February 2010 - Boost - lists.preview.boost.org

[iostreams]mapped_file bug on Win32?
by Nelson, Erik - 2 28 Feb '10

28 Feb '10

Or maybe a feature? Or maybe I'm just using it incorrectly. I'm trying to create a new file of a certain size, regardless of whether or not a file of the same name exists. If I run a test program along the lines of boost::iostreams::mapped_file file; boost::iostreams::mapped_file_params p("test.txt"); p.new_file_size = 1201; p.length = 1; p.mode = ios_base::in | ios_base::out; file.open(p); It fails with the error 'failed setting file size: Cannot create a file when that file already exists.' if file 'test.txt' already exists. It seems to me that this error is a bug caused by incorrect error checking in mapped_file.cpp in function mapped_file_impl::open_file. At the call to CreateFileA, dwCreationDisposition=CREATE_ALWAYS and a valid handle value is returned. The Win32 docs say that in this case the call to CreateFileA has succeeded and the last-error code is set to ERROR_ALREADY_EXISTS. http://msdn.microsoft.com/en-us/library/aa363858%28VS.85%29.aspx Immediately after the call to CreateFileA, the handle is checked for validity but the last-error code is not reset. Shortly thereafter is a call to SetFilePointer. The docs say that the proper way to check for an error from SetFilePointer is to compare its return value to INVALID_SET_VALUE_POINTER. http://msdn.microsoft.com/en-us/library/aa365541%28VS.85%29.aspx This isn't done in the code... Instead, GetLastError() is called, which apparently returns the ERROR_ALREADY_EXISTS code generated by CreateFileA, which wasn't an error at all. It seems to me that a couple of things need to be changed to make this correct- 1) after the check for valid handle creation by CreateFileA, call SetLastError(NO_ERROR) 2) when resizing the file the code if (::GetLastError() != NO_ERROR || !::SetEndOfFile(handle_)) should be something like if (::SetFilePointer(handle_, sizelow, &sizehigh, FILE_BEGIN) == INVALID_SET_VALUE_POINTER || !::SetEndOfFile(handle_)) Does that make sense? Or am I just setting the mapped_file_params incorrectly to force creation of a new file? Erik

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[ITL] Short remarks on the lastest 3 Reviews
by Joachim Faulhaber 28 Feb '10

28 Feb '10

Hi Barend, Vicente and Thomas, thank you for your efforts to synchronize the submission of your reviews as an attack on my Sunday evening =) First and foremost I'd like to thank Barend, who obviously did a really thorough investigation of the ITL, creatively testing own applications and going into the detail of the probably bewildering possibilities to use the generalized addition, subtraction and intersection operations on interval_maps. This was extremely important for me, because I realized how much those concepts and possibilities transcend the expectations of potential users. I have spent a lot of time investigating generalized operations on interval_maps and I am fairly sure that the definitions of their semantics based on axioms (laws) are pretty sound. I think that the usefulness and flexibility of the ITL that Barend discovered comes from that base. I have tried to describe all those semantical issues in the documentation. But obviously, due to limited time resources of readers, I am afraid that this has not been well received. Also I'd like to thank to Vicente and Thomas for their reviews and the included remarks. I am going to address all of your questions, problems and objections, but probably not at once, during the next days. Best Regards, Joachim

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[date_time] monotonic_time() proposal
by Dmitry Goncharov 28 Feb '10

28 Feb '10

This proposal suggests adding monotonic_time() static member function to the boost::date_time::microsec_clock and second_clock classes. usage example: #include <unistd.h> // for sleep() #include <iostream> #include <boost/date_time/posix_time/posix_time.hpp> #include "monotonic_time.hpp" int main() { namespace pt = boost::posix_time; typedef ext::microsec_clock<pt::ptime> usclock_t; // namespace ext instead of boost::date_time pt::ptime now = usclock_t::monotonic_time(); sleep(1); pt::ptime later = usclock_t::monotonic_time(); std::cout << later - now << std::endl; } Prototype implementation can be found in the attachment. If there is interest i am willing to finish the implementation and documentation. BR, Dmitry

