December 2016 - Boost-users - lists.preview.boost.org

[msm] Transitions not atomic with orthogonal regions
by Stian Zeljko Vrba 26 Dec '16

26 Dec '16

I have spent almost an hour debugging the following issue. I have a "main" orthogonal region with a couple of states and an "error" region with RUNNING and PAUSED states, like this: struct PAUSED : public msm::front::interrupt_state<new_job> {}; struct RUNNING : public msm::front::state<> {}; There are transitions PAUSED --new_job--> RUNNING and RUNNING --failed--> PAUSED. Then, in one of the main states, I have struct MAIN_STATE1 : public msm::front::state<> { template<typename Event, typename FSM> void operator()(const Event& e, FSM& fsm) { if (error_condition) fsm.process_event(failed{}); } } and in the FSM I have using initial_state = mpl::vector<MAIN_STATE0, PAUSED>; Now, when new_job is processed and MAIN_STATE1::on_entry called, the machine is in (MAIN_STATE1, PAUSED). In this state, process_event(failed{}) is ignored and not queued because PAUSED is interrupt state. Then, the next orthogonal region is processed and the machine goes into (MAIN_STATE1, RUNNING), which destroys the rest of the logic around which the FSM is designed... Adding using active_state_switch_policy = msm::active_state_switch_after_exit; to the machine did not help in any way. Reordering the states in initial_state fixed the problem, but this is a rather unsatisfactory fix because it doesn't solve the underlying problem of transition atomicity. This is counter-intuitive, being on the border between a bug and lack of clear documentation. Specifically: 1. State switch should be atomic. By using active state switch after exit, I had *expected* that first all exit handlers of the current state are called, the state is atomically switched to the new state, and then all entry handlers are called. What I have *observed* is that on_entry handler of a state in one orthogonal region is called before the other orthogonal region has switched *its* state. Thus, with orthogonal regions, the machine can be in an "impossible" intermediate combination of states. Because not all side-effects have run, this has consequences for all actions/guards acting on state or FSM data, which is illustrated by the following: 2. process_event eagerly evaluates is_event_handling_blocked_helper for each orthogonal region in order. The event should be queued unconditionally, and only after the transition has completed, the machine should dequeue events and check whether processing is blocked etc. This, I think, would make at least process_event to appear atomic wrt state switch. Which leads me to conclude that MSM is seductively declarative on the surface, but that it's rather tricky operationally.

1 0

Boost 1.63.0 Release Candidate 2
by Marshall Clow 25 Dec '16

25 Dec '16

The second release candidate for the 1.63.0 release is now available at: https://sourceforge.net/projects/boost/files/boost/1.63.0/ The only changes are in Boost.Config, Boost.Context, and Boost.Fiber. The SHA256 checksums are as follows: 25db3956a8d58187ac7a0702cc917e9bab47ff90baafc35e4e789dca1ce5f423 boost_1_63_0_rc2.7z beae2529f759f6b3bf3f4969a19c2e9d6f0c503edcb2de4a61d1428519fcb3b0 boost_1_63_0_rc2.tar.bz2 fe34a4e119798e10b8cc9e565b3b0284e9fd3977ec8a1b19586ad1dec397088b boost_1_63_0_rc2.tar.gz 97ce6635df1f44653a597343cd5757bb8b6b992beb3720f5fc761e3644bcbe7b boost_1_63_0_rc2.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The release managers

2 2

cross compile application include boost-lib
by Thomas Schmiedl 24 Dec '16

24 Dec '16

Hello, I try to use this application https://github.com/repetier/Repetier-Server on my mips-based router. Sorry, I'm not a developer. Please could someone explain the cross-compiling steps for Linux (I use Ubuntu 14 x86 as build system). gcc/g++ toolchain for mips is from this project http://freetz.org/wiki/help/howtos/common/newbie.en. Do I have also to cross-compile boost for mips or only install the Ubuntu-source-package (sudo apt-get install libboost-all-dev). Thanks for your help and best regards, Thomas

2 2

[boost] [build] [context] Mac build options for Boost.Context
by Nat Goodspeed 23 Dec '16

