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Boost.ASIO C++ 20 coroutine equivalent of PPL task_completion_event or JavaScript Promise.resolve?
by Willem Mitchell 09 Apr '24

09 Apr '24

I'm trying to write a simple ASIO send/receiver that uses message queueing. The goal is to have a number of virtual streams over a single TCP connection. This is pretty simple using callbacks, but I can't figure out the coroutines alternative. Here is my simplified sample code. Note that I'm using asio::experimental::promise the same way I would use std::promise which obviously doesn't work, but it illustrates what I'm trying to do. What is the simplest solution to my problem? #pragma once #include "asio.hpp" #include "asio/co_spawn.hpp" #include "asio/detached.hpp" #include "asio/experimental/co_composed.hpp" #include "asio/experimental/promise.hpp" #include "asio/use_awaitable.hpp" #include <coroutine> #include <cstdint> #include <map> #include <memory> #include <queue> struct Message { uint64_t id; uint64_t streamId; uint64_t priority; }; class NetworkConnection { public: NetworkConnection(asio::io_context &ioContext) : ioContext_(ioContext), sendTimer_(ioContext_), receiveTimer_(ioContext_){}; asio::awaitable<std::unique_ptr<Message>> receive(uint64_t streamId) { auto promise = std::make_shared< asio::experimental::promise<std::unique_ptr<Message>>>(); auto future = promise->get_future(); receives_[streamId] = promise; if (!receiving_) { receiving_ = true; co_spawn(ioContext_, startReceiving(), asio::detached); } co_return co_await future; } asio::awaitable<void> send(std::unique_ptr<Message> message) { auto promise = std::make_shared<asio::experimental::promise<void>>(); auto future = promise->get_future(); sends_[message->id] = promise; if (!sending_) { sending_ = true; co_spawn(ioContext_, startSending(), asio::detached); } co_await future; co_return; } private: asio::io_context &ioContext_; asio::steady_timer receiveTimer_; asio::steady_timer sendTimer_; std::map<uint64_t, std::shared_ptr< asio::experimental::promise<std::unique_ptr<Message>>>> receives_; std::map<uint64_t, std::shared_ptr<asio::experimental::promise<void>>> sends_; std::queue<std::unique_ptr<Message>> sendQueue_; bool receiving_ = false; bool sending_ = false; void completeSend(uint64_t messageId) { auto it = sends_.find(messageId); if (it != sends_.end()) { it->second->set_value(); // This resumes the send operation sends_.erase(it); // Clean up } } void completeReceive(std::unique_ptr<Message> message) { auto it = receives_.find(message->streamId); if (it != receives_.end()) { it->second->set_value( std::move(message)); // This resumes the send operation sends_.erase(it); // Clean up } } asio::awaitable<void> startReceiving() { while (!receives_.empty()) { // Simulate receiving a message sendTimer_.expires_after(std::chrono::seconds(1)); co_await sendTimer_.async_wait(asio::use_awaitable); auto message = std::make_unique<Message>(); message->id = 1; message->streamId = 1; message->priority = 1; completeReceive(std::move(message)); } receiving_ = false; co_return; } asio::awaitable<void> startSending() { while (!sends_.empty()) { sendTimer_.expires_after(std::chrono::seconds(1)); auto message = std::move(sendQueue_.front()); sendQueue_.pop(); co_await sendTimer_.async_wait(asio::use_awaitable); completeSend(message->id); } sending_ = false; co_return; } }; class Stream { public: Stream(std::shared_ptr<NetworkConnection> connection) : connection_(std::move(connection)) {} asio::awaitable<std::unique_ptr<Message>> receive() { co_return co_await connection_->receive(id_); } asio::awaitable<void> send(std::unique_ptr<Message> message) { message->streamId = id_; co_return co_await connection_->send(std::move(message)); } private: uint64_t id_; std::shared_ptr<NetworkConnection> connection_; };

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Re: [Boost-users] [beast] I can't write a hello world server
by Mohammad Nejati [ashtum] 08 Apr '24

