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Boost Asio Multicast
by Georg Gast 18 Dec '23

18 Dec '23

Hi there, I wrote an application that is to a good part based on https://www.boost.org/doc/libs/1_83_0/doc/html/boost_asio/example/cpp11/mul… https://www.boost.org/doc/libs/1_83_0/doc/html/boost_asio/example/cpp11/mul… It worked OK on my laptop as the packages arrived in my vm and my host. As we tried it on real machines the packages did not arrive. (all windows machines). With *netsh interface ip show joins* I could see on my laptop that the join was on the ethernet card. On the real machines it choose "the wrong" network card. I tried with "outbound_interface" to change it but didn't work... It's all ipv4. Can or should I use a static route to get the packages into the right net segment? Bye Georg

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[Boost.Asio] Asynchronous queue?
by accelerator0099 16 Dec '23

16 Dec '23

Consider the producer-consumer model: producer -+- consumer1 +- consumer2 +- consumer3 +- consumer4 +- consumer5 The producer periodly push items into a queue, and those consumers wait on that queue for items It's easy to implement in a synchronous, multi-threaded environment: the producer just locks the queue and push into it, and notify one consumer through a condition variable. Consumers waiting on that condition variable will be woken one by one, popping items and consume them How to do those in a asynchronous environment? Consumers async_pop() on that queue, posting their completion tokens into the executor. When there are items available, the executor notify one consumer by calling its completion token Is it right? How do the producer tell the executor "The asynchronous operation is done, You should call that completion token"? My implemention of a possible async queue (based on timers): #include <boost/asio.hpp> #include <deque> #include <iostream> using namespace std::literals; namespace io = boost::asio; using io::awaitable; auto& uawait = io::use_awaitable; template<class D> awaitable<void> delay(const D& dur) { io::steady_timer tm{ co_await io::this_coro::executor }; tm.expires_after(dur); co_await tm.async_wait(uawait); } template<class T> class aqueue { std::deque<T> mq; public: using reference = T&; using const_reference = const T&; size_t size() const noexcept { return mq.size(); } bool empty() const noexcept { return mq.empty(); } awaitable<T> async_pop() { while (empty()) { co_await delay(1ms); } auto t = std::move(mq.front()); mq.pop_front(); co_return t; } awaitable<void> async_push(T t) { mq.push_back(std::move(t)); co_return; } }; class consumer { public: const int id; aqueue<int>& queue; consumer(int _i, aqueue<int>& _q) : id{ _i }, queue{ _q } {} awaitable<void> operator()() { std::cout << "Consumer " << id << " started\n"; auto i = co_await queue.async_pop(); std::cout << "Consumer " << id << " got " << i << '\n'; } }; int main() { io::io_context ctx; aqueue<int> aq; auto producer = [&]() -> awaitable<void> { std::cout << "Producer started\n"; for (int i{}; i != 5; ++i) { co_await delay(1s); co_await aq.async_push(i); } }; io::co_spawn(ctx, producer, io::detached); for (int i{}; i != 5; ++i) io::co_spawn(ctx, consumer{ i, aq }, io::detached); std::cout << "RUN\n"; ctx.run(); return 0; } Is it a proper way to do so using timers? I think there should be a better way

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Fin boost with cmake in config mode
by Alain O' Miniussi 15 Dec '23

15 Dec '23

Hi, I'd like to find Boost 1.84 from cmake 3.28 in config mode (https://cmake.org/cmake/help/latest/command/find_package.html#id6) My Boost distribution is in a non standard location <mypath> meaning, IF i UNDERSTAND CORRECTLY, that cmake will try to set Boost_DIR to <mypath>/lib/cmake/Boost-1.84.0/BoostConfig.cmake. Which environnement should I set so that it works ? Thanks ---- Alain Miniussi DSI, Pôles Calcul et Genie Log. Observatoire de la Côte d'Azur Tél. : +33609650665

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Cobalt documentation error
by Josué Andrade Gomes 14 Dec '23

14 Dec '23

I’m seeing the following error while browsing the recently released Cobalt library documentation [1]: Failed to generate image: mmdc failed: Error: Failed to launch the browser process! /root/.cache/puppeteer/chrome/linux-1108766/chrome-linux/chrome: error while loading shared libraries: libatk-1.0.so.0: cannot open shared object file: No such file or directory TROUBLESHOOTING: https://pptr.dev/troubleshooting at Interface.onClose (file:///root/.nvm/versions/node/v18.18.1/lib/node_modules/@mermaid-js/mermaid-cli/node_modules/@puppeteer/browsers/lib/esm/launch.js:253:24) at Interface.emit (node:events:529:35) at Interface.close (node:internal/readline/interface:534:10) at Socket.onend (node:internal/readline/interface:260:10) at Socket.emit (node:events:529:35) at endReadableNT (node:internal/streams/readable:1368:12) at process.processTicksAndRejections (node:internal/process/task_queues:82:21) [1] https://www.boost.org/doc/libs/1_84_0/libs/cobalt/doc/html/index.html

