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Condition Variable Notify
by Matt Fair 25 Mar '12

25 Mar '12

Hello, I'm using a condition variable to notify when I get an ack message back. For the most part it is working like it is suppose to, but I have a situation where it doesn't work. Luckly the problem is repeatable and seems to be specific to my condition variable being notified, I've included a simplified version of the code, are there any outstanding issues? I have two threads, waitForAck() is called in one and receiveAck() is called in another. class Foo { public: void waitForAck(); void receiveAck(); private: boost::mutex m_ackMutex; boost::condition_variable m_ackCond; bool m_receivedAck; }; void Foo::waitForAck() { boost::mutex::scoped_lock lock(m_ackMutex); m_receivedAck=false; //wait 8 seconds for ack boost::system_time const waitingTime=boost::get_system_time()+boost::posix_time::seconds(8); do { if(m_receivedAck) { //got ack, break out of loop break; } //Waiting for ack... } while (m_ackCond.timed_wait(lock, waitingTime)); if(!m_receivedAck) { //wait for ack timed out } } void Foo::receiveAck() { boost::mutex::scoped_lock lock(m_ackMutex); m_receivedAck = true; lock.unlock(); m_ackCond.notify_one(); } So for most of the time, this works as expected. However, at a particular part of my code waitForAck is called, then receiveAck is called in the other thread, notify is sent out but for some reason even though i'm waiting in the timed_wait in thread 1 it waits for 8 seconds and then says there was a timeout. So my questions are: 1. Does anything look off, am I using the condition variable and mutex correctly? 2. In waitForAck, I have a scope_lock that is locked, when I enter into timed_wait, does this unlock the mutex and the re-locks it when m_ackCond.notify_one() is called? 3. Are there any special circumstances with condition variable (besides receive happens before wait) where this code shouldn't behave as it should? Thanks for your help, I've been banging my head against the wall here with this! Matt

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use of boost::noncopyable ?
by John M. Dlugosz 24 Mar '12

24 Mar '12

1>V:\Trunk\stable\src\Include\Tools/unique_RAII.h(61): error C2248: 'boost::noncopyable_::noncopyable::operator =' : cannot access private member declared in class 'boost::noncopyable_::noncopyable' .... This diagnostic occurred in the compiler generated function (the normal copy constructor) That kind of defeats the purpose, doesn't it? I have to declare a dummy copy constructor to get the class to compile.

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implementing custom iterators
by MM 24 Mar '12

24 Mar '12

Hello, Can you help choosing between boost/operators.hpp(iterator_helper) and boost::iterator_facade for the implementation of a number of custom c++11-compliant iterators? What questions are to be asked? How to choose between the 2 libraries? rds, MM

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[Statechart] Does Statechart require updating?
by Dick Bridges 24 Mar '12

24 Mar '12

I used Statechart quite a bit 3-5 years ago to great advantage. Having not used it since the adoption of C++11 and seeing only a few recent related mail items, I wonder if it can still be used "as-is" or is it going to require 'adjustments' (e.g., from boost::threads to C++11 threads, etc.)? Any opinions, observations, search terms or guidelines would be greatly appreciated. In the meantime, since the projects tend to be anything but simple so I'm going to start using it as if I needn't care. Maybe I'll be able to provide some answers to my own question. 8:P Regards, Dick Bridges The opinions and data in this missive are my own and do not necessarily represent the positions, strategies, or opinions of Western Digital Corporation. [Description: Description: glenda_planet] IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses. Glenda: http://glenda.cat-v.org/gallery/

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spherical bessel functions
by David Bergman 24 Mar '12

24 Mar '12

I am using boost spherical bessel functions and get an overflow error for the following call. double ytest; double x = 12.6; int n = 8; ytest = boost::math::sph_neumann(n, x); the value of x in not relevant as long as you're away from 0. it's the index that causes the problems, for n = 8, the call to cyl_neumann(n,x) causes the overflow. I tested this with other index values less than 8 and they all work fine. I have not tried greater than 8. MATLAB is well defined for these values and I can see no reason why this case would be special. Any ideas? Thanks, David

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Troubles with boost's shared_array, among other things
by Ted Byers 24 Mar '12

