JOBB_PROVIDER> Foreman<JOBB, JOBB_PROVIDER>::Foreman(int threads, JOBB_PROVIDER* provider) : m_threads(threads), m_provider(provider) { jb = new JOBB[m_threads]; } template<class JOBB, class JOBB_PROVIDER> Foreman<JOBB, JOBB_PROVIDER>::~Foreman() { delete[] jb; } template<class JOBB, class JOBB_PROVIDER> void Foreman<JOBB, JOBB_PROVIDER>::handler(void) { bool all_done; do { boost::mutex::scoped_lock lock(m_cond_mutex); all_done = true; for(int i = 0; i < m_threads; ++i) { int state = jb[i].getState(); if(state == Job::STATE_IDLE) { if(m_provider->provide(jb[i])) { jb[i].doCommand(Job::CMD_EXEC); all_done = false; } else { m_finished = true; } } else { all_done = false; } } if(m_finished || all_done) { return; } m_condition.wait(lock); } while(1); // (!m_finished || !all_done); } template<class JOBB, class JOBB_PROVIDER> void Foreman<JOBB, JOBB_PROVIDER>::spawn(void) { for(int i = 0; i < m_threads; ++i) { jb[i].set_foreman_data(&report_mutex, &m_condition); jb[i].init(); jb[i].fork(); } m_finished = false; // me = new boost::thread(boost::bind(handler, this)); handler(); } template<class JOBB, class JOBB_PROVIDER> void Foreman<JOBB, JOBB_PROVIDER>::cleanup(void) { // me->join(); } template<class JOBB, class JOBB_PROVIDER> void Foreman<JOBB, JOBB_PROVIDER>::abort(void) { } template<class JOBB, class JOBB_PROVIDER> bool Foreman<JOBB, JOBB_PROVIDER>::is_finished(void) { return m_finished; } #endif ######## my_job.h: #ifndef MY_JOB_H #define MY_JOB_H 1 #include "job.h" class MyJob : public Job { int m_suspect; bool is_prime; public: MyJob(); virtual void execute(void); virtual void report(void); void setJobStuff(int suspect); }; class MyJobProvider : public JobProvider { int m_actual; public: MyJobProvider(); bool provide(MyJob& j); }; #endif ######## my_job.cc: #include <iostream> #include <math.h> #include "my_job.h" #include "job.h" MyJob::MyJob() { m_suspect = 0; } void MyJob::setJobStuff(int suspect) { m_suspect = suspect; } void MyJob::execute(void) { int root = (int)sqrt((double)m_suspect); for(int j = 2; j <= root; j++) { if(is_stopped()) { return; } if((m_suspect % j) == 0) { is_prime = false; return; } } is_prime = true; } void MyJob::report(void) { if(is_prime) { std::cout << m_suspect << " is prime" << std::endl; } } MyJobProvider::MyJobProvider() : m_actual(3) {} #define NN 100 bool MyJobProvider::provide(MyJob& j) { j.setJobStuff(m_actual); m_actual++; if(m_actual > NN) return false; return true; } ######## qwe.cc: #include <iostream> #include "job.h" #include "my_job.h" #include "foreman.h" boost::mutex io_mutex; void test1(void) { MyJobProvider p; MyJob j; while(p.provide(j)) { j.execute(); j.report(); } } void test2(void) { MyJobProvider p; Foreman<MyJob, MyJobProvider> fm(7, &p); fm.spawn(); do { } while(!fm.is_finished()); fm.cleanup(); } int main(int argc, char** argv) { test2(); return 0; }

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Serializing a Method
by at forum 07 Oct '07