23 Dec '16

Building Boost 1.57 on OS X 10.11, but building it *for* OS X down to 10.9, we're passing bjam a cxxflags command-line argument including -mmacosx-version-min=10.9. We see that switch (along with our other cxxflags switches) in most "g++" lines in the build output, since we also pass -d2 -d+4. But for the assembly source files in Boost.Context, the lines do not contain our requested -mmacosx-version-min switch. In fact they don't seem to contain any of our cxxflags switches. As a result, the assembly object files are built for the OS X version on the build host, 10.11. At executable link time, this produces messages: ld: warning: object file (packages/lib/Release/libboost_context-mt.a(jump_x86_64_sysv_macho_gas.o)) was built for newer OSX version (10.11) than being linked (10.9) ld: warning: object file (packages/lib/Release/libboost_context-mt.a(make_x86_64_sysv_macho_gas.o)) was built for newer OSX version (10.11) than being linked (10.9) (These are the only two .o files producing such messages.) I'm afraid that the resulting executable won't run on OS X 10.9 or 10.10, and that segment of the population is still interesting to us. How should we propagate the cxxflags=-mmacosx-version-min=10.9 feature to the assembler command for Boost.Context?

2 2

Units: Are scales for bytes really working?
by Akim Demaille 21 Dec '16

21 Dec '16

Hi, I’m trying to run the example given in http://www.boost.org/doc/libs/1_62_0/doc/html/boost_units/Examples.html#boo…, and the result is puzzling. $ cat foo2.cc #include <iostream> #include <boost/units/systems/information/byte.hpp> #include <boost/units/io.hpp> using namespace std; using boost::units::binary_prefix; using boost::units::engineering_prefix; using boost::units::no_prefix; using boost::units::symbol_format; using boost::units::quantity; using boost::units::information::byte_base_unit; int main() { cout << BOOST_VERSION << endl; // Don't forget that the units name or symbol format specification is persistent. cout << symbol_format; // Resets the format to the default symbol format. quantity<byte_base_unit::unit_type> b = 2048. * byte_base_unit::unit_type(); cout << b << endl; cout << engineering_prefix << b << endl; // 2.048 kb cout << symbol_format << binary_prefix << b << endl; // "2 Kib" } $ g++-6 foo2.cc -o foo2 $ ./foo2 106200 2048 B 16.384 kb 16 Kib What am I doing wrong? Note that there are a couple of issues in the example as given: - there should not be any endl after cout << symbol_format; - using ‘\n’ instead of endl, too many people seem to believe that std::endl is the normal way to end the lines - it would be nice to provide all the needed includes

1 0

Re: [Boost-users] [boost] Stacktrace library starts review today 14th Dec
by Antony Polukhin 17 Dec '16

17 Dec '16

2016-12-17 20:51 GMT+03:00 Andrey Semashev <andrey.semashev(a)gmail.com>: <...> > That said, I'd like to thank Antony for the submission and encourage > him to continue his work on the library. The library does try to fill > an important gap. Thank you for the review! I'd like to discuss a proposed changes. Thing that I'm worried about: * replacing class `stacktrace` with vector<void*> will definitely break the most common use case std::cout << get_stacktrace(); as it's not a good idea to overload ostream operator for vector of void pointers * addr2line and forking is not nice. Is linking with a GPL licensed code an acceptable alternative? * removing `basic_stacktrace` will definitely remove all the possibilities for optimization of caching COM/parsed DWARF. This is a quick win that later may turn into big troubles. -- Best regards, Antony Polukhin

1 0

Trouble with std::forward and fusion vector using clang 3.4 and older library - is there a workaround?
by Stan Blakey 16 Dec '16

