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

mutex Locks!
by Wesley Khandavalli 29 Oct '08

29 Oct '08

Dear all, i am new to threading. i want to know the following. Given a shared object which is accessed by more than one process, where should we implement the mutex locking? Is it in the shared object or in the critical section of the Processes? If locking is done in process, will it work having different names for the locks in the processes? class A { .......... ........ public: execute() { ......... lock(mutex1) //write data to shared object unlock(mutex1) ......... } }; class B { .......... ........ public: execute() { ......... lock(mutex2) //write data to shared object unlock(mutex2) ......... } }; SharedObject { ........... .......... }; -- Wesley K

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serialization 1.36.0 extended_type_info exit issue(s)
by Tim St. Clair 13 Oct '08

13 Oct '08

Folks, I'm running some serialization unit-tests which pass with flying colors under 1.35.0 and earlier, however they seg-fault on exit when run through 1.36.0. The error appears to deal with destruction of extended_type_info_typeid objects, and *only* manifests itself when I load an archive through a shared_ptr<T>. The load will appear to function properly, then on exit of the application, <<Death>>. This occurs even if I remove BOOST_CLASS_EXPORT && BOOST_CLASS_TYPE_INFO as the shared_ptr is to the derived element, and I'm not testing through a base. My lastest guess is that I may be missing some #define BOOST_SOME_MAGIC_NEW_OPTION //////////////////////////// pseduo code: //////////////////////////// BOOST_AUTO_TEST_CASE( MyTestClass_Serialization ) { boost::shared_ptr<MyTestClass> outtie ( new MyTestClass() ); boost::shared_ptr<MyTestClass> innie; std::ofstream os( "MyTestClass_Serialization.xml", std::ios_base::out ); my_pack< MyTestClass >( os, outtie ); os.close(); std::ifstream is( "MyTestClass_Serialization.xml", std::ios_base::in ); my_unpack< MyTestClass >( is, innie ); is.close(); BOOST_CHECK_NO_THROW(); } //////////////////////////// ddd output: //////////////////////////// *** No errors detected [New Thread 0xb73e26c0 (LWP 4715)] Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0xb73e26c0 (LWP 4715)] 0xb76bb56b in std::_Rb_tree_rebalance_for_erase () from /usr/lib/libstdc++.so.6 (gdb) bt #0 0xb76bb56b in std::_Rb_tree_rebalance_for_erase () from /usr/lib/libstdc++.so.6 #1 0xb7a38221 in std::_Rb_tree<boost::serialization::detail::extended_type_info_typeid_0 const*, boost::serialization::detail::extended_type_info_typeid_0 const*, std::_Identity<boost::serialization::detail::extended_type_info_typeid_0 const*>, boost::serialization::detail::type_compare, std::allocator<boost::serialization::detail::extended_type_info_typeid_0 const*> >::erase (this=0xb7a93c94, __position={_M_node = 0x810a3f8}) at /usr/include/c++/4.2/bits/stl_tree.h:1261 #2 0xb7a38270 in std::multiset<boost::serialization::detail::extended_type_info_typeid_0 const*, boost::serialization::detail::type_compare, std::allocator<boost::serialization::detail::extended_type_info_typeid_0 const*> >::erase (this=0xb7a93c94, __position={_M_node = 0x810a3f8}) at /usr/include/c++/4.2/bits/stl_multiset.h:346 #3 0xb7a37482 in boost::serialization::detail::extended_type_info_typeid_0::type_unregister (this=0x810749c) at /opt/tomodev/env/boost/libs/serialization/src/extended_type_info_typeid.cpp:93 #4 0x080b001a in ~extended_type_info_typeid (this=0x810749c) at /opt/tomodev/env/boost/boost/serialization/extended_type_info_typeid.hpp:80 #5 0x0809ebe2 in __tcf_49 () at /opt/tomodev/env/boost/boost/serialization/singleton.hpp:104 #6 0xb74f7084 in exit () from /lib/tls/i686/cmov/libc.so.6 #7 0xb74df458 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6 #8 0x0809e691 in _start () Cheers, Timothy St. Clair [timothysc(a)gmail.com]

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Visual C++ 2003 and Boost 1.35
by Tomek Jerzykowski 13 Oct '08

