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

[boost.iostreams] Can't be able to read gzipped file
by Marc Viala Perso 06 Feb '08

06 Feb '08

Hello, During the implementation of a TARFILE module based on Boost.Iostream, I've faced a problem during reading operation of a boost::iostream::filtering_stream<> with a GZip codec. To illustrate it, you will find hereafter a small code snippet that reproduces my problem: namespace io = boost::iostreams ; namespace fs = boost::filesystem ; const fs::path test_file("test.txt.gz") ; const std::string s("Test..................") ; { io::filtering_stream<io::output> ofilter ; ofilter.push(io::gzip_compressor()) ; ofilter.push(io::file_descriptor_sink( test_file.external_file_string() , std::ios::binary)) ; ofilter << s ; } { io::filtering_stream<io::input> ifilter ; ifilter.push(io::gzip_decompressor()) ; ifilter.push(io::file_descriptor_source( test_file.external_file_string() , std::ios::binary)) ; std::string rs ; ifilter >> rs ; // <- Here process is blocked in file_description.cpp @ line 145 //boost::scoped_array<char> buffer(new char[512]) ; //const std::streamsize count = io::read(ifilter, buffer.get(), 512) ; } The problem occurs during the reading operation @ line: "ifilter >> rs": the process is blocked in boost/iostreams/src/file_description.cpp @ line 145 ("if (!::ReadFile(pimpl_->handle_, s, n, &result, NULL))") when this line is executed. I've tried to use boost::iostream::read() template function without more success. I've checked the file after the writing operation w/ 7z and everything is fine at this point. I've tried the same code snippet w/ ZLib and BZip2 codecs without trouble. My environment is: Visual C++ 7.1 Boost 1.34.1 Windows XP SP2 Is there any bug in GZip decompressor with the file_descriptor_source? Or I've missed something? Any help will be appreciated. Best regards, Marc VIALA

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Thread creation overhead & efficiency
by James Sutherland 05 Feb '08

05 Feb '08

I am a new user of boost::thread. After implementing it I found that it slowed down execution of my code. I suspect that it may be due to the overhead of thread creation. I am creating/destroying thread_group ojects many times (tens of thousands) during code execution. Pardon my naïve question, but is this a problem for performance? I noticed some reference to a thread pool on this list. Is a thread pool the best alternative in this situation? Thanks for any guidance, James

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[Boost Interprocess] - Windows 64-bit / 32-bit mixed process support
by Richard Brown 01 Feb '08

01 Feb '08

Ion, I have a server process and multiple client processes which successfully share a managed_shared_memory vector as well as two message_queues. All processes are 32-bit, and run under both Windows XP and 64-bit XP Server (using 32-bit Wow emulation). However I am trying to take advantage of the Windows XP 64-bit OS, so I have attempted to build the Server process as 64-bit, while leaving the client processes at 32-bit (unfortunately I'm stuck with some 32-bit libraries and cannot move the client processes to x64 at this time). Both the server and clients (64 bit and 32 bit respectively) can see the shared memory file that Interprocess creates, and my class members use fixed-sized datatypes (__int32, __int64), but after walking some of the code it became apparent that Interprocess is having issues with mixing the different processes. Example: message_queue::do_receive(block_t block, void *buffer, std::size_t buffer_size, std::size_t &recvd_size, unsigned int &priority, const boost::posix_time::ptime &abs_time) ... ... //Thre is at least message ready to pick, get the top one detail::msg_hdr_t *top_msg = p_hdr->top_msg(); //Paranoia check if (top_msg == 0) { throw interprocess_exception(); } //Get data from the message recvd_size = top_msg->len; priority = top_msg->priority; ... ... The contents of top_msg appear to be "shifted", such that "top_msg->len;" now returns a 0. Obviously much of this is due to std::size_t being sized differently on the server process (at 64-bit) vs. the client (32-bit) processes. II thought of doing a bit of experimentation, whereby I could replace all instances of std::size_t in the library with something windows specific - like "unsigned __int64", but I have no idea if variations in data type size are the only issue. Should I give it a try or perhaps a different approach would be better? Thanks, Rich Brown if (Nabble.searchterms != null && Nabble.searchterms.length > 0) { Nabble.hilt(Nabble.searchterms, Nabble.get("nabble.msgtxt15191825")); }  //Nabble.gquery = 'test'; //Nabble.topicDumpSearch = true; if (Nabble.gquery!=null) { if (Nabble.topicDumpSearch) { Nabble.get('nabble.searchResults').innerHTML = '<h1> Other threads matching \"<strong>'+Nabble.gquery+'</strong>\":</h1>'+ '<p style=\"margin-left: 3em;\">looking for matching threads...</p>'; Nabble.loadScript('/forum/TopicDump$SearchJs.jtp?query='+encodeURIComponent(Nabble.gquery)+'&post=15191825'); Nabble.setVar('prev',null); } else { Nabble.setVar('prev', '<big><a id="nabble.prev_search" href="/forum/Search.jtp?query='+encodeURIComponent(Nabble.gquery)+'">Search Nabble for "<b>'+Nabble.gquery+'</b>"</a>' ); } } if( Nabble.prev ) Nabble.writeReturnToLink(Nabble.prev);