08 Apr '24

> Then I wait almost 4 seconds for a successful compilation. `-O2` and `-Og -g` are worse at 6 seconds. You are right, Asio and Asio based libraries are usually heavily templated as they need to work with generic executors, buffers and stream types. There are new facilities in Asio for alleviating this issue like any_executor and any_completion_handler which you can utilize to implement async operations in a source file. > I figured I'd write a wrapper, that would confine boost/asio/beast includes to a single compilation unit. The API I'm aiming for looks like this I think you might just use `beast::http::request<string_body>` and `beast::http::response<string_body>` types, you don't need to include all header files, you can just include `boost/beast/http/message.hpp`. > And yet I can sense a potential problem right off the bat: in the `http_server()` function, we call `std::move(socket)`. This move seems to be mandatory here, because removing triggers a compilation error. My point is, it looks like upon incoming connection we move the socket out of its outer context, such that it is no longer bound to the IO context. Is this another error in the example? You don't need to pass a socket to acceptor, it has multiple overloads: https://www.boost.org/doc/libs/1_84_0/doc/html/boost_asio/reference/basic_s… One of them creates a socket and passes it to the completion token, so, you can use it like: acceptor.async_accept([](auto ec, auto socket){ // ... }); Regards, Mohammad On Thu, Apr 4, 2024 at 4:50 PM Loup VAILLANT via Boost-users <boost-users(a)lists.boost.org> wrote: > > Hello, > > So this is rather embarrassing. After working more than 2 days full time I can't even get the most basic code running. I've scoured the docs and tried to find some tutorial, no luck. My onboarding experience so far has been… less than perfect. > > The reason I'm taking the time to ask here is because I feel there is something fundamental, likely obvious to the experts, that I don't understand about how beast (and, I'm guessing, asio) works, and how I'm supposed to use it. Which is probably why seemingly innocuous changes to official example code are causing memory corruptions left and right. > > Let's start at the beginning. > > My first attempt with beast was getting this code to work: > https://www.boost.org/doc/libs/1_73_0/libs/beast/example/http/server/small/… > > Compiling it with `g++ -std=c++20`, gets me a compilation error, thankfully easily fixed. > Then I wait almost 4 seconds for a successful compilation. `-O2` and `-Og -g` are worse at 6 seconds. > > I know many developers would say a few seconds are no big deal (though wen we get to XKCD sword fights it kind of is), but my problem here is that I didn't want to wait every time I made a business logic change to my code. But since 95% of compilation time came from including a huge header-only library, I figured I'd write a wrapper, that would confine boost/asio/beast includes to a single compilation unit. The API I'm aiming for looks like this: > > struct Http_message { > std::unordered_map<std::string, std::string> headers; > std::string body; > }; > struct Http_request : public Http_message { > std::string method; > std::string target; > }; > struct Http_response : public Http_message { > int status; > }; > typedef std::function<Http_response(const Http_request &request)> response_cb; > void http_start(unsigned short port, response_cb on_respond); > > (Note 1: I want web sockets as well, but one problem at a time) > (Note 2: I tried wrapping around http::request and http::response more directly to avoid unnecessary copies, but I ran into lifetime issues.) > > To its credit, this small server example seemed to run well enough, and could serve as a starting point. Before I untangle the business code from the HTTP specific stuff though, I needed to simplify this example a bit. So *this* is my actual starting point: > > > #include <boost/beast/core.hpp> > #include <boost/beast/http.hpp> > > namespace beast = boost::beast; > namespace http = beast::http; > namespace net = boost::asio; > using tcp = boost::asio::ip::tcp; > > class http_connection : public std::enable_shared_from_this<http_connection> > { > public: > http_connection(tcp::socket socket) : socket_(std::move(socket)){} > > void start() > { > auto self = shared_from_this(); > http::async_read( > socket_, buffer_, request_, > [self](beast::error_code ec, std::size_t) { > if(!ec) { self->process_request(); } > }); > deadline_.async_wait( > [self](beast::error_code ec) { > if(!ec) { self->socket_.close(ec); } > }); > } > > private: > tcp::socket socket_; > beast::flat_buffer buffer_{8192}; > http::request <http::dynamic_body> request_; > http::response<http::dynamic_body> response_; > net::steady_timer deadline_ { > socket_.get_executor(), std::chrono::seconds(60) }; > > void process_request() { > response_.version(request_.version()); > response_.keep_alive(false); > response_.result(http::status::ok); > response_.set(http::field::server, "Beast"); > response_.set(http::field::content_type, "text/plain"); > beast::ostream(response_.body()) > << "Target = " << request_.target() << "\n" > << "Method = " << std::string(request_.method_string()) << "\n"; > response_.set(http::field::content_length, > std::to_string(response_.body().size())); > > auto self = shared_from_this(); > http::async_write( > socket_, response_, > [self](beast::error_code ec, std::size_t) { > self->socket_.shutdown(tcp::socket::shutdown_send, ec); > self->deadline_.cancel(); > }); > } > }; > > void http_server(tcp::acceptor& acceptor, tcp::socket& socket) > { > auto cb = [&](beast::error_code ec) { > if(!ec) {std::make_shared<http_connection>(std::move(socket))->start();} > http_server(acceptor, socket); > }; > acceptor.async_accept(socket, cb); > } > > int main(void) > { > auto const address = net::ip::make_address("0.0.0.0"); > unsigned short port = 8080; > net::io_context ioc {1}; > tcp::acceptor acceptor{ioc, {address, port}}; > tcp::socket socket {ioc}; > http_server(acceptor, socket); > ioc.run(); > return 0; > } > > > So far it works. It listens to port 8080, and a curl request or 3 to the server works as expected: > > > $ curl -XYOLO -v http://localhost:8080/foobar > * Trying 127.0.0.1:8080... > * Connected to localhost (127.0.0.1) port 8080 (#0) > > YOLO /foobar HTTP/1.1 > > Host: localhost:8080 > > User-Agent: curl/7.81.0 > > Accept: */* > > > * Mark bundle as not supporting multiuse > < HTTP/1.1 200 OK > < Connection: close > < Server: Beast > < Content-Type: text/plain > < Content-Length: 31 > < > Target = /foobar > Method = YOLO > * Closing connection 0 > > And yet I can sense a potential problem right off the bat: in the `http_server()` function, we call `std::move(socket)`. This move seems to be mandatory here, because removing triggers a compilation error. My point is, it looks like upon incoming connection we move the socket out of its outer context, such that it is no longer bound to the IO context. Is this another error in the example? > > Okay then, how about I pass the socket all the way by reference instead? Let the constructor get a `tcp::socket&`, store this in a `tcp::socket&` member variable, remove all the `std::move`. It compiles, it runs the first query, but at the second query my program just freezes. Or loops, I don't know. > > So that's the first thing. I am _really confused_ about how this socket is supposed to work. Why does it block when I remove the standard moves? Isn't it supposed to be the same socket bound to the same IO context all the way? And I don't think it falls out of scope before the program ends either, it lives on the stack of the `main()` function, and the `ioc.run()`we call at the end blocks until we're done with the async reads (which is, never). > > **Can someone explain to me what the hell is going on with this socket?** > > Right now though I can accept that some dark secret lies behind this `std::move()`, and leave it alone for now. > > Moving on, I'll just admit for the time being that something magical and forbidden lies between this mysterious `std::move()` and prudently leave it behind. Now it's working again, and I can move (no pun intended) to the next step: extracting the business logic to an external function. I start with a trivial extraction: > > void respond(http::response<http::dynamic_body> &response, > const http::request <http::dynamic_body> &request) > { > response.result(http::status::ok); > response.set(http::field::content_type, "text/plain"); > beast::ostream(response.body()) > << "Target = " << request.target() << "\n" > << "Method = " << std::string(request.method_string()) << "\n"; > } > > And modify `process_request()` accordingly: > > void process_request() { > response_.version(request_.version()); > response_.keep_alive(false); > response_.set(http::field::server, "Beast"); > respond(response_, request_); > response_.set(http::field::content_length, > std::to_string(response_.body().size())); > > auto self = shared_from_this(); > http::async_write( > socket_, response_, > [self](beast::error_code ec, std::size_t) { > self->socket_.shutdown(tcp::socket::shutdown_send, ec); > self->deadline_.cancel(); > }); > } > > That works, but this is not quite enough: my goal here is to isolate my user code from the overly long compilation times imposed by this huge boost::beast. Maybe I can include the request & response headers without pulling in the kitchen sink with it, but I don't quite trust it. So let's wrap the `http::response` in some class so I can keep my headers nice and small: > > > class http_response { > public: > http_response(http::response<http::dynamic_body> &response) > : response_(response) {} > > void set_status(int status) { > response_.result(status); > } > void set_header(const std::string &title, > const std::string &value) { > response_.set(title, value); > } > void set_body(const std::string &body) { > beast::ostream(response_.body()) << body; > } > > private: > http::response<http::dynamic_body> &response_; > }; > > > Nothing fancy. And with a forward declaration I should be able to avoid including the response in the header that defines that class. Now I need to modify my business code accordingly: > > > void respond(http_response &response, > const http::request<http::dynamic_body> &request) > { > response.set_status(200); > response.set_header("Content-Type", "text/plain"); > response.set_body( > "Target = " + std::string(request.target()) + "\n" + > "Method = " + std::string(request.method_string()) + "\n"); > } > > > Still not free from `http::request <http::dynamic_body>` yet, but one step at a time. And finally, I need to adjust `process_request()`: > > void process_request() { > response_.version(request_.version()); > response_.keep_alive(false); > response_.set(http::field::server, "Beast"); > http_response response(response_); > respond(response, request_); > response_.set(http::field::content_length, > std::to_string(response_.body().size())); > > auto self = shared_from_this(); > http::async_write( > socket_, response_, > [self](beast::error_code ec, std::size_t) { > self->socket_.shutdown(tcp::socket::shutdown_send, ec); > self->deadline_.cancel(); > }); > } > > > Huh, what do you know, this time around it worked. I no longer experience the lifetime issues I've once had. Okay, I guess I'll add the request wrapper, then: > > > class http_request { > public: > http_request(const http::request<http::dynamic_body> &request) > : request_(request) {} > > std::string target() const { return std::string(request_.target()); } > std::string method() const { return std::string(request_.method_string()); } > > private: > const http::request<http::dynamic_body> &request_; > }; > > void respond(http_response &response, const http_request &request) > { > response.set_status(200); > response.set_header("Content-Type", "text/plain"); > response.set_body( > "Target = " + request.target() + "\n" + > "Method = " + request.method() + "\n"); > } > > void process_request() { > response_.version(request_.version()); > response_.keep_alive(false); > response_.set(http::field::server, "Beast"); > http_response response(response_); > http_request request (request_); > respond(response, request); > response_.set(http::field::content_length, > std::to_string(response_.body().size())); > > auto self = shared_from_this(); > http::async_write( > socket_, response_, > [self](beast::error_code ec, std::size_t) { > self->socket_.shutdown(tcp::socket::shutdown_send, ec); > self->deadline_.cancel(); > }); > } > > > And it still works! Maybe it'll work out in the end? > Regardless, thanks for the rubber ducking I guess. > > My first question remains though: what the hell is going on with the socket? Why can't I just pass a reference along? Why do we even need a move constructor? Is there some special semantics, or `boost::asio` specific arcane, I should be privy to? > > Loup. > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > https://lists.boost.org/mailman/listinfo.cgi/boost-users

