[Feature] Improve allocation policy when interacting with Lua

contrib/libucl/lua_ucl.c

 	size_t keylen;
 	const char *k;
 	bool is_array = true, is_implicit = false, found_mt = false;
-	int max = INT_MIN;
+	size_t max = 0, nelts = 0;
 
 	if (idx < 0) {
 		/* For negative indicies we want to invert them */
 			} else if (strcmp (classname, UCL_ARRAY_TYPE_META) == 0) {
 				is_array = true;
 				found_mt = true;
+#if LUA_VERSION_NUM >= 502
+				max = lua_rawlen (L, idx);
+#else
+				max = lua_objlen (L, idx);
+#endif
+				nelts = max;
 			} else if (strcmp (classname, UCL_IMPL_ARRAY_TYPE_META) == 0) {
 				is_array = true;
 				is_implicit = true;
 				found_mt = true;
+#if LUA_VERSION_NUM >= 502
+				max = lua_rawlen (L, idx);
+#else
+				max = lua_objlen (L, idx);
+#endif
+				nelts = max;
 			}
 		}
 
 					}
 				} else {
 					/* Keys are not integer */
-					lua_pop (L, 2);
 					is_array = false;
-					break;
 				}
 			} else {
 				/* Keys are not numeric */
-				lua_pop (L, 2);
 				is_array = false;
-				break;
 			}
 			lua_pop (L, 1);
+			nelts ++;
 		}
 	}
 
-	if (is_array) {
-#if LUA_VERSION_NUM >= 502
-		max = lua_rawlen (L, idx);
-#else
-		max = lua_objlen (L, idx);
-#endif
-	}
-
 	/* Table iterate */
 	if (is_array) {
 		int i;
 
 		if (!is_implicit) {
 			top = ucl_object_typed_new (UCL_ARRAY);
+			ucl_object_reserve (top, nelts);
 		}
 		else {
 			top = NULL;
 	else {
 		lua_pushnil (L);
 		top = ucl_object_typed_new (UCL_OBJECT);
+		ucl_object_reserve (top, nelts);
+
 		while (lua_next (L, idx) != 0) {
 			/* copy key to avoid modifications */
-			k = lua_tolstring (L, -2, &keylen);
-			obj = ucl_object_lua_fromelt (L, lua_gettop (L), flags);
+			lua_pushvalue (L, -2);
+			k = lua_tolstring (L, -1, &keylen);
+			obj = ucl_object_lua_fromelt (L, lua_gettop (L) - 1, flags);
 
 			if (obj != NULL) {
 				ucl_object_insert_key (top, obj, k, keylen, true);
 			}
-			lua_pop (L, 1);
+			lua_pop (L, 2);
 		}
 	}
 

contrib/libucl/ucl_hash.c

 			khash_t(ucl_hash_caseless_node) *h = (khash_t(
 					ucl_hash_caseless_node) *)
 					hashlin->hash;
-			kh_resize (ucl_hash_caseless_node, h, sz);
+			kh_resize (ucl_hash_caseless_node, h, sz * 2);
 		} else {
 			khash_t(ucl_hash_node) *h = (khash_t(ucl_hash_node) *)
 					hashlin->hash;
-			kh_resize (ucl_hash_node, h, sz);
+			kh_resize (ucl_hash_node, h, sz * 2);
 		}
 	}
 }