September 2009 - Boost-users

[graph] Optimizing graph definition
by Maxime van Noppen 26 Sep '09

26 Sep '09

Hi, I'm using a quite large boost::graph (~ 100 000 vertices with 8 to 10 edges each) and am trying to get the best of the structure to be able to increase vertices & edges. The graph is mainly read-only. I add 99.99% of the vertices & edges in a big loop at the beginning. I never delete vertices or edges. After that I mainly use dijkstra and A* algorithms with some full traversals. I use very often the edge(v1, v2, g) function to get the edge (if it exists) between two vertices. My priority is to optimize the use of the graph rather than the creation but I'd like to keep the creation time reasonable. For now I use : typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, my_vertex, my_edge > graph_t; I didn't find enough informations about complexity of functions and algorithms regarding to the graph definition to find out be myself what would be the best parameters for my use case. Is something improvable here ? Thanks ! -- Maxime

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Re: [Boost-users] Sockets and structures?
by OvermindDL1 26 Sep '09

26 Sep '09

On Fri, Sep 25, 2009 at 6:49 PM, Daniel F. Savarese <dfs(a)savarese.org> wrote: > > In message <3f49a9f40909251225p28d497b6i6d73c2dd53e3ba3e(a)mail.gmail.com>, Overm > indDL1 writes: >>Boost.Serialization is good if you are going to serialize up vast >>hierarchies with lots of pointers that can be self referencing and >>such, but it tends to be very costly in execution speed. Something >>like Boost.Spirit2.1 can serialize things up to a binary format as >>well, and *very* fast. Although something like Google's open source >>message system could serialize up messages even better (we need a >>Boost implementation of that system... hmm...). > > To the OP, I would advise you not take statements such as the above as > gospel without performing measurements yourself. My experience[1] is > directly contrary to the above. I find boost::serialization execution > time to be negligible (for binary archives) and entirely suitable for high > performance networking applications even if that was not the creator's > original objective (a credit to Robert Ramey's skill). > > No tool is suitable for all purposes. So figure out your requirements > and do some testing to see what works best before choosing a solution. > Just because boost::serialization works great for me in a particular > application doesn't mean it's going to work great for someone else with > a different set of requirements. Also, talking about performance > cost/overhead is pointless without precise quantification. Run your > own tests in the context of your anticipated usage and see how it > works out. > > daniel > > [1] www.igfip.com: All interprocess communication and object serialization > uses boost::serialization. Play a game of Reversi or Chess (against the > computer or another player) or chat with another player and see if > boost::serialization in any way impacts the real-time/instantaneous > response to your actions. Behind the scenes, boost::serialization's > impact on CPU time isn't even measurable. It is quite slow when you need speed though. You will not notice it in those times, but compared to other methods it tends to be many many orders of magnitude slower. It is the registery that slows it down though (I have profiled it, AMD Code Analyst). It is, however, *wonderful* for like save/load functionality, I still use it for that, but for heavy network utilization on never idle programs (say a real-time 3d action game), I never would. Use the proper tools for the proper purposes. :)

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Re: [Boost-users] [boost user list] Portal Web Design Support of Boost C++
by OvermindDL1 25 Sep '09

25 Sep '09

Do not send this message to me, send it to boost. :) On Fri, Sep 25, 2009 at 1:51 PM, Ray Burkholder <ray(a)oneunified.net> wrote: >> > >> > Does boost C++ support the design of portal web pages or processing >> of >> > database data from web pages depending on user selection of controls >> on the >> > web page? >> >> That has 'nothing' to do with your chosen language, rather with the >> web library you use, the most popular of which is (Fast)CGI, which >> does support it all (what do you think PHP/Python/Java/etc... are all >> built to use, CGI, it can do it all). >> >> Thus, this is not a boost question. > > You may instead be looking for something like http://www.webtoolkit.eu/wt > which makes use of some boost functionality. I however have been looking for something like that, thanks for the link!

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Sockets and structures?
by pedro chaparro 25 Sep '09

25 Sep '09

hi, i'm wondreing if using asio library can i send a structure and not just string messages using the boost::asiio:write command? or how could i do to send a structure which have many information fields? thanks -- Ing Pedro Alonso Chaparro Valero Ciudad Politecnica de la Innovación iTEAM - Mobile Communications Group Polytechnic University of Valencia C\ Camino de Vera S/N, Edificio 8G 46022 Valencia, Spain

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[boost user list] Portal Web Design Support of Boost C++
by Boost lzw 25 Sep '09

25 Sep '09

Hi there, Does boost C++ support the design of portal web pages or processing of database data from web pages depending on user selection of controls on the web page? Thanks in advance, Robert

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Boost serialization libray 1.32 & 1.39 compatibility issue ( from "To DO" list)
by sam p 25 Sep '09

