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

[ASIO / Serialization] How to avoid the copy?
by Dan Eaton 25 May '09

25 May '09

Hello, Referring to the boost::asio "Serialization" example, and specifically to the file connection.hpp which handles serialization over sockets: http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/example/serializat… When new data is to be received, first the message header is read, which contains the number of bytes for the body. Storage must be allocated to receive the body, and is then passed into ::read as boost::asio::buffer. For the purpose of using Serialize, it must then be converted to an std::istream, (in the example above, istringstream). As shown in the example, this requires an extra copy to be held in memory for the std::string. What's the best route to avoid this copy? Thanks, Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[ASIO / Serialization] How to avoid the copy?
by Dan Eaton 25 May '09

25 May '09

Ah, yes, it looks like it does have something like that (an implementation of streambuf). Thanks! Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[serialization] appending to an archive
by hurcan solter 25 May '09

25 May '09

I am trying to append one or more records to the existing archive file, using something like this; void Logger::save(const std::string& fileName) { assert(fileName != "logger.dmp"); bp::time_duration endRecordTime = getCurrentTime(); ofs.flush(); path dst = complete(path(fileName, native)); path src = complete(path("logger.dmp", native)); remove(dst); copy_file(src, dst); ofstream saveFile(dst,std::ios::app); ArchiveType archive(saveFile,boost::archive::no_header); *mArchive << endRecordTime } although i specify no_header flag, it inserts a '0' as a preamble, how can i turn it off? have you guys ever needed to use serialization like this? what was your solution Thanks in advance Hurcan

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[Container] ptr_set with user define compare function
by 梁绍池 25 May '09

25 May '09

I've defined a function object as below: struct BaseAddrLess : public std::binary_function<Base, Base, bool> { result_type operator() (const first_argument_type& lhs, const second_argument_type& rhs) const { return &lhs < &rhs; } }; and use as a compare function in ptr_set like this: ptr_set<Base, BaseAddrLess> bset; when the class Base is a abstract class the vc9 compiler will complain use of undefined type 'boost::result_of<F>' What causes this problem? How to solve it? Thank you for your patience to read my poor english. S.C. Leung

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exception: use of error_info can mask real exceptions
by Andrew Venikov 25 May '09

25 May '09

Just wanted to ask if there were commonly accepted solutions to the following problem: typedef boost::error_info<struct tag_f1, std::string> f1_descr; and then throw f1exception() << f1_descr("blah blah blah"). and later catch(f1exception & ex){...} The constructor of std::string may throw an exception in which case f1exception will never be thrown. This is not necessarily the desired outcome as the intention was obviously to indicate f1exception error, not the string() error. This problem pertains to any type that throws exceptions in its constructor and is used with error_info idiom. What may be more appropriate is something like this typedef boost::error_info<struct tag_f1, shared_pointer<string> > f1_descr ... error condition is detected shared_ptr<string> pErrStr; try { pErrStr = new string("Error description"); } catch(bad_alloc & ex) { } throw f1exception() << f1_descr(pErrStr); Meaning that if string fails to allocate memory, I'm willing to forgo the error description but still throw the intended exception. Is there a cleaner way to do that? Thanks, Andy.

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boost::thread_specific_ptr
by jono 25 May '09

25 May '09

hi all, i'm using thread_specific_ptr (boost 1.33.1, sorry) in a plugin architecture, where the tls identifies a singleton object of type Context (initialized using DCLP). boost::thread_specific_ptr<Context> Context::instance_; i also have a set of shared libraries and a main executable linked against a static library defining the Context class. this all works fine so long as the libraries are loaded and the threads created in that order, however, if a library is loaded after thread is started, then the thread_specific_ptr in that thread appears to be reset to null, without calling cleanup(). if i use the debugger to inspect the singleton ptr before and after loading the second module, it is, before: $1 = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_tss = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_slot = 8}} ..and after: $2 = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_tss = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_slot = 1}} is this correct behaviour for thread_specific_ptr? is there a way i can obtain a handle for the first Context object before it is destroyed? here's some info about my system. $ cat /proc/cpuinfo ... AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ ... $ uname -a Linux lumpen 2.6.19 #2 SMP Fri Jan 12 17:58:33 NZDT 2007 x86_64 x86_64 x86_64 GNU/Linux $ gcc -v Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux Thread model: posix gcc version 4.1.1 20060525 (Red Hat 4.1.1-1) any help would be appreciated. cheers, Jono

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Build 1.39.0 under VC2010?
by Mantas Matelis 24 May '09

24 May '09

Hi, is vc10 support implemented? And if so, is this the right way to build for vc10:bjam.exe --build-dir="c:\development\boost" --prefix="c:\development\boost" --build-type=complete toolset=msvc-100 stage > C:\development\boost\build-output-vc10.txt When running this, everything builds, but the files have improper names. Visual studio expects libboost_filesystem-vc100-mt-gd-1_39.lib but in the stage directory there are no files with vc100, just vc.