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[release] Boost 1.85.0 beta 1 is available
by Marshall Clow 14 Mar '24

14 Mar '24

Boost release 1.85.0 beta 1 is now available at: https://boostorg.jfrog.io/artifactory/main/beta/1.85.0.beta1/source/ The SHA256 checksums are: c13b76f420684a8d5b2eb0f297c281348ba0311d50354d952c5ce7c689e7879b boost_1_85_0_b1.zip e65d529023c7b08d0b92c53fff24ce9df9568cc0fe667c90caf8a9dbc5e63b0d boost_1_85_0_b1.7z 9c1ce4793342e8e57eb34c61f774a9dac0c6fc036084785e416613a18091bacc boost_1_85_0_b1.tar.gz cf7449faedeac9b76bade8ee59007cc4456a14de375dfcbd9e6e38aabe8a1334 boost_1_85_0_b1.tar.bz2 There was one problem reported during the beta release process; when you build the release using b2, it will emit a warning: [errno 2] failed to scan file '': No such file or directory This is harmless, and will be fixed for the final release. the release notes are available at: https://www.boost.org/users/history/version_1_85_0.html Please try the beta and report any problems you encounter. Thanks to everyone who contributed to the release. -- Boost Release Team

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Can SIMD in boost unordered be disabled without disabling SIMD for full compile.
by Ivan Matek 13 Mar '24

13 Mar '24

Hi, I have some small maps where I am pretty sure SIMD tricks that are amazing in general will just slow down the lookups since I never lookup items not in the map and map is so small that benefits of not looking up into the big array and trashing the cache are miniscule. I know I can force compiler to not support SIMD with march, but I want to keep the SIMD optimizaitons for rest of the code, including large boost unordered objects. If you do not believe me I can write a custom benchmark, from what I see all benchmarks in docs start at 1E+4. P.S. I know I can just use an array, but I am in that "size range" where iteration becomes slower than a hash map. regards, Ivan

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Re: [Boost-users] Hi all,
by Pavel Vazharov 06 Mar '24

06 Mar '24

Hi, The most obvious error that I see is that you use `std::vector<char> buffer_data(1024);`as local variables and then they are destroyed but you continue to keep references to them via the boost::asio::buffer. The latter will not keep the `std::vector`s alive. You need to keep the std::vector as a member variable and only when you call the asio functions use the `boost::asio::buffer` function. Like m_socketHandler->socket.async_read_some(boost::asio::buffer(m_buffer_data), ... Where the m_buffer_data is a member variable of type `std::vector<char>`. HTH, Pavel.