13 Oct '08

Hello! I'm having a problem with using Boost 1.35 on Visual C++ 2003 SP1. Take a look at the following very simple program: ------------------------------------ #include "stdafx.h" #include <boost/interprocess/sync/interprocess_upgradable_mutex.hpp> int _tmain(int argc, _TCHAR* argv[]) { int i = 0; unsigned int j = 2; j < i; return 0; } ------------------------------------ It does nothing, just emits a compiler warning. Unfortunately, this warning is followed by lots of meaningless messages related to the included Boost header: ------------------------------------ BoostTest2.cpp c:\BoostTest2\BoostTest2.cpp(11) : warning C4018: '<' : signed/unsigned mismatch c:\Program Files\boost\boost_1_35_0\boost\interprocess\sync\interprocess_upgradable_mut ex.hpp(621) : see reference to class template instantiation 'boost::interprocess::upgradable_lock<M>' being compiled with [ M=boost::interprocess::interprocess_mutex ] c:\Program Files\boost\boost_1_35_0\boost\interprocess\sync\interprocess_upgradable_mut ex.hpp(621) : see reference to class template instantiation 'boost::interprocess::upgradable_lock<M>' being compiled with [ M=boost::interprocess::interprocess_mutex ] ------------------------------------ If I remove #include <boost..., the extra messages go away. It looks to me like compiler bug. The exe produced is probably ok, but the amount of spam in output window makes using Boost very cumbersome. Is there any way to make these messages go away?

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boost::program_options
by Duy Nguyen 09 Oct '08

09 Oct '08

When I try to use the boost::program_options library to read a property file, I got the error when I run "make" on Cygwin (I installed Cygwin on WIndows XP). > make g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe TestInit.o Test.o TestDriver.o -o "TestDriver" -L/cygdrive/c/MyTest/Test1/lib -lboost_program_options-gcc34-mt-d-1_34_1 -lg2c Info: resolving vtable for boost::program_options::variables_mapby linking to __imp___ZTVN5boost15program_options13variables_mapE (auto-import) Then when I run my program, it does not work. If I comment out the "try ... catch" block which uses the boost::propram_options library then it compiles and works fine. Please show me how to fix it. Thank you.

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[filesystem] Problem mixing read and write on io fstream
by Sachin Garg 08 Oct '08

08 Oct '08

I have a program which opens a boost fstream in binary input+output mode, creating the file if it doesn't exists. But writing doesn't works after reading, it must be something obvious that I am not aware of. filename is a wpath. f.open(filename,ios::in | ios::out | ios::binary | ios::trunc) The program flow is 1) write some data 2) read the data 3) overwrite old data //this fails I am aware that mixing reading and writting is complicated due to buffering and as far as I know the solution is to do a seekg or seekp when changing between reading and writting, I am doing this between 1, 2 and 3. In 'my' program, writting in step 3 fails. I wrote a simple program that does just the above 3 steps with seeks and it works but in my program, it sets the failbit. After lots of debugging in internal fstream code I figured that an internal flag _IOREAD gets set somehow in step 2 which indicates that the stream is now readonly and causes subsequent writes to fail. It also seems that _IOREAD is set anytime any read operation is done on a read+write file, is this correct? And now how do I 'unset' this flag? I tried calling f.clear and f.seekp but that doesnt helps. What might be special in my program that causes this read-mode flag to remain set while this doesn't happens in a barebone/simple test program. I am not doing anything except f.seekg, f.get, f.read. Sachin Garg ps. If it matters, I am using visual studio 9.0. Problem might not be boost specific as boost only uses stl fstream but any help will be really useful.

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cross-platfrom binary serialization?
by Ákos Maróy 27 Sep '08

27 Sep '08

Hi, I'm working on a cross-platform project, where we're serializing data and sending it over TCP, using boost::serialization and boost::asio. As the data is quite big, and is mainly numeric, binary serialization provides a nice advantage over XML-based serialization, both in terms of performance and data size. But, I've found that the serialized data itself is not cross-platform. E.g. if I have a simple app, that sends serialized data via a TCP connection, it works fine as long as both ends of the connection are on the same platform (say both are Linux x86_64, or both are Windows XP). but they don't interact with each other - the data sent by one platform is not accepted 'as is' by the other. I wonder what provisions have to be done to achieve binary serialization that would work in such a context? Akos

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boost::filesystem exception not caught on MacOS X
by Lothar May 21 Sep '08

