如何知道 tcp::acceptor 何时准备好？

Question

我正在编写一个 HTTP 服务器。我写了以下内容并且效果很好：

boost::asio::io_context io_context;
tcp::acceptor acceptor(io_context, ...);
acceptor.async_accept(...);
auto server_thread = std::jthread([] { io_context.run(); });
// How do I ensure the server is ready? (before calling sendHTTPRequests)
sendHTTPRequests();

我想立即开始发送 HTTP 请求。有没有办法确保服务器已经启动并运行？

Answer 1

你总是可以等待。

代码草图（未经测试...）：

struct Sync
{
   std::mutex mutex;
   std:condition_variable condition;
   bool ready=false;
};
auto sync=std::make_shared<Sync>();

io_context.post([sync]() {
   {
      std::lock_guard<decltype(sync->mutex)> lock(sync->mutex);
      sync->ready=true;
   }
   sync->condition.notify_all();
});

// Finally, a line from your code :-)
auto server_thread = std::jthread([] { io_context.run(); });

{
   std::unique_lock<decltype(sync->mutex)> lock(sync->mutex);
   sync->condition.wait(lock, [sync]() { return sync->ready; } );
}

sync.reset(); // or just let it drop out of scope