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Hi all,
by Maria Tirindelli 06 Mar '24

06 Mar '24

I am experiencing an issue with boost 1.74 on linux. I am trying to have a server that asynchronously reads data from a tcp socket, and then closes when the client disconnect. My code looks like: class SimpleTCPServerTest::SocketHandler { public: explicit SocketHandler(boost::asio::ip::tcp::socket inputSocket ) : socket(std::move(inputSocket)) { socket.set_option(boost::asio::socket_base::keep_alive(true)); } boost::asio::ip::tcp::socket socket; }; SimpleTCPServerTest::SimpleTCPServerTest(std::string address, int port) : m_address(std::move(address)), m_port(port), m_ioc(boost::asio::io_context(1)), m_acceptor(boost::asio::ip::tcp::acceptor(m_ioc)), readTimer(m_ioc){ std::vector<char> buffer_data(1024); this->m_buffer = boost::asio::buffer(buffer_data); } bool SimpleTCPServerTest::open() { //auto const address = boost::asio::ip::make_address(ip); boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), static_cast<unsigned short>(m_port)); boost::system::error_code ec; // Open the acceptor m_acceptor.open(endpoint.protocol(), ec); if (ec) { LOG_ERROR("SimpleTCPServerTest", "Failed to open acceptor: " << ec.message()); return false; } // Allow address reuse m_acceptor.set_option(boost::asio::socket_base::reuse_address(true), ec); if (ec) { LOG_ERROR("SimpleTCPServerTest", "Failed to set reuse option in acceptor: " << ec.message()); return false; } // Bind to the server address m_acceptor.bind(endpoint, ec); if (ec) { LOG_ERROR("SimpleTCPServerTest", "Failed to bind acceptor: " << ec.message()); return false; } // Start listening for connections m_acceptor.listen(boost::asio::socket_base::max_listen_connections, ec); if (ec) { LOG_ERROR("SimpleTCPServerTest", "acceptor failed to start listening: " << ec.message()); return false; } m_acceptor.async_accept(boost::asio::make_strand(m_ioc), [this](boost::system::error_code ec, boost::asio::ip::tcp::socket socket) { on_accept(ec, std::move(socket)); }); m_iocRunThread = boost::thread([this] { m_ioc.run(); LOG_INFO("Exiting run thread"); }); return true; } } void SimpleTCPServerTest::on_accept(boost::system::error_code ec, boost::asio::ip::tcp::socket socket) { LOG_INFO("Client is connected"); m_socketHandler = std::make_unique<SocketHandler>(std::move(socket)); read(); } void SimpleTCPServerTest::read() { LOG_INFO("SimpleTCPServerTest", "Waiting a new message"); readTimer.expires_from_now(boost::posix_time::milliseconds(50)); readTimer.async_wait([this](boost::system::error_code ec) { LOG_INFO("Timer expired"); if (ec != boost::asio::error::operation_aborted) return; LOG_INFO("Timer expired with error"); m_socketHandler->socket.cancel(); }); m_socketHandler->socket.async_read_some(m_buffer, [this](const boost::system::error_code error, // Result of operation. std::size_t bytes_transferred) { if (error) { LOG_INFO("Client disconnected: " << error.message()); signalReadyToStop.emitSignal(); // HERE IT CRASHES return; } std::string dataString(boost::asio::buffer_cast<const char*>(m_buffer), bytes_transferred); LOG_INFO("Data was received: Size: " << bytes_transferred << " " << dataString); // Reset the buffer std::vector<char> buffer_data(1024); this->m_buffer = boost::asio::buffer(buffer_data); this->read(); }); } SimpleTCPServerTest::~SimpleTCPServerTest() { LOG_INFO("Terminating"); readTimer.cancel(); m_acceptor.cancel(); m_socketHandler->socket.cancel(); m_ioc.stop(); m_iocRunThread.join(); } The client is a simple python client that sends a few messages before disconnecting. my main.cpp is like: std::atomic<bool> m_runFlag = true; SimpleTCPServerTest server; server.signalReadyToStop.connect([&m_runFlag](){ m_runFlag =false; }); server.open(); while(m_runFlag) { std::this_thread::sleep_for(std::chrono::milliseconds(1000)); } LOG_INFO("Exiting test"); } The problem is that the code always crashes when returning from the async_read (indicated with "HERE IT CRASHES COMMENT") with error SIGABRT tcache_thread_shutdown(): unaligned tcache chunk detected. Even if I remove the return statement there, I still have the crash when calling m_ioc.stop(). It seems the error occurs when exiting from the m_iocRunThread (the "Exiting run thread" log is executed) What am I doing wrong? Thanks everyone

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tommath.h and boost\multiprecision\tommath.hpp
by Helmut Zeisel 28 Feb '24

28 Feb '24

I tried to use boost muiltiprecision with Visual Studio 2022, 64 bit and got the following error message: boost\multiprecision\tommath.hpp(444,36): error C2664: 'mp_err mp_radix_size(const mp_int *,int,size_t *)': cannot convert argument 3 from 'int *' to 'size_t *' I used tommath.h from https://github.com/libtom/libtommath/blob/develop/tommath.h that has (line 583) mp_err mp_radix_size(const mp_int *a, int radix, size_t *size) MP_WUR; but boost\multiprecision\tommath.hpp, lineS 443/444 are int s; detail::check_tommath_result(mp_radix_size(const_cast< ::mp_int*>(&m_data), base, &s)); I compared with cygwin, there tommath.h is mp_err mp_radix_size(const mp_int *a, int radix, int *size) MP_WUR; So I am not sure: do I need some different tommath for Visual Studio 2022, 64 bit, or should boost\multiprecision\tommath.hpp be changed? Helmut

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boost::stacktrace::stacktrace AND addr2line
by Foelsche, Peter 19 Feb '24

19 Feb '24

Dear All, Thanks for outstanding quality of boost! I'm using the stacktrace object together with debug info and BOOST_STACKTRACE_USE_ADDR2LINE defined. Would it be possible to cache the output of addr2line assuming that during the lifetime of the calling process the queried executable or shared objects do not change? Thanks Peter

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[boost::interprocess] between Rosetta and native apps - please advice how to fix issue
by Frank G 08 Feb '24

08 Feb '24

We need named IPC between Rosetta and native apps. In boost this seems not compatible, for example with Native app and we are unable to find the "MAP_FNAME" in find_and_construct on the Rosetta process. Works fine when each process is on same arch. " typedef boost::interprocess::managed_shared_memory shared_mem;shared_mem* seg;seg = new shared_mem(boost::interprocess::open_or_create, SHARED_FILENAME, F_MAX_TOTALBUF_SIZE );Img = seg->find_or_construct<imgtype>(MAP_FNAME)(); " Root cause seems to be MemoryAlgorithm and alignment.This has alignment of 16 for Rosetta and 8 for native.The 8 byte shift seems to be the root cause and I can see this when viewing memory. Looking deeper over the last few days we can see this from the difference in frontend size (from MemoryAlgorithm): "boost::interprocess::open_or_create This creates different sized frontend (iset_index 8 or 16)for Native vs Rosetta. frontend is defined from: boost::interprocess::ipcdetail::basic_managed_memory_impl<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index, 16> *const Then perform segment->find_or_construct<mtstruct>(MAP_FNAME)(); does not work across arch." Ideally we prefer not to write a bunch of complex custom allocators etc to get this to work with open_or_create and find_or_construct, and hoping there is some simplest solution. Questions: how can we workaround this? Can we force boost::interprocess::open_or_create to use same memory algo for both arch? Or force alignment to 16 for both arch?

