Add test for releasing connections back to the server

src/server.cpp

@@ -42,6 +42,13 @@ Server::Server(const weaseldb::Config &config, ConnectionHandler &handler,
       throw std::runtime_error("Failed to set provided listen fd non-blocking");
     }
   }
+
+  // Setup shutdown pipe for graceful shutdown
+  setup_shutdown_pipe();
+
+  // Create epoll instances immediately for createLocalConnection() support
+  create_epoll_instances();
+
   // If empty vector provided, listen_fds_ will be empty (no listening)
   // Server works purely with createLocalConnection()
 }
@@ -78,8 +85,7 @@ Server::~Server() {
 }
 
 void Server::run() {
-  setup_shutdown_pipe();
-  create_epoll_instances();
+  // Shutdown pipe and epoll instances are now created in constructor
 
   // Create I/O threads locally in this call frame
   // CRITICAL: By owning threads in run()'s call frame, we guarantee they are
@@ -140,7 +146,6 @@ void Server::receiveConnectionBack(std::unique_ptr<Connection> connection) {
     event.events = EPOLLOUT | EPOLLONESHOT;
   }
 
-  connection->tsan_release();
   int fd = connection->getFd();
   event.data.fd = fd;
 
@@ -159,7 +164,7 @@ void Server::receiveConnectionBack(std::unique_ptr<Connection> connection) {
 
 int Server::createLocalConnection() {
   int sockets[2];
-  if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, sockets) != 0) {
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) != 0) {
     perror("socketpair");
     return -1;
   }
@@ -167,6 +172,18 @@ int Server::createLocalConnection() {
   int server_fd = sockets[0]; // Server keeps this end
   int client_fd = sockets[1]; // Return this end to caller
 
+  int flags = fcntl(server_fd, F_GETFL, 0);
+  if (flags == -1) {
+    perror("fcntl F_GETFL on provided listen fd");
+    throw std::runtime_error(
+        "Failed to get flags for server side of local connection");
+  }
+  if (fcntl(server_fd, F_SETFL, flags | O_NONBLOCK) == -1) {
+    perror("fcntl F_SETFL O_NONBLOCK on provided listen fd");
+    throw std::runtime_error(
+        "Failed to set server side of local connection to non-blocking");
+  }
+
   // Create sockaddr_storage for the connection
   struct sockaddr_storage addr{};
   addr.ss_family = AF_UNIX;
@@ -304,9 +321,7 @@ void Server::start_io_threads(std::vector<std::thread> &threads) {
           // Handle existing connection events
           int fd = events[i].data.fd;
           std::unique_ptr<Connection> conn = connection_registry_.remove(fd);
-          if (conn) {
-            conn->tsan_acquire();
-          }
+          assert(conn);
 
           if (events[i].events & (EPOLLERR | EPOLLHUP)) {
             // unique_ptr will automatically delete on scope exit
@@ -468,7 +483,6 @@ void Server::process_connection_batch(
         event.events = EPOLLOUT | EPOLLONESHOT;
       }
 
-      conn_ptr->tsan_release();
       event.data.fd = fd; // Use file descriptor for epoll
       // Put connection back in registry since handler didn't take ownership.
       // Must happen before epoll_ctl