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[英]shared_from_this throws bad_weak_ptr with boost::asio
[英]bad_weak_ptr while using class inheriting from boost::asio::io_context::service
我開始練習使用boost asio和boost beast開發我自己的基本服務器和連接類。 最近,我遇到了bad_weak_ptr異常,無法弄清楚如何解決該問題。 這是代碼:
class server : public boost::asio::io_context::service
{
tcp::endpoint endpoint{ boost::asio::ip::address_v6::any(), 7654 };
tcp::acceptor acceptor;
boost::asio::strand<boost::asio::io_context::executor_type> strand;
std::vector<std::weak_ptr<tcp_connection_ui>> connections;
public:
static const boost::asio::execution_context::id id;
explicit tcp_server_ui(boost::asio::io_context& ioc)
: boost::asio::io_context::service{ ioc }
, acceptor{ ioc, endpoint }
, strand{ ioc.get_executor() }
{
}
void run()
{
boost::asio::post(strand, [this] {start_accept(); });
}
void start_accept()
{
tcp::socket socket{ acceptor.get_io_context() };
tcp_connection_ui::pointer new_connection =
tcp_connection_ui::create(std::move(socket));
connections.push_back(new_connection);
acceptor.async_accept(new_connection->web_socket().next_layer(),
boost::asio::bind_executor(strand, std::bind(
&tcp_server_ui::handle_accept,
this, new_connection, std::placeholders::_1)));
}
void handle_accept(tcp_connection_ui::pointer new_connection,
boost::system::error_code ec)
{
if (!ec) {
new_connection->run();
}
start_accept();
}
void broadcast(std::string&& msg)
{
std::cout << '+' << std::endl;
if (connections.empty())
return;
for (auto const & x : connections)
x.lock()->enqueue_message(std::move(msg));
}
};
還有代碼停止運行的地方:
class tcp_connection_ui : std::enable_shared_from_this<tcp_connection_ui>
{
public:
using pointer = std::shared_ptr<tcp_connection_ui>;
static pointer create(tcp::socket socket)
{
return std::make_shared<tcp_connection_ui>(tcp_connection_ui{ std::move(socket) });
}
void run()
{
ws.async_accept(boost::asio::bind_executor(strand, std::bind(
&tcp_connection_ui::on_accept, shared_from_this(),
std::placeholders::_1)));
} .../};
如果客戶端嘗試連接server :: handle_accept中的shared_from_this值,則等於_Wptr =空。 我認為我在理解io_context :: service和/或shared_from_this功能時遇到了一些麻煩。 任何幫助,將不勝感激。
基類必須公開繼承:
class tcp_connection_ui : public std::enable_shared_from_this<tcp_connection_ui>
否則, make_shared
或shared_ptr
將不會注意到它,並隨后無法初始化“隱藏”的weak_ptr
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