March 2009 - Boost-users - lists.preview.boost.org

Compiling probs with Filesystem in 1.38.0
by Loreene Dixon 11 Mar '09

11 Mar '09

I successfully used Boost 1.33.1 with VS 2005. Now I have the task of upgrading our software to VS 2008 ASAP and in so doing, I upgraded our Boost to 1.38.0. Apparently, Boost's Filesystem got revamped in 1.34.0 and the contents of exception.hpp got moved to path.hpp and into Interprocess (!) library's errors.hpp. We cannot call the error() routine anymore as it's no longer a member of filesystem_error. Here is an extract of our code (for Boost 1.33.1): -------------------------------------------------- #include <boost/filesystem/convenience.hpp> #include <boost/filesystem/exception.hpp> #include <boost/filesystem/operations.hpp> . . . vit::ViToolkitException& createViToolkitException(boost::filesystem::filesystem_error& e) { switch (e.error()) { case boost::filesystem::other_error: case boost::filesystem::path_error: case boost::filesystem::not_found_error: case boost::filesystem::not_directory_error: case boost::filesystem::already_exists_error: throw vit::BadPathException(e.what()); default: throw vit::GeneralException(e.what()); } } boost::filesystem::path createPath(const std::wstring& pathName) { try { return boost::filesystem::path(vit::wideStringToString(pathName), boost::filesystem::native); } catch (boost::filesystem::filesystem_error& e) { throw createViToolkitException(e); } } -------------------------------------------------- So basically we call Boost's methods and if an error occurs, we catch it and throw createViToolkitException where it examines the error to determine whether it's a bad path or general exception and throws a new appropriate error. When I attempted to compile Boost 1.38.0, my compiler errors were: File.cc File.cc(28) : error C2039: 'error' : is not a member of 'boost::filesystem::basic_filesystem_error<Path>' with [ Path=boost::filesystem::path ] File.cc(29) : error C2039: 'other_error' : is not a member of 'boost::filesystem' File.cc(29) : error C2065: 'other_error' : undeclared identifier File.cc(29) : error C2051: case expression not constant File.cc(30) : error C2039: 'path_error' : is not a member of 'boost::filesystem' File.cc(30) : error C2065: 'path_error' : undeclared identifier . . . I changed the #include <boost/filesystem/exception.hpp> to #include <boost/filesystem/path.hpp>. I could change all 'boost::filesystem::filesystem_error' references to 'boost::filesystem::basic_filesystem_error'. What can I do about the ' switch (e.error()) {' call since the error() call is no longer available? Is there a different method that I should call? And do I replace 'boost::filesystem::path_error' with 'boost::interprocess::path_error'? What do I need to do in order to recompile in Boost 1.38.0 and still have the same functionality? I inherited this code from our east coast developers and am somewhat a Boost newbie. Thanks!, Loreene

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[Build/make tools] My strong interest in some 'boost-config' script...
by François Mauger 11 Mar '09

11 Mar '09

Dear boosters, As a programmer under Unix-like systems, I really appreciate when a library (say `mylib') provides some `mylib-config' script that helps its users to build compiler flags. Several industrial strength libraries have such a tool: GSL, MySQL and, in the field of particle physics software I work: CLHEP, ROOT, CERNLIB... Here is an example for the GSL (GNU Scientific Library): >>> $ gsl-config Usage: gsl-config [OPTION] Known values for OPTION are: --prefix show GSL installation prefix --libs print library linking information, with cblas --libs-without-cblas print library linking information, without cblas --cflags print pre-processor and compiler flags --help display this help and exit --version output version information An external CBLAS library can be specified using the GSL_CBLAS_LIB environment variable. The GSL CBLAS library is used by default. <<< I makes really easy to write rather portable makefiles using things like: CPPFLAGS+=$(shell gsl-config --cflags) LDFLAGS+=$(shell gsl-config --libs) Up to now and AFAIK it seems Boost does not provide such script that could be generated at build stage for any Unix-like system. Of course, I wrote my own script for my own usage (and for people who work with me). But at the end, I think it would be better to use an `official' tool. For my experience, it is also a strong argument to convince newbies to use Boost on top of standard C++, because it comes in some rather transparent way. So I have a few questions: - Is there such a script hidden in the Boost source tree? - If not, is there any plan to provide one? - Is someone else interested with it? Thank you very much for your comments. [hope this topic has not been addressed in the past! I apologize in advance for that!] regards frc [PS: I previously posted this mail within the wrong thread... sorry!] -- F.Mauger

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[Interprocess] Deadlock when using interprocess_semaphore
by Derek Kivi 11 Mar '09

