3 ms·

Just remove the `static` keyword and there you go. But it's an "optimization", and avoiding previously attempted methods is the whole point of the trick. Other

• lazyjones 8y ago
  > Just remove the `static` keyword and there you go. That‘ll probably try all methods on every single file that is processed, so if method #16 is the one that works, you get 15 unnecessary syscalls for every file.
  • vortico 8y ago
    Exactly, that's what the parent comment was saying.
    • Sean1708 8y ago
      Lets say that there are only 3 methods and method #2 is the one that works initially. On the first call it'll try #1 and when that doesn't work it'll try #2 which will be successful. For the next however many calls it'll jump straight to #2. If #2 starts returning ENOSYS at some point it'll try #3 and if that works then all future calls will jump straight to #3. However if #3 stops working then it will keep on failing until #3 starts working again even if #1 started working after the first call. I think (I haven't actually tested it) you can do what the parent commenter wants by wrapping the whole thing in a do-loop but the original implementation is questionable enough, sticking an extra loop in there isn't doing anything to help make it less horrible. int set_the_mtime(...) { static int switch_step = 0; int loop_again = 1; do { switch (switch_step) { case 0: if (method_0_works(...)) return 0; switch_step++; /* FALLTHROUGH */ case 1: if (method_1_works(...)) return 0; switch_step++; /* FALLTHROUGH */ case 2: if (method_2_works(...)) return 0; } switch_step = 0; } while (loop_again--); return -1; /* ultimate failure */ }