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Fwd: Using ASIO to wait on a foreign socket being readable, with a timeout
by Dominique Devienne 19 Jan '24

19 Jan '24

Sorry, sent originally to the wrong list. And this is on Windows 10 too, BTW. Haven't tried Linux with that code yet. --DD ---------- Forwarded message --------- From: Dominique Devienne <ddevienne(a)gmail.com> Date: Thu, Jan 18, 2024 at 7:18 PM Subject: Using ASIO to wait on a foreign socket being readable, with a timeout To: <boost(a)lists.boost.org> Hi, I'm trying to use ASIO to wait until a socket is ready to read, or timeout. This is a blocking wait. But the socket is not "owned" by ASIO, but is from the libpq PostgreSQL connection. So ASIO should NOT consume any of the input on the socket, just notify me when that socket is "read-ready". I've cobbled together the following test code: ``` const int socket2 = PQsocket(conn2.handle()); BOOST_CHECK(socket2 > 0); int timr_err_code = 0; int sock_err_code = 0; bool timr_aborted = false; bool sock_aborted = false; std::string timr_err_msg; std::string sock_err_msg; bool timed_out = true; auto c1 = "C# 1"sv; conn2.listen(c1); conn1->notify(c1, "wake up!"sv); { boost::asio::io_context io_ctx; boost::asio::ip::tcp::socket io_sock(io_ctx); io_sock.assign(boost::asio::ip::tcp::v4(), socket2); boost::asio::steady_timer io_timer(io_ctx); io_timer.expires_from_now(std::chrono::milliseconds(100)); io_sock.async_wait( io_sock.wait_read, [&](const boost::system::error_code& errc) { if (errc) { sock_err_code = errc.value(); sock_err_msg = errc.message(); sock_aborted = (errc == boost::asio::error::operation_aborted); } timed_out = false; //io_timer.cancel(); io_ctx.stop(); } ); io_timer.async_wait( [&](const boost::system::error_code& errc) { if (errc) { timr_err_code = errc.value(); timr_err_msg = errc.message(); timr_aborted = (errc == boost::asio::error::operation_aborted); } io_sock.cancel(); io_ctx.stop(); } ); io_ctx.run(); // blocks until either async op above runs } // there's a notif to read, so io_sock.async_wait should have completed BOOST_CHECK_EQUAL(timr_err_code, 0); BOOST_CHECK_EQUAL(sock_err_code, 0); BOOST_CHECK_EQUAL(timr_err_msg, ""); BOOST_CHECK_EQUAL(sock_err_msg, ""); BOOST_CHECK_EQUAL(timr_aborted, false); BOOST_CHECK_EQUAL(sock_aborted, false); BOOST_CHECK_EQUAL(timed_out, false); auto notif = conn2.notification(); BOOST_REQUIRE(notif); BOOST_CHECK_EQUAL(notif.backend_pid(), pid1); BOOST_CHECK_EQUAL(notif.channel(), c1); BOOST_CHECK_EQUAL(notif.payload(), "wake up!"sv); ``` The io_sock.async_wait(io_sock.wait_read, ...) succeeds, the IO loop stops as expected, but when I try to PQconsumeInput() from the LIBPQ connection next (as shown in the code below) ``` Notification Connection::notification() { auto [lock, hndl] = ensure_handle(); if (1 != PQconsumeInput(hndl)) { throw std::runtime_error(error_msg()); // <<<<<< THROWS } PGnotify_uptr notif{ PQnotifies(hndl) }; return Notification(std::move(notif)); // may be null } ``` that calls fail with this error message: fatal error: in "NotificationTests/test_across_backends": class std::runtime_error: could not receive data from server: Socket operation on non-socket (0x00002736/10038) LIBPQ didn't like what ASIO somehow did on the socket descriptor. The LIBPQ doc says to select() the descriptor, but I thought ASIO would be cleaner, more C++, and perhaps more cross-platform. Can somehow help, telling me if I'm using ASIO incorrectly here? Thanks, --DD

2 2

[Scope] Peer review conclusion
by Дмитрий Архипов 15 Jan '24

15 Jan '24

Dear Boost community, the formal review of Boost.Scope has taken place between 26th of November and 5th of December of the previous year. I have received 5 reviews in total, including 4 here on the mailing list and 1 on Reddit. Two of the reviews recommended unconditional, and 3 conditional acceptance. The reviews came from: - Klemens Morgenstern, - Janko Dedic, - Julien Blanc, - David Sankel, - /u/jonesmz on Reddit. Also, several people have given insightful comments but did not provide a review. I would like to thank all of the people who took their time to write reviews or participate in the discussions. Your effort was very important and valuable. The outcome of the review is that Boost.Scope is ACCEPTED with several minor CONDITIONS. 1. noexcept specification on destructors of scope guards should be properly documented. Andrey has already commented that the technical hurdle that prevented it was eliminated. 2. There should be a good motivating example for scope_success. There was a lot of comments regarding scope_success and its seeming uselessness. Without a good example I see the same pattern occurring with future users. 3. The examples should better describe what they are trying to achieve. Several comments about examples suggested incorrect changes, which signals that readers failed to understand them. After a lot of consideration I decided against requesting the author to remove unique_resource and related functionality from the library. While several reviewers wanted a more "concise" library, all noted that the component is useful. One last thing I wanted to point out is that all reviewers and most commenters were adamant that compatibility with the Technical Specification on which this library was initially based should not be a goal. In fact, Andrzej Krzemienski even noted that such compatibility has prevented him from adequately evaluating the library on its own merit. In my opinion this should be a sign to all of us that people prefer better APIs over standard APIs. I recommend Andrey to re-evaluate those parts of the library's APIs that he copied from the TS and potentially pick better names for member functions. Thanks to Andrey for submitting this library to Boost. And thanks again to the reviewers and everyone who provided feedback, who ultimately made this review possible.