11 Mar '09

We are seeing a deadlock when making use of the interprocess_semaphore. In our case we have two running threads where the first thread is stuck waiting at a timed_wait() call while the second thread is stuck at a post() call. Also, a symptom we are seeing is that the lock value is set to 1 before both threads try to acquire the lock -- we think this is why the threads get stuck in the lock calls. We are running 1.36 at the moment. Have there been any fixes in 1.37 or 1.38 that might help us to avoid this problem? Thanks, Derek Here is what the stacks for each thread look like from the Visual C++ debugger: Thread1 ------- Singletons.dll!boost::interprocess::scoped_lock<boost::interprocess::int erprocess_mutex>::scoped_lock<boost::interprocess::interprocess_mutex>(b oost::interprocess::interprocess_mutex & m={...}) Line 78 + 0x27 bytes C++ Singletons.dll!boost::interprocess::interprocess_semaphore::timed_wait(c onst boost::posix_time::ptime & abs_time={...}) Line 55 + 0xc bytes C++ Singletons.dll!QSemaphoreImpl::Wait(const unsigned long timeoutMilliseconds=1000) Line 62 + 0xf bytes C++ Singletons.dll!QSemaphore::Wait(const unsigned long timeoutMilliseconds=1000) Line 24 C++ Singletons.dll!QUtilityThread::DefaultAction(quic::HpcSharedPtr<IThread, std::allocator> data={...}) Line 105 + 0x18 bytes C++ Thread2 ------- ntdll.dll!7c90e4f4() [Frames below may be incorrect and/or missing, no symbols loaded for ntdll.dll] ntdll.dll!7c90d1fc() kernel32.dll!7c8023f1() kernel32.dll!7c802455() Singletons.dll!boost::interprocess::winapi::sched_yield() Line 281 + 0xe bytes C++ Singletons.dll!boost::interprocess::detail::thread_yield() Line 51 + 0x8 bytes C++ Singletons.dll!boost::interprocess::interprocess_mutex::lock() Line 40 C++ Singletons.dll!boost::interprocess::interprocess_condition::notify(unsig ned long command=1) Line 50 C++ Singletons.dll!boost::interprocess::interprocess_condition::notify_one() Line 33 C++ Singletons.dll!boost::interprocess::interprocess_semaphore::post() Line 31 C++ Singletons.dll!QSemaphoreImpl::Post() Line 45 C++ Singletons.dll!QSemaphore::Post() Line 18 C++ Singletons.dll!QUtilityThread::RegisterTask(IBackgroundTask * pBackgroundTask=0x01002660) Line 54 C++ -- Derek Kivi Senior Software Developer QuIC Financial Technologies Inc. Office: +1 403 210 8282 Mobile: +1 403 863 5204 derek.kivi(a)quic.com Risk. Managed. www.quic.com Confidentiality Notice: The information transmitted is intended only for the person(s) or entity(ies) to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this email in error, please contact the sender and delete the email and any related material from any computer. ver. QuIC 0707

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How to suppress vcvarsall.bat call?
by Peter Klotz 11 Mar '09

11 Mar '09

Hello When compiling Boost 1.38.0 with this command, bjam 3.1.17 insists on calling vcvarsall.bat before executing the actual build commands. bjam -q -sNO_COMPRESSION=1 --build-type=complete --abbreviate-paths --toolset=msvc-8.0 architecture=x86 address-model=32 However my environment already includes all necessary settings to execute cl, link,... So I would like to skip the call to vcvarsall.bat. Is this possible using a bjam command line argument? Regards, Peter.

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[boost-users] converting InputIterator to ForwardIterator
by Igor R 11 Mar '09

11 Mar '09

Hello, I'd like to do the subj, in order to be able to apply some std algorithms to files, like this: ifstream file("myfile", std::ios::binary|std::ios::in); std::string delim("\r\n\r\n"); // sequence to search typedef std::istreambuf_iterator<char> iterator; iterator begin(file), end; iterator pos = std::find_end(begin, end, delim.begin(), delim.end()); // won't work, because istreambuf_iterator is *not* ForwardIterator I found something called multi_pass in boost::spirit. However, I'm not sure if it's relevant or deprecated class (it seems to be a part of the "old" Spirit), and whether this's the only Boost utility I can use to perform the above conversion. Thanks.

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[interprocess] Memory mapped file based allocator
by dhruva 11 Mar '09

11 Mar '09

Hi, I am looking for a memory mapped file based allocator that does not map the whole file into memory. The size may be huge and I would not want to map all the contents into process memory. Since my read and write access are sequential, I would like the mapping to happen on demand (based on access violation trying to read an unmapped region of memory). Is there something like that in Interprocess/Boost (since the implementation needs to work both on M$ and GNU/Linux)? regards, dhruva Bollywood news, movie reviews, film trailers and more! Go to http://in.movies.yahoo.com/

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[Random] Sigma equal to zero in normal distribution.
by Rodolfo Federico Gamarra 11 Mar '09