07 Oct '07

Hi to all I am new to the boost library, I downloaded it and I am doing some tests. I was using MFC serialization. I want to do something like this : template<class _CReceiver, class _CMemberType> class CASetMemberCommand { friend class boost::serialization::access; public: typedef void (_CReceiver::* Action)(_CMemberType) ; protected: _CReceiver *m_pReceiver; _CMemberType m_Property; Action m_fnAction; public: CASetMemberCommand() { m_pReceiver = NULL; } CASetMemberCommand(_CReceiver *pReceiver, Action fnAction, _CMemberType memberProperty) { m_pReceiver = pReceiver; m_fnAction = fnAction; m_Property = memberProperty; } ~CASetMemberCommand() { } virtual void Execute() { if(m_pReceiver) (m_pReceiver->*m_fnAction)(m_Property); } template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ ar & BOOST_SERIALIZATION_NVP(m_pReceiver) //& BOOST_SERIALIZATION_NVP(m_fnAction) & BOOST_SERIALIZATION_NVP(m_Property); } void Save(const char * filename) { std::ofstream ofs(filename); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(this); } void Load( const char * filename) { std::ifstream ifs(filename); assert(ifs.good()); boost::archive::xml_iarchive ia(ifs); ia >> BOOST_SERIALIZATION_NVP(*this); } }; int main(int argc, char *argv[]) { gps_position pos(32,52,25.0f); CASetMemberCommand<gps_position,int> cmd(&pos,&gps_position::SetMinutes,25); CASetMemberCommand<gps_position,int> cmd4(&pos,&gps_position::SetDegrees,25); cmd.Execute(); SaveCommand(cmd,"D:/test.xml"); cmd.Save("D:/Test2.xml"); CASetMemberCommand<gps_position,int> cmd2; cmd2.Load("D:/Test2.xml"); return 0; } the problem is that BOOST_SERIALIZATION_NVP(m_fnAction) is not working (compile errors); Is there any way to save a methode of w class, so it can be loaded and used later? Thank you

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Allocator and smart_ptrs
by Seweryn Habdank-Wojewódzki 06 Oct '07

06 Oct '07

Dears I found that only shared_ptr can use allocator. Is there any possibility to join the existing allocator and the other smart_ptrs. Why the rest smart_ptrs can not use allocators? Regards. -- |\/\/| Seweryn Habdank-Wojewódzki \/\/

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Need a help about boost.thread
by Steven Woody 06 Oct '07

06 Oct '07

hi, i am doing a job and considering if boost.thread can help. what i am doing is writing some code for other one's use. my code will be called by many threads, and accessing some shared data. my problem is how to keep my code thread-safe. i have no way to control how those other threads were created ( actually, those had already done by another team using windows MFC, and, for some reasons, my code can not use MFC, is has to be portable bwteen Linux and Windows ). in breif, you can think my code in a way of producer/consumer pattern. the producer is a rouine which will be called by many threads ( which are actaully connected sockets created by a listening socket ), and the consumer routine will be called by another thread ( which is actually GUI's main thread ). what i expected is: 1, only one producer can write to the shared data; 2, when a producer is writting, other producers have to busy waiting; and the GUI thread should immediately exit; 3, when GUI thread is reading, no producer can write to the shared data; to my problem, does the boost.thread can help? thanks in advance. -- woody then sun rose thinly from the sea and the old man could see the other boats, low on the water and well in toward the shore, spread out across the current.

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Boost/C++ group on facebook
by Jan Stetka 06 Oct '07

06 Oct '07

Boost/C++ group on facebook: Already have 47 members! Show your support for boost (unofficially) http://www.facebook.com/group.php?gid=4200526117

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boost bindings
by e r 06 Oct '07

06 Oct '07

i, i looked at previous posts on this topic. did not help, a suggestion would be appreciated: installed atlas version 3.6.0-20.6 /usr/lib/atlas3-test runs just fine. header cblas.h and clapack.h are in /usr/include/ which is by default in my include path. Configuration: -I/usr/local/include/boost_1_34_1 -I/usr/local/include/boost-bindings -L/usr/lib/atlas -llapack -lblas i'm trying to run the program: #include <boost/numeric/bindings/atlas/clapack.hpp> #include <boost/numeric/bindings/traits/ublas_matrix.hpp> #include <boost/numeric/bindings/traits/std_vector.hpp> // #include <atlas/cblas.h> namespace ublas = boost::numeric::ublas; namespace atlas = boost::numeric::bindings::atlas; int main() { std::size_t n = 5; ublas::matrix<double> a(n, n); // fill matrix a std::vector<int> ipiv (n); // pivot vector atlas::lu_factor (a, ipiv); // alias for getrf() atlas::lu_invert (a, ipiv); // alias for getri() return 0; }; i get the error Building target: testing_numeric_bindings Invoking: GCC C++ Linker g++ -L/usr/lib/atlas -o"testing_numeric_bindings" ./main.o -llapack -lblas ./main.o: In function `boost::numeric::bindings::atlas::detail::getrf(CBLAS_ORDER, int, int, double*, int, int*)': /usr/local/include/boost-bindings/boost/numeric/bindings/atlas/clapack_overloads.hpp:87: undefined reference to `clapack_dgetrf' ./main.o: In function `boost::numeric::bindings::atlas::detail::getri(CBLAS_ORDER, int, double*, int, int const*)': /usr/local/include/boost-bindings/boost/numeric/bindings/atlas/clapack_overloads.hpp:163: undefined reference to `clapack_dgetri' collect2: ld returned 1 exit status make: *** [testing_numeric_bindings] Error 1 make: Target `all' not remade because of errors. Build complete for project testing_numeric_bindings