1 0

Using Boost in CLR Class
by 임성준 09 Jan '24

09 Jan '24

Hello, I have question about using Boost. I'm trying to using boost in clr class of Visual Studito 2022 When I build the project, I got following error Error C1189 #error: "This library now requires a C++11 or later compiler - this message was generated as a result of BOOST_NO_CXX11_REF_QUALIFIERS being set" ClassLibrary2 C:\Users\bussly\source\repos\ClassLibrary2\packages\boost.1.84.0\lib\native\include\boost\multiprecision\detail\check_cpp11_config.hpp 34 Error (active) E0035 #error directive: "This library now requires a C++11 or later compiler - this message was generated as a result of BOOST_NO_CXX11_REF_QUALIFIERS being set" ClassLibrary2 C:\Users\bussly\source\repos\ClassLibrary2\packages\boost.1.84.0\lib\native\include\boost\multiprecision\detail\check_cpp11_config.hpp 58 Even I didn't make any code, just add an include boost header. Following is the scenario of what I did - Visual Studio 2022 - Create new project -> CLR Class Library(.Net Framework) - Install NuGet Package -> boost 1.84.0 - Add include boost -> #include "boost/geometry.hpp" - Build solution - Error and following is properties of my project - Platform Toolset: Visual Studio 2022(v143) - C++ Language Standard: ISO C++ 20 Standard(/std:c++20) - C Language Standard: Default(Legacy MSVC) I tried with C++ 14 and C++ 17 also, but failed. Can I get any solution for this? Thank you.

1 0

[Boost.Redis] Single Connection Concurrency Inquiry
by Samarah Uriarte 08 Jan '24

08 Jan '24

Hello, I am using the Boost Redis library to write to a local Redis server and would like to inquire about how a single connection can handle concurrent calls. I have several C++ classes that have their own Boost.Redis connections, but this is leading to ASIO-related hanging behavior that is difficult to debug. I would like to simplify the design by initializing only one connection that can be used by all of these classes instead. I know the "async_exec" method supports concurrency but I wonder if this might cause any future issues with larger workloads. Thank you in advance. Sincerely, Samarah Uriarte

1 0

Problems downloading boost on Linux
by Gonzalo Garramuño 01 Jan '24

01 Jan '24

I have tried downloading boost 1.76 on Linux from Argentina with: curl -# -L -o boost_1_76_0.zip.tmp https://boostorg.jfrog.io/artifactory/main/release/1.76.0/source/boost_1_76… and also from the boost web page. This leads to a redirect to JFrog. I tried creating an account with both Google (which led to Invalid credentials - you might not be a registered MyJFrog user. Please try again. ) and with a new account on JFrog which sent me an email requesting my company: To confirm this request, please include the license owner or any other support contact associated with your company's subscription approval in this email thread. Are the boost libraries at www.boost.org available for free or only under subscription? I found I can still download them from sourceforge, of course, but I would need to patch any dependencies that point to the older web-site. -- Gonzalo Garramuño ggarra13(a)gmail.com