11 Mar '09

Hi all, The documentation for the normal distribution (http://www.boost.org/doc/libs/1_38_0/libs/random/random-distributions.html#…) states: "Members explicit normal_distribution(const result_type& mean = 0, const result_type& sigma = 1); Requires: sigma > 0" In the actual code of this constructor (http://www.boost.org/doc/libs/1_38_0/boost/random/normal_distribution.hpp) it can be seen "assert(_sigma >= result_type(0));". That is, acepts sigma == 0. Indeed, there's no "division-by-zero" or so, because the method that is used ("Box-Muller") doesn't actually divide by sigma: return _cached_rho * (_valid ? cos(result_type(2)*pi*_r1) : sin(result_type(2)*pi*_r1)) * _sigma + _mean; So, in this case, the numbers will be all equal to _mean. From the mathematical point of view there's no such thing as a normal distribution with sigma equal to zero; but, computationally, may be handy to allow that. What's the expected behavior? Is there a typo in the docs? Or is it that the case sigma equal to zero is indeed undefined (so that anything could happen)? Thanks in advance, cheers. -- Rodolfo Federico Gamarra

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Thread usage in boost other then boost.thread??
by Bill Taylor 11 Mar '09

11 Mar '09

Hello, I joined the list because I am helping a PHD candidate run a very long program with Condor. But the mode we need to use does not work if pthreads are used because we can not save the state of the job when it needs to run somewhere else. Is it known what components in the boost library use threads? Bill Taylor Condor Project

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[asio] when to use io_service::post or deadline_timer::async_wait?
by Markus Werle 11 Mar '09

11 Mar '09

Hi! After reading the referece docs I got the impression that the only difference between io_service::post and deadline_timer::async_wait is the fact that the former triggers execution immediately (after the caller function returns?) while the latter waits until timer expires before execution of the function object. Is this really the only difference or is there any other issue to be considered? Markus

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Generalised compile-time hash function
by Nikhilesh S 11 Mar '09

11 Mar '09

Hey guys! I'm not very familiar with boost.mpl, or boost.preprocessor, so I wanted to ask. I've written a compile-time hash function. Here's an example that uses it:- #include <iostream> using namespace std; //Compile-time hasher. #define HASH(partial,c) (((partial) << 1) ^ (c)) #define HASH_1(p1) HASH(0,(p1)) #define HASH_2(p1,p2) HASH(HASH_1(p1),(p2)) #define HASH_3(p1,p2,p3) HASH(HASH_2(p1,p2),(p3)) #define HASH_4(p1,p2,p3,p4) HASH(HASH_3(p1,p2,p3),(p4)) #define HASH_5(p1,p2,p3,p4,p5) HASH(HASH_4(p1,p2,p3,p4),(p5)) #define HASH_6(p1,p2,p3,p4,p5,p6) HASH(HASH_5(p1,p2,p3,p4,p5),(p6)) #define HASH_7(p1,p2,p3,p4,p5,p6,p7) HASH(HASH_6(p1,p2,p3,p4,p5,p6),(p7)) #define HASH_8(p1,p2,p3,p4,p5,p6,p7,p8) HASH(HASH_7(p1,p2,p3,p4,p5,p6,p7),(p8)) #define HASH_9(p1,p2,p3,p4,p5,p6,p7,p8,p9) HASH(HASH_8(p1,p2,p3,p4,p5,p6,p7,p8),(p9)) #define HASH_10(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10) HASH(HASH_9(p1,p2,p3,p4,p5,p6,p7,p8,p9),(p10)) #define HASH_11(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11) HASH(HASH_10(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10),(p11)) #define HASH_12(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12) HASH(HASH_11(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11),(p12)) #define HASH_13(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13) HASH(HASH_12(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12),(p13)) #define HASH_14(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14) HASH(HASH_13(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13),(p14)) #define HASH_15(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15) HASH(HASH_14(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14),(p15)) #define HASH_16(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15,p16) HASH(HASH_15(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15),(p16)) /* .. omitted the rest, but it's there till around HASH_30 .. */ //Runtime hasher. unsigned int hash(char const *p) { unsigned partial = 0; while (*p) { partial <<= 1; partial ^= *p; ++p; } return partial; } //Test it in a main() int main() { char str[31] = "thisisatest"; //Yay! Switch on strings! switch (hash(str)) { case HASH_11('t','h','i','s','i','s','a','t','e','s','t'): cout << "You said, 'this is a test'!"; break; case HASH_16('y','e','t','a','n','o','t','h','e','r','s','t','r','i','n','g'): cout << "You said, 'yet another string'!"; break; } return 0; } So, I was wondering how I could use boost.preprocessor to be able to write a more generic hash function, something like HASH_GENERIC(mystring), or at least HASH_GENERIC(8,mystring). BTW, here's a vim script that changes any thing like '@something@' on the curent line into "HASH_9('s','o','m','e','t','h','i','n','g')", when you type ',h':- map ,h :s/@$.\+$@/\='HASH_'.strlen(submatch(1))."('".join(split(submatch(1), '\zs'), "','")."')"/<CR> ;-) -- Nikhilesh S http://nikki.drupalsite.org

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