25 Sep '09

Hi, I am facing backward compatibility problem with boost serialization library 1.39. My setup is something like this, (1) I have one version of my program that is built using boost 1.32 serialization library, lets call it 1_32.exe (2) I have another version of my program that is built using boost 1.39 serialization library, lets call it 1_39.exe (3) These two versions of my program communicate with each other over network and they use boost text serialization to exchange data. (4) Program 1_39.exe is able to deserialize data sent by 1_32.exe but 1_32.exe is not able to deserialize data sent by 1_39.exe While debugging this problem I realized that program 1_39.exe is putting archive version as “5” and 1_32.exe is putting archive version as “3”. This results into 1_32.exe throwing “Unknown version” exception. While going through boost documentation I read about “Back Versioning” description provided at http://www.boost.org/doc/libs/1_39_0/libs/serialization/doc/todo.html#backv… Looks like its not very difficult to address this issue if we modify some code in boost serialization library. Are you planning to address this in near future or can you please advice me on the files those need to be changed? Or is there any simple workaround as a stop gap measure to fix this issue? Thanks, Sameer

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Passing reference params to boost::thread, parameter copies.
by Jason Cipriani 25 Sep '09

25 Sep '09

At the end of this message is a test program that uses boost::thread to create two threads. The first is one that takes a parameter by value, the second takes a parameter by reference. I have a couple of questions about some behavior here: 1) When passing by value, why are so many copies of the data made? The program output indicates that there are 9 (!) objects created (at most 5 exist simultaneously), when ideally there would be only 2 (the original and the copy passed to the thread). 2) When passing by reference, why is the data being copied? The copying behavior when passed by reference is identical to when the param is passed by value (9 objects created, 5 simultaneously). Also, and this isn't shown in the program below, but I would therefore expect the program to crash if the boost::thread outlived the referenced object (of course, it does not, since the object is copied). So, I'm surprised by the number of copies, this seems unreasonable, and also I'm confused about why by value and by reference behave identically. Thanks, Jason === BEGIN EXAMPLE === #include <boost/thread/thread.hpp> #include <cstdio> using namespace std; class test { public: test () { printf("%p\n", (void *)this); } test (const test &t) { printf("%p from %p\n", (void *)this, (void *)&t); } ~test () { printf("~%p\n", (void *)this); } }; void expected_copy (test) { printf("in expected_copy\n"); } void expected_nocopy (const test &) { printf("in expected_nocopy\n"); } int main () { printf("expected_copy:\n"); { test t; boost::thread thr(expected_copy, t); thr.join(); } printf("expected_nocopy:\n"); { test t; boost::thread thr(expected_nocopy, t); thr.join(); } printf("complete\n"); getchar(); } === END EXAMPLE ===

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Boost unit_test.cpp problem when try to compile simple program
by Robert Matusewicz 25 Sep '09

25 Sep '09

I tried to use Boost test module in my project but I have a little problem. When I try to compile simple program: #define BOOST_TEST_MAIN #include <boost/test/included/unit_test.hpp> it fails to compile on Visual Studio 2008 with three errors: c:\program files (x86)\boost\boost_1_39\boost\test\impl\exception_safety.ipp(513) : error C2491: 'boost::itest::exception_safety' : definition of dllimport function not allowed c:\program files (x86)\boost\boost_1_39\boost\test\impl\logged_expectations.ipp(228) : error C2491: 'boost::itest::logged_expectations' : definition of dllimport function not allowed c:\program files (x86)\boost\boost_1_39\boost\test\impl\unit_test_main.ipp(174) : error C2491: 'boost::unit_test::unit_test_main' : definition of dllimport function not allowed On Linux machines everything works OK. So, anybody could help me with that? Need more data? Robert

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import boost cstdint into default namespace
by V S P 25 Sep '09

25 Sep '09

Can I somehow import the boost/cstdint definitions into the default namespace without importing any other things from the boost namespace (I am trying to compile a source code that relies on having stdint.h but VC 2008 does not have it so I want to use boost/cstdint but without much modifications to the source at question) thank you -- Vlad P author of C++ ORM http://github.com/vladp/CppOrm/tree/master -- http://www.fastmail.fm - Access your email from home and the web

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BOOST_SYSTEM_NO_DEPRECATED and boost/filesystem/convenience.hpp
by Paul 25 Sep '09

25 Sep '09

Hi, If i compile with -DBOOST_SYSTEM_NO_DEPRECATED and #include <boost/filesystem/convenience.hpp> The compile will fail with the message: boost/filesystem/convenience.hpp: In function ‘typename boost::enable_if<boost::filesystem::is_basic_path<Path>, bool>::type boost::filesystem::create_directories(const Path&)’: boost/filesystem/convenience.hpp:48: error: ‘posix’ is not a member of ‘boost::system’ BOOST_FS_FUNC(bool) create_directories(const Path& ph) { if (ph.empty() || exists(ph)) { if ( !ph.empty() && !is_directory(ph) ) boost::throw_exception( basic_filesystem_error<Path>( "boost::filesystem::create_directories", ph, make_error_code( boost::system::posix::file_exists ) ) ); return false; } The line with boost::system::posix::file_exists is the key problem. In boost/system/error_code.hpp, posix is defined as a namespace # ifndef BOOST_SYSTEM_NO_DEPRECATED namespace posix = errc; namespace posix_error = errc; # endif but ONLY if I don't define NO_DEPRECATED... Maybe time for regression tests with BOOST_SYSTEM_NO_DEPRECATED defined? thanks, Paul

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