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boost serialization memory leaks
by ohad barta 27 Nov '11

27 Nov '11

Hi Im using boost (version 1.47), to serialize a wide variaty of objects (include the stl containers vector and map). All the things are working fine exept from a memory leaks that I (=the memory tool that I work with) detected in the boost code. What am I doing wrong? Thanks In Advance Ohad Barta

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BEGINNER - separate array for each client
by wempwer＠gmail.com 27 Nov '11

27 Nov '11

I'm learning boost. I'd like to write a simple application that allows user to store data on server. User can insert new data using PUT command followed by ID number and data value, and retrieve data using GET command followed by ID. User requests are processed in analyze_user_request function and are subsequently written to or read from array. The thing is that I want every client to refer to his own array. That means that if one client saves something under particular ID this data is visible only to him. I wonder, how can I associate array with different clients, and create a new array when a new client connects? I tried encapsulating private data in class, but it doesn't seem to work, because now a new array is created every time user enters any request. This is my code: //CLIENT #include <cstdlib> #include <cstring> #include <iostream> #include <boost/asio.hpp> using boost::asio::ip::tcp; enum { max_length = 1000000 }; int main(int argc, char* argv[]) { while(1) { try { if (argc != 3) { std::cerr << "Usage: blocking_tcp_echo_client <host> <port>\n"; return 1; } boost::asio::io_service io_service; tcp::resolver resolver(io_service); tcp::resolver::query query(tcp::v4(), argv[1], argv[2]); tcp::resolver::iterator iterator = resolver.resolve(query); tcp::socket s(io_service); s.connect(*iterator); using namespace std; // For strlen. std::cout << "Enter message: "; char request[max_length]; std::cin.getline(request, max_length); if (request == "\n") continue; size_t request_length = strlen(request); boost::asio::write(s, boost::asio::buffer(request, request_length)); char reply[max_length]; boost::system::error_code error; size_t reply_length = s.read_some(boost::asio::buffer(reply), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. std::cout << "Reply is: "; std::cout.write(reply, reply_length); std::cout << "\n"; } catch (std::exception& e) { std::cerr << "Exception: " << e.what() << "\n"; exit(1); } } return 0; } //SERVER #include <cstdlib> #include <iostream> #include <boost/bind.hpp> #include <boost/smart_ptr.hpp> #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/regex.hpp> #include <boost/lexical_cast.hpp> #include <string> using boost::asio::ip::tcp; const int max_length = 1000000; typedef boost::shared_ptr<tcp::socket> socket_ptr; unsigned short analyze_user_request(std::string& user_request, short unsigned* ID, std::string* request_value) { // function returns: // 0: if user request is incorrect // 1: if user requests "PUT" operation // 2: if user requests "GET" operation // Furthermore, if request is correct, its value (i.e. ID number and/or string) is saved to short unsigned and string values passed by pointers. boost::regex exp("^[[:space:]]*(PUT|GET)[[:space:]]+([[:digit:]]{1,2})(?:[[:space:]]+(.*))?$"); boost::smatch what; if (regex_match(user_request, what, exp, boost::match_extra)) { short unsigned id_number = boost::lexical_cast<short unsigned>(what[2]); if (what[1] == "PUT") { boost::regex exp1("^[a-zA-Z0-9]+$"); std::string value = boost::lexical_cast<std::string>(what[3]); if (value.length() > 4095) return 0; if (!regex_match(value, exp1)) return 0; else { *request_value = value; *ID = id_number; return 1; } } if (what[1] == "GET") { *ID = id_number; return 2; } } if (!regex_match(user_request, what, exp, boost::match_extra)) return 0; } class Session { public: void handleRequest(socket_ptr sock) { try { for (;;) { char data[max_length]; boost::system::error_code error; size_t length = sock->read_some(boost::asio::buffer(data), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. // convert buffer data to string for further procession std::string line(boost::asio::buffers_begin(boost::asio::buffer(data)), boost::asio::buffers_begin(boost::asio::buffer(data)) + length); std::string reply; // will be "QK", "INVALID", or "OK <value>" unsigned short vID; unsigned short* ID = &vID; std::string vrequest_value; std::string* request_value = &vrequest_value; unsigned short output = analyze_user_request(line, ID, request_value); if (output == 1) { // PUT reply = "OK"; std::cout << "PUT operation - ID: " << *ID << " request value: " << *request_value << "\n"; user_array[*ID] = *request_value; } else if (output == 2) { // GET std::cout << "GET operation - ID: " << *ID << " request value: " << *request_value << "\n"; reply = user_array[*ID]; if (reply == "") reply = "EMPTY"; } else reply = "INVALID"; boost::system::error_code ignored_error; size_t ans_len=reply.length(); boost::asio::write(*sock, boost::asio::buffer(reply)); } } catch (std::exception& e) { std::cerr << "Exception in thread: " << e.what() << "\n"; } } private: std::string user_array[100]; }; typedef boost::shared_ptr<Session> SessionPtr; void server(boost::asio::io_service& io_service, short port) { std::cout << "In \"server\" function\n"; tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(), port)); for (;;) { socket_ptr sock(new tcp::socket(io_service)); a.accept(*sock); SessionPtr newSession(new Session()); boost::thread acceptThread(boost::bind(&Session::handleRequest, *newSession, sock)); } } int main(int argc, char* argv[]) { try { if (argc != 2) { std::cerr << "Usage: blocking_tcp_echo_server <port>\n"; return 1; } boost::asio::io_service io_service; using namespace std; // For atoi. server(io_service, atoi(argv[1])); } catch (std::exception& e) { std::cerr << "Exception: " << e.what() << "\n"; } return 0; }

