rgw: remove some useless codes

[Yan-waller]

We have no need to genarate an oid_rand and pass it into the prepare
function, which will do nothing with oid_rand as following:

  virtual int prepare(RGWRados *_store, string *oid_rand) {
    store = _store;
    return 0;
  }

On the other hand, the RGWObjManifest::generator::create_begin will
genarate a different rand oid suffix as well as we need.

[mattbenjamin]

@Yan-waller , @yehudasa at first glance, should save a few cycles. however, I'm not sure if the cleanup is really complete. it would be bad if we needed a oid_rand with a different update processor--they're dynamically selected; it sort of looks like the processor prepare api may be a bit out-of-sync with the current behavior, and that the real cleanup would address that?

[Yan-waller]

@mattbenjamin , @yehudasa yeah, the processor prepare api seems to be incomplete, maybe it should handle the input parameter oid_rand, store or/and set it as prefix of manifest (RGWObjManifest.set_prefix()), so that the RGWObjManifest::generator::create_begin later can use this oid_rand as what we expected ?

[Yan-waller]

@mattbenjamin I have fixed it, could you help to take a look?

[mattbenjamin]

@Yan-waller this looks better, @yehudasa ?

[yehudasa]

@Yan-waller @mattbenjamin I think that at the moment this code would have zero effect on anything, as we'll only call prepare() with oid_rand not NULL when dealing with multipart upload, in which case this isn't going to be called. It will just add another path of untested code.

[Yan-waller]

thanks all, it's my mistake, dropped it.

[Yan-waller]

retest this please