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Question about Boost Interfaces
by Martin de Lasa 01 Feb '08

01 Feb '08

Hi, Does anyone know the status of the Boost.Interfaces Library proposed by Chris Diggins in 2004? I have found a few references to it on the internet, including one on the Boost Wiki, but it seems to not have ever made it into the official Boost library. I am interest in exploring how Aspect-Oriented Programming techniques might be incorporate into an existing code-base, and would prefer to use a library based solution, rather than a special preprocessor (eg. apsectc++). Since Boost has come to the rescue in the past (with elegant solutions), in this respect, I thought I would start here. If boost.interfaces is dead, does anyone have any suggestions for C++ library-based AOP solutions that have worked for them. Thanks in advance. Martin

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Boost 1.34.1 build fails on openSUSE 10.3
by Christoph Duelli 01 Feb '08

01 Feb '08

Trying to build Boost 1.34.1 on OpenSuse 10.3 fails for me: soft@mxt2:/tmp/boost_1_34_1> ./configure Building Boost.Jam with toolset gcc... tools/jam/src/bin.linuxx86/bjam Detecting Python version... 2.5 Detecting Python root... /usr Unicode/ICU support for Boost.Regex?... not found. Generating Boost.Build configuration in user-config.jam... Generating Makefile... soft@mxt2:/tmp/boost_1_34_1> make ./tools/jam/src/bin.linuxx86/bjam --user-config=user-config.jam /bin/sh: line 1: 15631 Segmentation fault ./tools/jam/src/bin.linuxx86/bjam --user-config=user-config.jam Not all Boost libraries built properly. soft@mxt2:/tmp/boost_1_34_1> cat /etc/*release LSB_VERSION="core-2.0-noarch:core-3.0-noarch:core-2.0-ia32:core-3.0-ia32" openSUSE 10.3 (i586) VERSION = 10.3 I have built Boost (both this and older versions) on other machines before, so I assume the "./configure; make" should work (although I usually do specify a --prefix). Does anyone know (the cause of) this error? Thank you in advance and best regards Christoph

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BGL: return all available paths between two vertices
by Ioannis Nousias 01 Feb '08

01 Feb '08

Hello everyone. This is a Boost Graph library question. Is there an algorithm in the library that can return all available paths between two vertices? If not, which algorithm from the library is best to use as a bases, to define a custom visitor for it? (assuming that is the preferred approach) regards, Ioannis

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How to expose self defined type in boost.python
by Huang You Gong 01 Feb '08

01 Feb '08

Hi, I try to use boost.python to invoke C++ library in Python, so I need to expose types and classes. Here is the c++ head file: *typedef int XTYPE;* *class XCLASS* *{* *public:* * XTYPE getvalue( void ){ return XTYPE( 3 ); }* *};* So I write exposing code in BOOST_PYTHON_MODULE like this: *BOOST_PYTHON_MODULE( x )* *{* * class_< XCLASS >( "XCLASS" )* * .def( "getvalue", &XCLASS::getvalue, return_value_policy< copy_non_const_reference >() )* * ;* *}* but there is compiling error as using of undefined type. what shall I do to make the type XTYPE known by boost.python? Thanks in advance! -- Huang You Gong

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boost python: linking with pythonxx_d.lib
by Christian Hoffmann 01 Feb '08

01 Feb '08

Hi, I tried to compile boost python so that it links against the debug version. I therefore run bjam toolset=msvc-9.0 threading=multi python-debugging=on link=shared variant=debug libs\python\build Running it with -n shows, that it sets -DBOOST_DEBUG_PYTHON, but it still links with python25.lib. It only picks "right" python25_d.lib, if I add something to my user-config.jam, like the following: using python : 2.5 : C:\\src\\Python-2.5\\PCBuild\\python ; using python : 2.5 : C:\\src\\Python-2.5\\PCBuild\\python_d : # includes : # libs : <python-debugging>on ; What is the difference between the two methods (as a bjam argument and in the user-config.jam), and is there a way to combine both on the command line? Thanks and regards, Chris

