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[Thread] TLS / locking ?
by beet 24 Nov '13

24 Nov '13

Hi there, I have a number of threads and, within the context of each thread, a large number of objects may be active. I would now like to provide all objects accessed by a thread with a common random number generator. i.e., there would be as many random number generators as there are threads, and all objects active inside of a given thread would access the same generator, but objects in different threads use different generators. The obvious approach would be to store the generator in thread-local storage. I am concerned, however, about the performance implications. In particular, does access to thread-local storage implicitly involve locking of sorts? If so, the (very) frequent access to the random number generator would effectively serialize my application. Thanks and Best Regards, Beet

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Design query using Boost.
by Rahul Mathur 24 Nov '13

24 Nov '13

All, I have a design sinerio. I have different struct (C structures) having different data's but NO similarities between struct and each struct does different operations. The struct for example are - struct Apple { int A; char B; long C; double d; .. ..}; struct Orange { char A; int B; unsigned int C; long d; .. }; and maybe few more. Above few struct data members have dynamic data and other members have fixed/hardcoded datas. The complete struct is send as a buffer to a remote machine through native send()/read() API calls which has been successfully implemented. Please note this data as tested were hard coded or completely static but didn't had combination of dynamic/real and static data.. Now such operations (viz different or repeated) with ONE/MULTIPLE SET of data could be many as 1000, I wish now to send complete operations to remote machine, get a ACK from it and work on this struct data with modification/cancellation/reject/etc operations. One way could be to work with something similar - struct Apple { ... ..}; vector <Apple> data; data.insert (begin();end()) --- But, I have few questions - 1. I can have "std::map<string, vector>" and send this data as native send(). Latter read/recv() with string. Am I correct as I would have multiple operations? 2. I do wish to maintain synchronisation using Boost::lockfree mechanism latter? 3. Any other techniques? Thanks.

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[log] Why aren't logger operations const ?
by Mauricio Carneiro 24 Nov '13

24 Nov '13

I am trying to use a severity channel logger but I hit the problem with BOOST_LOG_SEV not being a const method -- I'm thinking because of both open_record() and push_record() This will basically force me to make all methods in my classes not const because they want to write out to their loggers. I can't really afford to do that -- so I'm restricted to global loggers at the moment. In my current implementation, each class has a logger with the class name as the channel (initialized in their constructors), and it issues log messages at any point with BOOST_LOG_SEV(this->logger, level) I'd love to hear the reason behind the non-constness and if my design is not the intended for Boost::Log. Thank you for your help. Mauricio Carneiro, Ph.D. http://www.broadinstitute.org/~carneiro/

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Re: [Boost-users] New-style for on an iterator-range of filter_iterator of strings crashes/hangs
by Ami Tavory 24 Nov '13

24 Nov '13

Steven Watanabe: > AMDG > > On 11/23/2013 11:12 AM, Ami Tavory wrote: > > <snip> > > typedef > > filter_iterator<function<bool (const string &)>, > > vector<string>::const_iterator> > > filter_it_t; > > auto r = make_iterator_range(filter_it_t(fn, ss.begin()), > > filter_it_t(fn, ss.end())); > > <snip> > > > > yields an executable that crashes with > > {{{ > > Segmentation fault (core dumped) > > }}} > > > > <snip> > > > > You're not constructing the filter_iterators correctly. > From the documentation: > > filter_iterator(Predicate f, Iterator x, Iterator end = Iterator()); > > Effects: > > Constructs a filter_iterator where m_iter is either > the first position in the range [x,end) such that > f(*m_iter) == true or else``m_iter == end``. The > member m_pred is constructed from f and m_end from end. > > You need to pass the end iterator as well. (Or use > the Boost.Range version) > > In Christ, > Steven Watanabe Many thanks!

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New-style for on an iterator-range of filter_iterator of strings crashes/hangs
by Ami Tavory 24 Nov '13

24 Nov '13

Hello, Using g++ 4.8.1 (g++ (Ubuntu/Linaro 4.8.1-10ubuntu8) 4.8.1) with boost 1.5.3, building the code below with {{{ g++ -o example/filter.out -std=c++0x -Wall -g -rdynamic -I/usr/include/boost example/filter.cpp }}} {{{ #include <vector> #include <string> #include <iostream> #include <functional> #include <boost/iterator/filter_iterator.hpp> #include <boost/range/iterator_range.hpp> using namespace std; using namespace boost; int main() { vector<string> ss{"hello", "world"}; // function<bool (const string &)> fn = [](const string &s){return false;}; function<bool (const string &)> fn = [](const string &s){return s.size() > 3;}; cout << fn("Hello") << endl; // (1) cout << fn("world") << endl; // (2) typedef filter_iterator<function<bool (const string &)>, vector<string>::const_iterator> filter_it_t; auto r = make_iterator_range(filter_it_t(fn, ss.begin()), filter_it_t(fn, ss.end())); for(const string &a: r) cout << a << endl; return 0; } }}} yields an executable that crashes with {{{ Segmentation fault (core dumped) }}} Exchanging the comment in the two lines {{{ // function<bool (const string &)> fn = [](const string &s){return false;}; function<bool (const string &)> fn = [](const string &s){return s.size() > 3;}; }}} (so that the first lambda is used) yields an executable that hangs. In either case, the application first prints the results of the lines marked (1) and (2). Can't figure out what I'm doing wrong, and would appreciate advice. Thanks, Ami

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self_loop=false for Unique R-MAT generator
by Николай Кинаш 23 Nov '13

23 Nov '13

>The R-MAT graph model is different from the BA model; are you sure you >want R-MAT? Hmm.... I`m not sure. How to create BA model in BPGL? Thanks.

