rs_get_fill
ASSERT3U(rs_get_fill(rs, rt) + delta, !=, 0);
ASSERT3U(rs_get_fill(rs, rt) + delta, <=, rs_get_end(rs, rt) -
rs_set_fill(rs, rt, rs_get_fill(rs, rt) + delta);
fill += rs_get_fill(rs, rt);
uint64_t before_fill = rs_get_fill(rs_before, rt);
uint64_t after_fill = rs_get_fill(rs_after, rt);
uint64_t before_fill = rs_get_fill(rs_before, rt);
uint64_t after_fill = rs_get_fill(rs_after, rt);
ASSERT3U(rs_get_fill(rs, rt), <=, rs_get_end(rs, rt) -
ASSERT3U(rs_get_fill(rs, rt), ==, rs_get_end(rs, rt) -
if (rs_get_fill(rs, rt) == size) {