16 Dec '16

I am trying to compile using clang 3.4 and -std=c++11. With the -std=c++11 it compiles and runs without any issue. With -std=c++11 I get boost_1_60_0\boost/fusion/container/vector/vector.hpp:126:20: error: no template named 'forward' in namespace 'std'; did you mean 'advance_detail::forward'? return std::forward<result>(*advance_c<N>(begin(seq))); and many similar errors. I have tried all the boost BOOST_NO_CXX11_HDR_ macros but not found one that resolves this issue. I don't have any choice about compiler version or library version due to other constraints. Any suggestions appreciated, Stan *#include* <boost/fusion/tuple.hpp> *#include* <boost/fusion/algorithm.hpp> *#include* <string> *#include <iostream>* *using* *namespace* boost::fusion; *struct* print { *template* <*typename* *T*> *void* *operator()*(*const* *T* &t) *const* { std::cout << std::boolalpha << t << '\n'; } }; *int* *main*() { *typedef* tuple<*int*, std::string, *bool*, *double*> tuple_type; tuple_type t(10,"Boost", *true*, 3.14); for_each(t, print()); }

2 4

Boost 1.63.0 Release Candidate 1
by Marshall Clow 15 Dec '16

15 Dec '16

The release candidates for the 1.63.0 release are now available at: https://sourceforge.net/projects/boost/files/boost/1.63.0/ The SHA256 checksums are as follows: 010699561c6011e6d97dc453d55bc5e54cdc192622434eff7b8ac559efac846c boost_1_63_0_rc1.7z d8ebf8d90b2f823f04119445ac339d704395d655907333ec0fab863040119d24 boost_1_63_0_rc1.tar.bz2 dabe29b8a60369ae7c15c20681a32717f3c37d97e5dc6d39c5b2fd0494b8e995 boost_1_63_0_rc1.tar.gz 1683942022fd63c205c48fb2155af6094c67ef67aa13ffb3e1db78fecf817efe boost_1_63_0_rc1.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The release managers

7 12

Stacktrace library starts review today 14th Dec
by Niall Douglas 15 Dec '16

15 Dec '16

The formal review of the Stacktrace library by Antony Polukhin starts today 14th Dec and will conclude before Christmas. I appreciate we are likely a bit tired out from the many library reviews recently and of course it's Christmas, but given the lack of a portable way to work with stack backtraces, which you inevitably need to do eventually in any non-toy production application, Stacktrace needs your review! Stacktrace is an optionally header-only library providing four implementation backends, libunwind (POSIX only), windbg (Windows only), backtrace (from the C library on most POSIX implementations) and a null backend. At its very simplest it lets you capture the stack backtrace for the calling thread and to print it to a std::ostream& of your choice. The basic_stacktrace<> class quacks like a STL container of frame object instances. The rest of the API pretty much follows STL design principles for the most part. Use is therefore unsurprising. You can find the documentation at http://apolukhin.github.io/stacktrace/index.html and the github repo at https://github.com/apolukhin/stacktrace. Review guidelines ================= Reviews should be submitted to the developer list (boost(a)lists.boost.org) preferably with '[stacktrace]' in the subject. Or if you don't wish to for some reason or are not subscribed to the developer list you can send them privately to me at 's_sourceforge at nedprod dot com'. If so, please let me know whether or not you'd like your review to be forwarded to the list. For your review you may wish to consider the following questions: - What is your evaluation of the design? - What is your evaluation of the implementation? Most of my personal concerns with this library are with the implementation and I would hugely appreciate feedback from others with substantial experience of using stacktracing "in anger" in non-trivial use case scenarios. - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should attempt to answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Even if you do not wish to give a full review any technical comment regarding the library is welcome as part of the review period and will help me as the review manager decide whether the library should be accepted as a Boost library. Any questions about the use of the library are also welcome. Finally, thanks to Edward whose announcement of the Synapse library review I borrowed heavily from as I thought it very well structured. Hopefully the above is just as clear. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

3 3

SSDLC Compliance - Boost C++ Libraries
by GAN Kok Leong, Adrian 14 Dec '16

14 Dec '16

Hi, We have a cybersecurity requirement for all software. We would like to know whether Boost C++ Libraries is developed and comply with Secure Software Development Life Cycle (SSDLC)? Regards Adrian Gan [This e-mail is confidential and may be privileged. If you are not the intended recipient, please kindly notify us immediately and delete the message from your system; please do not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] ---ST Electronics Group---

2 1