January 2010 - Boost-users - lists.boost.org

Fw: generate an n-deep runtime for loop
by Hicham Mouline 23 Jan '10

23 Jan '10

----- Original Message ----- From: "Hicham Mouline" <hicham(a)mouline.org> To: <boost-users(a)lists.boost.org> Sent: Saturday, January 23, 2010 8:56 PM Subject: Re: [Boost-users] generate an n-deep runtime for loop > I have a fusion sequence (const Seq& seq), and during the recursion > process, I want to process the front element, then pass to the next step, > the remainder of the seq. > > I can't seem to find the algorithm for this, > > rds, pop_front it is, I was sure I had seen something before, rds,

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Adding a thread to a Singleton class
by Stephen Torri 23 Jan '10

23 Jan '10

I would like to have a logging class, called Trace, that I can off load the string formatting of logging the status of my program to a separate thread. Right now my logging class is written as a singleton object. This code is located within a shared library and used extensively in it to write tracing information to a file. Right now all the string formatting occurs on the main thread which degrades performance. QUESTION #1: I was wondering if the way in which I am attempting to have a central point for logging information via a Singleton without passing around a variable is a practical solution to this problem? I followed the Singleton guideline from Boost cookbook ( http://www.boostcookbook.com/Recipe:/1235044 ) of how to implement my singleton. I was thinking that I could add a boost::thread to my logging class, called Trace, and use a queue to pass objects over to be logged. A boost::condition would be used to signal the boost::thread to wake up and lock the queue, copy the contents then start writing the string formatted to a file. Below is my initial code. I would appreciate comments on the design, ideas for better designs and suggestions. Stephen Torri ---------------- SINGLETON class ---------------------------- #ifndef SINGLETON_H #define SINGELTON_H #include <boost/utility.hpp> #include <boost/thread/once.hpp> #include <boost/scoped_ptr.hpp> namespace myproject { namespace trace { template <typename T> class Singleton : boost::noncopyable { public: static T& Instance() { boost::call_once ( init, m_flag ); return *m_obj; } static void init () { m_obj.reset ( new T () ); } protected: ~Singleton(){} Singleton(){} private: static boost::scoped_ptr<T> m_obj; static boost::once_flag m_flag; }; } // namespace trace } // namespace trace template <typename T> boost::scoped_ptr<T> myproject::trace::Singleton<T>::m_obj ( 0 ); template <typename T> boost::once_flag myproject::trace::Singleton<T>::m_flag = BOOST_ONCE_INIT; #endif // define SINGELTON_H ---------------- Trace class ----------------------- #ifndef myproject_TRACE_H #define myproject_TRACE_H #include <boost/cstdint.hpp> #include <boost/shared_ptr.hpp> #include <boost/thread/mutex.hpp> #include <boost/thread/condition_variable.hpp> #include <boost/thread/thread.hpp> #include <boost/utility.hpp> #include <vector> #include "Trace_State.h" namespace myproject { namespace trace { // // Turn Trace into a singleton class that contains a worker thread // - Wait for data // - If data exists then process // - Else wait // Add method for adding a ITraceable object. This will lock the logging vector, add // element then signal the boost condition variable class Trace : public Singleton<Trace> { friend class Singleton<Trace>; public: void add_Trace ( interface::ITraceable::ptr_t trace ); private: Trace(); // Worker thread functions void threadMain(); void processTraces(); // Synchronization variables boost::mutex m_lock; boost::condition_variable m_condition; // Data variables typedef std::vector < interface::ITraceable::ptr_t > QueueType; QueueType m_queue; // Thread variables boost::shared_ptr<boost::thread> m_thread; volatile bool m_hasWork; // Logging Trace_State m_state; }; } /* namespace trace */ } /* namespace myproject */ #endif /* myproject_TRACE_H */ ----------------- Trace Source ----------------------- #include "Trace.h" #include "myproject/errors/Internal_Exception.h" #include <boost/bind.hpp> namespace myproject { namespace trace { Trace::Trace () : m_hasWork ( true ), m_state ( "Trace", "Trace" ) { m_thread = boost::shared_ptr<boost::thread> ( new boost::thread ( boost::bind ( &Trace::threadMain, this ) ) ); } Trace::~Trace() { // stop thread m_hasWork = false; } void Trace::add_Trace ( boost::shared_ptr<interface::ITraceable> trace ) { // Add ITraceable object to the queue { // lock queue { boost::lock_guard<boost::mutex> lock ( m_lock ); m_queue.push_back ( trace ); } m_condition.notify_one(); } } void Trace::threadMain() { boost::unique_lock<boost::mutex> lock ( m_lock ); while ( m_hasWork ) { while ( m_queue.size() == 0 ) { m_condition.wait ( lock ); } this->processTraces(); } } void Trace::processTraces() { QueueType local_queue; // Lock queue and copy { boost::lock_guard<boost::mutex> lock ( m_lock ); std::copy ( m_queue.begin(), m_queue.end(), local_queue.begin() ); } for ( QueueType::iterator pos = local_queue.begin(); pos != local_queue.end(); pos++ ) { // Process ITraceable object and write to a file } } } /* namespace trace */ } /* namespace myproject */

