I stucked on a question with boost. I have a factory with ioc and method that give access to ioc:

boost::asio::thread_pool::executor_type GetExecutor()
{
    if (!m_ioc)
        m_ioc = boost::make_shared<boost::asio::thread_pool>(2);
    return m_ioc->get_executor();
}

I use the factory and this method to create TCP connection and use GetExecuter as constructor parameter:

TcpConnection::TcpConnection(
    boost::asio::any_io_executor ex,
    const eka::string8_t& to,
    const eka::string8_t& port,
    const Config& config)
    : BaseConnection(to, port)
    , m_socket(make_strand(ex), boost::asio::ip::tcp::v4())
    , m_resolver(m_socket.get_executor())
    , m_timeout(config.timeoutRequest)
{}

In Connect method I have MinimumPromise for controlling connection progress.

void TcpConnection::Connect(stopToken)
{
    auto promise = std::make_shared<MinimumPromise>();

    boost::asio::post(m_socket.get_executor(),
        [this, promise, self = shared_from_this()]() mutable { DoConnect(promise); });

    promise->Wait(m_timeout); // throws if doesn't establish connection in m_timeout
}

void TcpConnection::DoConnect(std::shared_ptr<MinimumPromise> promise)
{
    m_resolver.async_resolve(
        boost::asio::ip::tcp::v4(), m_to.c_str(), m_port.c_str(),
        [this, promise, self = shared_from_this()]
        (const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator eps) mutable {
            if (ec) {
                promise->SetException(std::make_exception_ptr(PREPARE_CONNECTION_EXCEPTION(ec, m_to)));
            }
            else {
                boost::asio::async_connect(
                    m_socket, eps,
                    [this, promise, self = shared_from_this()]
                    (const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator it) mutable {
                        if (ec) {
                            promise->SetException(std::make_exception_ptr(PREPARE_CONNECTION_EXCEPTION(ec, m_to)));
                        }
                        else {
                            promise->Set();
                        }
                    });
            }
        });
}

Hypothetical situation: I wait in promise for 10 seconds, after promise throws exception. Posted connection task stay in queue - it will die on tcp timeout? How I can remove if from queue? If I destroy make_strand(ex) result it will clean queue? Will it affect other connections that use same threadpool? P.S. Idea of MinimalPromise is a timeout. I have TcpConnection with TLS and if connect TCP with TLS to TCP server program infinitly waiting for TLS handshake. This promise helping avoid this situation. Thank you

I stucked on a question with boost. I have a factory with ioc and method that give access to ioc:

boost::asio::thread_pool::executor_type GetExecutor()
{
    if (!m_ioc)
        m_ioc = boost::make_shared<boost::asio::thread_pool>(2);
    return m_ioc->get_executor();
}

I use the factory and this method to create TCP connection and use GetExecuter as constructor parameter:

TcpConnection::TcpConnection(
    boost::asio::any_io_executor ex,
    const eka::string8_t& to,
    const eka::string8_t& port,
    const Config& config)
    : BaseConnection(to, port)
    , m_socket(make_strand(ex), boost::asio::ip::tcp::v4())
    , m_resolver(m_socket.get_executor())
    , m_timeout(config.timeoutRequest)
{}

In Connect method I have MinimumPromise for controlling connection progress.

void TcpConnection::Connect(stopToken)
{
    auto promise = std::make_shared<MinimumPromise>();

    boost::asio::post(m_socket.get_executor(),
        [this, promise, self = shared_from_this()]() mutable { DoConnect(promise); });

    promise->Wait(m_timeout); // throws if doesn't establish connection in m_timeout
}

void TcpConnection::DoConnect(std::shared_ptr<MinimumPromise> promise)
{
    m_resolver.async_resolve(
        boost::asio::ip::tcp::v4(), m_to.c_str(), m_port.c_str(),
        [this, promise, self = shared_from_this()]
        (const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator eps) mutable {
            if (ec) {
                promise->SetException(std::make_exception_ptr(PREPARE_CONNECTION_EXCEPTION(ec, m_to)));
            }
            else {
                boost::asio::async_connect(
                    m_socket, eps,
                    [this, promise, self = shared_from_this()]
                    (const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator it) mutable {
                        if (ec) {
                            promise->SetException(std::make_exception_ptr(PREPARE_CONNECTION_EXCEPTION(ec, m_to)));
                        }
                        else {
                            promise->Set();
                        }
                    });
            }
        });
}

Hypothetical situation: I wait in promise for 10 seconds, after promise throws exception. Posted connection task stay in queue - it will die on tcp timeout? How I can remove if from queue? If I destroy make_strand(ex) result it will clean queue? Will it affect other connections that use same threadpool? P.S. Idea of MinimalPromise is a timeout. I have TcpConnection with TLS and if connect TCP with TLS to TCP server program infinitly waiting for TLS handshake. This promise helping avoid this situation. Thank you

• c++
• tcp
• boost-asio

1 Answer 1

That's not a feature. You can however:

• associate a cancellation_slot with the handler and check the cancellation state from within your operation

• stop() and restart() the entire execution context (e.g. asio::io_context::restart)

Of course, you can (and probably should) use other means of queuing workloads.

Posted connection task stay in queue - it will die on tcp timeout?

See https://live.boost./doc/libs/1_87_0/doc/html/boost_asio/reference/ip__basic_resolver/cancel.html