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Thread events
by Johan 't Hart 09 Sep '05

09 Sep '05

(I'm not that familiair with news servers, so this post might appear for the second time. I hope to get an answer though) Hello, I'm quite a newbie in the boost world, and I read the documentation about boost::threads. Inthere I read that events were not included in boost because they were too error-phrone. That made me wonder how to do multithreading without events, for example, how do you make a thread wait for something to do without events? I don't know how to implement that with just mutexes. Can someone help me? Thanks in advance. Johan 't Hart -- -- Mijn Postvak In wordt beschermd door SPAMfighter 11622 spam-mails zijn er tot op heden geblokkeerd. Download de gratis www.SPAMfighter.com vandaag nog!

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bbv2 filesystem link issue?
by Daniel Schlyder 09 Sep '05

09 Sep '05

Hi, I'm in the process of upgrading to Boost.Build v2 and have run into a problem with Boost.Filesystem (or my use of it). Executables using this library crash when built with my BBv2 files, but work fine with my old BBv1 files. I'm using Boost CVS HEAD, MinGW GCC 3.4.4 and Boost.Jam 03.01.11. The crash is a SIGSEGV in std::string::find_first_of() when called from boost::filesystem::windows_name(). It doesn't matter whether I use a shared or static variant of the library. Moving the definition of windows_invalid_chars into windows_name() fixes it as long as I use a static variant. I guess this should give some clue as to what is going wrong, but I don't get it. I tried comparing the build commands of BB v1 and v2 but if there is anything wrong I don't have the knowledge to see it. I tried duplicating the crash using a simple BBv2 Jamroot and a "hello world"-ish Boost.Filesystem program, but that works fine. I'm completely stuck here and any help would be much appreciated. Thanks, -- Daniel Schlyder http://bitblaze.com/

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Re: [Boost-users] Thread events
by Gottlob Frege 09 Sep '05

09 Sep '05

> > Date: Thu, 8 Sep 2005 21:06:12 +0200 > From: "Johan 't Hart" <jopie64(a)hotmail.com> > Subject: Re: [Boost-users] Thread events > To: <boost-users(a)lists.boost.org> > Message-ID: <BAY109-DAV27468EBFC3012D63D9A99B4990(a)phx.gbl> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > Thanks for your replies. > > To me boost::condition looks very much like the old event variable, except > that it works together with a mutex. I am now wondering why you should > lock > a mutex before waiting for the condition? Is there a rationale about this? > > Johan Also note that the wait() on the condition unlocks the mutex until you return from the wait call. That's not always obvious from the examples.

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request: make atomic operations (boost/detail/atomic_count*) available for library users
by Paul Pogonyshev 08 Sep '05

08 Sep '05

Hi, Is it possible that atomic operations in Boost are made available for library users? `shared_ptr' is good, but sometimes one might need the low-level operations too. Paul

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Boost licensing applied
by Ted Carter 08 Sep '05

08 Sep '05

I'm considering using Boost in a commercial product, but after reading the licensing statement I'm not clear what is required. The candidate project ships to end-users in binary, and sometimes to oems as sources. Does the license statement need to be included with all sources, dependent files, or just in the Boost library sources? Legalese isn't my strong point. Regards, Ted.

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[BGL] what is the "Power-Law Out Degree" algorithm?
by Rui Carvalho 08 Sep '05

08 Sep '05

Hi, What is the PLOD algorithm http://www.boost.org/libs/graph/doc/plod_generator.html My understanding is that this is NOT the Barabasi-Albert model. Could someone post a reference (paper/book) to the algorithm, please. Thanks, Rui

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[graph] king ordering: get rid of "comparison between signed and unsigned" warning
by Marco Morandini 08 Sep '05