24 Mar '12

I highlighted in bold the remarks of most interest to boost users. The rest just shows you what I have done, and provides the context in which my problem arises. I commented out the problem code below, in an effort to determine why the core dump happened, only to see another problem, with the execution path not even entering my regressionPCA constructor. My program is short and simple, designed to test my PCA regression class. My basicGenerator, declared in data.generator.h, is already known to work flawlessly. This program is the unti test for my regressionPCA class. #include <iostream> #include <vector> #include "data.generator.h" #include "reg.class.h" int main(int argc, char* argv[]) { std::cout << "Flag A" << std::endl; basicGenerator bg; std::cout << "Sample size: " << bg.get_sampleSize() << std::endl; bg.makeData(); std::cout << "Flag B" << std::endl; std::vector<std::vector<double> > x; std::vector<double> y; bg.getDataForRegression(x,y); unsigned int imax = y.size(); for (unsigned int i = 0 ; i < imax ; i++) { std::cout << i << "\t" << y[i] << "\t" << x[i][0] << "\t" << x[i][1] << std::endl; } std::cout << "Flag C" << std::endl; regressionPCA rpca(x,y); return 0; } Here is the tail end of the output it produces: 89 0.416356 0.565407 -0.114605 90 -0.258883 -0.585597 -0.183372 91 0.833355 0.914344 0.81171 92 -0.0338814 -0.00264442 -0.118973 93 1.13764 0.41599 1.33175 94 -1.86323 -1.90867 -1.35118 95 0.907604 1.14917 0.621669 96 2.1166 1.06194 1.1703 97 0.159543 0.14446 -0.665135 98 -0.508617 -0.370597 -0.703225 99 2.69086 2.75267 1.40633 Flag C Ted@Ted-acer-i7w7 ~/New.System/tests $ As you can see, the last output is from the flag I set immediately before creating my instance of regressionPCA on the stack. Here is the declaration of that class. #ifndef REG_CLASS_H #define REG_CLASS_H #include <iosfwd> #include <vector> //#include <boost/smart_ptr/shared_array.hpp> #include <gsl/gsl_linalg.h> class regressionPCA { private: unsigned int nrows, ncols; // boost::shared_array<double> B, Y, U, V, S; regressionPCA(void) {}; // makes default construction impossible public: regressionPCA(const std::vector<std::vector<double> >&, const std::vector<double>&); void Reset(const std::vector<std::vector<double> >&, const std::vector<double>&); inline void setNrows(unsigned int v) { nrows = v;}; inline void setNcols(unsigned int v) { ncols = v;}; inline unsigned int getNrows(void) const { return nrows; }; inline unsigned int getNcols(void) const { return ncols; }; }; #endif Please note that instead of just dying without producing output, the program died most ungracefully with a core dump when I included boost's shared_array. I have no idea why. Here is the implementation of the regressionPCA class: #include "reg.class.h" #include <iostream> #include <algorithm> #include <gsl/gsl_linalg.h> regressionPCA::regressionPCA(const std::vector<std::vector<double> >&data, const std::vector<double>& Ydata) { std::cout << "Flag ALPHA" << std::endl; Reset(data,Ydata); } void regressionPCA::Reset(const std::vector<std::vector<double> >&data, const std::vector<double>& Ydata) { unsigned int r(0),c(0),n(0); std::cout << "r: " << r << "\tc: " << c << "\tn: " << n << std::endl; c = data.size(); std::cout << "r: " << r << "\tc: " << c << "\tn: " << n << std::endl; r = data[0].size(); std::cout << "r: " << r << "\tc: " << c << "\tn: " << n << std::endl; setNrows(r); setNcols(c); n = r * c; std::cout << "r: " << r << "\tc: " << c << "\tn: " << n << std::endl; double* B = new double[c]; double* Y = new double[r]; double* U = new double[n]; double* V = new double[c*c]; double* S = new double[c]; /* boost::shared_array<double> B(new double[c]), boost::shared_array<double> B(new double[c]), Y(new double[r]), U(new double[n]), V(new double[c*c]), S(new double[c]); B = Btmp; Y = Ytmp; U = Utmp; V = Vtmp; S = Stmp;*/ double *bptr = U.get(); std::cout << "Flag1" << std::endl; std::vector<std::vector<double> >::const_iterator it = data.begin(), end = data.end(); while (it != end) { bptr = std::copy(it->begin(), it->end(),bptr); ++it; } std::cout << "Flag2" << std::endl; bptr = Y.get(); std::copy(Ydata.begin(),Ydata.end(),bptr); gsl_matrix_view Um = gsl_matrix_view_array(U.get(), getNrows(), getNcols()); gsl_matrix_view Ym = gsl_vector_view_array(Y.get(), getNrows()); gsl_matrix_view Bm = gsl_vector_view_array(B.get(), getNcols()); gsl_matrix_view Sm = gsl_vector_view_array(S.get(), getNcols()); gsl_matrix_view Vm = gsl_matrix_view_array(U.get(), getNcols(), getNcols()); std::cout << "Flag3" << std::endl; gsl_linalg_SV_decomp_jacobi(Um,Vm,Sm); std::cout << "Flag4" << std::endl; gsl_linalg_SV_solve(Um,Vm,Sm,Ym,Bm); std::cout << std::endl << std::endl << "Sv = " << gsl_vector_get(Sm,0) << "\t" << gsl_vector_get(Sm,1) << std::endl; std::cout << std::endl << std::endl << "V = " << std::endl; std::cout << "\t" << gsl_matrix_get(Vm,0,0) << "\t" << gsl_matrix_get(Vm,0,1) << std::endl; std::cout << "\t" << gsl_matrix_get(Vm,1,0) << "\t" << gsl_matrix_get(Vm,1,1) << std::endl; std::cout << std::endl << std::endl << "Beta = " << gsl_vector_get(Bm,0) << "\t" << gsl_vector_get(Bm,1) << std::endl; }; Note, I know the execution path does not get into the constructor becuase the line "std::cout << "Flag ALPHA" << std::endl;" does not produce output. So, a couple mysteries. 1) Why does merely including boost's shared_array cause a core dump? 2) when I resort to naked array pointers (yes, I know about the memory leak, but that is the least of my troubles right now, and I would have avoided that had boost's shared array worked for me), why does execution not enter my constructor? Any insights would be appreciated. BTW: If you notice me doing something silly with GSL, I'd appreciate knowing about it, even though my problems do not appear to be related to GSL.