2 2

Cobalt link error
by Josué Andrade Gomes 23 Dec '23

23 Dec '23

I'm trying to build a minimal Cobalt library sample. I'm getting link errors: Build and installed Boost with: ./bootstrap.sh --prefix=$HOME/.local ./b2 install Sample: #include <boost/cobalt.hpp> #include <iostream> boost::cobalt::main co_main(int, char *[]) { std::cout << "Hello world\n"; co_return 0; } CMakeLists.txt cmake_minimum_required(VERSION 3.20) project(coro_study) set(CMAKE_EXPORT_COMPILE_COMMANDS ON) set(CMAKE_CXX_STANDARD 20) set(CMAKE_VERBOSE_MAKEFILE ON) set(Boost_VERBOSE 1) set(Boost_DEBUG 1) find_package(Boost REQUIRED COMPONENTS system) add_executable(sample sample.cpp) target_include_directories(sample4 PRIVATE ${Boost_INCLUDE_DIRS}) target_link_libraries(sample4 PRIVATE ${Boost_LIBRARIES}) cmake output: dev ~/Projects/coroutines/x64-linux-debug $ cmake .. -- The C compiler identification is GNU 11.4.0 -- The CXX compiler identification is GNU 11.4.0 -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: /usr/bin/cc - skipped -- Detecting C compile features -- Detecting C compile features - done -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: /usr/bin/c++ - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Found Boost 1.84.0 at /home/dev/.local/lib/cmake/Boost-1.84.0 -- Requested configuration: QUIET REQUIRED COMPONENTS system -- BoostConfig: find_package(boost_headers 1.84.0 EXACT CONFIG REQUIRED QUIET HINTS /home/dev/.local/lib/cmake) -- Found boost_headers 1.84.0 at /home/dev/.local/lib/cmake/boost_headers-1.84.0 -- BoostConfig: find_package(boost_system 1.84.0 EXACT CONFIG REQUIRED QUIET HINTS /home/dev/.local/lib/cmake) -- Found boost_system 1.84.0 at /home/dev/.local/lib/cmake/boost_system-1.84.0 -- Boost toolset is gcc11 (GNU 11.4.0) -- Scanning /home/dev/.local/lib/cmake/boost_system-1.84.0/libboost_system-variant*.cmake -- Including /home/dev/.local/lib/cmake/boost_system-1.84.0/libboost_system-variant-shared.cmake -- [x] libboost_system.so.1.84.0 -- Including /home/dev/.local/lib/cmake/boost_system-1.84.0/libboost_system-variant-static.cmake -- [ ] libboost_system.a -- Adding boost_system dependencies: headers -- Found Boost: /home/dev/.local/lib/cmake/Boost-1.84.0/BoostConfig.cmake (found version "1.84.0") found components: system -- Configuring done -- Generating done -- Build files have been written to: /home/dev/Projects/coroutines/x64-linux-debug make output: dev ~/Projects/coroutines/x64-linux-debug $ make /usr/bin/cmake -S/home/dev/Projects/coroutines -B/home/dev/Projects/coroutines/x64-linux-debug --check-build-system CMakeFiles/Makefile.cmake 0 /usr/bin/cmake -E cmake_progress_start /home/dev/Projects/coroutines/x64-linux-debug/CMakeFiles /home/dev/Projects/coroutines/x64-linux-debug//CMakeFiles/progress.marks make -f CMakeFiles/Makefile2 all make[1]: Entering directory '/home/dev/Projects/coroutines/x64-linux-debug' make -f CMakeFiles/sample4.dir/build.make CMakeFiles/sample4.dir/depend make[2]: Entering directory '/home/dev/Projects/coroutines/x64-linux-debug' cd /home/dev/Projects/coroutines/x64-linux-debug && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/dev/Projects/coroutines /home/dev/Projects/coroutines /home/dev/Projects/coroutines/x64-linux-debug /home/dev/Projects/coroutines/x64-linux-debug /home/dev/Projects/coroutines/x64-linux-debug/CMakeFiles/sample4.dir/DependInfo.cmake --color= make[2]: Leaving directory '/home/dev/Projects/coroutines/x64-linux-debug' make -f CMakeFiles/sample4.dir/build.make CMakeFiles/sample4.dir/build make[2]: Entering directory '/home/dev/Projects/coroutines/x64-linux-debug' [ 50%] Building CXX object CMakeFiles/sample4.dir/sample4.cpp.o /usr/bin/c++ -DBOOST_SYSTEM_DYN_LINK -DBOOST_SYSTEM_NO_LIB -isystem /home/dev/.local/include -std=gnu++20 -MD -MT CMakeFiles/sample4.dir/sample4.cpp.o -MF CMakeFiles/sample4.dir/sample4.cpp.o.d -o CMakeFiles/sample4.dir/sample4.cpp.o -c /home/dev/Projects/coroutines/sample4.cpp [100%] Linking CXX executable sample4 /usr/bin/cmake -E cmake_link_script CMakeFiles/sample4.dir/link.txt --verbose=1 /usr/bin/c++ CMakeFiles/sample4.dir/sample4.cpp.o -o sample4 /home/dev/.local/lib/libboost_system.so.1.84.0 /usr/bin/ld: CMakeFiles/sample4.dir/sample4.cpp.o: in function `co_main(co_main(int, char**)::_Z7co_mainiPPc.Frame*) [clone .actor]': sample4.cpp:(.text+0x2a9): undefined reference to `boost::cobalt::detail::main_promise::final_suspend()' /usr/bin/ld: CMakeFiles/sample4.dir/sample4.cpp.o: in function `main::reset_res::operator()(std::pmr::memory_resource*)': sample4.cpp:(.text._ZZ4mainEN9reset_resclEPNSt3pmr15memory_resourceE[_ZZ4mainEN9reset_resclEPNSt3pmr15memory_resourceE]+0x1c): undefined reference to `boost::cobalt::this_thread::set_default_resource(std::pmr::memory_resource*)' /usr/bin/ld: CMakeFiles/sample4.dir/sample4.cpp.o: in function `main': sample4.cpp:(.text.main[main]+0x5b): undefined reference to `boost::cobalt::this_thread::set_default_resource(std::pmr::memory_resource*)' /usr/bin/ld: sample4.cpp:(.text.main[main]+0xc2): undefined reference to `boost::cobalt::detail::main_promise::run_main(boost::cobalt::main)' /usr/bin/ld: CMakeFiles/sample4.dir/sample4.cpp.o: in function `bool boost::cobalt::detail::promise_receiver<void>::awaitable::await_suspend<boost::cobalt::detail::fork::promise_type>(std::__n4861::coroutine_handle<boost::cobalt::detail::fork::promise_type>)': sample4.cpp:(.text._ZN5boost6cobalt6detail16promise_receiverIvE9awaitable13await_suspendINS1_4fork12promise_typeEEEbNSt7__n486116coroutine_handleIT_EE[_ZN5boost6cobalt6detail16promise_receiverIvE9awaitable13await_suspendINS1_4fork12promise_typeEEEbNSt7__n486116coroutine_handleIT_EE]+0x7f): undefined reference to `boost::cobalt::detail::already_awaited()' /usr/bin/ld: CMakeFiles/sample4.dir/sample4.cpp.o: in function `boost::cobalt::detail::promise_receiver<void>::awaitable::interrupt_await() &': sample4.cpp:(.text._ZNR5boost6cobalt6detail16promise_receiverIvE9awaitable15interrupt_awaitEv[_ZNR5boost6cobalt6detail16promise_receiverIvE9awaitable15interrupt_awaitEv]+0x33): undefined reference to `boost::cobalt::detail::detached_exception()' collect2: error: ld returned 1 exit status make[2]: *** [CMakeFiles/sample4.dir/build.make:101: sample4] Error 1 make[2]: Leaving directory '/home/dev/Projects/coroutines/x64-linux-debug' make[1]: *** [CMakeFiles/Makefile2:86: CMakeFiles/sample4.dir/all] Error 2 make[1]: Leaving directory '/home/dev/Projects/coroutines/x64-linux-debug' make: *** [Makefile:94: all] Error 2