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Sexpr Parser example of utree compiles error--function and symbol cannot be resolved
by 风在漂 27 Nov '11

27 Nov '11

Hi, I am new to the boost, I download the boost 1.49.0 and try to build the utree example – Sexpr Parser(environment: eclipse +CDT + gcc4.5.2), but It failed and I got the error info about the “sexpr_gemerator.hpp” as follows: Function ‘attr_cast’ could not be resolved Function ‘call’ could not be resolved Symbol ‘boo_policies’ could not be resolved Symbol ‘String_inserter’ could not be resolved Actually, I check the header, It already has ‘#include <boost/spirit/include/karma.hpp>’ which will finally include ‘#include <boost/spirit/home/karma/numeric/bool.hpp>’, where karma::attr_cast is defined Does anyone know the reason? how can I make the example run successfully? thanks By the way, I can build other exmple like “mini-xml parser” in the doc library. Best, Feng

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Re: [Boost-users] Problems of cross compiling: ar and ranlib tools naming ((Mark Brand)
by Iron Bug 26 Nov '11

26 Nov '11

> You might want to look at mingw-cross-env [1] which includes boost. It > doesn't have 64-bit support yet though. > > There's a link there to browse the development version. Look for file > src/boost.mk if you want to see the boost recipe. > > Mark Thanks a lot! That's really useful set of scripts. Exactly what I was doing manually for many years, building numerous libraries for different cross compilation variants. They use SED's in boost case. Seems, there's no other way to make it generate the right library format for cross compilation. I thought a good idea about names was chrooting to special /bin with links to proper toolset, but even in this case the format of libraries would need correction. So now I've got the idea and can adopt the scripts for my needs. I will recommend the tools for other programmers, that use cross compiling. Sincerely, Yana A. Kireyonok

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[unordered] Iterator default constructor usage
by andpar83＠gmail.com 26 Nov '11

26 Nov '11

Hi all. Is it a correct usage of default constructor of iterators? Are any gurantees that it will always equals to the iterator returned by end()? : typedef boost::unordered_map<std::string, int> map; map x; x["one"] = 1; assert(x.find("missing") == x.end()); assert(x.find("missing") == map::iterator()); assert(map::iterator() == x.end()); Andrey

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Help needed with boost::shared_mutex
by Kelvin Chung 26 Nov '11

26 Nov '11

I need assistance on how to properly use boost::shared_mutex. Suppose I have this routine, which I want to make thread-safe: class FunctionEvaluationCache { // Assume singleton std::unordered_map<Function, std::map<Input, int>> cache; // cache of results to Function::evaluate() } class Function { // Copyable bool operator==(const Function& fn2); // All Functions that operator==() share a cache entry int evaluate(const Input& in) { // Expensive operation, hence the cache if (cache.count(*this) == 0 || cache[*this].count(in) == 0) { // Not in cache, do expensive operation // Add result to cache cache[*this][in] = result; } return cache[*this][in]; } } Clearly, the big obstacle to a threadsafe version of Function::evaluate() is this cache. I believe that I will need a boost::shared_mutex for cache, as well as each cache entry. I'm not sure on how to use boost::shared_mutex, however: the straightforward way would be to expose the boost::shared_mutex instances publicly and modify evaluate() to get the proper locks, while the other line of thinking is that I should not expose the boost::shared_mutex instances at all and have a series of methods that evaluate() can use. But what I would like to do is not modify evaluate() in any way. Is it possible to do this?