08 Sep '05

This patch allows to get rid of the "comparison between signed and unsigned" warning, issued by gcc 3.4.4 at -Wall. I'm not sure of the correctness of the (int)Qptr->size() cast. Regards, Marco Morandini --- /home/marco/Programmi/boost_1_33_0/boost/graph/king_ordering.hpp 2005-09-06 19:20:56.000000000 +0200 +++ king_ordering.hpp 2005-09-08 13:55:10.000000000 +0200 @@ -63,7 +63,7 @@ //heap the vertices already there std::make_heap(rbegin, rend, boost::bind<bool>(comp, _2, _1)); - int i = 0; + typename Buffer::size_type i = 0; for(i = index_begin; i != Qptr->size(); ++i){ colors[get(vertex_map, (*Qptr)[i])] = 1; @@ -168,7 +168,7 @@ int parent_location = Qptr->size() - heap_parent_location; bool valid = (heap_parent_location != 0 && child_location > index_begin + offset && - parent_location < Qptr->size()); + parent_location < (int)Qptr->size()); while(valid && comp((*Qptr)[child_location], (*Qptr)[parent_location])){

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boost v1.33 on VS2005
by Oleg Smolsky 08 Sep '05

08 Sep '05

Hi all, just reporting that entire boost compiled on August CTP of VS2005 aka VC8. Best regards, Oleg.

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boost threads: threads priority
by Amit Itzkovich 07 Sep '05

07 Sep '05

Hi, I was looking into using boost threads. However, it seems there isn't anyway to change thread priorities. I need to use a high priority thread in order to perform time-critical midi processing under Windows XP and MacOSX. Did I miss something? Thanks, Amit

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compile-time mapping: a[1] --> a1 ?
by Steven Allmaras 07 Sep '05

07 Sep '05

I would like to do a compile-time mapping of an array accessor to a list of scalars as in the following class: class MyArray1 { public: double& operator[](int n) { ??? } private: double a0, a1, a2, a3 ; } ; int main() { MyArray1 x ; x[1] = 2. ; } I've left off all the extraneous stuff like constructors. I don't know how to write the MyArray1::operator[] so that it will evaluate to one of the data members at compile time; an if-test would correctly evaluate but might not be optimized away and run slowly. Is there some way to do the compile-time evaluation using the MPL? I looked thru the tutorial but did not find anything that looked like it would work. One possibility that I considered was the C preprocessor concatenation operator ##, #define PICKMEMBER(n) a##n double& operator[](int n) { PICKMEMBER(n) ; } Unfortunately, this will not work for expressions like x[i+1]. It probably has additional problems other than being quite distasteful. Obviously, this would all be easy if I just implemented the member data with an array, class MyArray2 { public: double& operator[](int n) { return data[n] ; } private: double data[4] ; } ; In fact, I did do so and everything works fine. The reason that I am trying to implement the list of scalars method is to see if there are any CPU timing differences for my application, which amounts to matrix-vector operations for small, dense vectors whose sizes are known at compile time. I have tried uBlas but was disappointed with the timing results (and yes, I did compile with -DNDEBUG). I've also looked at other packages such as tvmet (it did worse). I finally tried rolling my own vector and matrix classes with lazy evaluation of binary operators via Eckel's "Thinking in C++, Vol 2"; I also studied source for uBlas and tvmet. So far, I am able to beat uBlas on my choice of compilers/platforms, but I'm still not getting the consistent performance that I was hoping for. Why am I so interested in performance? Two reasons. First, if I can get consistently good performance (i.e. performance that is close to raw C or Fortran) for fairly straightforward operations, then I can be more confident that as I increase abstraction, performance will not deteriorate substantially. Second, I am evaluating C++ for applications that have been traditionally written in Fortran -- in my case, CFD codes for airflow simulation. Issues of modularity, extensibility, maintenance, and the fact that very few students are learning Fortran anymore may not be enough to convince my peers. I think I will also need to show that we will not experience a substantial performance hit with C++. Thanks in advance for any help. Steven Allmaras Boeing Commercial Airplanes

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