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Re: [Boost-users] [boost] Subversion repository closing. Conversion to Git imminent.
by Beman Dawes 23 Nov '13

23 Nov '13

On Fri, Nov 22, 2013 at 6:09 PM, Edward Diener <eldiener(a)tropicsoft.com>wrote: > On 11/22/2013 11:52 AM, Beman Dawes wrote:... > >> >> Please make no svn commits after that time. We will be adding a pre-commit >> hook that prevents commits, but please do not wait for that becomes >> active. >> >> After svn is closed, the conversion will be run one last time, and then >> turned off. Then there is a week set aside for final validity checks, >> testing, and general scurrying around. When that is done, the boostorg >> repo >> on GitHub will open for business. If everything goes smoothly, it may take >> less than a week but if there are glitches it may take longer. >> > > Can the boostorg repo on GitHub be pulled from at any time during that > week or is the idea to wait until everything has been verified first. > The boostorg repos, both super-project and individual libraries, can be cloned and that might be useful for some limited testing. For example, creating a private branch "experiments" and making some trial changes and commits. But there is still a risk that any changes pushed up to the GitHub boostpro public repo will get overwritten. This would happen if we decide to rerun the conversion one last time to fix some showstopper that surfaces during testing. So other than throw-away experiments, best bet is to relax, and don't depend on the GitHub public repos until we post a message saying we are totally live. Useful questions, Thanks! --Beman

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[Geometry] Finding polygon self-intersections efficiently
by Rob Conde 22 Nov '13

22 Nov '13

Given a possibly self-intersecting polygon, I'm trying to find the self-intersecting segments of the polygon. I can do this naively of course using Segment and intersects, but I'd like to know if there's a more efficient suggested approach in Boost.Geometry...I'm having a hard time finding anything from the documentation. Thanks, Rob Conde

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Re: [Boost-users] [Boost-docs] [boost] Improving Documentation
by Paul A. Bristow 22 Nov '13

22 Nov '13

> -----Original Message----- > From: Boost-docs [mailto:boost-docs-bounces@lists.boost.org] On Behalf Of Paul A. Bristow > Sent: Wednesday, November 20, 2013 12:09 PM > To: Discussion of Boost Documentation > Subject: [Boost-docs] FW: [boost] Improving Documentation I've had yet another go at Robert Ramey's challenge to document his to-be-proposed Safe Integers library You can see the results of my most recent efforts (now only for users) at https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… and as a single pdf file https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… Apart from the effort involved in providing Doxygen comments (which I believe is small, especially during writing the code, because there is lots of boiler plating possible), our main differences of view are on how to provide the 'concepts' information. The only true concepts used by this library (at present) are the ubiquitous assignable and copyconstructable. For the more common concepts, I have used a simple link to the concept like http://www.sgi.com/tech/stl/Assignable.html because the library is not using Boost.Concept (yet). (There is also a concept of a Numeric type but this is not enforced by the use of the library, although it can be tested using file https://dl.dropboxusercontent.com/u/43940943/safe_numerics/boost/safe_numer… provided). The information on type Numeric in this file is documented in my Doxygenated version here: https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… Robert has contrasted his presentation of concepts (and other information) thus http://htmlpreview.github.io/?https://raw.github.com/robertramey/safe_numer… doc/html/index.html with mine. I believe that it contains the same information (about Numeric) and can be found by using the automatically produced Index - see https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… l The other information about operators can also be found using the index, for example, operator>= see https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… /safe_compare/greater_than_equal.html The difference is that Robert provides a simple list, whereas I provide an index to individual operators (not all are currently documented - retrofitting is tedious!). IMO the user will find the index method easier (when that is the users' expectation). With a tiny library like this (chosen as a demo because it is small) it may be easy to find the concepts section, but for a typical much larger library making the table and finding it will be less attractive. The size of the documentation is much, much bigger, but it is more likely to be complete, and more likely to be accurate, (and nearly all will be unread so its repetitions unimportant). A typical example of what the user is likely to read is about the key template 'safe': https://dl.dropboxusercontent.com/u/43940943/safe_numerics/libs/safe_numeri… /safe.html You will note how this references concepts DefaultConstructible,... If Concepts get into the C++ language, or Boost.Concept is used, or the method using by Boost.GIL - see http://www.boost.org/doc/libs/1_55_0/libs/gil/doc/html/g_i_l_0286.html I believe we could make this fairly automatic, but I think the library must do this as it is conceived. Views welcome. Paul PS A more typical library with Doxygen comments in the C++ reference section is at https://dl.dropboxusercontent.com/u/43940943/circular_buffer/libs/circular_… l showing the info about circular buffer, for example at https://dl.dropboxusercontent.com/u/43940943/circular_buffer/libs/circular_… cular_buffer.html --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Re: [Boost-users] [BGL] visitors.hpp:138: error: no type named 'event_filter' in 'class dijkstra_custom_visitor'
by The Maschine 22 Nov '13

22 Nov '13

Well Jeremiah, My email and the assumptions are completely wrong. Im sorry. just forget about it, next time Ill have my coffee before debuting code :) thanks

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