21 Sep '08

Hi, I have a strange problem that an exception thrown by a boost::filesystem directory_iterator is not caugth on MacOS X. Please consider the following code: ("const string &dir" is a parameter) bool retVal = true; try { directory_iterator i(dir); directory_iterator end; while (i != end) { // do something ++i; } } catch (...) { retVal = false; } While this works perfectly on Windows and Linux (the exception is caught fine), on MacOS I get the following: terminate called after throwing an instance of 'boost::filesystem::basic_filesystem_error<boost::filesystem::basic_path<std::string, boost::filesystem::path_traits> >' what(): boost::filesystem::basic_directory_iterator constructor Abort trap The program runs fine (withouth the trap) if I comment out the upper lines. I use the boost 1.34.0 lib built as universal binary on MacOS 10.5, according to the instructions at http://svn.boost.org/trac/boost/wiki/CMakeConfigAndBuild I link to the static non-debug mt version of boost_filesystem. Exceptions within my program are caught fine, just this boost exception is not caught. The program is also compiled as non-debug. Any help would be very much appreciated. Regards, Lothar

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boost serialization and datatype mismatch
by sam p 12 Sep '08

12 Sep '08

Hi, How to validate datatype before it gets deserialized? e.g. struct Abc { std::map<string,string> tmpMap; int a; float d; std::list<string> stringList; void serialize(boost::archive::polymorphic_oarchive & ar, const unsigned int file_version) { ar & tmpMap; ar & a; ar & d; ar & stringList; } void serialize(boost::archive::polymorphic_iarchive & ar, const unsigned int file_version) { ///////////////////////////////////////////////////////////////////// /* Now the right thing to do over here is ar & tmpMap; ar & a; ar & d; ar & stringList; */ /////////////////////////////////////////////////////////////////////// //But instead, if by mistake user writes something like ar & a; ar & d; ar & stringList; ar & tmpMap; /* So how to handle such problem? Can I validate data somehow before it gets deserialized? On some platforms like SuSE linux I have observed that such thing doesn't throw exception and we get SEGV. */ } }; Thanks, Sameer

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asio::serial_port how to know how many bytes are available for read
by Jean-Sebastien Stoezel 08 Sep '08

08 Sep '08

Hi, Is there a way to know how many bytes are available for read from a serial port, using asio::serial_port::read_some? The sockets have bytes_readable or something similar... Any equivalent for the serial ports? Thanks! Jean

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Boost Graph Library and Boehm Garbage Collector
by FBSL 08 Sep '08

08 Sep '08

Hello I am having trouble to garbage-collect adjacency_list<>. I have instanciated it with correctly garbage-collected vectors and lists (I have copied vecS and listS definitions, and added Boehm GC's default allocator so that they are garbage-collected). In my application I need to dynamically allocate many graphs, but it does not work, there is a (big) memory leak. Unfortunately, there is no template argument in adjacency_list<> to specify Boehm GC's allocator. Does anyone have a hint ? Snippet code "main.cpp" follows, compiled with Boost Graph Library 1.32, Boehm GC 6.4 and G++ 3.3.5, with command line : $ g++ -o main main.cpp -lgc -lgccpp -- #include <boost/graph/adjacency_list.hpp> #include <gc/gc_allocator.h> #include <gc/gc_cpp.h> #include <iostream> #include <vector> #include <list> using namespace std; using namespace boost; namespace boost { struct collected_vecS {}; struct collected_listS {}; template <class ValueType> struct container_gen<collected_vecS, ValueType> { typedef vector<ValueType,gc_allocator<ValueType> > type; }; template <class ValueType> struct container_gen<collected_listS, ValueType> { typedef list<ValueType,gc_allocator<ValueType> > type; }; template <> struct parallel_edge_traits<collected_vecS> { typedef allow_parallel_edge_tag type; }; template <> struct parallel_edge_traits<collected_listS> { typedef allow_parallel_edge_tag type; }; namespace detail { template <> struct is_random_access<collected_vecS> { enum { value = true }; typedef true_type type; }; } } typedef adjacency_list<collected_vecS, collected_vecS, directedS, no_property, no_property, no_property, collected_listS> graph; int main() { // leaks... while(true){ graph * g=new (UseGC) graph; for(unsigned int i=0; i<100; ++i){ add_vertex(*g); } for(unsigned int i=0; i<100; ++i){ for(unsigned int j=0; j<100; ++j){ add_edge(i,j,*g); } } } }

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