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[BGL] Implementing own graph types: Overloading in namespace boost or ADL?
by Philipp Moeller 23 Mar '12

23 Mar '12

The documentation does not explicitly mention which of both approaches is recommended to implement the free function of the graph concepts for a custom graph. Usually the graph will be in its own namespace. Should the free functions be declared in the boost namespace or in the same namespace as the graph? This also would determine if BGL functions should be called qualified or unqualified outside of namespace boost. -- Philipp Moeller GeometryFactory

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[Asio] Binding tcp socket to a particular network interface
by De Sousa, Dan 23 Mar '12

23 Mar '12

I'm trying to figure out the best cross platform solution to guarantee that a particular boost socket always binds to a particular network interface (eth0, eth4, etc). I know how to resolve the interface to an address and I see that I can specify an tcp endpoint to tcp socket on construction or with bind, but I also need to specify the port. Since I could be connecting to multiple servers in one instance, and have to deal with multiple instances of this library on the same machine, I can't rely a fixed port number. So my question(s): Is there a reliable cross platform way to get an endpoint to an address without a port? Or to do what boost tcp socket does by default, to get an unbound port for an address? Or generally guarantee that the socket is bound to a particular network interface? Short of finding a way to resolve ports, I don't see a way to do this repeatedly. For some context, we are trying to eliminate routing tables to specify the interface to particular servers. Thanks in advance for any suggestions! Dan ________________________________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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[Regex] Is it possible to match any "linebreak"
by Christoph Duelli 23 Mar '12

23 Mar '12

Is there a way to have a regex like [[:digit:]]{3}([^\n]+)\n? have \n match any line breaking character? (The processed files might have Unix or DOS line endings.) I know I could modify the regex [[:digit:]]{3}([^\n\r]+)[\n\r]* but I was hoping there might be an easier solution like a character class [[:linebreak:]], or maybe an escaped character like \R or something like that. (I am using Boost 1.43 in the relevant project.) Thank you and best regards Christoph

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BOOST_PP_ARRAY_PUSH_BACK
by petros 23 Mar '12

23 Mar '12

Hi, the following piece of code: #include <boost/preprocessor/array.hpp> #include <boost/preprocessor/array/push_back.hpp> #include <boost/preprocessor/iteration/local.hpp> #define barfoo (2, (1, 2) ) BOOST_PP_ARRAY_PUSH_BACK( barfoo, 3 ) gived the following compilation error ( MSVC2010, win7 ) : 1>Build started 3/22/2012 4:06:39 PM. 1>ClCompile: 1> opexp.cpp 1>opexp.cpp(6): error C2059: syntax error : 'constant' Any ideas why this happens ? Any help will be greatly appreciated. TIA, Petros

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