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[chrono] v0.4 New thread_clock
by vicente.botet 28 Feb '10

28 Feb '10

Hi, I'm pleased to announce the version 0.4 of the Boost.Chrono library. The implementaton is stable, I don't plan to add more features before review. I'll concentrate in improving the documentation and the tests. I know that review managers are hard to find, so if you are interested in the library, please contact me or the Review Wizards. The library can be downloaded from http://www.boostpro.com/vault/index.php?action=downloadfile&filename=chrono… and the documentation is online on the sandbox http://svn.boost.org/svn/boost/sandbox/chrono/libs/chrono/doc/html/index.ht…. New Features since v0.3.2: * Suspendible Clock concept + template class suspendible_clock<> * Added scope_suspend which do suspend/resume if the Clock is a model of Suspendible Clock concept, and nothing otherwise. * thread_clock support on platforms providing it natively. * Added support for wide character for stopwatch_reporter, stopclock, and stopclock_accumulator. * digital_time renamed t24_hours Perf * Added performances measures. Bug Fixes * Bug on timeval_demo. time_point t(duration(xtime(0))); // this was taken as a function declaration gettimeofday((timeval*)&t, 0); return t; time_point t(duration(xtime(0))); // this was taken as a function declaration gettimeofday((timeval*)&t, 0); return t; by timeval tv; gettimeofday(&tv, 0); xtime xt( tv.tv_sec, tv.tv_usec); return time_point(duration(xt)); * Bug on run_timer_test (add a global variable to avoid optimization that removes completely the code to be measured Best regards, _____________________ Vicente Juan Botet Escribá

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[vault] Can you login?
by Lorenzo Caminiti 28 Feb '10

28 Feb '10

Hi all, Can you login into the Boost Vault? I get the errors below on my browser when I try to login. I tried logging in from Linux and Windows using Firefox, Chrome, and Explorer. Regards, Lorenzo Warning: fopen(/home/rene/boost.vault/var/users/lcaminiti) [function.fopen]: failed to open stream: Permission denied in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 616 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 617 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 618 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 619 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 620 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 621 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 622 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 623 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 624 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 625 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 626 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 628 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 629 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 630 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 631 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 632 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 633 Warning: fwrite(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 634 Warning: fclose(): supplied argument is not a valid stream resource in /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php on line 635 Warning: Cannot modify header information - headers already sent by (output started at /home/rene/boost.vault/phpATM-1.30-patched/include/functions.php:616) in /home/rene/boost.vault/phpATM-1.30-patched/login.php on line 395

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[log] link problems with keywords::format
by Michael Caisse 28 Feb '10

28 Feb '10

Using msvc 8 I am having a link issue with the following code snippet. Commenting out the line with blog::keywords::format will cause the link error to go away. --------------------------------------------------- #include <iostream> #include <boost/log/attributes.hpp> #include <boost/log/common.hpp> #include <boost/log/core.hpp> #include <boost/log/exceptions.hpp> #include <boost/log/filters.hpp> #include <boost/log/formatters.hpp> #include <boost/log/sinks.hpp> #include <boost/log/trivial.hpp> #include <boost/log/utility/init/to_file.hpp> #include <boost/log/utility/init/common_attributes.hpp> namespace blog = boost::log ; int main() { blog::init_log_to_file( blog::keywords::file_name = "foo_%N.log", blog::keywords::rotation_size = 10 * 1024 * 1024, blog::keywords::format = "[%TimeStamp%]: %_%", blog::keywords::open_mode = std::ios_base::app ); BOOST_LOG_TRIVIAL(trace) << "A trace severity message"; return 0; } ------------------------------------------------------ main.obj : error LNK2019: unresolved external symbol "class boost::function2<void,class std::basic_ostream<char,struct std::char_traits<char> > &,class boost::log_mt_nt5::basic_record<char> const &> __cdecl boost::log_mt_nt5::parse_formatter<char>(char const *,char const *)" (??$parse_formatter@D@log_mt_nt5@boost@@YA?AV?$function2@XAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@ABV?$basic_record@D@log_mt_nt5@boost@@@1@PBD0@Z) referenced in function "class boost::function2<void,class std::basic_ostream<char,struct std::char_traits<char> > &,class boost::log_mt_nt5::basic_record<char> const &> __cdecl boost::log_mt_nt5::parse_formatter<char>(char const *)" (??$parse_formatter@D@log_mt_nt5@boost@@YA?AV?$function2@XAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@ABV?$basic_record@D@log_mt_nt5@boost@@@1@PBD@Z) bin\msvc-8.0\release\threading-multi\trivial.exe : fatal error LNK1120: 1 unresolved externals ------------------------------------------------------ Any ideas? michael -- ---------------------------------- Michael Caisse Object Modeling Designs www.objectmodelingdesigns.com