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Problems of cross compiling: ar and ranlib tools naming
by Iron Bug 26 Nov '11

26 Nov '11

I'm trying to build full cross compiled toolchain and boost is almost ok, except of some details in static libs. The problem is that it uses patterns like $(command-string) -print-prog-name=ar (and ranlib as well) for getting the ar and ranlib for the toolset. But due to some bug in i686-w64-mingw32 and a whole bunch of similar instruments (on debian, ubuntu, etc) the XXX-gcc -print-prog-name=ar returns simply "ar", without tool prefix. Same about ranlib. And they seem not being apt to fix it: http://groups.google.com/group/linux.debian.bugs.dist/browse_thread/thread/… I saw an old bug ticket about this problem in old boost archives: https://svn.boost.org/trac/boost/ticket/3373 It's marked as fixed. I added some strings to my project-config.jam like: using gcc : : i686-w64-mingw32-gcc : <rc>i686-w64-mingw32-windres <archiver>i686-w64-mingw32-ar <ranlib>i686-w64-mingw32-ranlib But it evidently had no effect, by some reason: in output I still see strings like "/usr/bin/ar", "usr/bin/ranlib" and the librarian error ("could not read symbols: Archive has no index; run ranlib to add one") is still there when trying to use the libraries. I found the place in gcc.jam tool script where ar-tool name is defined: # - The archive builder. local archiver = [ common.get-invocation-command gcc : [ NORMALIZE_PATH [ MATCH "(.*)[$(nl)]+" : [ SHELL "$(command-string) -print-prog-name=ar" ] ] ] : [ feature.get-values <archiver> : $(options) ] : $(bin) : search-path ] ; toolset.flags gcc.archive .AR $(condition) : $(archiver[1]) ; if $(.debug-configuration) { ECHO notice: using gcc archiver :: $(condition) :: $(archiver[1]) ; } ranlib is similar, windres is kind of case of some variants. I'm not that smart in boost build scripts but it looks like it tries to get the name from -print-prog-name (that is buggy). Am I correct? Maybe I'm just setting parameters in some wrong way? I would like to get some hints how I could make it take my options from project-config.jam and take the -print-prog-name by default. To get the resulting tools strings like i686-w64-mingw32-ar, etc, be it a parameters setting or patch for tools jam file, whatever that solves the problem. Sincerely, Yana A. Kireyonok

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[thread] Stress testers sought for a new "Recursive MRSW" locking class TCLock
by U.Mutlu 25 Nov '11

25 Nov '11

Today I wrote a locking class for the "many readers/single writer, with recursion (MRSW-R)" - problem (ie. shared recursive locking). The current version is for Linux/Unix like systems only. Anybody seriously interessted in stress testing / performance testing it drop me a note. This locker has automatic "Upgrade" (and also "Downgrade") feature built-in, ie. nothing sepereate needed (see examples below). It's just a small mutex class and one locker class which can do both read and write locking (ie. just pass the kind via ctor-param...). (of course one can derive seperate classes for Read and Write) Of course it uses boost (especially atomic primitives like atomic_inc32(), atomic_dec32() etc.) Examples: TCLockVar LV; // this is our special mtx var void f() // called from many threads { TCLock L(LV); // a Read-Lock ... } void g() // called from many threads { TCLock L(LV, true); // a Write-Lock ... } void h() // called from many threads { TCLock L(LV); // a Read-Lock ... if (fNeedToUpdate) { TCLock L(LV, true); // a Write-Lock within a Read-Lock; that's OK! :-) ... } ... } Just drop me an email if interessted in stress testing TCLock. -- U.Mutlu www.mutluit.com

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Problems using mpl::if_ and function_types::result_type
by Allan Nielsen 25 Nov '11

25 Nov '11

Hi I'm new to the boost::mpl library, and have some "beginners-problems" template < typename F > struct A { typedef boost::function_types::parameter_types<F> P; typedef typename boost::function_types::result_type<F>::type R; typedef typename boost::mpl::if_< boost::is_same< R, void >, boost::function< void ( void ) > , boost::function< void ( R ) > >::type TTT; A() { } }; int main(int argc, const char *argv[]) { A<int(int, float)> ok; // working A<void(int, float)> compile_error; // non-working return 0; } xxx.cxx: In instantiation of ‘A<void(int, float)>’: xxx.cxx:108:25: instantiated from here xxx.cxx:100:77: error: invalid parameter type ‘boost::mpl::aux::wrapped_type<boost::mpl::aux::type_wrapper<void> >::type’ xxx.cxx:100:77: error: in declaration ‘A<F>::TTT’ What is the problem here, and how can I solve it. To my understanding only the selected part of mpl::if_ should be evaluated by the compiler.... Regards Allan W. Nielsen

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Why does CMake use relative linking when I replace a shared object?
by Mathias Gaunard 25 Nov '11

25 Nov '11

There is some strange CMake behaviour I don't quite understand. In the project attached, I build a shared library for which I want to specify a custom build command; to do this I generate a dummy library which I then replace by another file in a POST_BUILD command (alternatives involving imported libraries do not work properly across different scopes). If I do not replace the library, then the executable correctly links against libtest.so. If I do, it links instead with ../baz/libtest.so (sic), which of course, fails when trying to run the program. Why is it putting a relative path into my executable? Why is it different depending on whether I replace the .so by another one or not? Thank you very much for any insight on what's happening.

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