August 2008 - Boost-users - lists.preview.boost.org

[Thread] Resetting interruption request
by Christian Larsen 15 Aug '08

15 Aug '08

Hello, I'm afraid this is a frequently asked question, but my attempts at searching have not been successful. My question is whether there is a smarter way to reset the interruption request (if any) than this: try { boost::this_thread::interruption_point(); } catch (boost::thread_interrupted&) { // ignore } Which I find a little messy for what I want to achieve. I'm using version 1.35.0. Best regards, Christian Larsen

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recursive_timed_mutex::timed_lock()
by Eduardo Tavares 15 Aug '08

15 Aug '08

Hello ALL, I'm having problems using recursive_timed_mutex::timed_lock() on Linux -- an assertion failure occurs at line 171 (thread/pthread/recursive_mutex.hpp) : pthread_mutex_timedlock() returns ETIMEDOUT instead of expected EBUSY. After some hours of headache I checked out it's cousin -- mutex::timed_lock() -- and realized the (in my opinion) correct implementation. Is it a bug in recursive_timed_mutex.hpp ? Thanks in advance. Eduardo Tavares.

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Thread example using a function object and using the return value
by Stephen Torri 15 Aug '08

15 Aug '08

I would like to have a function object that I can use the return value of its operator() function. Here is what I think best explains my request class Apple { public: int operator()( int x ) { int value = x * 2; return value; } } void main (int, char**) { int thread_count = 2; // 2-Core cpu // Create a pool of Apple threads typedef boost::shared_ptr<boost::thread> Thread_Ptr_t; typedef std::list < Thread_Ptr_t > Thread_Pool_t; Thread_Pool_t m_thread_pool; // Create threads for ( int index = 0; index < thread_count; ++index ) { Thread_Ptr_t new_thread_ptr ( new boost::thread ( boost::bind ( &Apple, _1, )( index ) ) ); m_thread_pool.push_back ( new_thread_ptr ); } // Wait for all threads to finish for ( Thread_Pool_t::iterator pos = m_thread_pool.begin(); pos != m_thread_pool.end(); ++pos ) { (*pos)->join(); } } Where is the point I should be catching return from the operator() function? I want the thread to do work and then have the opportunity to get some results from it. Is there a code example someone can show me? Stephen

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user-config.jam settings for building boost::MPI on windows Intel?
by Jesse Perla 15 Aug '08

15 Aug '08

I am trying to build the boost::mpi (1.36) on: 1) Windows vista 2) Visual Studio 2008 3) Intel C++ 10.1 (though could switch to the built in Microsoft compiler here if it would help) 4) With the open source MPICH2 libraries installed. I can link, compile, and test properly according to the beginning of the MPI intstructions ( http://www.boost.org/doc/libs/1_35_0/doc/html/mpi/getting_started.html) Now, I added "using intel ; " and "using mpi ; " to my user-config.jam, but I guess it can't autodetect since it spits out: C:\apps\boost\boost_1_36_0>bjam --with-mpi > The system cannot find the path specified. > The system cannot find the path specified. > The system cannot find the path specified. > MPI auto-detection failed: unknown wrapper compiler mpic++ > > Does anyone know the set of config settings that would work for the setup I described? When I tried to get debugging info out of the build, it said something about trying to detect windows cluster server, which I am not using (instead, MPICH2 as above). I guess part of the question is whether Intel C++ needs a "wrapper compiler" as discussed later in the getting started. Since I was able to compile and run the (non boost) MPI code, it doesn't seem so to me. (or are there binaries for the MPI libraries? I had trouble finding them...) Thanks, Jesse

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Pooling for fragmentation problem
by rottyguy 15 Aug '08

15 Aug '08

Hi, I am new to boost and was looking for a little guidance in using the right pool classes to help me with memory fragmentation. I have a hash_map indexed by a std::string --> smart_ptr<bufferObject> where bufferObject is a struct that holds a dynamically created char[] buffer and length integer. As this hash_map will hold millions of records (gigabytes of data), there will be plenty of objects created/destroyed many times over the amount of memory available to the system. I would like to employ a recyclable memory pool (to combat memory fragmentation). Here are my dynamic objects: key - std:string --> allocates based on a given string during an insert (a few 100 bytes to 2k max) value - bufferObject --> allocated to be held by the smart_ptr. bufferObject, itself, will hold dynamically allocated data. These bytes can range from a few hundred bytes to 4k max hash_map - millions of these key/value pairs created/destroyed. various vectors that are used throughout to copy over portions of the cache for retrieval. Any guidance is appreciated. TIA

