netmgr: actively close all sockets when shutting down server

without this change, named could sometimes lag for a while on shutdown
while it waited for open TCP connections to time out.

lib/isc/netmgr/netmgr-int.h

@@ -116,12 +116,9 @@ typedef enum isc__netievent_type {
 	netievent_tcpstoplisten,
 	netievent_tcpclose,
 	netievent_closecb,
+	netievent_shutdown,
 } isc__netievent_type;
 
-typedef struct isc__netievent_stop {
-	isc__netievent_type        type;
-} isc__netievent_stop_t;
-
 /*
  * We have to split it because we can read and write on a socket
  * simultaneously.
@@ -209,10 +206,13 @@ typedef struct isc__netievent {
 	isc__netievent_type	type;
 } isc__netievent_t;
 
+typedef isc__netievent_t isc__netievent_shutdown_t;
+typedef isc__netievent_t isc__netievent_stop_t;
+
 typedef union {
 		isc__netievent_t		  ni;
-		isc__netievent_stop_t		  nis;
-		isc__netievent_udplisten_t	  niul;
+		isc__netievent__socket_t	  nis;
+		isc__netievent__socket_req_t	  nisr;
 		isc__netievent_udpsend_t	  nius;
 } isc__netievent_storage_t;
 
@@ -523,6 +523,13 @@ isc__nm_async_closecb(isc__networker_t *worker, isc__netievent_t *ievent0);
  * Issue a 'handle closed' callback on the socket.
  */
 
+void
+isc__nm_async_shutdown(isc__networker_t *worker, isc__netievent_t *ievent0);
+/*%<
+ * Walk through all uv handles, get the underlying sockets and issue
+ * close on them.
+ */
+
 isc_result_t
 isc__nm_udp_send(isc_nmhandle_t *handle, isc_region_t *region,
 		 isc_nm_cb_t cb, void *cbarg);
@@ -555,6 +562,12 @@ isc__nm_tcp_close(isc_nmsocket_t *sock);
  * Close a TCP socket.
  */
 
+void
+isc__nm_tcp_shutdown(isc_nmsocket_t *sock);
+/*%<
+ * Called on shutdown to close and clean up a listening TCP socket.
+ */
+
 void
 isc__nm_async_tcpconnect(isc__networker_t *worker, isc__netievent_t *ievent0);
 void

lib/isc/netmgr/netmgr.c

@@ -309,6 +309,12 @@ isc_nm_destroy(isc_nm_t **mgr0) {
 	mgr = *mgr0;
 	*mgr0 = NULL;
 
+	for (size_t i = 0; i < mgr->nworkers; i++) {
+		isc__netievent_t *event = NULL;
+		event = isc__nm_get_ievent(mgr, netievent_shutdown);
+		isc__nm_enqueue_ievent(&mgr->workers[i], event);
+	}
+
 	/*
 	 * Wait for the manager to be dereferenced elsehwere.
 	 */
@@ -512,6 +518,9 @@ async_cb(uv_async_t *handle) {
 		case netievent_closecb:
 			isc__nm_async_closecb(worker, ievent);
 			break;
+		case netievent_shutdown:
+			isc__nm_async_shutdown(worker, ievent);
+			break;
 		default:
 			INSIST(0);
 			ISC_UNREACHABLE();
@@ -1174,6 +1183,27 @@ isc__nm_async_closecb(isc__networker_t *worker, isc__netievent_t *ievent0) {
 	isc_nmsocket_detach(&ievent->sock);
 }
 
+static void
+shutdown_walk_cb(uv_handle_t *handle, void *arg) {
+	isc_nmsocket_t *sock = NULL;
+
+	UNUSED(arg);
+
+	switch(handle->type) {
+	case UV_TCP:
+		isc__nm_tcp_shutdown((isc_nmsocket_t *) handle->data);
+		break;
+	default:
+		break;
+	}
+}
+
+void
+isc__nm_async_shutdown(isc__networker_t *worker, isc__netievent_t *ievent0) {
+	UNUSED(ievent0);
+	uv_walk(&worker->loop, shutdown_walk_cb, NULL);
+}
+
 bool
 isc__nm_acquire_interlocked(isc_nm_t *mgr) {
 	LOCK(&mgr->lock);

lib/isc/netmgr/tcp.c

@@ -688,3 +688,10 @@ isc__nm_async_tcpclose(isc__networker_t *worker, isc__netievent_t *ievent0) {
 
 	tcp_close_direct(ievent->sock);
 }
+
+void
+isc__nm_tcp_shutdown(isc_nmsocket_t *sock) {
+	REQUIRE(VALID_NMSOCK(sock));
+
+	sock->rcb.recv(sock->tcphandle, NULL, sock->rcbarg);
+}