unix, windows: add uv_has_ref() function

include/uv.h

@@ -281,6 +281,7 @@ UV_EXTERN void uv_stop(uv_loop_t*);
  */
 UV_EXTERN void uv_ref(uv_handle_t*);
 UV_EXTERN void uv_unref(uv_handle_t*);
+UV_EXTERN int uv_has_ref(const uv_handle_t*);
 
 UV_EXTERN void uv_update_time(uv_loop_t*);
 UV_EXTERN uint64_t uv_now(uv_loop_t*);

src/uv-common.c

@@ -426,6 +426,11 @@ void uv_unref(uv_handle_t* handle) {
 }
 
 
+int uv_has_ref(const uv_handle_t* handle) {
+  return uv__has_ref(handle);
+}
+
+
 void uv_stop(uv_loop_t* loop) {
   loop->stop_flag = 1;
 }

src/uv-common.h

@@ -186,6 +186,9 @@ void uv__fs_poll_close(uv_fs_poll_t* handle);
   }                                                                           \
   while (0)
 
+#define uv__has_ref(h)                                                        \
+  (((h)->flags & UV__HANDLE_REF) != 0)
+
 #if defined(_WIN32)
 # define uv__handle_platform_init(h)
 #else

test/test-list.h

@@ -128,6 +128,7 @@ TEST_DECLARE   (pipe_ref2)
 TEST_DECLARE   (pipe_ref3)
 TEST_DECLARE   (pipe_ref4)
 TEST_DECLARE   (process_ref)
+TEST_DECLARE   (has_ref)
 TEST_DECLARE   (active)
 TEST_DECLARE   (embed)
 TEST_DECLARE   (async)
@@ -377,6 +378,7 @@ TASK_LIST_START
   TEST_ENTRY  (pipe_ref4)
   TEST_HELPER (pipe_ref4, pipe_echo_server)
   TEST_ENTRY  (process_ref)
+  TEST_ENTRY  (has_ref)
 
   TEST_ENTRY  (loop_handles)
   TEST_ENTRY  (walk_handles)

test/test-ref.c

@@ -413,3 +413,15 @@ TEST_IMPL(process_ref) {
   MAKE_VALGRIND_HAPPY();
   return 0;
 }
+
+
+TEST_IMPL(has_ref) {
+  uv_idle_t h;
+  uv_idle_init(uv_default_loop(), &h);
+  uv_ref((uv_handle_t*)&h);
+  ASSERT(uv_has_ref((uv_handle_t*)&h) == 1);
+  uv_unref((uv_handle_t*)&h);
+  ASSERT(uv_has_ref((uv_handle_t*)&h) == 0);
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}