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[program_options] prompt for a password
by "Stanisław T. Findeisen" 23 Jan '10

23 Jan '10

[This question is about Boost.program_options library.] Sometimes you need a password option, but you don't want it specified as a program parameter (so that it won't be visible to other users via, for example, ps(1)). Is prompting for an option supported by Boost.program_options? STF http://eisenbits.homelinux.net/~stf/ OpenPGP: DFD9 0146 3794 9CF6 17EA D63F DBF5 8AA8 3B31 FE8A

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[Asio] read_some throws exception with IOCP disabled
by Collin Dauphinee 22 Jan '10

22 Jan '10

I have a piece of code that works completely fine with IOCP enabled, but when I disable it via the BOOST_ASIO_DISABLE_IOCP define, any attempts to call socket.read_some will throw an exception. This exception states that "An operation was attempted on something that is not a socket." However, I am able to write to this socket without problems; no exception is thrown and the data is received by the server. I've also tried reading and writing with the native Windows socket. Any calls to send() will succeed, but calls to recv() will return the error given above. This includes a write, read, write sequence; the first write will succeed, the read will fail, the second write will succeed even though the read told me that the handle isn't a socket. Only synchronous operations are being done on this socket. It's connected normally, no strange options are set on it, etc; the code is more or less the same as that found in the synchronous TCP client examples. Any solutions or workarounds to this problem would be greatly appreciated. I need to have IOCP disabled, so re-enabling it isn't a solution.

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[uBLAS] howto combine sparse AND symmetric?
by Tim Odenthal 22 Jan '10

22 Jan '10

Hi! I need to solve the classical linear equation A*x=b with x the unknown vector and A a very large, sparse and symmetrical matrix. I want to try the conjugate gradient iterative method to solve the problem (unless somebody knows a definitely much better one). Now I've seen that uBLAS provides the symmetric_adaptor class - should I use this one in combination with one of the sparse matrix classes? Does this reduce the memory usage as compared to only using a sparse matrix? Many thanks in advance Tim Odenthal

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[BGL] bundled GraphProperties
by Damien Maupu 22 Jan '10

22 Jan '10

Dear all, Are bundled properties available for GraphProperties (for adjacency list)? If no, why? Thank you Damien

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advance calculation statistical calculation
by eial＠cs.bgu.ac.il 22 Jan '10

22 Jan '10

hello. using boost::math::normal, mean and sd can I retrieve the value corresponding with percentage of the space of the created by the function which is bounded by the bell borders and a straight vertical line? e.g. the corresponding x value of the red line (by calculation of the space between the blue bell borders and the red vertical line in this picture http://img714.imageshack.us/img714/4789/normal2.png thanks

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[1.42.0] Beta 1 available on Sourceforge
by Beman Dawes 22 Jan '10

22 Jan '10

1.42.0 beta 1 is now available. This release contains one new library and numerous bug fixes for existing libraries. For details, including download links, see http://beta.boost.org/users/news/version_1_42_0 The release can also be downloaded directly from SourceForge. See http://sourceforge.net/projects/boost/files/ There are a few known problems in the beta: * An odd 'simplesectsep' tag that doxygen creates which has turned up in the generated documentation, such as at http://tinyurl.com/ygbgkge. * Doxygen isn't expanding some of the macros in Boost.Accumulators. * A nasty bug in Spirit affecting copy construction of rules (rev. 50156) has been tracked down and fixed, but the fix was too late for the beta. These will be fixed in the final release. Please report any other problems by responding to this message on either the users or the main developers mailing lists. Thanks, --The Boost release team

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How to create a Graph with BOOST Bib (e.g. adjacency_list)?
by Konstantin Silav 22 Jan '10

22 Jan '10

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[Boost] [Fusion] Help with tuple adapter
by Bill Nell 22 Jan '10

22 Jan '10

Hi all, I'm having some trouble getting the boost fusion tuple adapter working (the one that makes boost::tuples into conforming sequence types). I'm assuming that the adapted tuple should now be a legal MPL sequence but mpl::is_sequence yields false and consequently mpl::for_each doesn't work on the tuple type either. The following program is an illustration of what I am trying to do. I guess I must be missing something simple? Any help would be appreciated. Bill #include <iostream> #include <typeinfo> #include <boost/mpl/is_sequence.hpp> #include <boost/mpl/for_each.hpp> #include <boost/fusion/tuple.hpp> #include <boost/fusion/sequence.hpp> #include <boost/fusion/iterator.hpp> #include <boost/fusion/mpl.hpp> #include <boost/fusion/adapted/boost_tuple.hpp> struct helper { template <typename TT> void operator()(TT) { std::cout << typeid(TT).name() << std::endl; } }; int main() { typedef boost::fusion::tuple<int,char,double> FTUP; typedef boost::tuple<int,char,double> BTUP; // this works std::cout << boost::mpl::is_sequence<FTUP>::value << std::endl; std::cout << "fusion tuple\n"; boost::mpl::for_each<FTUP>(helper()); // this doesn't work std::cout << boost::mpl::is_sequence<BTUP>::value << std::endl; // the following lines won't compile because the BTUP is not a // sequence type. //std::cout << "boost tuple\n"; //mpl::for_each<BTUP>(helper()); return 0; }

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