esp32/modsocket: Try garbage collection if the socket limit is reached.

If the hard socket limit (default 16) is reached then it's possible that
socket allocation fails but garbage collection would allow it to succeed.

Perform a GC pass and try again before giving up, similar to the logic
elsewhere in MicroPython that tries a GC pass before raising MemoryError.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

ports/esp32/modsocket.c

@@ -36,6 +36,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "py/gc.h"
 #include "py/runtime0.h"
 #include "py/nlr.h"
 #include "py/objlist.h"
@@ -274,6 +275,13 @@ STATIC mp_obj_t socket_make_new(const mp_obj_type_t *type_in, size_t n_args, siz
     sock->state = sock->type == SOCK_STREAM ? SOCKET_STATE_NEW : SOCKET_STATE_CONNECTED;
 
     sock->fd = lwip_socket(sock->domain, sock->type, sock->proto);
+    if (sock->fd < 0 && errno == ENFILE) {
+        // ESP32 LWIP has a hard socket limit, ENFILE is returned when this is
+        // reached. Similar to the logic elsewhere for MemoryError, try running
+        // GC before failing outright.
+        gc_collect();
+        sock->fd = lwip_socket(sock->domain, sock->type, sock->proto);
+    }
     if (sock->fd < 0) {
         mp_raise_OSError(errno);
     }