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Re: [Boost-users] Could sprintf be replaced with snprintf?
by Matt Borland 14 Dec '23

14 Dec '23

> On Dec 13, 2023, at 9:32 PM, Karsten Ahnert <karsten.ahnert(a)gmx.de> wrote: > > Yes, please go on. It would be great if odeint will be maintained in the future. Thank you! > > What are your GitHub user names? I can add you as maintainer but I want to be sure to use right name and avoid a potential name collision. > > Karsten Karsten, My GitHub username is mborland (https://github.com/mborland) and Nick is NAThompson (https://github.com/NAThompson) Let me know if you need anything else. Thanks, Matt

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[release] Boost 1.84.0
by Marshall Clow 14 Dec '23

14 Dec '23

Release 1.84.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contain two new libraries, numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.84.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.84.0/source> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. -- The Boost Release Team Marshall Clow, Glen Fernandes

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Re: [Boost-users] Could sprintf be replaced with snprintf?
by McGrath, Justin M 13 Dec '23

13 Dec '23

Has there been any movement on having someone else maintain ODEINT? I don't know that I would be of much use, but I'm willing to help where I can. There is one other issue that isn't critical, but it would save our group from having to do some hand editing of ODEINT for use with our project. Some of the paths are long enough that after they're included in our project they have nonportable lengths, requiring use to rename them. I made an issue last year: https://github.com/boostorg/odeint/issues/54. Changing the names would surely break code, and I don't know if this is a feasible change. Given that it's pretty easy for people to update include directives though, maybe it's not too intrusive. If it's a welcome change, I can submit a PR on GitHub. Best wishes, Justin ________________________________________ From: McGrath, Justin M <jmcgrath(a)illinois.edu> Sent: Monday, December 4, 2023 11:53 AM To: Matt Borland; Karsten Ahnert Cc: mario.mulansky(a)gmx.net; Nick Thompson Subject: Re: [Boost-users] Could sprintf be replaced with snprintf? Thank you everyone. It would be great if someone could continue managing the package. It's a great resource. Best wishes, Justin ________________________________________ From: Matt Borland <matt(a)mattborland.com> Sent: Friday, December 1, 2023 2:04 AM To: Karsten Ahnert Cc: McGrath, Justin M; mario.mulansky(a)gmx.net; Nick Thompson Subject: Re: [Boost-users] Could sprintf be replaced with snprintf? > On Nov 30, 2023, at 9:27 PM, Karsten Ahnert <karsten.ahnert(a)gmx.de> wrote: > > Merged the pull request. We are not actively maintaining the library anymore. > > But I will keep an eye on any upcoming changes. > Karsten, Thanks. Would you be interested in new maintainers stepping in for the library? Nick Thompson (cced) and I are maintainers on several other Boost libraries (math, multiprecision, random, and test), and we would be interested in helping out. He’s a mathematician, and I am a full-time Boost developer. If you would like to schedule a call or anything to discuss we can do that. Matt

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coroutine condition_variable
by Keith Bennett 07 Dec '23

07 Dec '23

I'm using asio's awaitable. Couroutines are pretty neat. One of the things that keeps cropping up in the ability to notify another function that something has finished. In the past, I would use condition_variable and wait on that. Is there a better way to do that with coroutines? eg, I want to do something like: asio::awaitable<void> function(std::mutex& mtx, condition_variable& cv) { std::unique_lock lock{mtx}; // suspend this function until notified or 30 seconds expired auto expired = co_await cv.wait_until(lock, std::chrono::seconds(30)); if (expired) { // or something log("expired"); co_return; } do_some_work(); } then somewhere else I might do: asio::awaitable<void> somewhere_else(condition_variable& cv) { do_other_work(); cv.notify_one(); } I understand that it's a bad idea to hold a lock during co_await. What other problems prevent something like this from being created? Does something like this already exist? It's not clear from asio reference. I'm using boost 1.81.0 but I can upgrade if that is a problem -- Keith Bennett

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[python] to_python_converter , is by value needed?
by MM 04 Dec '23

04 Dec '23

Hello, I have posted a question here some time ago, I thought to try here as well https://stackoverflow.com/questions/77552946/to-python-converter-is-by-valu… The community of experts in boost.python seems to have moved off to other concerns? Rds,

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Could sprintf be replaced with snprintf?
by McGrath, Justin M 30 Nov '23

30 Nov '23

I am using some Boost libraries in a code base that does not want any use of sprintf. An automatic test flags any calls to it or vsprintf. Is it possible to replace all uses of sprintf with snprintf? I really doubt there are actually any security issues here, but I'm hoping this wouldn't be too difficult or cause any problems other than the effort to do it. Cheers, Justin

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