Use weak_ptr and wait for shutdown (#7337)

* Use weak_ptr and wait for shutdown

* Use future instead of busy wait

Author: TheMarex

include/server/server.hpp

@@ -17,6 +17,7 @@
 #include <sys/types.h>
 #endif
 
+#include <future>
 #include <memory>
 #include <string>
 #include <thread>
@@ -126,10 +127,13 @@ class Server : public std::enable_shared_from_this<Server>
 
     void Stop()
     {
+        auto stop_promise = std::make_shared<std::promise<void>>();
+        auto stop_future = stop_promise->get_future();
+
         // Posting the close to the acceptors strand ensures
         // we do not have a race condition with async_accept.
         boost::asio::post(acceptor.get_executor(),
-                          [self = shared_from_this()]()
+                          [self = shared_from_this(), stop_promise]()
                           {
                               boost::beast::error_code ec;
                               (void)self->acceptor.close(ec);
@@ -139,7 +143,11 @@ class Server : public std::enable_shared_from_this<Server>
                               }
                               // Stop the io_context
                               self->io_context.stop();
+                              stop_promise->set_value();
                           });
+
+        // The above function is async, this simply waits until it succeeded
+        stop_future.wait();
     }
 
     void RegisterServiceHandler(std::unique_ptr<ServiceHandlerInterface> service_handler_)
@@ -152,9 +160,14 @@ class Server : public std::enable_shared_from_this<Server>
     {
         // The new connection gets its own strand
         acceptor.async_accept(boost::asio::make_strand(io_context),
-                              [self = shared_from_this()](boost::beast::error_code ec,
-                                                          boost::asio::ip::tcp::socket socket)
-                              { self->OnAccept(ec, std::move(socket)); });
+                              [weak_self = std::weak_ptr<Server>(shared_from_this())](
+                                  boost::beast::error_code ec, boost::asio::ip::tcp::socket socket)
+                              {
+                                  if (auto self = weak_self.lock())
+                                  {
+                                      self->OnAccept(ec, std::move(socket));
+                                  }
+                              });
     }
 
     void OnAccept(boost::beast::error_code ec, boost::asio::ip::tcp::socket socket)