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Relationship of Lambda and Phoenix
by Scott Meyers 01 Feb '08

01 Feb '08

At BoostCon 2007, I was told that the functionality of Boost.Lambda was essentially present via Phoenix in Boost.Spirit. From what I can tell, both Lambda and Spirit/Phoenix will be present in 1.35, leading me to wonder what advice to give people who are interested in experimenting with the use of lambda functions in Boost. Are people to be encouraged to use Phoenix over Lambda, or are there features in Lambda that Phoenix doesn't have? I'll be giving an overview of some Boost libraries at the Software Development conference in March, and I'll be showing some examples of Lambda. If I should be telling people to use Phoenix for future work, I'd like to know that. Thanks, Scott

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Compilation error for Boost.Function 1.34.x fix with TR1 headers.
by Robert Fairlie-Cuninghame 31 Jan '08

31 Jan '08

Hi all, I recently applied the Boost.Function critical bug fix (Dec 17) to my boost 1.34.1 library and I came up against a compilation error. However, I found that if I removed the boost/tr1/tr1 include path when building then the fixed library would compile correctly. Has anyone got the fix to work with the TR1 include paths? I haven't see any other reports of problems with it. I'm using gcc 3.3.5. The first compile error is a suspicious BOOST_FUNCTION_NUM_ARGS redefinition by the TR1 headers. The compile output was as follows: C++ build/CommandLineOptions.o In file included from release/boost-1_34_1/boost/preprocessor/iteration/detail/iter/forward1.hpp:47, from release/boost-1_34_1/boost/function.hpp:62, from release/boost-1_34_1/boost/tr1/functional.hpp:99, from release/boost-1_34_1/boost/tr1/tr1/functional:27, from release/boost-1_34_1/boost/function/function_base.hpp:18, from release/boost-1_34_1/boost/function/detail/prologue.hpp:16, from release/boost-1_34_1/boost/function/function_template.hpp:12, from release/boost-1_34_1/boost/function/detail/maybe_include.hpp:18, from release/boost-1_34_1/boost/function/function1.hpp:11, from release/boost-1_34_1/boost/program_options/value_semantic.hpp:13, from release/boost-1_34_1/boost/program_options/options_description.hpp:13, from release/boost-1_34_1/boost/program_options.hpp:13, from src/CommandLineOptions.cpp:26: release/boost-1_34_1/boost/function/detail/function_iterate.hpp:13:1: "BOOST_FUNCTION_NUM_ARGS" redefined ******** note first error here ******* In file included from release/boost-1_34_1/boost/program_options/value_semantic.hpp:13, from release/boost-1_34_1/boost/program_options/options_description.hpp:13, from release/boost-1_34_1/boost/program_options.hpp:13, from src/CommandLineOptions.cpp:26: release/boost-1_34_1/boost/function/function1.hpp:10:1: this is the location of the previous definition In file included from release/boost-1_34_1/boost/function/detail/maybe_include.hpp:13, from release/boost-1_34_1/boost/function/detail/function_iterate.hpp:14, from release/boost-1_34_1/boost/preprocessor/iteration/detail/iter/forward1.hpp:47, from release/boost-1_34_1/boost/function.hpp:62, from release/boost-1_34_1/boost/tr1/functional.hpp:99, from release/boost-1_34_1/boost/tr1/tr1/functional:27, from release/boost-1_34_1/boost/function/function_base.hpp:18, from release/boost-1_34_1/boost/function/detail/prologue.hpp:16, from release/boost-1_34_1/boost/function/function_template.hpp:12, from release/boost-1_34_1/boost/function/detail/maybe_include.hpp:18, from release/boost-1_34_1/boost/function/function1.hpp:11, from release/boost-1_34_1/boost/program_options/value_semantic.hpp:13, from release/boost-1_34_1/boost/program_options/options_description.hpp:13, from release/boost-1_34_1/boost/program_options.hpp:13, from src/lCommandLineOptions.cpp:26: release/boost-1_34_1/boost/function/function_template.hpp:98: error: variable declaration is not allowed here release/boost-1_34_1/boost/function/function_template.hpp:98: error: syntax error before `{' token .... and then a bunch more errors before it gives up. If anyone else has got this scenario to work then I'll know it must be something screwy in our setup. Cheers, Robert.

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