3 4

Handshake Error 10009
by Jens Kallup 23 Dec '23

23 Dec '23

Hello, I tried use the boost::asio to create a SSL-Server, but I fail. The Code I used is attached to this Text. acceptor_ and context_ give me true result, but the start_accept() methode give me a Handshake-Error: 10009 (invalid descriptor handle). How can I avoid this, and how can I fix the Code in the right point ? Thanks for reading paule32 // ----------------------------------------------------------------- // File: BoostServer.cc // Author: (c) 2023 Jens Kallup - paule32 // All rights reserved // // only for education, and non-profit usage ! // ----------------------------------------------------------------- # include <stdio.h> # include <stdlib.h> # include <sys/types.h> # include <iostream> # include <string> # include <functional> # include <thread> # include <memory> # include <boost/asio.hpp> # include <boost/asio/ssl.hpp> using namespace boost::asio; using namespace std; // ----------------------------------------------------------------- // @brief namespace name for Version 1.0.0 of our project ... // ----------------------------------------------------------------- namespace dBaseRelease { std::string ApplicationExeName; // ----------------------------------------------------------------- // @brief This member handle the exception message text that is use // to "try catch" exception's during the runtime of the // application. // // @param std::string& message - The e.what() message. // @return nothing // // @since dBaseRelease // @author paule32 // ----------------------------------------------------------------- void handle_exception(const std::string& message) { std::string error_message; for (int len = 0; len < message.length(); ++len) { if (message[len] == '[') break; error_message.push_back(message[len]); } std::cerr << "Exception " << error_message << std::endl; } class SSLServer: public std::enable_shared_from_this<SSLServer> { public: SSLServer(io_service& service, uint16_t port): acceptor_(service, ip::tcp::endpoint(ip::tcp::v4(), port)), context_ (ssl::context::tlsv12) { context_.set_options( ssl::context::default_workarounds | ssl::context::sslv2 | ssl::context::sslv3 | ssl::context::tlsv12); if (isAcceptorInitialized() && isContextInitialized ()) { std::cout << "acceptor ok" << std::endl; std::cout << "context ok" << std::endl; start_accept(); } else { std::cout << "server init error" << std::endl; } } private: void start_accept() { ssl_socket_ = std::make_shared<ssl::stream<ip::tcp::socket> >(acceptor_.get_executor(), context_); // ---------------------------------- // Starte den asynchronen Handshake // ---------------------------------- ssl_socket_->async_handshake(ssl::stream_base::server, [this](const boost::system::error_code& error) { if (!error) { // ----------------------------------- // Wenn der Handshake erfolgreich ist, // akzeptiere die Verbindung // ----------------------------------- if (ssl_socket_ && ssl_socket_->lowest_layer().is_open()) { std::cout << "SSL-Handshake erfolgreich und verbunden." << std::endl; acceptor_.async_accept(ssl_socket_->lowest_layer(), [this](const boost::system::error_code& accept_error) { if (!accept_error) { handle_client(); } else { std::cerr << "Accept error: " << accept_error.message() << std::endl; } }); } else { std::cerr << "SSL-Handshake erfolgreich, aber Verbindung nicht geöffnet." << std::endl; } } else { std::cerr << "Handshake error: " << error.message() << " (" << error.value() << ")" << std::endl; } }); } void handle_client() { // ------------------------------------ // Lese/Schreibe Daten mit ssl_socket_ // ------------------------------------ boost::asio::async_read_until(*ssl_socket_, buffer_, '\n', [this](const boost::system::error_code& read_error, std::size_t bytes_transferred) { if (!read_error) { std::istream is(&buffer_); std::string received_data; std::getline(is, received_data); std::cout << "Received data from client: " << received_data << std::endl; // ----------------------------------------- // Hier kannst du auf die empfangenen Daten // reagieren und die Antwort vorbereiten // ----------------------------------------- std::string response = "Hello from the server!\n"; // ----------------------------------------- // Sende die Antwort an den Client // ----------------------------------------- boost::asio::async_write(*ssl_socket_, boost::asio::buffer(response), [this](const boost::system::error_code& write_error, std::size_t) { if (!write_error) { // ----------------------------- // Schließe die Verbindung // ----------------------------- ssl_socket_->lowest_layer().close(); // ----------------------------- // Starte die nächste Akzeptanz // ----------------------------- start_accept(); } else { std::cerr << "Write error: " << write_error.message() << std::endl; } }); } else { std::cerr << "Read error: " << read_error.message() << std::endl; } }); } // ------------------------------------------------ // Überprüfung, ob der Acceptor initialisiert wurde // ------------------------------------------------ bool isAcceptorInitialized() const { return acceptor_.is_open(); } // ------------------------------------------------ // Überprüfung, ob der Context initialisiert wurde // ------------------------------------------------ bool isContextInitialized() { try { // ---------------------------------- // load certificate, and private key // ---------------------------------- context_.use_certificate_chain_file("server.crt.pem"); context_.use_private_key_file("server.key.pem", ssl::context::pem); return true; } catch (const boost::system::system_error& e) { handle_exception(e.what()); return false; } } private: ip::tcp::acceptor acceptor_; ssl::context context_; std::shared_ptr<ssl::stream<ip::tcp::socket>> ssl_socket_; boost::asio::streambuf buffer_; }; } // namespace: dBaseRelease int main(int argc, char **argv) { using namespace dBaseRelease; try { ApplicationExeName = argv[0]; io_service service; std::shared_ptr<SSLServer> server = std::make_shared<SSLServer>(service, 12345); service.run(); } catch (const std::exception& e) { std::cerr << "Exception: " << e.what() << std::endl; return EXIT_FAILURE; } return EXIT_SUCCESS; } -- Diese E-Mail wurde von Avast-Antivirussoftware auf Viren geprüft. www.avast.com

1 0

Abwesenheitsnachricht: Re: Cobalt link error
by Sören Textor 23 Dec '23

23 Dec '23

Derzeit bin ich nicht im Hause Ihre E-Mail wird nicht weitergeleitet. In dringenden Fällen bitte support(a)ditec-gmbh.de oder Telefonhotline +49-6221-31698-110 oder die Zentrale +49-6221-31698-0 kontaktieren. Mit freundlichen Grüßen Dr. Sören Textor ----------------------------------------------- DiTEC Dr. Siegfried Kahlich & Dierk Langer GmbH Im Breitspiel 19 | 69126 Heidelberg | Germany Handelsregister | Mannheim | HRB 341229 Dieses Dokument ist vertraulich zu behandeln. Die Weitergabe, sowie Vervielfältigung, Verwertung und Mitteilung seines Inhalts ist nur mit unserer ausdrücklichen Genehmigung gestattet. Alle Rechte vorbehalten, insbesondere für den Fall der Schutzrechtsanmeldung. This document has to be treated confidentially. Its contents are not to be passed on, duplicated, exploited or disclosed without our express permission. All rights reserved, especially the right to apply for protective rights.

1 0

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

2 1

[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

3 2

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

2 1

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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