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ublas/matrix product/efficiently compute A * B * C
by e r 05 Oct '07

05 Oct '07

currently i do: boost_auxiliary::matrix_double D; boost::numeric::ublas::axpy_prod(A, B, D, true); boost::numeric::ublas::axpy_prod(D, C, D, true); there must be a better way? A * B * C generates an ambiguous overloaded operator* message (ambiguous with element-wise product, i read). pls help.

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[interprocess] - Usage of boost::interprocess::open_or_create mode
by Srinivas Gardas 05 Oct '07

05 Oct '07

Hi, I am quite new to boost. Are there any code examples around usage of 'open_or_create' mode for ceating the shared_memory_object? My problem is, after we create a 'shared_memory_object' using 'open_or_create' there is no way to know whether it created 'created' a file or 'opened' an already existing file. We need this apparently, because if we are creating a new file, we have to '*construct<container>("MySharedMemory") *' the file with the desired container, otherwise we have to '* find<container>("MySharedMemory")*'. All the usage examples I could get were only around 'create_only' and then 'open_only' modes.. My idea is to write one single method, that'd use the 'open_or_create' mode so that we don't have to bother.. a sequence of creation and then usage.. I am not sure if I was clear enough in putting my problem across, please feel free to respond with questions. Really appreciate any help around this. Thanks & Regards, Srinivas Gardas

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[random] getting a 50% probability generator
by Jeffrey Holle 05 Oct '07

05 Oct '07

I am at the point in my application where I must introduce randomness to a sort routine. Basically when 2 elements are equal, I need to create a 50% probability that they will be swapped. What is the correct boost::random library resource to code this? I've attempted to use uniform_01, by creating an instance of it with this type: typedef boost::uniform_01<boost::minstd_rand, double> rand_gen_t; However, after getting it constructed as a class attribute, I find accessing it with: cout << (*pRand_gen++) << endl; It produces numbers like 1 134784888 134784288 2 134784845 134784224 134785176 5 0 134784376 134785328 0. What I want is a sequence like 0 1 0 1 0 1 0 0 0 1 1 1 1 0 1 0 1 that is sort of random.

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[boost-users] enable_if on boost::operators compile error on visual c++.
by chun ping wang 05 Oct '07

05 Oct '07

Given this code which is suggested by David Abraham.... template <class T, class U> char (& is_op_test(boost::operators<T,U> const&) )[2]; template <class T> char is_op_test(T const&); template<class T> T const& make(); template <class T> struct is_operators : boost::mpl::bool_<(sizeof(is_op_test(make<T>())) == 2)> {}; and this function declaration. template <typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT > typename boost::enable_if<boost::mpl::or_<boost::is_integral<T>, boost::is_operators<T> >, CONT<T> >::type primelist(const T& MAX_BOUND, const T& K, boost::function<bool(const T&, const T&)> f); I compile with T = int and it works. When i compile with T = BigInteger I get the following errors. ./cs512/c++/primeMain.cpp(78) : error C2770: invalid explicit template argument(s) for 'boost::enable_if<boost::mpl::or_<boost::is_integral<T>,boost::is_operators<T> >,CONT<T>>::type primelist(const T &,const T &,boost::function<bool(const T &,const T &)>)' ./cs512/c++/primeMain.cpp(24) : see declaration of 'primelist'" BigInteger class declaration looks like this.. class BigInteger : public BigUnsigned, boost::operators<BigInteger>, boost::operators<BigInteger, int> { }; thanks for the help.

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