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mpl
by Hicham Mouline 15 Aug '08

15 Aug '08

hello, relating to my earlier post, the code for the 2-seq and 3-seq cross product is: #include <boost/mpl/pair.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/fold.hpp> #include <boost/mpl/vector/vector10.hpp> #include <boost/mpl/copy.hpp> #include <boost/mpl/transform.hpp> namespace mpl = boost::mpl; using namespace mpl::placeholders; template <typename T> struct pair_with : mpl::pair<T, _> {}; template <typename pair> struct triple_with : mpl::vector3<typename pair::first, typename pair::second, _> {}; // public metafunction template<typename Sequence1, typename Sequence2> struct sequence2_cross_product : mpl::fold< Sequence1, mpl::vector0<>, mpl::copy< mpl::transform< Sequence2, pair_with<_2> >, mpl::back_inserter<_1> > > {}; template< typename SequencePair, typename Sequence> struct seq_seqpair_product : mpl::fold< SequencePair, mpl::vector0<>, mpl::copy< mpl::transform< Sequence, triple_with<_2> >, mpl::back_inserter<_1> > > {}; // public metafunction template<typename Sequence1,typename Sequence2,typename Sequence3> struct sequence3_cross_product : seq_seqpair_product< typename sequence2_cross_product<Sequence1,Sequence2>::type, Sequence3> {}; usage is like: S1: any MPL sequence with T11, T12, T13...T1k types S2: any MPL sequence with T21, T22, T23...T2m types S3: any MPL sequence with T31, T32, T33...T3n types typedef sequence2_cross_product<S1, S2>::type binary_product; /* this will be a mpl::vector< pair<T11, T21>, pair<T11, T22>, ... pair<T11, T2m>, pair<T12, T21>, pair<T12, T22>, ... pair<T1k, T2m> > */ // and typedef sequence3_cross_product<S1, S2, S3>::type ternary_product; /* this will be same mpl::vector, but with vector3<T11, T21, T31> ..... instead */ 1) I'm trying to make these metafunctions general enough, perhaps in the future i might use them for something i'm not thinking about now.... i would like to let the caller (me), choose what tuple/template to embed the resulting Tij, Tkl in... . for the sequence2_cross_product metafunction, mpl::pair, or mpl::vector2 or any class template that takes 2 type template arguments, or i could restrict the user to something that interacts well with mpl, is it "lambda expressions" or "metafct" or "metafct class"? . for the sequence3_cross_product metafunction, mpl::vector3 or any class template that takes 3 type template args... same question 2) I have a class template RT (not metafct or metafct class), that takes 3 template args, for each of these args, i have a list of possible types (in an mpl sequence), then i have a class R. I would like to define 2.1. typedef boost::variant< R, RT<T11, T21, T31>, RT<T11, T21, T32>.... > R; 2.2. do an explicit template instantiation of all the RT<..,..,..> Should i use Boost.PP for this, e.g.: #include <boost/preprocessor/seq/for_each_product.hpp> #include <boost/preprocessor/seq/enum.hpp> #define Type1 (T11)(T12)(T13)...(T1k) #define Type2 (T21)(T22)(T23)...(T2k) #define Type3 (T31)(T32)(T33)...(T3k) #define M(r, product) template class RT<BOOST_PP_SEQ_ENUM(product)>; BOOST_PP_SEQ_FOR_EACH_PRODUCT(M, (Type1)(Type2)(Type3)) #undef Type1 #undef Type2 #undef Type3 #undef M and what about variant<...>, how would i write it with PP? comment, thoughsts are appreciated, thanks, regards,

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New compiler warnings triggered by Boost 1.36
by cowwoc 15 Aug '08