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[move] one more dumb question
by DE 27 Feb '10

27 Feb '10

how do i make a function return an object by value and other object to, say, move assign from that returned object within current C++ std? i.e. my_type foo() {/*...*/} //... my_type a; a = foo(); //move assignment is intended here -- Pavel

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[Review] ITL review planned to end tomorrow, February 28th
by Hartmut Kaiser 27 Feb '10

27 Feb '10

Hey all, We're almost at the planned end of Joachim Faulhabers ITL review (see the original review announcement here: http://comments.gmane.org/gmane.comp.lib.boost.announce/253) Now would be a good time to submit your reviews. If you need more time, please let me know. Regards Hartmut --------------- Meet me at BoostCon www.boostcon.com

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[Filesystem V3] file_status over-design?
by Beman Dawes 27 Feb '10

27 Feb '10

Both Filesystem V2 and V3 status() functions return an object of class file_status. file_status is just a thin wrapper around a file_type enum: enum file_type { status_error, file_not_found, regular_file, directory_file, symlink_file, block_file, character_file, fifo_file, socket_file, type_unknown }; It was designed that way on the assumption that file_status would eventually include additional state information. But that never happened, so it looks like over-design my part. The fix would be to rename the enum as file_status, and remove the current class file_status entirely. That would break a certain amount of existing code, but I suspect the C++ committee would force such a change anyhow for TR2, so better to get it over with now. Comments? Opinions? --Beman

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[function] improvements/proposals
by Domagoj Saric 27 Feb '10

27 Feb '10

A while back, in various threads more or less related to the topic, I posted various ideas and/or code contributions to the effect of improving boost::function in terms of efficiency (concentrated on invocation speed, assignement performance/overhead and reducing template and RTTI bloat) and configurability, however there was no "official response" as to whether it was any good, or whether any of it would be accepted or what's wrong with it if not. IMHO the results { - 'Speed': the test presented here http://marc.info/?l=boost&m=118835709647084&w=2 modified to work with boost::signals2 (because it is a header only library/does not require a recompilation of boost if something in boost::function changes) with the dummy mutex/no threading support and a simple recompilation with the new boost::function<> code yielded a ~10% boost, changing the default policy to be nothrow the boost doubled to ~20% - 'Size': my real life project, that uses heavy metaprograming for generating function objects (that as a consequence have _very_ long type names, and thus RTTI records) to assign to boost::functions shrunk by ~10% simply by using the modified boost::function (with RTTI features disabled)...This post http://lists.boost.org/Archives/boost/2009/12/160202.php has more detailed and updated results when my project grew further (with an even bigger difference) } show/hint that there is room for improvement in boost::function and therefor warrant atleast some kind of response (even if along the lines of 'it's no good' or 'there is no time for this now')...which is the reason for (re)posting this (in a separate thread). The relevant threads with more detail are these: http://thread.gmane.org/gmane.comp.lib.boost.devel/196906 http://thread.gmane.org/gmane.comp.lib.boost.devel/194514/focus=195351 since then I've moved the modified code from the vault into the sandbox SVN (under the obvious name "function" :) -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley

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