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

[thread][repost] recursive shared mutex
by JOAQUIN M. LOPEZ MUÑOZ 29 Nov '10

29 Nov '10

[Trying my luck again with this query.] Hi, Boost.Threads provides a recursive mutex and a shared mutex, but no recursive *and* shared mutex. Would it be a good idea to add this to the library? How hard is it to construct a recursive shared mutex from boost::sahred_mutex (i.e. adding reentrancy to boost::shared_mutex)? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Another decompression issue?
by Bryan 27 Nov '10

27 Nov '10

I'm using Boost 1.43 and I've run across a situation where I'm getting unexpected results when reading the uncompressed stream. I originally thought that it was an issue with my data format interpretation, but it turns out that something seems to be consuming a character from the input stream. Here's a sample of reading the stream a character at a time: cur = 80, next = 80 cur = 80, next = 38 cur = 38, next = 8c cur = 8c, next = c cur = b4, next = db <--- Cur != previous next cur = db, next = 1 cur = 1, next = 1 cur = 1, next = dd This debugging output shows the discontinuity in the stream. The code is pretty simple: boost::iostreams::filtering_istream instream; std::fstream infile; uint8_t d; instream.push(boost::iostreams::bzip2_decompressor()); infile.open("file.bz2", std::ios::binary|std::ios::in); instream.push(infile); while (true){ instream >> d; fprintf(stderr, "cur = %x, next = %x\n", d, instream.peek()); } Reading a large chunk of data from the stream via read() does not have the same issue. I see that there are a few changes for compression in 1.44 [Fix several issues with compression and decompression (#2318, #4091, #3348, #2783, #1579, #3853). ] but it's unclear if this is one of them. Thanks in advance for any help. B

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Linker error on windows
by Lars Mogensen 22 Nov '10

22 Nov '10

Hi, I am using BOOST to do math and have not been able to get the "findroot_demo.cpp" example of root finding to work. There seem to be a reference to rint(), which is not implemented in the C++ library for windows. How can I solve this - my understanding of BOOST is that it is cross-platform? 1>------ Build started: Project: boostfindzero, Configuration: Debug Win32 ------ 1>Compiling... 1>findroot_demo.cpp 1>Linking... 1>findroot_demo.obj : error LNK2019: unresolved external symbol _rint referenced in function "public: static double __cdecl boost::numeric::interval_lib::detail::x86_rounding::to_int(double const &)" (?to_int@x86_rounding@detail@interval_lib@numeric@boost@@SANABN@Z) 1>D:\dokumenter\lvm_AM\Visual Studio 2008\Projects\boostfindzero\Debug\boostfindzero.exe : fatal error LNK1120: 1 unresolved externals 1>Build log was saved at "file://d:\dokumenter\lvm_AM\Visual Studio 2008\Projects\boostfindzero\boostfindzero\Debug\BuildLog.htm" 1>boostfindzero - 2 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Thanks in advance. /Lars

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[netlib] throwing exceptions with http_client.cpp
by Christian Henning 19 Nov '10

19 Nov '10

Hi there, I'm trying to run http_client.cpp taken from the netlib examples. But unfortunately it's throwing a lot of exceptions. The line: cout << body(response) << endl; results into the following exceptions: First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x002cece0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. Unhandled exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x002cece0.. here is my stack: msvcr100d.dll!_CxxThrowException(void * pExceptionObject=0x000000000030ee20, const _s__ThrowInfo * pThrowInfo=0x000000013f526cd8) Line 157 C++ test_netlib_vc10.exe!boost::exception_detail::clone_impl<boost::system::system_error>::rethrow() Line 421 C++ test_netlib_vc10.exe!boost::rethrow_exception(const boost::shared_ptr<boost::exception_detail::clone_base const > & p={...}) Line 413 C++ test_netlib_vc10.exe!boost::detail::future_object_base::wait(bool rethrow=true) Line 170 + 0x11 bytes C++ test_netlib_vc10.exe!boost::detail::future_object<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >::get() Line 331 C++ test_netlib_vc10.exe!boost::shared_future<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >::get() Line 847 + 0x12 bytes C++ test_netlib_vc10.exe!boost::network::http::async_message<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> >::body() Line 107 + 0x18 bytes C++ test_netlib_vc10.exe!boost::network::http::impl::body_wrapper<boost::network::http::basic_response<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> > >::operator std::basic_string<char,std::char_traits<char>,std::allocator<char> >() Line 30 + 0x12 bytes C++ test_netlib_vc10.exe!boost::network::http::body<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> >(const boost::network::http::basic_response<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> > & message={...}) Line 41 + 0x1f bytes C++ test_netlib_vc10.exe!main(int argc=2, char * * argv=0x00000000004f7850) Line 86 + 0x15 bytes C++ test_netlib_vc10.exe!__tmainCRTStartup() Line 555 + 0x19 bytes C test_netlib_vc10.exe!mainCRTStartup() Line 371 C I'm using boost trunk with Visual Studio 10 compiling x64 bit code. Anyone any idea what going on here? Thanks, Christian

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Interest in B-tree library for Boost?
by Beman Dawes 17 Nov '10

