Unless there's a server shutdown, keep accepting connections on error

Previously, it was possible for wthttp to stop accepting new connections
if an error occurred during accept (e.g. by exceeding the open file
limit)

We should always try to accept again, unless the operation is aborted
due to server shutdown.

Author: RockinRoel

src/http/Server.C

@@ -609,27 +609,40 @@ void Server::handleTcpAccept(TcpListener *listener, const Wt::AsioWrapper::error
   if (!e) {
     connection_manager_.start(listener->new_connection);
     listener->new_connection.reset(new TcpConnection(wt_.ioService(), this,
-	  connection_manager_, request_handler_));
-    listener->acceptor.async_accept(listener->new_connection->socket(),
-                                    accept_strand_.wrap(
-                                      std::bind(&Server::handleTcpAccept, this,
-                                      listener, std::placeholders::_1)));
+                                                     connection_manager_, request_handler_));
+  } else if (!listener->acceptor.is_open()) {
+    // server shutdown
+    LOG_DEBUG("handleTcpAccept: async_accept error (acceptor closed, probably server shutdown): " << e.message());
+    return;
+  } else {
+    LOG_ERROR("handleTcpAccept: async_accept error: " << e.message());
   }
+
+  listener->acceptor.async_accept(listener->new_connection->socket(),
+                                  accept_strand_.wrap(
+                                          std::bind(&Server::handleTcpAccept, this,
+                                                    listener, std::placeholders::_1)));
 }
 
 #ifdef HTTP_WITH_SSL
 void Server::handleSslAccept(SslListener *listener, const Wt::AsioWrapper::error_code& e)
 {
-  if (!e)
-  {
+  if (!e) {
     connection_manager_.start(listener->new_connection);
     listener->new_connection.reset(new SslConnection(wt_.ioService(), this,
-          ssl_context_, connection_manager_, request_handler_));
-    listener->acceptor.async_accept(listener->new_connection->socket(),
-                                    accept_strand_.wrap(
-                                      std::bind(&Server::handleSslAccept, this,
-                                      listener, std::placeholders::_1)));
+                                                     ssl_context_, connection_manager_, request_handler_));
+  } else if (!listener->acceptor.is_open()) {
+    // server shutdown
+    LOG_DEBUG("handleSslAccept: async_accept error (acceptor closed, probably server shutdown): " << e.message());
+    return;
+  } else {
+    LOG_ERROR("handleSslAccept: async_accept error: " << e.message());
   }
+
+  listener->acceptor.async_accept(listener->new_connection->socket(),
+                                  accept_strand_.wrap(
+                                          std::bind(&Server::handleSslAccept, this,
+                                                    listener, std::placeholders::_1)));
 }
 #endif // HTTP_WITH_SSL