Fix type confusion

src/server.cpp

@@ -43,7 +43,7 @@ void Server::run() {
   // Add shutdown pipe to epoll instance
   struct epoll_event shutdown_event;
   shutdown_event.events = EPOLLIN;
-  shutdown_event.data.fd = shutdown_pipe_[0];
+  shutdown_event.data.ptr = const_cast<char *>(&shutdown_pipe_tag);
 
   if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, shutdown_pipe_[0], &shutdown_event) ==
       -1) {
@@ -54,7 +54,7 @@ void Server::run() {
   // Add listen socket to epoll with EPOLLEXCLUSIVE to prevent thundering herd
   struct epoll_event listen_event;
   listen_event.events = EPOLLIN | EPOLLEXCLUSIVE;
-  listen_event.data.fd = listen_sockfd_;
+  listen_event.data.ptr = const_cast<char *>(&listen_socket_tag);
   if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, listen_sockfd_, &listen_event) == -1) {
     perror("epoll_ctl listen socket");
     throw std::runtime_error("Failed to add listen socket to epoll");
@@ -290,13 +290,11 @@ void Server::start_io_threads() {
         int batch_count = 0;
         for (int i = 0; i < event_count; ++i) {
           // Check for shutdown event
-          // TODO type confusion in data union
-          if (events[i].data.fd == shutdown_pipe_[0]) {
+          if (events[i].data.ptr == &shutdown_pipe_tag) {
             return;
           }
           // Check for new connections
-          // TODO type confusion in data union
-          if (events[i].data.fd == listen_sockfd_) {
+          if (events[i].data.ptr == &listen_socket_tag) {
             listenReady = true;
             continue;
           }

src/server.hpp

@@ -110,6 +110,10 @@ private:
   int epollfd_ = -1;
   int listen_sockfd_ = -1;
 
+  // Unique tags for special events to avoid type confusion in epoll data union
+  static inline const char listen_socket_tag = 0;
+  static inline const char shutdown_pipe_tag = 0;
+
   // Private helper methods
   void setup_shutdown_pipe();
   void setup_signal_handling();