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How do I build with an alternate compiler location?
by Eric Brown 24 May '09

24 May '09

I'm trying to build on freebsd 4. (Those are my production machines, so I'm stuck.) The default install is gcc 2.95 and freebsd's old ports tree contains patches to build boost's libraries. However, when I try to include boost include files, it inevitably complains about any number of templates gcc can't grok. I suppose I can maybe build the libs with gcc 2.95 and my code with gcc 3.4.6, but I'd rather build boost with 3.4.6 too. Plus, the patches are for boost 1.32 and I'd rather use a later version of boost. However, gcc34 installs into /usr/local/bin/gcc34 and a bunch of include files I'd usually specify -I directives in my CXXFLAGS in my makefile. I'm just not clear how to set these overrides for bjam. I've looked at the bjam docs, but it just seems a lot more complicated than it should be. Cheers, Eric

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ICMP Ping ASIO
by cmicel1＠cct.lsu.edu 23 May '09

23 May '09

I am trying to recreate a simple ping utility that utilizes the Internet Control Message Protocol(ICMP) to gather information about a host. Boost ASIO has an implementation of the ICMP protocol and presents this protocol as a method to transmit messages similar to UDP or TCP. I need to create ICMP messages that are crafted with certain control messages (0 - Echo Reply, 8 - Echo Request), but I am unsure of how asio crafts messages when this protocol is in use. I do not want to utilize a server application for my network diagnosis and figured that this would be the appropriate method. Any information on the subject matter would be helpful to me. -Chris

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Noob question - undefined reference to boost::system::get_system_category
by mx270a 23 May '09

23 May '09

I'm a relatively new to programming on Linux, previous experience was with VB.net in Windows. I'm trying to make the switch to C++, but I'm having a difficult time. I started to follow one of the basic tutorials for Boost ASIO, but I can't get it to compile with the ASIO.hpp file included. The environment is Kubuntu 9.04 and Kdevelop 3.5.3. Code: ---------------- #include <boost/asio.hpp> int main() { return 0; } ---------------- Compile Messages and Errors: ---------------- cd '/home/lance/TS1/debug' && WANT_AUTOCONF_2_5="1" WANT_AUTOMAKE_1_6="1" LC_MESSAGES="C" LC_CTYPE="C" make -k make all-recursive Making all in src compiling ts1.cpp (g++) mv -f .deps/ts1.Tpo .deps/ts1.Po linking ts1 (g++) linking ts1 (g++) ts1.o: In function `__static_initialization_and_destruction_0': /usr/include/boost/system/error_code.hpp:205: undefined reference to `boost::system::get_system_category()' /usr/include/boost/system/error_code.hpp:206: undefined reference to `boost::system::get_generic_category()' /usr/include/boost/system/error_code.hpp:211: undefined reference to `boost::system::get_generic_category()' /usr/include/boost/system/error_code.hpp:212: undefined reference to `boost::system::get_generic_category()' /usr/include/boost/system/error_code.hpp:213: undefined reference to `boost::system::get_system_category()' ts1.o: In function `boost::asio::error::get_system_category()': /usr/include/boost/asio/error.hpp:218: undefined reference to `boost::system::get_system_category()' ts1.o: In function `posix_tss_ptr': /usr/include/boost/asio/detail/posix_tss_ptr.hpp:47: undefined reference to `pthread_key_create' ts1.o: In function `~posix_tss_ptr': /usr/include/boost/asio/detail/posix_tss_ptr.hpp:61: undefined reference to `pthread_key_delete' collect2: ld returned 1 exit status make[2]: *** [ts1] Error 1 make[2]: Target `all' not remade because of errors. make[2]: Nothing to be done for `all-am'. make[1]: *** [all-recursive] Error 1 make: *** [all] Error 2 *** Exited with status: 2 *** ---------------- How do I resolve the boost::system errors? Thanks, Lance -- View this message in context: http://www.nabble.com/Noob-question---undefined-reference-to-boost%3A%3Asys… Sent from the Boost - Users mailing list archive at Nabble.com.

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