15 Aug '08

When I compile my code against Boost 1.36 I get: 3>C:\Program Files\boost_1_36_0\boost/config/abi_prefix.hpp(19) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/thread/exceptions.hpp(22) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\exceptions.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/config/abi_suffix.hpp(20) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/thread/exceptions.hpp(108) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\exceptions.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/config/abi_prefix.hpp(19) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>c:\program files\boost_1_36_0\boost\thread\win32\thread_primitives.hpp(151) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\win32\thread_primitives.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/config/abi_suffix.hpp(20) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>c:\program files\boost_1_36_0\boost\thread\win32\thread_primitives.hpp(396) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\win32\thread_primitives.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/config/abi_prefix.hpp(19) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>c:\program files\boost_1_36_0\boost\thread\win32\interlocked_read.hpp(14) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\win32\interlocked_read.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>C:\Program Files\boost_1_36_0\boost/config/abi_suffix.hpp(20) : warning C4103: 'c:\program files\boost_1_36_0\boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 3>c:\program files\boost_1_36_0\boost\thread\win32\interlocked_read.hpp(78) : warning C4103: 'c:\program files\boost_1_36_0\boost\thread\win32\interlocked_read.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) I don't recall seeing this in 1.35 and I compiled against it two days ago. I am compiling under Visual Studio 2008, in x64 mode. How do I fix these warnings? Thank you, Gili -- View this message in context: http://www.nabble.com/New-compiler-warnings-triggered-by-Boost-1.36-tp18994… Sent from the Boost - Users mailing list archive at Nabble.com.

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[serialization] using serialization in shared library plugin
by Mojmir Svoboda 15 Aug '08

15 Aug '08

hello, i have big problem using boost::serialization under windows xp (vs2005sp). the thing is: there is a main application and there are .dll as plugins. i'd like to use boost::serialization from within the plugin, but i get segmentation faults immeadiately when boost_serialization.*.dll is loaded into memory. i traced it to some static_register and then i lost the trace. my guess is that the library tries to allocate some memory, but our own allocator is not loaded and initialized yet... do you have, please, some recommendations how to use the serialization in this way? many thanks in advance, mojmir

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[filesystem] major problem with 1.36 on OS X
by Matthias Schabel 15 Aug '08

15 Aug '08

Attempting to compile and link the following code with a default build of 1.36 on OS X 10.5.4 (Intel) // test.cpp #include <fstream> #include <iostream> #include <string> #include <vector> //#include <boost/system/error_code.hpp> //#include <boost/system/system_error.hpp> #include <boost/filesystem/operations.hpp> #include <boost/filesystem/path.hpp> int main (int argc, char * const argv[]) { boost::filesystem::create_directory("blah"); return 0; } results in a linker error, even though the method in question is defined inline in <boost/system/error_code.hpp> : Undefined symbols: "boost::system::error_code::message() const", referenced from: boost::system::system_error::what() constin ccyMBSNr.o ld: symbol(s) not found collect2: ld returned 1 exit status This is reproducible both from a clean XCode 3.0 project and from the command line : gcc test.cpp -I/usr/local/include -I .. -L/usr/local/lib - lboost_filesystem-xgcc40-mt -lboost_system-xgcc40-mt -lstdc++ Uncommenting the explicit includes doesn't help, either. This is a weird one... Matthias

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Thoughts & questions on adding serialization
by Daryle Walker 14 Aug '08

