t.Fatalf("failed to drop constraint %v, got error %v", name, err)
		}

		if DB.Migrator().HasConstraint(&User{}, name) {
			t.Fatalf("constraint %v should been deleted", name)
		}

		if err := DB.Migrator().CreateConstraint(&User{}, name); err != nil {
			t.Fatalf("failed to create constraint %v, got error %v", name, err)
		}

				IsOwner:         owner,
				Claims:          cred.Claims,
			}) {
				writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrAccessDenied), r.URL)
				return
			}
		}
	}

	// Parse incoming location constraint.
	_, s3Error = parseLocationConstraint(r)
	if s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

//          must have a single output (these operations are typically
//          placeholders created for the sole purpose of representing
//          an input. We can relax this constraint if there are
//          compelling use cases).
//          - If an array is given (`num_opers` >= 0), all operations
//          in it will become part of the function. In particular, no

   * penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.
   *
   * This implementation uses a per-segment queue to record a memento of the additions, removals,
   * and accesses that were performed on the map. The queue is drained on writes and when it exceeds

   * penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.
   *
   * This implementation uses a per-segment queue to record a memento of the additions, removals,
   * and accesses that were performed on the map. The queue is drained on writes and when it exceeds