17 Nov '10

A Boost B-tree library would provide disk-based associative containers that scale all the way from really, really, small to really, really, large. B-trees perform well on hardware ranging from ancient floppy disk drives all the way up to humongous disk arrays. They are the technology behind most high-performance disk file systems and databases. If you don't know what a B-tree is, or think that "B-tree" is an abbreviation for "Binary tree", you might want to read the Wikipedia B-Tree article: http://en.wikipedia.org/wiki/B-tree. Knuth and other computer science texts also supply descriptions. See http://mysite.verizon.net/beman/btree/index.html for a more complete description of the proposed library. A preliminary implementation is available. Download http://mysite.verizon.net/beman/btree/btree-preview-1.zip, and unpack into a current Boost distribution. A few existing Jamfiles will be overwritten. The only compilers tested and working so far are VC++ 10 and GCC/MinGW 4.5. You can view the library online at http://github.com/Beman/Boost-Btree There is no detailed documentation yet, but if you know how to use std::map and other standard library associative containers, you already know most of what you need to know. Critical differences are documented in the Library Characteristics section of the index.html page referenced above. Initial timing tests have been very encouraging. The time test compares the btree_map implementation to std::map. As expected, a btree_map is many times slower than a std::map, given a cold operating system file cache and constraining the btree_map's caching to a minimum. But at the other extreme, when the O/S file cache is warm and the btree_map's cache is as large as the file, the btree_map is very similar in speed to std::map.The btree library's code is still very new, so timings and everything else may be subject to lots of revision. Any interest? --Beman

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[StateChart] event processing order in async machine
by Igor R 16 Nov '10

16 Nov '10

Hello, I've got an async. state machine (1.44, MSVC10), and sometimes I observe a very strange behavior: events being processed not in the order they are queued. I spent some time trying to investigate this issue, but due to the asynchronous nature of the processing, it's quite not trivial. So, before I start sinking too deep, I'd like to ensure I don't miss something trivial. Unfortunately, I don't have at the moment any self-contained code, but a very simplified model of my FSM is as follows. Assume there are 2 events: Ev1, Ev2. The both are queued to the FMS from the same thread, always in the same order: Ev1, Ev2. The FSM processes them in another thread. The FMS has some "entry" chain of states that defer the both events: S1 /[defer(Ev1, Ev2)] --> S2 /[defer(Ev1, Ev2)] and finally 2 orthogonal sub-states, one of them ignores the both events, and the other processes the both: ...S2 --> S3<S3_1, S3_2>, S3_1 /[custom_reaction(Ev1), in_state_reaction(Ev2)] What I see is that *sometimes* the reaction for Ev2 is invoked *before* the reaction for Ev1. This "sometimes" really puzzles me: I'm absolutely sure that the order of queuing is always the same - so where can be a "race"? Any idea would be appreciated!

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[Program Options] Positional args in help message
by Lindley M French 10 Nov '10

10 Nov '10

The examples for how to use positional arguments are great and seem to work fine. However, I'm wondering if there's an automatic way to include that information in the help message. In particular, since the tutorial goes to the trouble of telling you how to exclude the positional options from the options help, it would be nice to know what to replace it with. I could manually write a line detailing the usage before outputting the options description, of course, but I was wondering if there was anything in PO to handle this automatically.

3 2

boost MPI issue on windows
by Nick Collier 08 Nov '10

08 Nov '10

Hi, I've got an MPI application that uses the boost mpi libraries. It runs fine on OSX and Linux when compiled using both debug and more optimized compiler flags. Unfortunately, on windows, the application only runs when compiled using Visual Studio 2008 debug configuration. When I run the executable compiled in the release configuration it crashes, but not in the same place every time in my code. It does only occur though when I make communicator::send and communicator::recv calls, sending and receiving vectors of ints. In those cases, I get exceptions like: {routine_=0x00d37d38 "MPI_Send" result_code_=805931010 message="MPI_Send: Invalid count, error stack: MPI_Send(176): MPI_Send(buf=0x001BF950, count=-1833296, MPI_PACKED, dest=1, tag=2001, MPI_COMM_WORLD) failed MPI_Send(101): Negative count, value is -1833296" } Sometimes its for a send and sometimes for a receive, but the exception is always for a "negative count" which looks suspiciously like an uninitialized integer. I figured I'm doing something wrong either in how I've compiled the boost libraries or in my own code (although its odd that it works in both linux and osx). Any suggestions obviously appreciated. This is for boost-1.39. We are prevented from using anything newer because the machine we ultimately deploy on has boost-1.39 installed. On windows, I'm using microsoft's mpi implementation (based on MPICH2) under windows 7. The boost mpi libraries are compiled in both static debug and release mt versions. thanks very much, Nick

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What's so cool about Boost.MPI?
by David Abrahams 07 Nov '10

07 Nov '10

Just wanted to call some attention to this article I wrote about Boost.MPI: http://daveabrahams.com/2010/09/03/whats-so-cool-about-boost-mpi/ I think it might be useful to link that from the Boost.MPI docs, too. -- Dave Abrahams BoostPro Computing http://www.boostpro.com

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[Asio]What's the behavior of socket.async_write() after socket.close() is called?
by 鑫炜廖 05 Nov '10

05 Nov '10

Hi, If I call socket.close() but I still have some data in my buffer, can I call async_write() later? When I call socket.close(), maybe an async_write operation is running, when it's complete I want to send data in another buffer(data written while previous async_write() is running, before socket.close() was called), but the socket is closed.Does it work in this situation?If not, what's the alternative way? The code looks like this: char front_buffer[kBufferSize]; char back_buffer[kBufferSize]; void HandleWrite(...) { //socket is closed. Does this work? socket.async_write(back_buffer, ...); } socket.async_write(front_buffer, HandleWrite); // write data to back_buffer socket.close();

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