Handle luv_handle_t extra be gc correctly

other clibs can manage how to gc extra data in luv_handle_t

src/async.c

@@ -45,6 +45,7 @@ static int luv_new_async(lua_State* L) {
   }
   data = luv_setup_handle(L, ctx);
   data->extra = (luv_thread_arg_t*)malloc(sizeof(luv_thread_arg_t));
+  data->extra_gc = free;
   memset(data->extra, 0, sizeof(luv_thread_arg_t));
   handle->data = data;
   luv_check_callback(L, (luv_handle_t*)handle->data, LUV_ASYNC, 1);

src/handle.c

@@ -97,8 +97,8 @@ static int luv_close(lua_State* L) {
 static void luv_handle_free(uv_handle_t* handle) {
   luv_handle_t* data = (luv_handle_t*)handle->data;
   if (data) {
-    if (data->extra)
-      free(data->extra);
+    if (data->extra_gc)
+      data->extra_gc(data->extra);
     free(data);
   }
   free(handle);

src/lhandle.c

@@ -51,6 +51,7 @@ static luv_handle_t* luv_setup_handle(lua_State* L, luv_ctx_t* ctx) {
   data->callbacks[1] = LUA_NOREF;
   data->ctx = ctx;
   data->extra = NULL;
+  data->extra_gc = NULL;
   return data;
 }
 

src/lhandle.h

@@ -39,12 +39,15 @@
 #define LUV_FS_POLL 1
 #define LUV_RESET 1
 
+typedef int (*luv_handle_extra_gc) (void* ptr);
+
 /* Ref for userdata and event callbacks */
 typedef struct {
   int ref;
   int callbacks[2];
   luv_ctx_t* ctx;
   void* extra;
+  luv_handle_extra_gc extra_gc;
 } luv_handle_t;
 
 #ifdef LUV_SOURCE