14 Aug '08

I was thinking about adding serialization to some times I've been working on in the sandbox. First I tried to recall how Mr. Ramey said serialization can be tested. I couldn't find the specific post I was thinking about, but others that were found gave me the answer. Reading other posts in that search prompted me to ask more questions. I could reduce the classes I'm working with to: //============================================= class computer; class context { public: typedef boost::array<uint_least32_t, 4> value_type; context(); // use auto copy-ctr, copy-=, dtr void operator ()( bool ); // consumer bool operator ==() const; // equals bool operator !=() const; // not-equals value_type operator ()() const; // producer private: friend class computer; boost::uint_fast64_t length; boost::array<uint_fast32_t, 4> buffer; boost::array<bool, 512> queue; template < class Archive > void serialize( Archive &ar, const unsigned int version ); }; class computer : public convenience_methods_base<context> { // An object of type "context" is incorporated in this object // due to the base class. A mutable/const pair of non-static // member functions named "context()" gives access to the inner // context object. public: typedef context::value_type value_type; // Put various access member functions here that forward to the // internals of the "context" type, which work because of the // friend declaration. private: template < class Archive > void serialize( Archive &ar, const unsigned int version ); }; //============================================= I initially planned to have serialization functions for these two classes, the "convenience_methods_base" base class template, plus two other class templates (a base class and a support class) that "convenience_methods_base" uses. But the e-mail search I mentioned found a thread from May 2007 (on the main Boost list) the suggested that the serialization of a non-primitive should match the user's external representation of the type, and not the type's particular internal structure. So I decided to keep the serialization protocol just for the two public-facing classes, "context" and "computer." I figured that the "computer" object can be serialized like: //============================================= template < class Archive > inline void computer::serialize( Archive &ar, const unsigned int version ) { ar & boost::serialization::make_nvp("context", this->context()); } //============================================= Which leaves how "context" objects are serialized. After thinking about it for hours, I decided to just whip out something quick & dirty and refine it later. So: //============================================= template < class Archive > inline void context::serialize( Archive &ar, const unsigned int version ) { ar & BOOST_SERIALIZATION_NVP( length ) & BOOST_SERIALIZATION_NVP( buffer ) & BOOST_SERIALIZATION_NVP( queue ); } //============================================= would give a final serialization, in my test file, of: //============================================= <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>1</length> <buffer class_id="2" tracking_level="0" version="0"> <elems> <count>4</count> <item>1732584193</item> <item>4023233417</item> <item>2562383102</item> <item>271733878</item> </elems> </buffer> <queue class_id="3" tracking_level="0" version="0"> <elems> <count>512</count> <item>1</item> <item>0</item>  <item>0</item> </elems> </queue> </context> </test> </boost_serialization> //============================================= Now I started refining, keeping the principle of not leaking implementation details in mind. The problem here is the array- counts, which I don't need since they'll never change. The first one I can fix by writing each element separately: //============================================= <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>1</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message-tail class_id="2" tracking_level="0" version="0"> <elems> <count>512</count> <item>1</item> <item>0</item>  <item>0</item> </elems> </message-tail> </context> </test> </boost_serialization> //============================================= I've always wanted to use something like a base-64 string encoding of the bit array, because it's cool and it'd save space. I added conversion functions to/from the bit array and a std::string, and then (de)serialized the string. I also had to separate "serialize" into "save" and "load" since conversion is complementary, not identical. So now I have: //============================================= <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>1</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message-tail>g</message-tail> </context> </test> </boost_serialization> //============================================= Then I added tests for: exactly 6 bits (i.e. one base-64 letter); a sextet (actually two) and a partial sextet together; filling a queue to capacity (actually one short of that since a full queue automatically activates a turnover); and going past capacity resulting in a new hash buffer and an empty message-tail. //============================================= <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>1</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message-tail>g</message-tail> </context> </test> </boost_serialization> <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>6</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message-tail>q</message-tail> </context> </test> </boost_serialization> <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>14</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message-tail>qQg</message-tail> </context> </test> </boost_serialization> <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>511</length> <buffer-A>1732584193</buffer-A> <buffer-B>4023233417</buffer-B> <buffer-C>2562383102</buffer-C> <buffer-D>271733878</buffer-D> <message- tail>ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789- _AAAAAAAAAAH__________g</message-tail> </context> </test> </boost_serialization> <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="5"> <test class_id="0" tracking_level="0" version="0"> <context class_id="1" tracking_level="0" version="0"> <length>512</length> <buffer-A>2631642121</buffer-A> <buffer-B>80961853</buffer-B> <buffer-C>4033330630</buffer-C> <buffer-D>497373075</buffer-D> <message-tail></message-tail> </context> </test> </boost_serialization> //============================================= If you want to see the actual work, look at revision/change-set #48131 in Boost's Subversion set-up. Now to the actual questions: 1. If there's only one sub-object, base or member, that has any significant data, could someone call the "serialize" member function of that sub-object directly in the wrapping class's "serialize"? (This assumes that friendship is set up.) This would make the wrapping class look identical to the sub-object's class, right? Is this a good idea? 2. Before actually trying to serialize a string, I was worried that the string's serialization would include a length count. This would be unnecessary because the object's "length" attribute already implies the length of the string (int( ceil( double( length % 512 ) / 6.0 ) )). Here, we see that the string's length isn't explicitly included in the XML archive, so I have no worries. But what about non-XML archives? Will be string's length be directly serialized, wasting space? If so, how can I fix that? 3. Having to add std::string to support serialization makes my class header heavier. My class uses fixed-sized arrays, so is there any way that I can avoid allocating a string? For writing out, could I set up a char-array with the encoding and write that out? For reading in, can I read the string in piecemeal to a char-array just in case someone added more characters than required. My converter currently ignores illegal characters and stops when enough legal characters have been read. If what I ask is possible, would the reading routine have to seek to the end of the entry so further serialization isn't messed up? -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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